INDIAN INSTITUTE OF TECHNOLOGY MANDI
SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS,
Program Schedule for MONDAY 9th October, 2017
Time Venue
Speaker Session
Chair
8.30-9.00 am Recreation
centre
Breakfast
Registration (A1-NKN)
9.00 -9.10 am
A1 NKN
Welcome
9.10-9.25 am Inaugural Function
9.25- 10.05am Prof. Tonu Pullerits,
Lund University (Plenary lecture)
Dr. Prem
Felix
10.05-10.40 am Prof. Anunay Samanta,
University of Hyderabad (Invited)
10.40-11 am A1 Ground
Floor
TEA
11.00-11.30 am
A1 NKN
Prof. J. P. Singh, IIT Delhi (Invited) Dr. Ajay Soni
11.30-12.00 pm Dr. Pradeep Kumar, IIT Mandi
12.00-12.30 pm Dr Kamal P Singh, IISER Mohali (Invited)
12.30-12.40 pm Mr Pawan Kumar, IIT Mandi
12.40-12.50 pm Mr Abdus Salam Sarkar, IIT Mandi
1.00-2.00 pm Recreation
centre
Lunch
2.00-2.30 pm A1 NKN Dr. Sobhan Sen, JNU (Invited)
Dr Chandra
Shekhar
2.30-2.40 pm Mr Ashish Tiwary, IIT Mandi
2.40-2.50 pm Mr Saurabh Singh, IIT Mandi
2.50-4.00 pm Recreation
centre
Tea & Poster (P1-P15)
4.00-4.30 pm A1 NKN Dr. Khadga Jung Karki,
Lund University (Invited)
Dr Kaustav
Mukherjee
4.30-5.00 pm Dr Suman Kalyan Pal, IIT Mandi
5.00-5.30 pm Dr Abir De Sarkar, INST Mohali
5.30-6.00 pm Dr Ajay Soni, IIT Mandi
7.15 pm Recreation
centre
Dinner
INDIAN INSTITUTE OF TECHNOLOGY MANDI
SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS,
Program Schedule for TUESDAY (10th October)
Time Venue
Speaker Session Chair
8.30-9.00 am Recreation
center
Breakfast
9.00 -9.40am
A1 NKN
Prof. K Gonsalves,
IIT Mandi (Invited)
Dr Subrata
Ghosh
9.40- 10.10am Dr. Arijit Kumar De,
IISER Mohali (Invited)
10.10-10.40 am Dr. Y Dwivedi,
NIT Kurukshetra (Invited)
10.40-11.40am A1 Ground
Floor
Tea/Poster (P-16 Onwards)
11.40-12.10 pm A1 NKN Dr. Rajiv Singh, NPL (Invited) Dr. Jaspreert
Kaur Randhawa 12.10-12.35pm Dr. Aditi Halder, IIT Mandi
12.35-12.55 pm Dr Bhupinder Singh, IIT Roorkee
12.55-1.05 pm Mr Mandeep Hooda, IIT Mandi
1.05-1.20 pm Vote of thanks/Prize distribution
1.30-2.2.15 pm Recreation
centre
Lunch
Invited Talks
I-1
From Light Absorption to Separated Charges: From Fundamentals
Towards Applications
Tonu Pullerits
Department of Chemical Physics, Lund University
Email: [email protected]
In this lecture I will give an overview of the studies of light harvesting materials in my
group during last few years. The topics covered include excitation dynamics in photosynthesis,
particularly the recently discussed aspect of coherence; photoinduced dynamics in colloidal
semiconductor quantum dots and their composites with metal oxides and graphene; excited state
and charge carrier properties in organometal halide perovskites. All materials are studied by using
a broad set of advanced laser spectroscopies.
I-2
Fluorescence Blinking, Photoactivation and Ultrafast Charge Carrier
Dynamics in All-Inorganic Perovskite Nanocrystals (CsPbX3)
Anunay Samanta
School of Chemistry, University of Hyderabad, Hyderabad 500 046, India
Email: [email protected]
Organic-inorganic lead halide perovskite nanocrystals have received great attention in
recent years due to their potential applications in low cost efficient photovoltaic devices [1]. More
recently, cesium based all inorganic perovskite nanocrystals have also come into prominence in
several promising applications [2]. However, despite growing interests on all-inorganic perovskite
nanocrystals, fundamental photo-induced processes, whose understanding is key to exploitation of
these substances in potential applications, have remained largely unexplored. In this talk, photo-
inducd behavior of all-inorganic perovskite nanocrystals, CsPbBr3, CsPbBr2I and CsPbBr1.5I1.5
will be presented [3,4]. Specifically, fluorescence blinking and photoactivation of these
substances, as revealed by fluorescence correlation technique, and complete ultrafast charge carrier
dynamics, as measured by femtosecond time-resolved pump-probe technique, will be discussed.
References:
[1] Green, M.A.; Ho-Baillie, A.; Snaith, H.J. Nature Photonics 8 (2014) 506.
[2] Yakunin, S.; Protesescu, L.; Krieg, F.; Badnarchuk, M.I.; Nedelcu, G.; Humer, M.; Luca,
G.D.; Fiebig, M.; Heiss W.; Kovalenko, M.V. Nature Communications 6 (2015) 8056.
[3] Seth, S.; Mondal, N.; Patra, S.; Samanta, A. J. Phys. Chem. Lett. 7 (2016) 266.
[4] Mondal, N.; Samanta, A. Nanoscale 9 (2017)
I-3
Surface Enhanced Raman scattering for Rapid and Sensitive
Detection of Pathogens
J. P. Singh
Physics Department, Indian Institute of Technology Delhi, HauzKhas, New Delhi 110016
Email: [email protected]
Surface enhanced Raman spectroscopy (SERS) has emerged as a promising technique for chemical
and biosensing applications as it combines molecular fingerprint specificity with potential single-molecule
sensitivity. Although SERS has emerged as a potential technique for chemical and biological sensing it has
few limitations like all the other techniques. Silicon wafers and glass slides are two of the most common
substrates used for the growth of SERS active layers. However, these substrates are rigid and brittle and
hence, limit some applications such as packaging or tracking where a flexible SERS substrate would be
more appropriate. Another limitation of these SERS substrates lies in a fact that they are mostly two-
dimensional (2D) planar systems. In 2D ordered substrates the number of hotspots is limited to only one
Cartesian x-y plane.Due to their one-time use, and considering the valuableness of the noble metals, these
SERS substrates cannot be completely explored as a routine analytical technique. Therefore, research has
been focused on developing reusable SERS-active substrates. A simple and elegant method to produce
highly uniform and arrays of nanostructures is glancing angle deposition (GLAD). This is a physical vapor
deposition process, which utilizes the self-shadowing effect that appears at highly oblique particle incidence
angles to create highly porous nanostructures. We have formed buckled AgNRs-PDMS SERS
substrates,which providebetter entrapment and increased contact area for P. aeruginosabacteria onto the
AgNRs giving rise to enhancement in the Raman signal. We have also demonstrated a simple and facile
method to fabricate a highly sensitive, flexible and robust SERS active substrate. The AgNRs arrays on
these flexible substrates retain their SERS activity after repeated cyclic tensile tests. As a proof of concept,
thiram pesticide with concentrations value 1000-fold lower than the level currently permissible in farming
has been detected on apple peels. Photocatalytic recyclable SERS substrates were fabricated by combining
plasmonic metal (Ag) with semiconductor TiO2. The Ag- TiO2 SERS substrates recovered after 150 min
in presence of UV light illumination. These revived substrates have shown to be successfully reused for
further SERS analyses with a correspondingly small decrease (on average 5% for each cycle) in the Raman
intensity. A simple method of chemical etching to create nanogaps in a zig-zag AgNR arrays which act as
SERS active hot spots for increased SERS detection sensitivity is also demonstrated. It was found that
SERS intensity increases with increase in the number of arm of zig-zag structure. The extremely high
electric field at the nanogap hot spots is responsible for enormous enhancement in SERS intensity.
References
1. A Rajput, S Kumar, JP Singh, Analytical Chemistry 10.1039/C7AN00851A (2107) 2 S Kumar, P Goel, JP Singh, Sensors and Actuators B: Chemical241, 577–583 (2017).
2. P Goel, S Kumar, J Sarkar, JP Singh, ACS applied materials & interfaces7, 8419-8426 (2015).
3. S Kumar, DK Lodhi, P Goel, P Mishra, JP Singh, Chemical Communications51, 12411-12414 (2015).
4. JP Singh, HY Chu, J Abell, RA Tripp, Y Zhao, Nanoscale4, 3410-3414 (2012).
I-4
Anomalous Phonons and Quasi-Particle Excitations in Iron-based
Superconductors
Pradeep Kumar
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi-175005, Himachal
Pradesh India
Email: [email protected]
Superconductivity, the resistance free flow of charge carriers, is one of the most exotic phenomena
in condensed matter physics. The phenomena of superconductivity, though discovered nearly a
century ago in 1911, still possess many fundamental questions, in particular the microscopic
pairing mechanism in high temperature superconductors. Discovery of superconductivity in Fe-
based systems by Kamihara et al., in 2008 breaks the monopoly of Cuprates as the only high
temperature superconductors. Their discovery is fundamentally important, in the sense that the
glue for the pairing mechanism may have magnetic origin; as well as raises many pertinent
questions like what is the role of magnetic degrees of freedom (DOF), electronic-nematicity and
it’s relation to underlying superconducting state, does superconductivity and magnetism truly
coexists, etc.
I will begin my talk with introducing this new class of iron-based superconductors (FeBS). Then
will discuss our temperature dependent Raman studies on different families of FeBS. Our studies
revealed the ubiquitous role of spin-phonon coupling in FeBS and coupled nature of spin and
orbital DOF, signalling the intricate role of these DOF in the pairing mechanism. Our studies
uncovered the non-degenerate nature Fe dxz/yz orbitals suggesting the electronic nematicity of
Fe3d-orbitals, which have very prominent role in determining their magnetic, electronic as well as
superconducting properties and are being debated hotly in FeBS.
I-5
The Processing and Heterostructuring of Silk with Light
Kamal P Singh
IISER Mohali
Email: [email protected]
The spider silk is an excellent biomaterial that is light weight, elastic yet tougher than steel.
In this talk, I will discuss, how we can use few-cycle fs pulses to process silk in air with nanoscale
precision exploiting its non-linear multiphoton interaction with light. We shall also show our
attempts to weld silk with metal, Kevlar and polymers to combine their favourable properties. This
allows silk-based novel topological structures and devices such as radiation-pressure force sensors
capable of operating in air, on water surface and in high vacuum.
I-6
Quantifying Reaction Kinetics in Solution at Single Molecule Level
Sobhan Sen
School of Physical Sciences, Jawaharlal Nehru University, New Delhi
E-mail: [email protected]
Ensemble averaged experiments are widely used to study molecular diffusion and chemical
reactions. However, from such experiments it is rather difficult to follow how individual molecules
in solution interact with others at the single molecular level – so as to perform the overall
ensemble-averaged molecular processes. Recent developments of single molecular fluorescence
techniques have encouraged tremendous applicability to uncover intricate details of simple kinetic
steps of complex chemical and biochemical reactions in solution and inside biological cells/tissues.
Fluorescence correlation spectroscopy (FCS) is such a technique which allows monitoring and
quantifying molecular diffusion and chemical kinetics down at single molecule level. This talk
will focus on the application of FCS to monitor and quantify the molecular interactions such as
association and dissociation rates of a fluorescent ligand to DNA and growth kinetics of nanorods
inside microemulsion droplets in solution. This talk will showcase how FCS as a technique can be
efficiently used to study molecular diffusion and chemical kinetic reactions at single molecule
level.
I-7
Linear and nonlinear functional spectroscopy based on modulated
light fields
Khadga Jung Karki
Department of Chemical Physics, Lund University
Email: [email protected]
A Recently, there has been a resurgence of spectroscopic methods based on modulated
light fields to investigate electronic structure and dynamics in various systems. One of the key
features of such methods is that one can isolate different kinds of linear and nonlinear signals in
the incoherent response, such as fluorescence and photocurrent, from the sample. This allows one
to directly probe the contribution of specific energy levels on the external "useful signal", thereby
providing in depth information about how electronic structure relates to the functionality. In this
tutorial talk, I will explain different kinds of spectroscopic methods based on modulated light fields
and types of information they provide.
I-8
Lifecycle of Photocarriers in Nanoscale Semiconductors
Suman Kalyan Pal
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of
Technology Mandi, Kamand, Mandi-175005, Himachal Pradesh, India.
Email: [email protected]
Semiconducting nanomaterials, quantum dots (QDs), and layered transition metal dichalcogenides
(TMDs) have shown promise for various optoelectronic applications including light emitting
diodes and solar cells. Understanding of basic mechanism of charge carrier generation and
knowledge about the lifecycle of the photocarriers in these materials are crucial to utilize them in
devices. In this talk, I will focus on photoinduced processes leading to charge carriers in few of
these excitonic materials. I will demonstrate hole transfer from ZnO to CdS QDs [1] following
Auger-assisted transfer mechanism (Figure 1) with the help of time-resolve emission spectroscopy.
Dissociation of excitons at the heterostructures of zero/two-dimensional (0D/2D) materials,
especially CdSe (cadmium selenide) QD/MoS2 (molybdenum disulfide) nanosheet via hole
transfer [2] will be shown. Femtosecond transient absorption measurements show the dissociation
of biexciton at the 0D/2D interface indicating that exploitation of ‘Multiple Exciton Generation’
effect is a feasible scenario. Migration of exciton from CdS as well as ZnS to CdSe site in segmented
CdSe@CdS/ZnS quantum rods will be addressed in this talk. Finally, some of our recent results of time-
resolved spectroscopic measurements on few-layer tin sulfide (SnS) and organo metal halide perovskites
(OMHPs) QDs will be presented.
Figure 1. Driving force vs rate constant plot. Filled squares are experimental data points.
References
[1] S. Ghosh, M. Ghosh, P. Kumar, A. S. Sarkar, S. K. Pal, J. Phys. Chem. C 2016, 120 (48),
27717-27723.
[2] A. Mushtaq, S. Ghosh, A. S. Sarkar, S. K. Pal, ACS Energy Lett. 2017, 2, 1879−1885.
400 600 800 1000
1E8
1E9
kH
T (
S-1
)
GHole (meV)
Auger-assisted
regime
Inverted
regime
Normal
regime
(a)
I-9
Ab initio study of nanomaterials for energy conversion and clean
environment
Abir De Sarkar
Institute of Nano Science and Technology, Phase - 10, Sector – 64, Mohali, Punjab-160 062
Email: [email protected], [email protected]
URL: https://sites.google.com/site/abirdesarkar/; http://www.inst.ac.in/faculty/Dr_Abir.html
Transition metal dichalcogenide (TMC) monolayers have been emerging as promising
alternatives to graphene on account of their intrinsic semiconducting band gap, which is a
prerequisite in electronics. Besides their intrinsic semiconducting properties, piezoelectric
properties arise in these monolayers owing to the broken inversion symmetry. MoS2 turns out to
be the most widely studied TMC. A synergic coupling between these two properties in single layer
MoS2 has been explored in our studies [J. Phys. Chem. C 121 (2017) 9181–9190] based on the
density functional theory for the optimization of nanoelectromechanical energy
conversion/harvesting and nanopiezotronic properties. MoS2 is also found to be interesting for 2D
thermoelectrics. The mechanism underlying the thermoelectric energy conversion in monolayer
MoS2 has also been investigated using density functional theory coupled to Boltzmann transport
equation [J. of Phys.: Cond. Matt. 29 (2017) 225501]. n-type doping is found to favorably enhance
the thermoelectric power factor in monolayer MoS2 nanosheet. Electronic properties and band gap
are found to be similarly sensitive to the application of mechanical strain. Both the electronic band
gap and the n-type Seebeck coefficient are found to reach their maxima, while the electron mobility
drops to its minimum at 3% compressive strain. Au catalysis for clean environment will then be
presented in my talk. Although Au is a noble metal in the bulk form, it shows high catalytic
activities at the nanoscale. The role of Aun (n=3-10) clusters in activating C2H2 molecules adsorbed
on it for further catalytic conversion of toxic HCN gas molecules into useful compounds such as
vinyl isocyanide, a versatile chemical intermediate, will also be covered in this talk [PCCP, 18
(2016) 13830-13843].
I-10
EUV DUV and MUV wavelengths: from the past and present to the
future- from micro to nanofabrication and beyond
Keneth Gonsalves
School of Basic Sciences, IIT Mandi
Email: [email protected]
This presentation will outline the trends in IC fabrication based on current and future trends
based on exposure wavelengths. The challenges of materials design and development will be
discussed and solution sought.
I-11
Dynamics of light harvesting: From ensemble measurements towards
single particle spectroscopy
Arijit K. De
Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER)
Mohali, Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India.
Email: [email protected]
In this talk, starting with a brief introduction on the discovery and importance of quantum
coherence in sunlight harvesting by natural systems, I will give a brief overview of ultrafast
energy/charge transfer within three quite different systems that is being pursued in our group: 1)
Bio-mimetic/Bio-inspired systems: Aggregates of xanthenes dyes, 2) Engineered systems:
Quantum dots and 3) Fluorescent proteins: GFP (WT) vs YFP (Venus)
If time permits, I’ll discuss how one can envisage the idea of spectroscopy of optically trapped
nanoparticles in solution by a femtosecond laser tweezer.
I-12
Fabrication and Application of Laser Scribed Photonic Structures
Y. Dwivedi
Department of Physics, National Institute of Technology, Kurukshetra
Email: [email protected]
Saga of Laser and its advancement is full of up and downs. Over the recent years, the laser
technology and its potentials have been exciting laser manufacturers as well as researchers and
industrial users. Lasers with their un-parallel precision and beam quality assured advantages and
improvements in high precision and material processing at the micro-scale. Besides the excellent
beam quality there are more advantages of the laser technology such as compact installation size,
high laser efficiency, moderate system price and easy to be integrated. Lasers are not only used as
a characterization tool but also can also be used as mechanical tool to manipulate the variety of
structures down to size micro and submicro meter. Laser structuring or Laser micromachining is a
general term that includes a variety of processes including hole drilling, ablation, milling, and
cutting. Lasers offer a wide range of wavelengths, pulse duration (from femtosecond to
microsecond) and repetition rates (from single pulse to Megahertz). These attributes allow
micromachining with high resolution in depth and lateral dimensions. Laser micromachining
techniques are currently used by the automobile and medical industries as well as in the production
of semiconductors and solar cell processing. The field of micro-machining includes manufacturing
methods like drilling, cutting, welding as well as ablation and material surface texturing, whereby
it is possible to achieve very fine surface structures ranging in the micrometer domain. Such
processes require a rapid heating, melting and evaporation of the material. The use of extremely
short nano- and pico- and even femtosecond pulse durations helps to minimize the thermal effects
such as melting and burr formation thus eliminating the need for any post processing measures. In
this lecture, in addition to the detailed discussion on laser micromachining and photolithography,
I will describe the application of femtosecond laser to writing different structures including
photonic structures like Grating, high quality fibers, lenses etc. and micro mechanical sensors for
car security systems, nozzle plates for printer, and optical elements for X-ray beam splitting.
Wherever the accuracy of etched silicon structures is not required, laser processes with short pulses
and small wave length can be an option with the advantage of shorter process time. A special
emphasis will be to describe waveguide (down to ~2 micrometer diameter) and volume grating
fabrication by a 1 MHz femtosecond Ti:Al2O3 laser in barium borate glasses and discuss its
structural and optical properties in detail. Waveguides fabricated are characterized by diffraction
and Raman analysis. Raman analysis indicates structural modification on fs laser irradiance.
Glasses doped with Pr and Eu show good emissive characteristics on excitation with UV/blue
radiations, spanning in the wide spectral range. Different emission pattern were obtained with
selective excitations in charge transfer band, 4f-5d band and 4f-4f band of Pr ion. Observed
properties will also be discussed in detail using absorption, excitation and lifetime analysis.
I-13
Charge Carrier Dynamics and Interfacial Interaction Study in
Organic Solar Cell
Rajiv Singh
National Physical Laboratory, K. S. Krishnan Marg, New Delhi
Email: [email protected]
The carrier dynamics been investigated by ultrafast fast absorption spectroscopy in organic
solar cell materials has leads insight view of various energy states in molecules and its decay
dynamics. The effect of surface plasmons of nanoparticles and charge species can also be identified
specifically with respect to their energy levels appearing in ultrafast time domain. Improvement in
recombination resistance at the various interfaces can be demonstrated by impedance spectroscopy
study. These studies can cumulative map the progress in efficient internal charge transfer and
reduction in recombination mechanism in organic materials for energy harvesting.
I-14
Role of Spectroscopy In the area of Non-Platinum Group
Fuel Cell Catalysts
Aditi Halder
School of Basic Science, Indian Institute of Technology, Mandi
Nitrogen doped carbon supported iron (Fe-N-C) framework has gained tremendous attention as
an excellent alternative of platinum for catalysis of oxygen reduction reaction (ORR) of proton
exchange membrane fuel cell (PEMFC). Spectroscopy is a useful technique for evaluating the
different functionalities arisen into the final catalysts materials after the chemical and thermal
treatment of precursor molecules while synthesizing the catalyst. The influence of various nitrogen
groups and metal precursors on the properties of electrocatalysts can only be evaluated with the
help of different spectroscopic techniques like X-ray diffraction and X-ray photoelectron
Spectroscopy. Electrochemical studies including hydrodynamic rotating ring disk electrode
measurement along with the various spectroscopic measurement, reveals the exact mechanism
followed in the catalytic process.
Contributory Talks
O-1
Atomically sharp edges and faceted voids in CVD grown WS2
monolayers
Pawan Kumara and B. Viswanathb
School of Engineering, Indian Institute of Technology Mandi, Kamand, India-175005 [email protected], [email protected]
Research on 2-dimensional (2D) materials explored as a paradigm shift in the field of
nanoscale material with the discovery of graphene like other nano-sheets such as transition metal
dichalcogenides (TMDCs: MoS2, WS2, MoSe2, etc.) due to their superior properties with reduced
layer thicknesses. Monolayer MoS2 and WS2 provide better performance of photoluminescence
with structural stability at ambient condition among the group of TMDCs. Two dimensional
flatland having enormously larger active surfaces and atomic terminated edges are undergoing
considerable interest owing to many interesting phenomena and processes when it interact with
ambiguous environment. We have grown large single crystalline, atomically thin monolayers of
WS2 in atmospheric pressure CVD system and investigated their intriguing behavior with various
spectroscopic as well as microscopic techniques. Time dependent dynamic as well as static void
evolution in atomically thin monolayers provide the structural rearrangement in hexagonal WS2.
Photoluminescence and Raman spectral analysis have been carried out to investigate the
atomically terminated edges behavior as well as flatland surface properties. The ability to
manipulate edges and voids in atomic monolayers provide new opportunities to control the
properties locally towards various optoelectronics and nanoelectronics applications.
References:
1. Mak, K. F.; Lee, C.; Hone, J.; Shan, J.; Heinz, T. F. Atomically thin MoS 2: a new direct-gap
semiconductor. Physical review letters 2010, 105, 136805.
2. Ye, G.; Gong, Y.; Lin, J.; Li, B.; He, Y.; Pantelides, S. T.; Zhou, W.; Vajtai, R.; Ajayan, P. M. Defects
Engineered Monolayer MoS2 for Improved Hydrogen Evolution Reaction. Nano Lett 2016, 16, 1097-103.
3. Gutierrez, H. R.; Perea-Lopez, N.; Elias, A. L.; Berkdemir, A.; Wang, B.; Lv, R.; Lopez-Urias, F.;
Crespi, V. H.; Terrones, H.; Terrones, M. Extraordinary room-temperature photoluminescence in
triangular WS2 monolayers. Nano Lett 2013, 13, 3447-54.
4. Hou, J.; Wang, X.; Fu, D.; Ko, C.; Chen, Y.; Sun, Y.; Lee, S.; Wang, K. X.; Dong, K.; Sun, Y.;
Tongay, S.; Jiao, L.; Yao, J.; Liu, K.; Wu, J. Modulating Photoluminescence of Monolayer Molybdenum
Disulfide by Metal–Insulator Phase Transition in Active Substrates. Small 2016, 12, 3976-3984.
O-2
Photophysical Properties of Emerging Two-Dimensional Materials
and Their van der Waals Heterostructures
Abdus Salam Sarkar and Suman Kalyan Pal
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of
Technology Mandi, Kamand, Mandi-175005, Himachal Pradesh, India.
Email: [email protected], [email protected]
Heterostructures of layered two-dimensional (2D) transition metal dichalcogenides
(TMDs) and organic semiconductors have emerged as promising candidates for next generation
electronics and optoelectronics. [1, 2] However, the development of advanced materials and detail
investigation of light-mater interactions are required to exploit them in real electronic
applications. In this talk, I will present a fully solution processable method (Figure 1) called
semiconductive polymer assisted chemical exfoliation (SPACE) of exfoliating layered
molybdenum disulfide (MoS2) forming polymer-MoS2 nanoheterojunctions. Efficient
dissociation of excitons in these heterostrojunctions will be demonstrated and explained.
Synthesized nanoheterojunctions show both photovoltaic and bipolar resistive switching effect.
[3] Temperature dependent Raman spectroscopic investigation has been undertaken to know
about the electron-phonon (e-p) interaction in these heterojunctions. [4] Furthermore, synthesis
and Raman spectroscopic studies of large area ultrathin (few-layer) tin(II) sulfide (SnS) will be
presented.
Figure 1. Schematic of SPACE method and atomic force microscopic image of ultrathin SnS
sheet.
References
1. K. F. Mak and J. Shan, Nat. Photon., 2016, 10, 216-226.
2. D. Jariwala, T.J. Marks and M. C. Hersam, Nat. Mater. 2017, 16,170-181.
3. A. S. Sarkar and S. K. Pal, J. Phys. Chem. C., 2017, DOI: 10.1021/acs.jpcc.7b07132.
4. A. S. Sarkar and S. K. Pal, ACS Omega, 2017, 2, 4333-4340.
O-3
Multifunctional magnetic and fluorescent hybrid core shell NPs
containing exceedingly small iron oxide nanocrystals for multimodal
imaging and biosensing Ashish Tiwari and Jaspreet Kaur Randhawa*
School of Engineering, Indian Institute of Technology Mandi, Himachal Pradesh, India
Email: [email protected]
The present study involves fabrication of biocompatible multifunctional magnetic and fluorescent
hybrid core shell nanoparticles (MFCSNPs) in single step synthesis method. Magnetic core of MFCSNPs
is iron oxide (Fe3O4) providing superparamagnetic properties which can be exploited for magnetic
resonance imaging (MRI) in cancer diagnostics. Fluorescent shell is carbon coating which enable optical
properties in MFCSNPs; saturated with carbonyl and hydroxyl groups making them advantageous for
bioimaging in cancer detection and therapy. Multiple surface functionalities of MFCSNPs offer a choice to
feat them as a drug carrier with efficient drug loading and targeting ability. Structural and morphological
features showed spherical core shell NPs with an average particle size of 230 nm containing small iron
oxide nanocrystals with an average size of 8 nm. Successful carbon coating on iron oxide nanocrystals was
confirmed by STEM images and elemental mapping. MFCSNPs showed superior superparamagnetic
behaviour with minimum coercivity and saturation magnetization of 29.34 emu/gm. CLSM imaging
displayed multicolour fluorescence spectra with tunable excitation wavelength. Achieving strong
fluorescence, superparamagnetic behaviour and good biocompatibility, MFCSNPs can be internalized into
the cells following accumulation in cell cytoplasm, which parade desirable capability for bioimaging in
therapeutic application. Moreover, systemic investigation of in vitro molecular interactions between
MFCSNPs with bovine serum albumin (BSA) were elucidated appropriately. The microenvironmental and
conformational changes of BSA induced by MFCSNPs were investigated by multi spectroscopic methods.
These results suggested that conformational change of BSA was significantly at secondary structure level
and biological activity of BSA was weakened dramatically in the presence of MFCSNPs.
Figure 1. TEM, PL and VSM spectra of MFCSNPs and PL and CD spectra of interaction with BSA.
References 1. Xiao, Lisong, et al. "Water-soluble superparamagnetic magnetite nanoparticles with biocompatible
coating for enhanced magnetic resonance imaging." ACS Nano 5.8 (2011): 6315-6324.
2. Wei, He, et al. "Exceedingly small iron oxide nanoparticles as positive MRI contrast agents." Proceedings
of the National Academy of Sciences (2017): 201620145.
O-4
Experimental and Theoretical Study of Oxide Materials for
Thermoelectric Applications
S. Singh, S. K. Pandey
School of Engineering, Indian Institute of Technology Mandi, Kamand, H.P.-175005 India. Email: [email protected]
In the past few decades, research in the field of thermoelectric (TE) materials have attracted
much attention for an alternate source of energy. For high temperature TE materials, an
investigation of oxides materials have more advantageous due to its nontoxic character, availability
in nature, structural and chemical stabilities, oxidation resistant properties over the conventional
TE materials (Be-Te, Pb-Te based alloys). Therefore, TE properties of oxide materials have been
explored by using experimental tool and electronic structure calculations (DFT+U).[1]
Measurement of α was carried out for the ZnV2O4, LaCoO3, La0.82Ba0.18CoO3, and
La0.75Ba0.25CoO3 compounds in 300-600 K range. [2-6] Experimental data of these compounds in
230-600 K temperature range have been explained successfully from the effective mass and
transport coefficient calculations. The consideration of temperature dependent energy gap is found
to be more effective in understanding the behaviour of α in ZnV2O4 and LaCoO3 compounds [4].
Also, the dependency of chemical potential on effective mass of charge carriers through
temperature plays a crucial role in the study of TE behaviour of both the compounds. The electronic
structure calculations shows the half-metallic character for La0.82Ba0.18CoO3 and La0.75Ba0.25CoO3
compound. In both the compound, consideration of temperature dependent relaxation time of up
and down-spin channel gives a reasonably good matching between experimental and calculated
values of α in 300-600 K. For La0.82Ba0.18CoO3, electrical resistivity measurement was also carried
out in 300-600 K range. DFT+U method was used to estimate the values of σ/τ, where the
temperature dependent values of relaxation time (τ), almost linear for up-spin (τup) and non-linear
for dn-spin (τdn), were used in two current model and estimated values were found to be in good
agreement with experimentally data in the entire temperature range [6]. Theoretically calculated
values of ZT for p-type doped ZnV2O4 (in 900-1400 K) and n-type doped LaCoO3 (in 600-1100
K) are found to be ~0.3 and ~0.35, respectively [2,3]. These values of ZT are nearly one third of
the well know thermoelectric oxide NaxCoO2 (ZT ~1 in 700-1000 K), this suggest that doped
LaCoO3 and ZnV2O4 compound can be good materials for the thermoelectric applications in
thermal power plant, spacecraft exhaust, armored vehicles exhaust, steel industry, etc.
References:
1) S. Singh and S. K. Pandey, Measurement, 102, 26-32 (2017).
2) S. Singh, R. K. Maurya, and S. K. Pandey, J. Phys. D: Appl. Phys., 49, 425601-10 (2016).
3) S. Singh and S. K. Pandey, Philosophical Magazine, 97:6, 451-463 (2017).
4) S. Singh and S. K. Pandey, Mater. Res. Express, 3, 105501-7 (2016).
5) S. Singh, D. Kumar and S. K. Pandey, J. Phys.: Condens. Matter, 29, 105601-7 (2017).
6) S. Singh, D. Kumar and S. K. Pandey, Phys. Lett. A 381, 3101 (2017).
O-5
ICPMS: A VERSATILE TOOL
Bhupender Singh
Institute Instrumentation Centre, I.I.T. Roorkee, Roorkee-247667
Email: [email protected]
Impurities at trace or ultra-trace level (ppm, ppb, ppt) significantly affect the physico-chemical
properties, efficiency and usability of the materials. In order to fabricate advanced functional
materials we need to monitor the elemental composition at the various stage. Inductively coupled
plasma–mass spectrometry (ICPMS) is the fastest and the sensitive tool multi-elemental analytical
technique to check the purity of the material. ICPMS technique have been widely used in area of
life sciences, environmental sciences, food sciences, health science, earth sciences, forensics,
material science, metallurgy, archaeological and other industrial applications. Advanced
hyphenated techniques have widened the scope of this technique
O-6
Enhanced Thermopower and low thermal conductivity in p-type
polycrystalline ZrTe5
M. K. Hooda and C. S. Yadav
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi-175005 (H.P.) India
Email: [email protected]
ZrTe5 is the well studied transition metal pentatelluride material due to its resistivity
anomaly in the temperature range 60 to 150 K and large thermoelectric power (S) which shows
electron dominance (negative S) below the anomaly temperature and above it hole dominance
(positive S) [1-2]. Recently another form of ZrTe5 (p-type) was discovered which shows hole
dominated S in the whole temperature range (2-340K) and semiconducting behavior [3-5]. We
have explored the thermoelectric properties of polycrystalline p-type ZrTe5 in temperature (T)
range 2 - 340 K. Thermoelectric power (S) is positive and reaches up to 458 V/K at 340 K on
increasing T. The value of Fermi energy 16 meV, suggests low carrier density of 9.5 1018 cm-
3. A sharp anomaly in S data is observed at 38 K, which seems intrinsic to p-type ZrTe5. The
thermal conductivity () value is low (2 W/m-K at T = 300 K) with major contribution from lattice
part. Electrical resistivity data shows metal to semiconductor transition at T ~150 K and non-
Arrhenius behavior in the semiconducting region. The figure of merit zT (0.026 at T = 300 K) is
~63% higher than HfTe5 (0.016), and better than the conventional SnTe, p-type PbTe and bipolar
pristine ZrTe5 compounds.
References:
[1] S. Furuseth, L. Brattas, and A. Kjekshus, Acta Chem. Scand. 27, 2357 (1973).
[2] H. Fjellavg and A. Kjekshus, Solid State Comm. 60, 91 (1986).
[3] A. Pariari and P. Mandal, Nature Scientific Reports 7, 40327 (2017).
[4] P. Shahi et al., arxiv:1611.06370 (2016).
[5] M. K. Hooda and C. S. Yadav, Appl. Phys. Lett. 111, 053902 (2017).
Poster Presentation
P-1
Analytical challenges in drug analysis and its impact and solution in
daily life
Ankur Kumar and Dr. Manjeet Agarwal
National Institute of Food Technology Entrepreneurship and Management
(Under Ministry of Food Processing Industries, Government of India), Haryana-131028
Email: [email protected]
Drug discovery is a commonly known area of Research and Development. Today, The
pharmaceutical industries and The Research organization are facing a lots of challenges like-non
compliance of Food and Drug Administration(FDA) standard because of non-conformity of
analytical result, violation of good laboratory practice(GLP) and good manufacturing
practice(GMP) norms .Analytical data represents the final report of a product before going into the
markets. Analytical problem can be resolved by selecting correct route of synthesis from the
beginning, correct specification, by following correct methodology for the analysis with validated
analytical methods as per International conference on harmonization (ICH), which is
internationally recognized, correct reporting of analytical result with respect to the standard
specification value. Investigation of out of trend results (OOT) and out of specification results
(OOS) and the systematic reporting of deviations with proper justification and corrective and
preventive actions (CAPA).
Key words- Analytical challenges, Drug analysis, FDA, GMP, GLP and ICH.
P-2
Electron Beam Lithography of sensitive resist based on photoacid
generator integrated terpolymer: potentiality of high-resolution
pattern transfer Santu Nandi1, Midathala Yogesh1, Pulikanti Guruprasad Reddy1, Satinder K. Sharma2,
Chullikkattil P. Pradeep1, Subrata Ghosh1* and Kenneth E. Gonsalves1*
1School of Basic Sciences, Indian Institute of Technology Mandi, H.P. 175005, India. 2 School Computing and Electrical Engineering, Indian Institute of Technology Mandi, H.P.
175005, India. *e-mail: [email protected], [email protected]
Nanolithography technology has been extensively used in semiconductor fabrication process to
manufacture micro/nano electronics. Photolithography has been recognized to be the fundamental
technology in IC manufacture for a very long time because it has a significant role to define a number of
discrete devices per integrated circuit. Now a days developing new photoresist materials for different
lithography applications, starting from high to low nodes, the potential of the resist in successful
pattern transfer has been the key role in semiconductor industries. The current semiconductor
industries are looking sub-10 nm features for potential manufacture of sophisticated nano-
electronics, however, the materials with lower node features particularly at sub-100 nm regime is
also equally important for current IC industries especially in the CMOS technology. Considering
these, we have designed and synthesized a new terpolymer viz. GBLMA-MAMA-MAPDST
photoresists for the electron beam lithography (EBL) applications. EBL studies reveal that the
synthesized terpolymer resist (GBLMA-MAMA-MAPDST) is sensitive to the radiations and able
to show 100 nm (L/S) and 70 nm isolated positive tone line features after TMAH development. The
sensitivity (E0) and contrast (γ) of this resist were calculated from the contrast curve analysis as
36.5µC/cm2 and 0.08 respectively. At last, the potential to transfer positive higher resolution nano
features on the silicon substrate has been achieved by suitable dry plasma etching technique.
Fig. 1. (a) Structure of Terpolymer, (b) EBL pattern of 100 nm L/S, (c) AFM image of
transferred pattern onto Silicon.
References:
1. S. Ghosh, C. P. Pradeep, S. K. Sharma, P. G. Reddy, S. P. Pal and K. E. Gonsalves, RSC Adv. 2016,
6, 74462.
2. K. E. Gonsalves, M. Wang, C. T. Lee, W. Yueh, M. T. Tapia, N. Batinad and C. L. Henderson, J.
Mater. Chem. 2009, 19, 2797.
P-3
Emission enhancement and color tuning for Lanthanide activated
Bi2SiO5 nanophosphor
Pushpa Kumari, and Y. Dwivedi
Department of Physics, National Institute of Technology Kurukshetra, Kurukshetra, Haryana –
136119 India
Email:[email protected]
A series of Dy3+ and Tb3+ ions doped and co-doped Bi2SiO5 nanophosphors were
synthesized by hydrothermal, combustion and co-precipitation methods. Bi3+ ions are very good
sensitizers of luminescence, which can absorb the UV light and transfer this energy to the
activator center. Various structural characterizations were made using X-ray diffraction,
Scanning electron microscopy, transmission electron microscopy etc. Bi2SiO5 crystalline phase
analysis was confirmed by X-ray diffraction technique of size ~25 nm and no any significant
change in phase and size with doping. We have explored the various vibrational and optical
properties including FTIR, Raman, absorption, photoexcitation and emission of synthesized
samples. Dy3+ ions activated Bi2SiO5 nanophosphor yields yellowish white light, which
perception change with Tb3+ ions. The energy transfer phenomenon between Dy3+ and Tb3+ ions
was validated in Dy3+/Tb3+ co-doped Bi2SiO5 nanophosphor and confirming the fact that the
dipole–dipole interaction is responsible for the energy transfer process of Dy3+→ Tb3+ from 4F9/2→ 6H15/2 level. Spectroscopic characterizations of these energy transferred were explore by
time resolved spectroscopy. Detail photophysics of the materials were explored and will be
discuss during the presentation.
Acknowledgment:
I would like to acknowledge the financial support from fellowship HSCST/2015/1, Haryana State
Council for Science & Technology.
P-4
Development of ZnO/ Polyaniline core-shell nanostructure for room
temperature LPG Sensing
Lalit Kumar, Divyanshu Katiyar, Randheer Gautam
Department of Physics, Hindu College, University of Delhi, Delhi-10007.
Email: [email protected]
Nanomaterials display great promise in the development of science and technology due to
their concomitant properties and interesting behaviour compared to their bulk counterparts.
Inorganic/organic hybrid semiconductor devices are being explored for their potential of added
electronic versatility by combining two contrasting but well-developed materials for novel
applications. In this work, hybrid inorganic-organic nanomaterial is investigated for gas sensing
property, with zinc oxide (ZnO) as inorganic part and polyaniline (PANI) as organic component.
We employed in-situ polymerization technique to synthesize ZnO/PANI core-shell structure. The
XRD pattern of core shell structure exhibited peaks corresponding to pure ZnO, indicating the
presence of pure ZnO in the core, which is further corroborated by SEM microscopy. We
investigated the LPG sensing property of ZnO/PANI core shell and found room temperature
response and recovery behaviour. Maximum sensitivity was achieved at 35 °C, indicating
suitability of ZnO/PANI core shell towards LPG sensing as compared to pure ZnO and PANI.
Figure: XRD pattern of pure ZnO, pure PANI and ZnO/PANI core-shell nanostructure
and TEM image of core-shell .
P-5
Fabrication of γ-MnS and γ-MnS/ S and N co-doped three-
dimensional graphene composite for electrochemical properties as an
electrode material for supercapacitors
Sushil Kumar, Khushboo Soni, Sk. Riyajuddin, Shivang Bajaj, Sabyasachi Karmakar and
Kaushik Ghosh*
Institute of Nano Science & Technology, Habitat Centre, Phase-10, Sector-64, Mohali- 160062
Email: [email protected]
With the rising fossil fuel prices and the increasing environmental problems resulting from burning
fossil fuels, global community is looking for environment-friendly energy resources, which require to be
sustainable and renewable. Electrochemical energy generation and storage devices, such as supercapacitor
for high energy storage due to its attractive advantages in terms of high power density, long cycle life, low
maintenance cost, simplicity and better safety compared with secondary batteries such as Li-ion or Lead
Acid batteries. MnS has three different polymorphs: the green stable rock salt structure (α-MnS), the pink
metastable zinc blende structure (β-MnS), and the wurtzite structure (γ-MnS). Till now, various shapes of
MnS nanoand microcrystals have been achieved by a hydrothermal, solvo-thermal, thermolysis, and spray-
produced process. Generally, the synthesis of metastable phase γ -MnS is still a challenging and intriguing
task. For electrode active materials, a graphene coating is an efficient way to enhance conductivity. If
nanostructured graphene is used as the matrix for γ -MnS based composites, it cannot only well
accommodate the γ-MnS particles, but also offer a smooth electrode/electrolyte interface for the charge-
transfer reaction. Here we demonstrate the effect of γ -MnS /graphene-based composite material for solid-
state-supercapacitors. γ -MnS and γ- MnS/S,N-3DG composite was successfully fabricated via a facile one-
pot solvothermal route. The γ- MnS hollow spheres consisting of γ- MnS nanoparticles or γ- MnS rods with
hierarchical architectures which create a facile interface via S and N codoped graphene with 3D graphene
electrodes.
Fig1:(a) Cyclic Voltametric analysis of γ- MnS from scan rate (10-100 mV/s), (b) SEM analysis
γ- MnS and insert γ- MnS/S,N-3D graphene composite.
γ-
S,N-
(a) (b)
P-6
Functionalization of Graphene Oxide Dispersions for Conductive
Inks and Supercapacitor Applications Mahesh Soni, 1 Ajay Soni,2 Satinder Kumar Sharma1
1School of Computing and Electrical Engineering, Indian Institute of Technology Mandi-175005,
HP, India
2School of Basic Sciences, Indian Institute of Technology, Mandi-175005, HP, India
Email: [email protected]
Recently, 2D layered materials such as graphene, derivatives graphene oxide (GO) and
reduced graphene oxide (rGO) have absorbed significant attention to explore novel functionalities
for technological applications like nano-electronics, photovoltaics, conductive inks, interconnects
and supercapacitors [1]. The interest towards GO/rGO is due to excellent electronic, optical,
mechanical properties, high surface to volume ratio and atomically thin dispersion in water [2].
Moreover, the electrical conductivity of the insulating GO can be tuned by reduction, rGO. The
rGO obtained via reduction of aqueous GO tends to agglomerate with time and hinders the
commercial scale applications for conductive inks and high-density energy storage. To address the
challenge, we will demonstrate a low-cost approach for large-scale production of rGO via photo-
catalytic functionalization of GO under UV illumination (λ ~ 253 nm) in presence of N-Methyl-
2-Pyrrolidone (NMP). The obtained rGO retains the long-term stable homogenous dispersion for
more than 160 days with 2D morphologies. The high stability of dispersion and electrochemical
performance of synthesized rGO is envisaged for potential applications in high density energy
storage and conductive inks for flexible electronics [3].
References
[1] X. Huang, Z. Yin, S. Wu, X. Qi, Q. He, Q. Zhang, et al., "Graphene‐based materials: synthesis, characterization,
properties, and applications," small, vol. 7, pp. 1876-1902, 2011.
[2] D. R. Dreyer, S. Park, C. W. Bielawski, and R. S. Ruoff, "The chemistry of graphene oxide," Chem Soc Rev, vol.
39, pp. 228-40, Jan 2010.
[3] M. Soni, P. Kumar, R. Kumar, S. K. Sharma, and A. Soni, "Photo-catalytic reduction of oxygenated graphene
dispersions for supercapacitor applications," Journal of Physics D: Applied Physics, vol. 50, 2017.
P-7
Band Modification and Soft Phonon Modes in Transition Metal and
Rare-Earth Element Doped SnTe
Somnath Acharya, Juhi Pandey and Ajay Soni*
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh
175005, India
*Email: [email protected]
The advancements on thermoelectric materials research are associated with band
engineering and phonon engineering, which can modify the electronic band structure and phonon
transport.[1, 2] In past few years, tin telluride (SnTe) based alloys are regarded as promising
thermoelectric material analogous to lead chalcogenides due to identical crystal structure and
complex band structure. The optimization of carrier concentration is a major challenge for SnTe
which can be achieved by self-compensation of Sn and doping at inherent Sn sites.[3, 4] The
presentation will discuss on the results of thermoelectric performance of transition metal and rare
earth element doped SnTe. The enhancement in thermopower has been explained with electronic
band modification and poor thermal conductivity is understood based on point defect scattering
and appearance of impurity driven soft phonon mode.[5, 6] The appearance of the soft phonon
modes and blue shift in Raman spectra of Mn doped samples justifies the role of Mn for breaking
center of inversion symmetry and acting as point defect scattering center for the major part of
broad spectrum of phonon frequencies.
References
[1] Y. Pei, H. Wang, and G. J. Snyder, Advanced Materials 24 (2012) 6125.
[2] W. Kim, Journal of Materials Chemistry C 3 (2015) 10336.
[3] R. F. Brebrick and A. J. Strauss, Physical Review 131 (1963) 104.
[4] G. Tan, L.-D. Zhao, F. Shi, J. W. Doak, S.-H. Lo, H. Sun, C. Wolverton, V. P. Dravid, C.
Uher, and M. G. Kanatzidis, Journal of the American Chemical Society 136 (2014) 7006.
[5] S. Acharya, J. Pandey, and A. Soni, Applied Physics Letters 109 (2016) 133904.
[6] S. Acharya and A. Soni, AIP Conference Proceedings 1832 (2017) 110028.
P-8
Highly luminous white light emission from organic dyes in a binary
system for WLED
Rashmi, Y.Dwivedi*
Department of Physics, National Institute of Technology Kurukshetra – 136119, Haryana
E-mail: [email protected]
Present works discuss spectroscopic investigations of organic laser dyes (C102, and Rh6G)
in mono and binary system in different polar environments namely (ethanol, acetone,
dimethylformamide, water, and cyclohexane). In the binary system energy transfer (ET) was
observed from C102 (donor) to Rh6G (acceptor) dye which was utilized in such a way to tune
white light. By properly tuning the mixing ratio of both the laser dyes (in ethanolic solution) to
achieve efficient energy transfer in order to balance the red and blue spectral emission contribution
of the binary system, a fairly pure and stable white light has been obtained with CIE-1931
chromaticity coordinates of (0.35, 0.33).
We have explored the various vibrational and optical properties including FTIR, UV-
Visible absorption, Photo-excitation and photoluminescence of samples. When compared, photo-
excitation and photoluminescence spectra (PLE and PL) of C102, Rh6G and binary system dye
shows different behavior like, variation in peak profile, FWHM, Stoke’s shift, and red-shift were
observed with the increase of the solvent polarity. The energy transfer and several related
parameters in the dyes were investigated and analyzed implementing time-resolved fluorescence
spectroscopy. Also, the thermal stability of the dyes was also investigated and a simple structure
which avoids color degradation is proposed. We have estimated various radiative parameters like
quantum efficiency, absorption and emission cross-section etc. Detail of the other result will be
discussed during presentation.
Reference
[1] K. Singh and G. C. Joshi, “Influence of donor-donor transport on excitation energy transfer
in binary system C343-Rh6G doped in Poly(methylmethacrylate),” IOSR J. Appl. Phys.,
vol. 7, no. 6, pp. 3–13, 2015.
P-9
Dynamics of different emissive states in CH3NH3PbBr3 perovskite
Supriya Ghosh,1 Suman Kalyan Pal,1 * Khadga jung Karki2*and Tonu Pullerits2*
1School of Basic Sciences, Indian Institute of Technology Mandi, H.P. 175005, India. 2 Department of Chemical Physics and NanoLund, Lund University, Lund, Sweden.
*Email: [email protected]
Organo metal halide perovskites (OMHPs) seem to have the potential to challenge
traditional silicon technology.1 Therefore, the understanding of the fundamental light-induced
processes in OMHPs from charge-photo generation, migration of charge carries2 through the
materials and finally their recombination is very important. We investigate the local changes in
photophysics at different micro-regions of a methyl-ammonium lead bromide (MAPbBr3)
perovskite crystal under illumination. The yield and spectrum of the emission from the structurally
homogeneous region does not vary with the illumination time, whereas inhomogeneous region
shown a distinct light induced changes in the spectra.3 Our results indicate that the bimolecular
band to band recombination is the main emission source for the homogenous region on the other
hand emission from the inhomogeneous regions is due to the defects. At long illumination time,
photo induced ion-migration passivate the defect centre and consequently inhibits the defects
related emission, thereby decreasing their contribution to the emission. The measurements of the
emission lifetime show that the kinetics is dominated by the defect related emission at short
illumination times and the band edge emission at the longer illumination times. Our work provides
a direct evidence for the light induced healing of the defect centers, which is important in the
design of photoactive devices of MAPbBr3.
Fig. 1. (a) Change of integrated PL with illumination time at homogeneous region (blue) and
inhomogeneous region (orange). (b) Illustration of defect passivation with illumination time.
References:
[1] S. D. Stranks, H. J. .Snaith, Nat. Nanotechnol. 2015, 10, 391-402.
[2] E. Mosconi, D. Meggiolaro, H. J. Snaith, S. D. Stranks, F. De Angelis, Energy Environ. Sci.
2016, 9, 3180-3187.
[3] S. Ghosh, S. K Pal, K. J. Karki, T. Pullerits S, ACS Energy lett. 2017, 2, 2133-2139.
0 10 20 30 40 50 60 70 80
105
106
Inte
gra
ted
PL
(a.
u.)
Illumination time (min)
(d)
δ+
e-
h+
e-
e-
h+
hνhν
Br-
2 ns
δ+
2 ns
Strongly emittingtrapping sites
Healing of the trappingsites due to halide ionmigration
Under lightillumination over time
(a) (b)
P-10
Enhancement of Luminescence Intensity in Red Emitting
NaYF4:Yb/Ho/Mn Upconversion Nanophosphors by Variation of
Reaction Parameters
K. Lingeshwar Reddy,a Vaddepally Srinivas,a Konathala Ravi Shankar,a,c Suneel Kumar,a Vipul
Sharma,a Ajay Kumar,a Ashish Bahuguna,a Kaustava Bhattacharyya,b and Venkata Krishnan*a aSchool of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology Mandi,
Kamand, Mandi, Himachal Pradesh, 175005, India. bChemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India. cCurrent address: School of Nano Sciences, Central University of Gujarat, Gandhinagar 382030, India
*E-mail: [email protected]
In the field of biomedicine, upconversion nanoparticles have wide ranging applications from
bioimaging to targeted cargo delivery, especially due to their excellent chemical and optical properties in
comparison to conventional fluorophores. However, their use in biomedical applications is largely hindered
due to strong absorption of short wavelength (< 600 nm) light by biological tissues/cells and feeble
luminescence. Hence, it is important to develop new strategies to increase the long wavelength (red)
emission efficiency. In this work, we report an effective strategy to improve the red luminescence efficiency
of NaYF4:Yb/Ho/Mn upconversion nanophosphors by varying the reaction conditions. The influence of
different synthesis parameters, such as solvent ratio, reaction temperature and reaction time, on the
luminescence, crystal phase and morphology of the upconversion nanophosphors has been studied in detail
and optimized. The improvement in the crystallinity of nanophosphors is claimed as the main origin for the
increase in the red emission intensity. This work could pave way for the versatile use of these bright red
emitting upconversion nanophosphors in biomedical applications.
Key words: Upconversion nanophosphors; NaYF4:Yb/Ho/Mn; red emission; enhanced luminescence;
synthesis parameters; crystal phase transition
Figure: Schematic representation of the synthesis of bright luminescent red emitting NaYF4:Yb/Ho/Mn
upconversion nanophosphors by variation of reaction parameters References [1] K. L. Reddy, V. Srinivas, K. R. Shankar, S. Kumar, V. Sharma, A. Kumar, A. Bahuguna, K. Bhattacharyya, V.
Krishnan, J. Phys. Chem. C, 121 (2017) 11783-11793.
P-11
Alternative route to ligand functionalization for understanding the
role of linker molecule in quantum dot sensitized solar cells
Monika Dahiya and Arijit K. De*
Indian Institute Of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81,
SAS Nagar, Punjab 140306, India.
Email: [email protected], *[email protected]
Dye sensitized solar cells (DSSCs) are inexpensive and have high efficiency but they are
facing limitations due to photo bleaching of dye and short lifetime [1]. Analogous to DSSCs,
Quantum dot sensitized solar cells (QDSSCs) have emerged as a promising approach for light
harvesting. They have opened up new ways of utilizing hot electrons and generate multiple exciton
upon absorption of a single photon. Significant efforts have been made during the past few years
to make them competitive with other existing thin films photovoltaic technologies but demands
further exploration. Our lab is interested in understanding the exciton dynamics within QDSSCs
using femtosecond resolved pump-probe spectroscopy. Due to the presence of bulky ligands
during synthesis, the surface needs to be modified with smaller ligands in order to increase the
adsorption of quantum dots (CdSe) on wide band gap semiconductor (TiO2 or ZnO). Our approach
is to modify the surface with cysteine linkers as they have shorter length which increases the
electron injection rate from quantum dots to wide band gap semiconductor [2]. It was reported that
electron injection from cysteine capped quantum dots is more efficient [3]. Also, we are interested
in understanding the role of trap states formed after functionalization and their role in electron and
hole transport. In this presentation, a new method of ligand functionalization for CdSe quantum
dots and how the dynamics of the charge carriers are modified for the two different approaches of
functionalization will be discussed.
References
[1]I.Robel, V. Subramanian, M. Kuno, P.V. Kamat; Quantum dot solar cells. Harvesting light
energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films, Langmuir, 2006,
128, 2385-2393.
[2] J.Chang, Y.Ogomi, C.Ding, Y.Zhang, T.Toyoda, S.Hayase, K.Katayamae, Qing Shen; Ligand-
dependent exciton dynamics and photovoltaic properties of PbS quantum dot heterojunction solar
cells, Phys. Chem. Chem. Phys., 2017, 19, 6358-6367.
[3] X.Xua, S.Giménezb, I.Serób, A.Abateb, J.Bisquertb, G.Xua; Influence of cysteine adsorption
on the performance of CdSe quantum dots sensitized solar cells, Material Chemistry and Physics,
2010, 124, 709-712.
P-12
Identification of Bacterial strains by MALDI-TOF Mass Spectrometry
Rakesh Kumar and Ramdhan Yadav
Department of Biochemistry, Panjab University Chandigarh 160014
Email: [email protected]
The MALDI-TOF (Matrix Assisted Laser Desorption/Ionization) mass spectrometer is a
very fast and usable technique to identify the cellular and protein component of bacteria. MALDI-
TOF uses in science in broad ways but in respect to the molecular weight of protein and peptide
have been used to identify bacteria. Many bacteria such as staphylococcus aureus, bacillus cereus,
pseudomonas fragi etc. are identified by MALDI-TOF MS. The sample of bacteria is ionized with
the help of laser. Population of ion is then passing through the electrostatic field and magnetic
analyzer. The analyzer monitors the selective ions that are able to produce the accurate information
of the sample under vacuum. The present poster covers the MALDI-TOF MS for bacterial
identification.
REFERENCE:
J.P. Anhalt and C. Fenselau; Anal. Chem., (1975) 47: 219–225
P-13
Multifunctional magnetic and fluorescent hybrid core shell NPs containing
exceedingly small iron oxide nanocrystals for multimodal imaging and
biosensing Ashish Tiwari and Jaspreet Kaur Randhawa*
School of Engineering, Indian Institute of Technology Mandi, Himachal Pradesh, India
Email: [email protected]
The present study involves fabrication of biocompatible multifunctional magnetic and fluorescent
hybrid core shell nanoparticles (MFCSNPs) in single step synthesis method. Magnetic core of MFCSNPs
is iron oxide (Fe3O4) providing superparamagnetic properties which can be exploited for magnetic
resonance imaging (MRI) in cancer diagnostics. Fluorescent shell is carbon coating which enable optical
properties in MFCSNPs; saturated with carbonyl and hydroxyl groups making them advantageous for
bioimaging in cancer detection and therapy. Multiple surface functionalities of MFCSNPs offer a choice to
feat them as a drug carrier with efficient drug loading and targeting ability. Structural and morphological
features showed spherical core shell NPs with an average particle size of 230 nm containing small iron
oxide nanocrystals with an average size of 8 nm. Successful carbon coating on iron oxide nanocrystals was
confirmed by STEM images and elemental mapping. MFCSNPs showed superior superparamagnetic
behaviour with minimum coercivity and saturation magnetization of 29.34 emu/gm. CLSM imaging
displayed multicolour fluorescence spectra with tunable excitation wavelength. Achieving strong
fluorescence, superparamagnetic behaviour and good biocompatibility, MFCSNPs can be internalized into
the cells following accumulation in cell cytoplasm, which parade desirable capability for bioimaging in
therapeutic application. Moreover, systemic investigation of in vitro molecular interactions between
MFCSNPs with bovine serum albumin (BSA) were elucidated appropriately. The microenvironmental and
conformational changes of BSA induced by MFCSNPs were investigated by multi spectroscopic methods.
These results suggested that conformational change of BSA was significantly at secondary structure level
and biological activity of BSA was weakened dramatically in the presence of MFCSNPs.
Figure 1. TEM, PL and VSM spectra of MFCSNPs and PL and CD spectra of interaction with BSA.
References 1. Xiao, Lisong, et al. "Water-soluble superparamagnetic magnetite nanoparticles with biocompatible
coating for enhanced magnetic resonance imaging." ACS Nano 5.8 (2011): 6315-6324.
2. Wei, He, et al. "Exceedingly small iron oxide nanoparticles as positive MRI contrast agents." Proceedings
of the National Academy of Sciences (2017): 201620145.
P-14
Ag Nanoparticle Aggregates Assembled on 3D heterojunction Configuration
Using Rhododendron Flower Petals for SERS Applications
Ramachandran Balaji, Nisha Kumari, Vipul Sharma and Venkata Krishnana*
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of
Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.
Email: [email protected]
Novel biomaterial based SERS substrates fabricated on rhododendron flower petal surfaces
is reported in this work. The substrates were fabricated by taking advantage of the unique pattern
of the surface micro/nanostructures found on the petal surface and the SERS activity was
demonstrated by using a model chemical analyte. In one of the cases, a three dimensional
heterojunction mirror-like configuration was created by sputter deposition of a 5 nm thin film of
Au metal followed by assembly of Ag nanoparticle aggregates, which were synthesized via curry
leaf extract, over them to form a hetero nano-junction. This nano-junction based SERS substrate
performed better than another substrate fabricated by simple drop casting of Ag nanoparticle
solution on the flower surface, which could be attributed to the enhanced plasmonic interactions
between the Ag nanoparticle aggregates with the 5 nm Au thin film. Such facile nano-junction
based systems having nanoparticles on 3D heterojunction mirror-like configurations fabricated on
naturally occurring materials can be conveniently used for chemical, forensic and biomedical
analysis.
References:
[1] Vipul Sharma, Ramachandran Balaji, Rajat Walia, Venkata Krishnan, Colloid and Interface
Science Communications 18 (2017) 9–12
[2] V. Sharma, S. Kumar, A. Jaiswal, V. Krishnan, Gold deposited plant leaves for SERS: role of
surface morphology, wettability and deposition technique in determining the enhancement factor
and sensitivity of detection, Chem. Sel. 2 (2017) 165–174.
[3] S.-Y. Chou, C.-C. Yu, Y.-T. Yen, K.-T. Lin, H.-L. Chen, W.-F. Su, Romantic story or Raman
scattering? Rose petals as eco-friendly, low-cost substrates for ultrasensitive surface-enhanced
Raman scattering, Anal. Chem. 87 (2015) 6017–6024.
P-15
SCHOTTKY ANOMALY IN ReBaCuFeO5 (Gd, Ho and Yb)
Surender Lal, K. Mukherjee , C. S. Yadav
School of Basic Sciences, Indian Institute of Technology, Mandi, Mandi-175005, (H.P.) India
Email: [email protected]
Keywords: Multiferroic, Heat capacity, Schottky Anomaly
Double perovskites materials are represented by general formula A'A''B'B''X6 where (A',
A'') sites are occupied by rare or alkaline earth metals, (B', B'') sites are occupied by transition
metal ions and X site is generally occupied by the oxygen or halide ions. Layered perovskite
materials are derivatives of double perovskites in which one of the oxygen is removed from the A'
plane [1]. Layered perovskite materials exhibits interesting structural, magnetic and multiferroic
properties [2,3]. These properties can be tuned by applying additional chemical pressure or
increasing the distortion in the system [4,5]. We present here the results of heat capacity of layered
perovskite ReBaCuFeO5 (Re = Gd, Ho, Yb) compounds, measured at different magnetic field. Low
temperature heat capacity shows an upside turn below 10 K. In the absence of any magnetic
transition, this anomaly is attributed to the Schottky anomaly [6]. This anomaly shifts towards
higher temperature on application of magnetic field. This anomaly can be attributed to the splitting
of ground sate levels of rare earth ions into two or more levels in the presence of crystalline electric
field. The crystalline electric field dominates the exchange interactions at low temperature (T < 10
K).
References
[1] L. Er-Rakho, C. Michel, P. Lacorre, and B. Raveau, J. Solid State Chem. 73, 531 (1988).
[2] V. Caignaert, I. Mirebeau, F. Bouree, N. Nguyen, A. Ducouret, J.-M. Greneche, and B.
Raveau, J. Solid State Chem. 114, 24 (1995).
[3] B. Kundys, A. Maignan, and C. Simon, Appl. Phys. Lett. 94, 72506 (2009).
[4] M. Morin, E. Canévet, A. Raynaud, M. Bartkowiak, D. Sheptyakov, V. Ban, M.
Kenzelmann, E. Pomjakushina, K. Conder, and M. Medarde, Nat. Commun. 7, 13758
(2016).
[5] S. Lal, S. K. Upadhyay, K. Mukherjee, and C. S. Yadav, EPL (Europhysics Lett.) 117,
67006 (2017).
[6] L. Xie, T. S. Su, and X. G. Li, Phys. C Supercond. 480, 14 (2012).
P-16
Orbiton-Phonon coupling in Ir5+(5d4) double perovskite Ba2YIrO6
Birender Singh1, G. A. Cansever2, T. Dey2, A. Maljuk2,S. Wurmehl2,3, B. Büchner2,3 and Pradeep
Kumar1
1School of Basic Sciences, Indian Institute of Technology Mandi,Mandi-175005, India 2Leibniz-Institute for Solid State and Materials Research, (IFW)-Dresden, D-01171 Dresden,
Germany 3Institute of Solid State Physics, TU Dresden, 01069 Dresden, Germany
Email: [email protected]
Ba2YIrO6, a Mott insulator, with four valence electrons in Ir5+d-shell (5d4) is supposed to be non-
magnetic, with Jeff = 0, within the atomic physics picture. However, recent suggestions of non-zero
magnetic order parameter have raised some fundamental questions about its origin. Focussing on
the phonon dynamics, probed via Raman scattering, as a function of temperature and different
incident photon energies, as an external perturbation. Our studies reveal strong renormalization of
the phonon self-energy parameters and integrated intensity for first-order modes, especially
redshift of the few first-order modes with decreasing temperature and anomalous softening of
modes associated with IrO6octahedra, as well as high energy Raman bands suggesting the
proposed magnetic nature may have its origin in strong electron-phonon coupling via orbital
excitations.The distinct renormalization of second-order Raman bands with respect to their first-
order counterpart suggest that higher energy Raman bands have strong contribution from orbital
excitations. Our observation reveals that strong anharmonic phonons coupled with electronic
degrees of freedom via orbital excitations provides a knob for tuning the conventional electronic
levels for 5d-orbitals, and this may give rise to non-zero magnetic order parameter as postulated
in recent theoretical calculations with rich magnetic phases.
References
B. Singh et al., arXiv:1702.00724
P-17
Amalgamated CaTiO3-g-C3N4 Heterojunction Photocatalyst for
Organic Pollutant Degradation Ashish Kumar, Christian Schuerings, Suneel Kumar, Ajay Kumar and Venkata Krishnana*
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of
Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.
Email: [email protected]
Perovskite based materials are currently used widely for photovoltaic and photocatalytic
applications, due to their superior properties as compared to the conventional materials. In this
work, a promising amalgamation of organic with inorganic semiconductor photocatalyst (g-
C3N4/CaTiO3) was performed in 1:1 ratio through a facile thermal method.1 The organic
semiconductor (g-C3N4) was prepared through pyrolysis of dicyandiamide, while perovskite
(CaTiO3) was prepared by polyacrylamide gel route.2,3 The as-prepared photocatalyst was
characterized by powder x-ray diffraction (XRD), scanning electron microscopy (SEM),
transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV-vis diffuse
reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The mechanistic
analysis revealed that amalgamation of organic semiconductor stimulated the utilization of solar
spectrum by enhancing the light absorption towards visible region, whereas perovskite activated
close interfacial interactions lead to enhanced efficiency of electron migration. The
photoluminescence spectroscopic study (PL) indicated the prolongation of the photogenerated
charge carriers. The photocatalytic activity of the perovskite composite was examined under UV,
visible and sun light by monitoring the degradation a model pollutant dye (Rhodamine B) and a
non-photosensitizing compound (Bisphenol A). The photocatalytic investigations clearly revealed
the dominant solar light harvesting capability of the developed perovskite amalgamated organic
photocatalyst.
References:
(1) K. H. Leong, Z. Z. Tan, L. C. Sim, P. Saravanan, D. Bahnemann and M. Jang, Chemistry
Select 2 (2017) 84.
(2) T. Xian, H. Yang and Y. S. Huo, Phys. Scr. 89 (2014) 115801.
(3) P. Niu , L. Zhang , G. Liu and H. M. Cheng, Adv. Funct. Mater. 22 (2012) 4763.
P-18
Structurally engineered biocompatible molecular probes for live
cell-imaging and localization of native DNA Pankaj Gaur and Subrata Ghosh
School of Basic Sciences, Indian Institute of Technology Mandi,Mandi-175005, India
Email: [email protected]
Because of their vitality toward genetic inheritance, governing and functioning of cellular
activities, nucleic acids have earned the prime focus out of other biomolecules. Therefore, deep
insight of their structural dynamics and its influence on the cellular functioning could be of great
importance in the physiological and pathological investigations. Hence, it became crucial to
visualize their dynamics in the cellular milieu, and the same directed the immense attention of the
researcher for the development of useful techniques for their real time monitoring at cellular level.
In this continuation, fluorescence microscopy using emissive molecular probes has grown as a
non-invasive optical tool for in-vitro/in-vivo cellular imaging to understand the role of various
biomolecules toward physiological changes and their influences at the cellular level. The
promising molecular markers with enhanced optical properties, cytocompatibility, photobleaching
resistance and target specificity constitute the backbone of fluorescence microscopy. Although,
the dedicated efforts led to the appreciable development of the molecular probes and their
successful employment for visualization of nucleic acids, the common shortcomings such as poor
photostability, cell-impermeant nature and photoinduced toxicity restrict their real applicability in
the biological fields. Moreover, the incorporation of aforementioned requisite parameters in a
single molecular probe has been rare and a challenging task. In this concern, we focused our keen
interest to crack these challenges and to bring the appreciable contributions toward the advanced
biochemical research. The molecular probes with a tailored donor-acceptor conjugated (D-π-A and
D-π-A-π-D pull-push systems) molecular architecture have been devised and synthesized. Their
optical behavior was studied both in solution as well as cellular milieu to explore their candidature
as promising DNA markers.
P-19
Modified Atomic Orbital Overlap: Molecular Level Proof of the
Nucleophilic Cleavage Propensity of Dinitrophenol-Based Probes Mangili Venkateswarulu,* Sunil Kumar, and Subrata Ghosh
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh
175005, India
Email: [email protected]
Out of six possible positional isomers of dinitrophenol, only 2,4-DNP has been used extensively
by many researchers for developing reactive molecular probes. But the question remains
unanswered: why has only the 2,4-isomer emerged as a labile protecting group? To answer this
question, six molecular probes using available DNP isomers were developed and investigated to
evaluate the effect of the extent of atomic orbital overlap on their reactivity. We have proved for
the first time at the molecular level that the o-NO2 group contributes less compared to the p-NO2
group toward the reactivity of 2,4-DNP-based probes. Crystal structure analysis revealed that the
2p orbital of N atom and the 2p orbital of the adjacent ring C atom to which the o-NO2 is attached
are inclined at >30° to each other, leading to substantial reduction in π overlap (as these two p-
orbitals loose coplanar state) resulting in a very weak −M effect of the o-NO2 group, whereas the
2p orbitals of the N atom of the p-NO2 group and the adjacent ring C atom are almost coplanar
(11° inclined to each other), leading to strong π overlap. Hence, the p-NO2 group contributes
largely toward the molecular reactivity through its −M effect.
Reference:
1. M. Venkateswarulu, P. Gaur, S. Sinha, A. Pramanik and S. Ghosh, J. Phys. Chem. C., 2015,
119, 19367-19375.
2. M. Venkateswarulu, Sunil kumar, and S. Ghosh, J. Org. Chem., 2017, 82, 4713–4720.
P-20
Multifunctional Metal organic framework for organic
transformation and photocatalysis application
Harpreet Kaur, M. Venkateswarulu, Pankaj Gaur, Suneel Kumar,Venkata Krishnan and Rik Rani
Koner*
School of Engineering and Basic Sciences, Indian Institute of Technology Mandi, Kamand,
Mandi 175005, Himachal Pradesh, India.
Email id – [email protected],[email protected]
In recent times, there is an enormous demand for developing materials, which can be used as
multifunctional materials for several industrial applications. Among the various kinds of materials,
metal organic frameworks(MOFs) have been found to be promising materials due to their tunable
structural property with different functional groups, high surface area etc.[1]MOFs have interesting
applications in the field of photocatalysis,[2] electrocatalysis as well as in various other areas. In
this direction, cadmium based MOF with 4,4’-bipyridine and 2-aminoteraphthalic acid moieties
has been developed[3]and investigated for sorption of iodine.Subsequently, the captured iodine was
employed for catalyzing various industrially relevant organic transformation reactions.The iodine
loaded MOF showed tremendous catalytic activity in the organic transformation of benzaldehyde
and o-phenylenediamine into benzimidazoles in a very short time (6 hr), which otherwise takes
more than 24h in the presence of simple molecular iodine. The same catalyst also showed
appreciable activity in the synthesis of 2-aminobenzothiazoles.In addition, this developed MOF
showed excellent photocatalytic activity towards the degradation of organic pollutant (MB dye)
under visible light irradiation.
References :
1. Li, Y. L., Zhao, Y., Wang, P., Kang, Y. S., Liu, Q., Zhang, X. D., & Sun, W. Y. 2016,Inorg.
Chem., 55(22), 11821-11830.
2. Wang, C. C., Li, J. R., Lv, X. L., Zhang, Y. Q., &Guo, G. 2014, Energy &Environ. Sci., 7(9),
2831- 2867.
3. Jiang, H. L., Tatsu, Y., Lu, Z. H., & Xu, Q. 2010, J. Am. Chem. Soc., 132(16), 5586-5587.
4. Kaur H.,Venkateswarulu M., Gaur P., Kumar S., Krishnan V., Koner R. 2017, manuscript
under preparation.
P-21
Tuning the surface enhanced Raman scattering activities of gold
nanorods by controlled coating of platinum
R. Gogoi, V. Sharma, N. Sinha, S. Dutt, M. Chawla and P. F. Siril*
Indian Institute of Technology Mandi, Mandi, (.H.P.)
Email: [email protected]
Gold is known to be a very good surface enhanced raman spectroscopy (SERS) active substrate. It can be further
enhanced when it is coated with non SERS active materials like Pt.1 But, the synthesis of core shell nanorods by
the galvanic replacement of silver (Ag) by platinum (Pt) on bi-metallic core shell nanorods (NRs)
having gold (Au) core and silver shell (Au@Ag) resulted in discontinuous coating of Pt over Au
(Au@Pt-DC) NRs due to the high cohesive and surface energies of Pt.2 However, a novel method
has been developed for the preparation of Au NRs having smooth and continuous coating of Pt
(Au@Pt-C NRs) in presence of
sulfuric acid as a source of
selective blocking agent. Here,
the role of the sulfuric acid in the
formation of differently coated
Au@Pt was analysed and the
effect of the nature of Pt shell
(i.e. whether continuous or
discontinuous) on SERS activity of the NRs was investigated with methylene blue (MB).
Additionally, prepared Au@Pt NRs have showed catalytic reduction of MB and 4- nitrophenol in
the presence of NaBH4 with Au@Pt-DC NRs showing almost three times better activity than Au
and Au@Pt-C NRs.
References
[1] L. Guerrini, E. Lopez-Tobar, J.V. Garcia-Ramos, C. Domingo, S. Sanchez-Cortes chem.
Commun., 47 (2011), p. 3174.
[2] E. Bus, J.A. van Bokhoven J. Phys. Chem. C, 111 (2007), p. 9761.
Figure 1: Galvenic replacement of Ag by Pt during the formation Au@Pt NRs.
P-22
Preparation and spectroscopic analysis of fluorescent banana fiber
A. Prasad
National Institute of Technology, Kurukshetra
Email: [email protected]
Banana fiber is a lingo-cellulosic fiber, which obtained from the pseudo-stem of the banana
plant. This constituted of cellulose, hemicellulose, lignin, pectin, wax and water-soluble
components. The abundance of this fiber combined with the case of its processing is an attractive
feature, which makes it a valuable substitute for synthetic fibers. In the present, we have extracted
banana fiber using a unique fiber extraction technique which preserves most of the fiber’s
mechanical and structural properties. The estimated mechanical properties of banana fibers were
found to be a function of diameter, testing speed, density etc. The thermal properties of the
composites have been evaluated using DSC and TGA while structural and spectroscopic properties
were explored using Scanning electron microscopy, Fourier transformed infrared and UV-Visible
absorption spectroscopy, PL etc. The prepared fibers emit bright yellow-red colors; however, a
clear shift in emission band was noticed. Detail result and analysis will be discussed during the
presentation.
P-23
Role of Nitrogen in the Activity Descriptor of Oxygen Reduction
Reaction in Iron based Catalysts
Ankita Mathur1, Aditi Halder2
1School of Engineering, Indian Institute of Technology Mandi, Mandi, HP, India
2School of Basic Sciences, Indian Institute of Technology Mandi, Mandi, HP, India
E-mail: [email protected]
Transition metal- nitrogen- carbon (M-N-C) based materials are suitable alternative of
platinum and effective electrocatalysts for oxygen reduction reaction (ORR) of polymer electrolyte
membrane fuel cell (PEMFC). Fe-N-C framework show very good catalytic activity towards ORR.
Nitrogen atoms have been found to play a significant role in creating active sites for the adsorption
of oxygen, such that with increase in FeN2 or FeN4 sites, the catalytic activity also increases.
Herein, we have prepared Fe-N-C based material by low cost hydrothermal treatment and annealed
in nitrogen atmosphere at 800°C. The electrocatalysts were characterized by X-Ray Diffraction
(XRD) for crystal structure, Field emission scanning electron microscope (FESEM) for structural
morphology and elemental composition determination, Raman Spectroscopy for vibrational modes
identification and X-Ray photoelectron spectroscopy (XPS) for determining the chemical bonding
between the elements. Electrochemical activity was also evaluated by rotating disc electrode and
rotating ring disc electrode. The reduction of oxygen occurs via four electron pathway, following
first order kinetics, leading to the formation of water as final product. By correlating the results of
physical and electrochemical characterizations it has been concluded that an optimum quantity of
nitrogen atoms create active sites and enhance the activity, beyond which they play no role in
activity descriptor.
Keywords: Polymer electrolyte membrane fuel cell, Oxygen reduction reaction, Non platinum
cathode electrocatalyst, iron oxide, Nitrogen atoms.
P-24
Perovskite (MAPbBr3) quantum dots: a potential color convertor Rajeev Ray, Supriya Ghosh, and Suman Kalyan Pal
Indian Institute of Technology Mandi, Kamand, Mandi, (.H.P.)
[email protected], [email protected]
Nowadays light-emitting diodes (LEDs) are used for both illumination and data communication in
the fields of solid-state lighting (SSL) and visible light communications (VLCs) [1]. However,
suitable materials for white and visible light emitting LEDs are still lacking. In this context, we
synthesize quantum dots (QDs) of MAPbBr3, which show green photoluminescence (PL) with
very high PL quantum yield (QY). The PL lifetime of the synthesized QDs are found to be 14.6
ns. A highly luminescent green emitting LED device was fabricated by embedding MAPbBr3 QDs
in a polymer matrix (PMMA) and using a blue LED. The fabricated device exhibits external
quantum efficiency as high as 47% suggesting the usefulness of the pervoskite QDs as colour
converter. Nonetheless, we investigate carrier dynamics of MAPbBr3 QDs using transient
absorption spectroscopy (TAS) to elucidate their PL properties.
Figure 1. (a) PL decay of MAPbBr3 QDs monitored at 505 nm. (b) Green emitting LED fabricated
using blue LED.
Reference
1. Burchardt, H.; Serafimovski, N.; Tsonev, D.; Videv, S.; Haas, H.VLC: Beyond point-to-
point communication. IEEE Commun. Mag. 2014, 52, 98−105.
P-25
Multiple Exciton Dissociation at CdSe-MoS2 Heterostructure
Aamir Mushtaq, Supriya Ghosh, Abdus Salam Sarkar and Suman Kalyan Pal
School of Basic Sciences and Advanced Material Research Center, Indian Institute of Technology Mandi,
Kamand 175005, H.P, India.
Email: [email protected]
van der Walls heterojunctions of layered transition metal dichalcogenides (TMDs) have shown promise for
the dissociation of excitons via fast charge transfer.1 Nowadays, scientists are trying to combine quantum
dots (QDs) and two-dimensional nanosheets into one nano-heterostucture for efficient energy and charge
transfers. We prepared a heterostructure of CdSe (cadmium selenide) QD and MoS2 (molybdenum
disulfide) nanosheet. Our steady state study reveals that the emission intensity of CdSe QDs found to be
greatly quenched in this heterostructure due to hole transfer from QD to MoS2 nanosheet as shown in the
figure 1(a).2 We have also obtained Transient absorption spectra for CdSe QDs with MoS2 nanosheets
following low laser fluences as shown in the figure 1(b) at 2.58 eV excitation. Our femtosecond transient
absorption studies divulge that exciton dissociates via hole injection in the timescale of 600 ps. Nonetheless,
we demonstrate extraction of two holes via dissociation of biexciton at the QD/nanosheet heterojunction.
We noticed that the first hole injects within 42 ps followed by slow injection of the second one as shown in
figure 2. Our study suggests that the exploitation of multiple exciton generation (MEG) effect by harvesting
multiple holes is possible.
Figure 1. (a) PL spectra of CdSe QDs and CdSe-MoS2 at 2.8 eV excitation. (b) TA spectra of
CdSe QDs with MoS2 nanosheets following 2.58 eV excitation(laser fluence 78J/cm2/pulse)
Figure 2. Biexciton dissociation and extraction of two holes at QD/MoS2 heterojunction.
(1) Hong, X.; Kim, J.; Shi, S.-F.; Zhang, Y.; Jin, C.; Sun, Y.; Tongay, S.; Wu, J.; Zhang, Y.; Wang, F. Ultrafast
charge transfer in atomically thin MoS2/WS2 heterostructures. Nat. Nanotechnol. 2014, 9, 682-686.
(2) Mushtaq, A.; Ghosh, S.; Sarkar, A. S.; Pal; S. K. Multiple Exciton Harvesting at Zero-Dimensional/Two-
Dimensional Heterostructures, ACS Energy Lett. 2017 (DOI: 10.1021/acsenergylett.7b00544).
P-26
Enantioselective gel formation and collapsing: A horizon for chiral
recognition
Diksha Gambhir, Gourab Dey, Venkata Krishnan and Rik Rani Koner*
School of Engineering and School of Basic Sciences, Indian Institute of Technology Mandi,
Kamand, Mandi 175005, Himachal Pradesh, India.
Gels are fascinating materials that can be encountered in everyday life in medicines, food items
and cosmetics. They exhibit interesting behaviors that are neither of a typical solid or a liquid thus
finding applications in a wide variety of fields including biotechnology, pharmacy, chemistry, and
material science. Enantioselective recognition garners a lot of attention due to its crucial role in
controlling events in pharmacological applications such as chiral sensors, enantioselective
separation and catalysis. Enantiomers tend to behave in the same manner in an achiral
environment, whereas in chiral environment they exhibit different properties. Therefore, different
chiral moieties have been designed in the last few decades such as chiral molecules(1), MOFs(2),
polymers(3), supramolecular gels(4) etc.. When chiral moiety is self-assembled into a gel, not only
the site selection but spatial selection could also be enhanced which in turn leads to enhanced chiral
recognition.(5) Thus, many research groups have keen interest in developing supramolecular gels
as chiral sensors.. Herein we report the self-assembling of an amino acid based optically active
pure ligand into gel by the selective incorporation of enantiomeric chiral amines and amino
alcohols. Additionally, the collapsing of gel in presence of different enantiomers validated its
enantioselective nature. The enantioselectivity is further supported by circular dichroism (CD)
spectroscopy.
References:
(1) Xu, S.-Y.; Hu, B.; Flower, S. E.; Jiang, Y.-B.; Fossey, J. S.; Deng, W.-P.; James, T. D.; Gao, H. J.;
Zhao, J. Z.; James, T. D. Chem. Commun. 2013, 49 (75), 8314.
(2) Wanderley, M. M.; Wang, C.; Wu, C.-D.; Lin, W. J. Am. Chem. Soc. 2012, 134 (22), 9050–9053.
(3) Yashima, E.; Iida, H.; Okamoto, Y. In Topics in current chemistry; 2013; Vol. 340, pp 41–72.
(4) Chen, X.; Huang, Z.; Chen, S.-Y.; Li, K.; Yu, X.-Q.; Pu, L. J. Am. Chem. Soc. 2010, 132 (21), 7297–
7299.
(5) Tu, T.; Fang, W.; Bao, X.; Li, X.; Dötz, K. H. Angew. Chemie Int. Ed. 2011, 50 (29), 6601–6605.
P-27
N-doped ZnO-MoS2 Binary Heterojunctions for Visible Light Driven
Photocatalytic Degradation of Tetracycline
Suneel Kumar,a Vipul Sharma,a Kaustava Bhattacharyyab and Venkata Krishnana*
aSchool of Basic Sciences and Advanced Materials Research Center, Indian Institute of
Technology Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.
bChemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra, India.
Email: [email protected]
Abstract
Pharmaceutical waste materials, mainly antibiotics such as tetracycline, have generated serious
threats to ecosystem and human life and their degradation into non-toxic compounds is of utmost
importance. In this work, we report the fabrication of binary semiconductor heterojunctions
comprising of N-doped ZnO nanorods loaded with two-dimensional MoS2 nanoflowers in varying
amounts, using a facile hydrothermal synthesis method. These semiconductor heterojunctions have
been demonstrated as highly efficient photocatalysts with enhanced performance under visible
light irradiation for the degradation of a pharmaceutical pollutant, tetracycline. The superior
photocatalytic activity of the heterojunctions can be attributed to the synergistic effect of N-doping
of ZnO and loading of MoS2 leading to higher absorption of visible light, efficient separation of
photo generated charge carriers and rapid charge transfer to reaction sites, as per the conduction
band potentials of both N-doped ZnO and MoS2. In addition, the two-dimensional nanoflower
morphology of MoS2 provides more reaction sites for the adsorption of pollutant, due to its large
surface area. Furthermore, the transfer of holes from the valence band of N-doped ZnO to the
valence band of MoS2 prevents the photocorrosion of N-doped ZnO resulting in enhanced
photostability of the catalyst during the reaction.
.
References:
[1] S. Kumar, V. Sharma, K. Bhattacharyya and V. Krishnan, N-doped ZnO-MoS2 binary heterojunctions: Dual role
of 2D MoS2 in the enhancement of photostability and photocatalytic activity under visible light irradiation for
tetracycline degradation, Mater. Chem. Front., 2017, 1, 1093-1106.
P-28
Lanthanide-doped NaYF4@CdS-Au-RGO nanocomposite with
upconversionluminescence property for photocatalytic applications Ajay Kumar, Kumbam Lingeshwar Reddy, Vipul Sharma, Suneel Kumar,Ashish Kumar and Venkata
Krishnan*
School of Basic Sciences and Advanced Materials Research Center, Indian Institute of Technology
Mandi, Kamand, Mandi 175005, Himachal Pradesh, India.
Email: [email protected]
In our work, we have made an attempt to prepare a novel multicomponent material, lanthanide-
doped NaYF4@CdS-Au-RGO nanocomposite and use this material for photocatalytic application.
Lanthanide-doped NaYF4@CdS core-shell structures decorated with Au nanoparticles supported
on reduced graphene oxide nanosheets were prepared using multi-step hydrothermal method. The
prepared nanoheterostructures were characterized by scanning electron microscopy (SEM),
transmission electron microscope (TEM), Raman spectroscopy, upconversion luminescence
(UCL), powder x-ray diffraction (PXRD) and x-ray photoelectron spectroscopy (XPS). As
Upconversion nanoparticles (UCNP) have the capability of converting infrared radiations into
visible light, they could be exploited for utilizing the infrared region of the sunlight for various
applications. Specifically in this work, we have utilized our multicomponent nanoheterostructures
for photocatalytic applications under natural sunlight. The different components of the prepared
nanoheterostructure could be efficiently used to utilize both the visible and infrared regions of the
sunlight. The photocatalytic application has been demonstrated by investigating the degradation
of a colored and a colorless pollutant.
References
(1) K. L. Reddy, M. Rai, N. Prabhakar, R. Arppe, S. B. Rai, S. K. Singh, J. M. Rosenholm, and V. Krishnan,
Controlled synthesis, bioimaging and toxicity assessments in strong red emitting Mn2+ doped NaYF4:
Yb3+/Ho 3+ nanophosphors. RSC Advances, 2016. 6(59), 53698-704.
(2) Z. Chen, S. Liu, M. Yang, and Y. Xu, Synthesis of Uniform Cds Nanospheres/Graphene Hybrid
Nanocomposites and Their Application as Visible Light Photocatalyst for Selective Reduction of Nitro
Organics in Water, ACS applied materials & interfaces, 2013. 5, 4309-19. (3) J. Zhang, Y. Huang, L. Jin, F. Rosei, F. Vetrone, and J. P. Claverie, Efficient Upconverting Multiferroic
Core@Shell Photocatalysts: Visible-to-Near-Infrared Photon Harvesting. ACS Applied Materials &
Interfaces, 2017, 9(9), 8142-50.
(4) Y. Tang, W. Di, X. Zhai, R. Yang, and W. Qin, NIR-responsive photocatalytic activity and mechanism of
NaYF4: Yb, Tm@ TiO2 core–shell nanoparticles. ACS Catalysis, 2013, 3(3), 405-12.
P-29
Spin-phonon coupling and exchange interaction in Gd substituted
YFe0.5Cr0.5O3
Karan Singh* Mohit K. Sharma and K. Mukherjee
School of Basic Sciences, Indian Institute of Technology Mandi, Mandi 175005, Himachal
Pradesh, India
E-mail: [email protected]
We report the evolution of physical properties due to partial substitution of Gd on the Y site in a
mixed metal oxide YFe0.5Cr0.5O3.This compound exhibits negative magnetization at low applied
fields. Our investigations on Y1-xGdxFe0.5Cr0.5O3 (x = 0.0, 0.2, 0.4 and 0.6) compounds is
carried out through magnetization and Raman spectroscopy studies. It is observed that even with
20% Gd substitution, the negative magnetization observed in YFe0.5Cr0.5O3 is suppressed. Due
to magnetic rare earth ion Gd3+, additional exchange interaction of the form GdO-Fe/Cr dominates
the magnetic interaction arising due to the transition metal ions. This results in positive
magnetization in Gd-substituted compounds. Temperature dependent Raman spectroscopy along
with magnetization studies revealed that the observed shifts of Raman mode is due to spin-phonon
coupling. Hardening of Raman mode observed below 240 K in YFe0.5Cr0.5O3 weakens and
softening of phonon modes was observed for Y0.4Gd0.6Fe0.5Cr0.5O3 compound. This implies
that additional magnetic interactions due to Gd ions play a dominating role in dictating the
behavior of the Gd-substituted compounds.
P-30
Facile Synthesis Of Pristine Graphene-Palladium Nanocomposites
With Extraordinary Catalytic Activities Using Swollen Liquid
Crystals
Tripti Vats1, Sunil Dutt2 , Raj Kumar 3and Prem Felix Siril 4
1 Indian Institute of Technology Mandi (IIT Mandi),Mandi ,INDIA
2,3,4 Indian Institute of Technology Mandi (IIT Mandi),Mandi ,INDIA
Email: [email protected]
Amazing conductivity, perfect honeycomb sp2 arrangement and the high theoretical surface area
make pristine graphene as one of the best materials suited for application as catalyst supports.
Unfortunately, the low reactivity of the material makes the formation of nanocomposite with
inorganic materials difficult. Here we report an easy approach to synthesize nanocomposites of
pristine graphene with palladium (Pd-G) using swollen liquid crystals (SLCs) as a soft template.
The SLC template gives the control to deposit very small Pd particles of uniform size on G as well
as RGO. The synthesized nanocomposite (Pd-G) exhibited exceptionally better catalytic activity
compared with Pd-RGO nanocomposite in the hydrogenation of nitrophenols and microwave
assisted C-C coupling reactions. The catalytic activity of Pd-G nanocomposite during nitrophenol
reduction reaction was sixteen times higher than Pd nanoparticles and more than double than Pd-
RGO nanocomposite. The exceptionally high activity of pristine graphene supported catalysts in
the organic reactions is explained on the basis of its better pi interacting property compared to
partially reduced RGO. The Pd-G nanocomposite showed exceptional stability under the reaction
conditions as it could be recycled upto a minimum of 15 cycles for the C-C coupling reactions
without any loss in activity.
P-31
Highly linear response Piezoresistive Strain Sensor based on
PDMS/g- C3N4/Graphene Heterostructure with tunable Bandgap
Sk Riyajuddin, Khushboo Soni, Aakanksha Sud, Sushil Kumar, Ehesan Ali, Kaushik Ghosh*
Institute of Nanoscience & Technology, Habitat Centre, Phase-10, Sector-64, Mohali- 160062,
India
Fig 1: Different Stacking pattern of graphene/gC3N4
Abstract:
Layered graphitic carbon nitride exhibit anomalous piezoresistivity attributed to the presence of
periodically spaced triangular holes resulting into a significant change in polarization on the
application of strain[1].This strain has also been used to modulate the electronic bandstructure of
graphene thereby enhancing piezoresistive behavior. Here Graphitic carbon nitride (g-C3N4)
nanosheets were encapsulated between a transparent and flexible heterostructures and uniaxial
strain upto ~22% was applied by two point bending setup. Resistance change has also been
reflected in IV characteristics with varying strain. This experimental analysis are strongly
supported by First-Principle Density Functional theory which predict a band-gap opening of
2.46eV for graphene/gC3N4 heterostructures under 20% uniaxial strain. For performing DFT we
Fig2: Band gap of graphene/gC3N4 bilayer
(a)
Graphene grown
on Cu foilC3N4 solution
Drop castPouring
PDMS
Curing
PDMSCopper
Etching
PDMS/gC3N4/Graphene
HeterostructureGraphene
Copper
PDMS
g-C3N4
(b)Bend 3(Max Bend)
No Bend
Bend 2
Bend 1
PDMS
Heterostructure
Graphene
Copper
PDMS
g-C3N4
Graphene grown
on Cu foil
Drop Casting of
C3N4 solution
Pouring
PDMS liquid
Curing PDMS
Etching of Copper
PDMS/gC3N4/Graphene
Heterostructure
(a)
0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24
0.10
0.15
0.20
0.25
0.30
R
/R0
0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24
-0.24
-0.22
-0.20
-0.18
-0.16
-0.14
-0.12
-0.10
-0.08
I/
I 0
(c)
0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0.22 0.24
0.0
0.4
0.8
1.2
1.6
2.0
Gauge Factor
Sensitivity
Ga
ug
e F
acto
r/S
en
siti
vit
y(
(d)
-1.0 -0.5 0.0 0.5 1.0
-5.00E-012
0.00E+000
5.00E-012
1.00E-011
1.50E-011
2.00E-011
2.50E-011
3.00E-011
I
V
PDMS / g-C3N
4 Max Bend
PDMS/ Graphene Max Bend
(e)
0.0 0.5 1.0
0.00E+000
2.00E-012
4.00E-012
6.00E-012
8.00E-012
1.00E-011
1.20E-011
I
V
PDMS / Graphene No Bend
PDMS / Graphene Max Bend
(f)
0.0 0.5 1.0
1.00E-011
2.00E-011
3.00E-011
4.00E-011
No Bend
Bend 1
Bend 2
Bend 3
I
V
(g)
0.0 0.5 1.0
0.00E+000
5.00E-012
1.00E-011
1.50E-011
2.00E-011
2.50E-011
3.00E-011
3.50E-011
I
V
PDMS/ g-C3N
4 Max Bend
PDMS/ g-C3N
4 No Bend
PDMS / Graphene No Bend
PDMS / Graphene Max Bend
(h)
(c)
(d)
(e)(f)
(b)
0.00 0.05 0.10 0.15 0.20 0.25
-0.25
-0.20
-0.15
-0.10
-0.05
0.00
I/
I 0
Strain (%)
Equation y = a + b*x
Weight No Weighting
?$OP:A=1 Intercept
?$OP:A=1 Slope
0.0 0.5 1.0
12
18
24
30
36 0%
7.6%
15.2%
22.2%
Cu
rren
t (
A)
Voltage (V)
500 1000 1500 2000 2500 3000
PDMS
Raman shift (cm-1)
PDMS/Graphene
Inte
nsi
ty
PDMS/C3
N4/Graphene
480
605
699 PDMS/ g-C3N4/Graphene Max Bend
PDMS/ g-C3N4/Graphene No Bend
PDMS / Graphene No Bend
PDMS / Graphene Max Bend
0.0 0.5 1.00
5
10
15
20
25
30
35
Cu
rren
t (
A)
Voltage (V)
0 4 8 12 16 20 24
0.00
0.05
0.10
0.15
0.20
0.25
0.30 Data points
Linear fit
R
/R0
Strain (%)
Equation y = a + b*x
Weight No Weighting
Residual Sum of Squares
6.62963E-4
Pearson's r 0.99341
Adj. R-Square 0.98028
?$OP:A=1 Intercept
?$OP:A=1 SlopeGF = 1.38
Fig3: Increase in relative resistance change with the
strain
Fig4: Band structure opening in graphene/gC3N4
bilayer
consider the generalized gradient approximation (GGA) with PBE-D2 fictional using the plane
wave basis Vienna Ab initio Simulation package (VASP) code. The structural optimization and
electronic structure calculations, the convergence tolerance of force on each atom was set at 0.01
eV Å-1. The convergence criterion for energy is chosen as 10-6 eV. The 2-D Brillouin zone is
sampled by 11x11x1 k-points within the Monkhorst-Pack scheme. The graphene/g-C3N4
heterostructure was constructed using a supercell which contains one g-C3N4 monolayer and one
graphene monolayer. The lattice parameters of graphene and g-C3N4 are 2.46 Å and 7.10 Å,
respectively. The lattice parameter of g-C3N4 is about three times larger than graphene monolayer,
which means a 1x1 supercell g-C3N4 and a 3x3 supercell graphene are used .In geometric
optimization, the position of all atoms in supercell are fully relaxed but the shape and volume of
supercell are fixed. We consider four staking patterns which are as follows(1)pattern I ,N atoms of
g-C3N4 are placed above C atoms of the graphene .(2)pattern II, C atoms of g-C3N4 are placed
above C atoms of graphene. (3) Pattern III, N and C atoms of g-C3N4 are placed right above C
atoms of graphene. (4) Pattern IV, part of C atoms of g-C3N4 are placed on bridge sites of graphene
surface as shown in Fig 1. Among all, pattern II (C atoms of g-C3N4 are placed above C atoms of
graphene) is more favourable than others because of higher binding energy. For understanding the
effect of band gap changes with strain applications [2]we have applied a uniaxial strain from -12%
to +20 % on pattern II (most stable) with interlayer distance of 3.14 Å .We found that the pattern
II can withstand strain from -4% to +20% without distorting the structure. For strains less than -
4% the structure gets unstable moreover the bilayer will be bent. The band gap increases with
increasing applied strain.[3]Fig2. For the strain of -6% the band gap increase to 0.64 eV and it
increase to 2.46 eV for strain of +20%. These results strongly support the enhancement of
resistance on the application of strain which may pave the way for tuning the bandgap of
semiconducting materials. Moreover, the proposed heterosture can serve as a good alternative for
developing new sensor which can be embedded into structural material and operate as
multifunctional sensor with high strain resolution on nanoscale.
References:
[1] M. Zelisko, Y. Hanlumyuang, S. Yang, Y. Liu, C. Lei, J. Li, P.M. Ajayan, P. Sharma,
ARTICLE Anomalous piezoelectricity in two-dimensional graphene nitride nanosheets, Nat.
Commun. 5 (2014).
[2] Xinru Li, Ying Dai, Yandong Ma,Shenhao Han , Baibiao Huang,Phys. Chem. Chem. Phys.,
2014.
[3] M.M. Dong,C.He,W.X.Zhang ,J.Mater.Chem.C,2017.
P-32
Dielectric Relaxation Phenomena of N,N-Dimethylformamide in
Different Solvents from Conductivity Measurement under 9.90 GHz
Electric Field.
Soumya Sundar Pattanayak, Tushar Bachar, Swagatadeb Sahoo
Department of Electronics & Instrumentation Engineering, National Institute of Technology,
Silchar, Assam 788010, India.
Email: [email protected]
Dielectric relaxation studies of N,N-dimethylformamide(DMF)(j) dissolved in various nonpolar solvents(i)benzene
(C6H6),dioxane (C4H8O2) and carbon tetracholaride (CCl4) at 250,350,450 and 550C are attempted by measuring the
conductivity of the solutions under 9.90 GHz electric field using Debye theory.Microwave has capacity to detect weak
molecular association[1,2].Measured dielectric properties are an intermediary vehicle for understanding, explaining
and empirically relating certain physico-chemical properties of the test material[3,4].Permittivity(εij) of polar-non
polar liquid mixture is measured using Rohde & Schwarz made ZNB-20 Vector Network Analyzer, Dielectric
Assessment Kit (DAK) and DAK Evaluation software .The estimated relaxation time (τj’s) and dipole moment (µj’s)
agree well with the reported values[5] signifying the validity of the proposed method. Solute-solvent and solute-solute
molecular associations are ascertained in different molecular environments[6,7]. The associational aspects are taken
into consideration from theoretical µtheo from the standpoint of inductive, mesomeric and electromeric effects within
the polar groups of the molecules. The thermodynamic energy parameters are calculated from Eyring rate theory to
predict the molecular dynamics of the system[8].
20 30 40 50 60
1.00E-029
1.20E-029
1.40E-029
1.60E-029
(I)
(II)
(III)
j
t in 0C
a)
b)
Figure 1. Variation of µj’s of polar-nonpolar
mixture at 250, 350, 450 and 550C temperatures
under 9.90 GHz electric field. (I) ── ──
DMF+C6H6 (II) ── ── DMF+ dioxane (III)
── ── DMF + CCl4 respectively.
Figure 2. Solute-solvent and solute-solute molecular
associations: a) DMF + CCl4 b) DMF + DMF.
References: [1] M. Robinovitz, A. Pines J. Am .Chem. Soc., 1969, 91(7), pp 1585-1589.
[2] R. Kumar, R. K. Chaudhary, V. S. Rangra Indian . J. Phys., 2012, 86(7), pp. 635-640.
[3] S. Sahoo , S. K. Sit Mat. Sc. EnggB., 2009, 163, pp. 31-39.
[4] S. Sahoo , S. K. Sit Can. J. Phys., 2016, 94, pp. 1-12.
[5] K. V. Gopalakrishna Trans. Faraday Soc., 1957, 53, pp. 767- 770.
[6] S. K. Sit, K. Dutta, S. Acharyya, T. Pal. Majumder , S. Roy Journal of Molecular Liquids., 2000, 89, pp. 111-126.
[7] S. Sahoo , S. K. Sit Pramana. J. Phys., 2017, 88, pp. 11-23.
[8] S. Sahoo,T. R. Middya , S. K. Sit Pramana. J. Phys., 2014, 83(4), pp. 579-595.
INDIAN INSTITUTE OF TECHNOLOGY MANDI
SPECTROSCOPY OF EMERGING FUNCTIONAL MATERIALS, OCT 9-10, 2017
The following committees have been formed for the organization of the symposium.
Registration & Welcome
Dr. Ajay Soni (Convener)
Members: Dr. Rik Rani Koner, Ms Stuti Sharma, Mr Supriya Ghosh, Juhi Pandey, Dr Dushyant
Kushavah, Diksha Gambhir, Shailija Sharma, Bulti Pramanick, Ms. Diksha Thakur
Program and Venue management
Dr Jaspreet Kaur (Convener)
Members: Dr Suman Kalyan Pal, Mr Prakash Negi, Mr Aamir Mushtaq, Ashish, Abdus Salam
Sarkar, Somnath Acharya
Accommodation & Transportation
Dr. Kaustav Mukherjee (Convener)
Members: Dr Pradeep Kumar, Mr Pavin Samuel, Mr. Rakesh Bhatt, Kavita Yadav, Rajeev Ray,
Birender Singh, Mohit Kumar Sharma
Food & Refreshments
Dr. Prem Felix Siril (Convener)
Members: Mr Anoop Kumar, Rituporn Gogoi, Surender Lal, Prateep Singh Sagara, Nagaraju
Nakka
Public Relation & Media Management
Dr. Chandra Shekhar Yadav (Convener)
Members: Dr. Subrata Ghosh, Ms. Chandan Sharma, Santu Nandi