2016-05 Summer school-Smirnov upload - National MagLab · Timeline 1923 – Inelastic light scattering is predicted by A. Smekel 1928 – Landsberg and Mandelstam see unexpected frequency

Optical Spectroscopy of Condensed Matter

Dmitry Smirnov Maglab Users Summer School May 2016



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Outline

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Study of interaction of matter with light (or photons)Spectrum : response of matter to EM radiation as a function of energy

Electromagnetic spectrum, after a diagram from SURA(D.Tanner, Optical Effects in Solids)

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Study of interaction of matter with light (or photons)Spectrum : response of matter to EM radiation as a function of E (or wn, or !)

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Wavelength1 km 1 m 1 mm 1 µm 1 nm

UVX-ray

Radio Microwave

IR

1 mm

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1 m Proto-ocean protected early life from the Sun’s UV

Photosynthesis harvesting Vis range photons

Vision in the visible range

Spectroscopist’s take on life’s development on Earth

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Probe various structural, electronic and magnetic states/excitations in matter

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Probe various structural, electronic and magnetic states/excitations in matter

introduce tunable length scale

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… interaction energy scale

!

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breaks time-reversal symmetrybreaks time-reversal symmetry !5*/(.'#NO%;4+,!!!?7

High magnetic fields in condensed matter physics

High magnetic fields in condensed matter physics

introduces tunable length scale

-

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introduces tunable length scale

lm ��

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… tunable orbital and electron spin energy scales

m* m ~ 0.1

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… interaction energy scale

!

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Raman scatteringPhoto-Luminescence (PL)

Reflection and Transmission Uv, Vis, IR, THz

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Temperature

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Photoconductivity, electroluminescence, ...

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Excitation spectroscopy

Broad-band spectroscopy

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High energy stateselectronic states or bandsimpurities

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Vis spectroscopy

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Physics spectroscopic probe of structural, electronic and magnetic states or excitations

Physics:

Chemistry

analytical tool to determine composition, structure, ...Biology…

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http://www.cryst.ehu.es

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http://www.cryst.ehu.es/html/lekeitio-docs/mihailova-presentation.pdf

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• Frequency domain spectroscopy (dispersive spectrometers)

UV-Vis-NIR spectral region : ~ 1 eV scale

• Raman spectroscopy

• Fourier transform infrared (FTIR) spectroscopyIR-THz spectral region ~ 1-1000 meV

UV-Vis-NIR (~ 1eV) probe of low energy excitations (~meV)

Conventional (dispersive) optical spectrometer based on a broadband source and dispersive elements (prism, grating)

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Price in 1704: £1Price today: $62,000

Frequency domain spectroscopy (UV-VIS-NIR)


Conventional (dispersive) optical spectrometer based on a broadband source and dispersive elements (prism, grating)

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s(") - complex transmission/reflection coefficient

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|s(!)|2 =Isample(!)

Iref (!)


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Czerny-Turner spectrometer for Vis spectroscopy, Raman scattering and PL

William Herschel, February 11th 1800

F.W. Herschel, Phil. Trans. Royal Soc. London 90, 49 (1800).

Birth of IR spectroscopy

Infrared spectroscopy

Infrared spectroscopy

Fourier transform infrared (FTIR) spectroscopy

Light source

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1. Interferogram

T (⌫) =Sair(⌫)

Svac(⌫)


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What is special about IR spectroscopy ?

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Timeline

1923 – Inelastic light scattering is predicted by A. Smekel1928 – Landsberg and Mandelstam see unexpected frequency shifts in scattering from quartz1928 – C.V. Raman and K.S. Krishnan see “feeble fluorescence” from neat solvents 1930 – C.V. Raman wins Nobel Prize in Physics

4<*2"%*'28&?]d]!+4*C.$9(/

"A new type of Secondary Radiation", Nature, 1928

1960 – Invention of laser made Raman experiments more effective and meaningful

1964 – Townes, Basov, Prochorov win Nobel Prize in Physics for the invention of the maser and the laser

Here again, Ted Maiman was the first to have a first working laser!

Raman spectroscopy

What is special about Raman spectroscopy ?

H(".*'+5*)#<$2'*a*Q**#$**Qbc*I**QbQd*&1+-+$)*#)*)%2O("(>*#$('2)9%2''.

Devereaux and Hackl,RMP. 79, 175 (2007)10-7

< 10-9Ram

an e

ffici

ency

What is special about Raman spectroscopy ?

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N e#(/!1#4*8G!&9/&!@9+%.$+9#(!+%.4'$#6.'.$+

CW Magneto-Optical Spectroscopy at MagLab

CW optical magneto-spectroscopy @ MagLab

FTIR Magneto-Spectroscopy


FTIR Magneto-Spectroscopy

d.($9R+.(!!"#$%G!!7He!Qbd!"])G!M]JIMI!"LMKM)

Interaction-induced Shift of the CR in Monolayer Graphene


Spatially resolved PL and Raman spectroscopy

Sample plate

x-y travel : ~2.5mmPiezo-stages

z travel : ~3mm

Excitationfiber

Collectionfiber

Working distance:~1.5mm


Spatially resolved PL and Raman spectroscopy

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J<:*+&<$-6/&%0C6'*&K</>&(&LM&A<'/*+& Magnet Temperatures Techniques

45T 1.5K-300K PL, Raman,

35T 1.5K-300K PL, Raman,

31T (cell#9)

300mK-70K 1.5K-300K

PL, Raman, spatially resolved

18T (SCM2)

300mK-70K 1.5K-300K

PL, Raman, spatially resolved

17.5T (SCM3)

4K-100K PL, Raman, spatially resolved

14.5T (EMR)

4.5K-300K PL, Raman, spatially resolved

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Spatial resolved micro-PL: Examples

Spectroscopyofexcitonsinmonolayersemiconduc9ngTMDs(MoSe2,WSe2)

Semiconducting monolayer TMDs

hνi

E

k

Photoluminescence (PL)

EPL

Neutral exciton

Charged exciton (trion)

e-h+

e-h+ EPL

e-

h+

Charged exciton (trion)

e-

h+

e-EPL

TMDs: Strongly bond excitons ! EX0: ~ 500 meVEX!: ~ 30 meV

h"excit

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MoSe2

WSe2

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-30

-20

-10

0

10

20

30

Field(

T)

1.761.721.68Energy(eV)

>i >M

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B


Magnet-Raman spectroscopy: Examples

Charge-lattice-spin coupling in Co[N(CN)2]2

Brinzari, T. V. et al. Phys. Rev. Lett. 111, 047202 (2013).

LAB PRACTICALS - Optical spectroscopy of Al203

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Two Al2O3 groups per unit cell

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Photoluminescence

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Outline

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Documents

2016-05 Summer school-Smirnov upload - National MagLab · Timeline 1923 – Inelastic light scattering is predicted by A. Smekel 1928 – Landsberg and Mandelstam see unexpected frequency