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J A D E C A R C A M O

The Raman effect was named

HISTORYThe Raman effect was named

after one of it’s discoverers, Chandrasekhara VenkataRaman, who observed the effect by means of sunlight He effect by means of sunlight. He won the Nobel Prize in Physics in 1930; by using sunlight he discovered that light of changed frequency passed changed frequency passed through the "crossed" filter.

Systematic pioneering theory of Systematic pioneering theory of the Raman effect was developed by George Placzekbetween 1930 and 1934. At the time mercury arc was the the time mercury arc was the principal light source, now lasers are used as light sources.

BASICS

It’s a spectroscopic technique based on inelastic scattering of inelastic scattering of monochromatic light.

Frequency of the reemitted photons is shifted up or down in comparison with original original monochromatic frequency, which is called the Raman Stokes scattering: photons with lower energy - phonon is emittedcalled the Raman effect.

Stokes scattering: photons with lower energy - phonon is emitted.Anti-stroke scattering: photon with higher energy - phonon absorbed.

BASICS CONT.There are different types of Raman

spectroscopy, including surface-enhanced Raman, tip-enhanced

Transmission Raman - Allows probing of a significant bulk of a turbid material, such as powders, capsules, living tissue, etc. It enhanced Raman, tip enhanced

Raman, polarized Raman, femtosecond broadband stimulated Raman, transmission Raman,

p , p , g ,was largely ignored following investigations in the late 1960s but was rediscovered in 2006 as a means of rapid assay of pharmaceutical dosage , ,

resonance Raman, spatially-offset Raman, and hyper Raman.

Resonance Raman spectroscopy - The excitation

p y p gforms.

Spatially Offset Raman Spectroscopy (SORS) - The Raman scatter is collected from regions laterally offset away from

wavelength is matched to an electronic transition of the molecule or crystal, so that vibrational modes associated with the excited electronic state are greatly enhanced.

from regions laterally offset away from the excitation laser spot, leading to significantly lower contributions from the surface layer than with traditional Raman

Hyper Raman - A non-linear effect in which the vibrational modes interact with the second harmonic of the excitation beam.

Raman.

SURFACE-ENHANCED RAMAN SPECTROSCOPY (SERS)Surface-enhanced Raman spectroscopy

(SERS) has been developed as a direct, extractionless, nonhydrolysistool to detect lake pigments and

(SERS)

p gcolorants of various classes used in a variety of artist materials.

SERS is a surface sensitive technique that results in the enhancement of Raman scattering by molecules

d b d h l fadsorbed on rough metal surfaces.

The enhancement factor can be as much as 10^14 – 10^15, which allows the technique to be sensitive enough to detect single molecules.

SER enables the detection of individual molecules and uniquely identifies the molecules.

Very careful consideration of all physical and y p ychemical factors should be done while interpreting SERS spectra which makes it extremely difficult for practical use.

TIP-ENHANCED RAMAN SPECTROSCOPY (TERS)Tip-enhanced Raman provides highly

localized enhancements and offers more uniform enhancement when scanning over the samplescanning over the sample.

Huge observed enhancements of 70-80x, corresponding to net enhancements of 10^4 have been achieved for brilliant cresyl blue test analyte using Ag coated tips made from or preAg-coated tips made from or pre-coated with low refractive index materials. The yield of tips giving significant enhancement to the Raman signals is found to be close to 100%.

POLARIZED RAMAN SPECTROSCOPY (PRS)

Polarized Raman spectroscopy is based on the control of the linear polarization states of the polarization states of the incident and scattered radiations.

The polarization of the Raman scattered light also contains scattered light also contains useful information. This property can be measured using (plane) polarized laser excitation and a polarization analyzerpolarization analyzer.

This technique is useful in teaching the connections between group theory, symmetry, Raman

ti it d k i th activity, and peaks in the corresponding Raman spectra.

FEMTOSECOND BROADBAND STIMULATED RAMAN SPECTROSCOPY (FSRS)

Femtosecond broadband stimulated Raman spectroscopy is a new ultrafast spectroscopic technique that provides vibrational structural information with high temporal (50-fs) and spectral (10-cm−1) resolution.

It produces high-quality vibrational spectra free from background fluorescence.

FSRS f d d l i d FSRS spectra of standard solutions and solvents such as aqueous Na2SO4, aqueous KNO3, methanol, isopropanol, and cyclohexane are

ll d i d Matteo Rini (left) and Andrea Cavalleri used femtosecond spectroscopy collected in seconds. Matteo Rini (left) and Andrea Cavalleri used femtosecond spectroscopy techniques with visible light to measure the speed at which thin films of vanadium dioxide make the phase transition from an electrical insulator to a conductor.

TEXTILE ANALYSIS

The discovery and exploitation of organic colorants as textile dyes

Researchers had little textiles to work with so identifying the y

and lake pigments is a distinguishing accomplishment of

so identifying the colorants was difficult until the SERSacco p s e t o

ancient civilizations. Compounds in plants and

insects were used as

SERS.The SERS is able to

identify dyes in insects were used as mordant dyes for textiles.

objects as small as 25 μm in diameter.

Guineau was the first person to use the SERS in this way, in 1987, when he obtained SERS spectra of alizarin extracted from madder dyed textile samples.

EGYPTIAN PAINTED LEATHERFRAGMENTThe SERS

successfully A 488 nm laser is

used with the

FRAGMENT

successfully identifies the dyestuff madder

used with the pink dye because there is an dyestuff madder

in a 25 μmsample from an

there is an increase in sensitivity when

ancient Egyptian painted leather f

handling such a small sample.

fragment.

EGYPTIAN PAINTED LEATHERFRAGMENT CONTThe archeological and historical significance of the

discovery is very remarkable: the detection of

FRAGMENT CONT.

discovery is very remarkable: the detection of madder in the 4000 year old leather fragment represents the earliest evidence so far for the chemical knowledge necessary to obtain a dye from a plant source.

BONE FRAGMENT & RED DYED WOOL THREAD

All SERS spectra were recorded between 2000 and 200 cm 1 by

The effectiveness of the SERS method was confirmed by the and 200 cm−1 by

collecting 30 scans with an exposure time of 4 s. The SERS

confirmed by the identification of Tyrianpurple on the purplish bone fragment found in

measurements were performed by focusing the laser beam on a drop of the dye

gthe tomb of the martyrs Gervase and Protasewhich was in good agreement with the drop of the dye–

nanoparticle system deposited on the surface of a glass slide.

agreement with the reference commercial material.

g

(a) 150 μl of DMF extract of a purplish bone fragment from the tomb of themartyrs Gervase and Protase in the Basilica of Sant’Ambrogio, Milano; (b) 150 μl of a DMF solution of commercial Tyrian purple, both added to 1 ml of Ag colloid prepared and (c) 150 μl of a MeOH solution of commercial indigo, added to 1 ml of Ag colloid prepared after the addition of 35 μl ofNaCl 1 M

Mi FTIR t f th t t bt i d f d d d l th d f d i th Micro-FTIR spectrum of the extract obtained from a red-dyedwool thread found in the Royal Tumulus of In Aghelachem, Libya.

CONCLUSION

The SERS spectroscopy was successfully applied on silver colloids to the identification of two natural organic dyes, Tyrian purple and madder, as reference commercial materials and verified the real effectiveness of the SERS methodreal effectiveness of the SERS method.

CHINESE SHANG DYNASTY KNEELING STATUE

Professor of materials science at Northwestern, Katherine Faber

The unusual color of the statue is likely to be the result of two factors Katherine Faber,

investigated a statue of a kneeling figure from the Shang Dynasty

result of two factors. Heating of the piece and subsequent treatment with Japanese wax, are g y y

(1600-1045 BC) in its ancient Chinese jade collection that is so dark as to be almost black

p ,the likely culprits.

as to be almost black –not the vibrant green one traditionally associates with jade jpieces.

ned

dra

gon

Jade

coi

leJ

Jade slit rings (jue) Jade congJade ornament for the top of an axe shaft

THE GAYER-ANDERSON CAT

One of the most famous pieces in the British Museum. Dating from around 600 BC.g

X-ray investigation indicated that the piece had been made using a lost-wax technique consistent with the period it was believed to have dated from but it also revealed was believed to have dated from, but it also revealed serious damage.

Further analysis with Raman Spectroscopy revealed chloride and copper oxide The analysis revealed a pigment that and copper oxide. The analysis revealed a pigment that resembled “Brunswick green.”

They also used endoscopy and found flax fibers and pieces of skin.

WORK CITED“Raman Spectroscopy Basics” -

http://content piacton com/Uploads/Princeton/Documents/Library/UpdatedLibrary/Rhttp://content.piacton.com/Uploads/Princeton/Documents/Library/UpdatedLibrary/Raman_Spectroscopy_Basics.pdf

“Tip Enhanced Raman Spectroscopy”- http://www.zenobi.ethz.ch/raman.html

“From polarized to polarimetric Raman spectroscopy” - http://www.epj-f /i d h ? i i l & d d&I id 129& l /conferences.org/index.php?option=com_article&access=standard&Itemid=129&url=/

articles/epjconf/pdf/2010/04/epjconf_API09_06002.pdf

“First Femtosecond X-Ray Spectroscopy at ALS” -http://www.lbl.gov/Publications/Currents/Archive/Sep-16-2005.html

“Chinese Jade” -http://www.britishmuseum.org/explore/online_tours/asia/chinese_jade/jade_coiled_dragon.aspx

“Looking over the Artist’s Shoulder” by Cordelia Sealy from Oxford Science Writing Ltd., g y y g ,Oxford, UK

“Identification of Organic Colorants in Fibers, Paints, and Glazes by Surface Enhanced Raman Spectroscopy” by Francesca Casadio, Marco Leona, John R. Lombadis, & Richard Van Duyney

“Microanalysis of organic pigments and glazes in polychrome works of art by surface-enhanced resonance Raman scattering” by Marco Leona

APPLICATION OF RAMAN TO ART

Jade CarcamoSeptember 29, 2010September 29, 2010

WHAT IS RAMAN?WHAT IS RAMAN?Raman spectroscopy it is p pybased on the detection of scattered light. It is a technique based on inelastic scattering of laser light that gives information about the vibrational, rotational, and other low-frequency modes of a molecular system. It has proved to be useful in

l i i i analyzing inorganic pigments in works of art and cultural heritage b it i d t ti because it is non-destructive and doesn't require sampling.

Surface-enhanced Raman spectroscopy is allowing art conservators to rewrite sections of art history.sect o s o a t sto y.

SERS Non-destructive and can identify natural

pigmentsTh t h i i b d th f t th t h The technique is based on the fact that when an incident photon in a laser beam is scattered inelastically by a material its frequency changesinelastically by a material, its frequency changes.

Raman spectroscopy is very helpful in the investigation of artwork.investigation of artwork.

Raman spectroscopy, is named after the Nobel laureate Sir Chandrasekhara Venkata Raman who discovered the effect.

Developed in the 1970s

I SERS l li hIn SERS, laser light(enhanced by striking

l f t la layer of metalnanoparticles) isscattered by smallamounts of organicamounts of organicpigment

FOR TO BE A FARMER’S BOY

American artist Winslow Homer watercolor i ti “F t b F ’ B ” 1887 painting “For to be a Farmer’s Boy” 1887 was

examined by the method Surface Enhance Raman Spectroscopy (SERS) Raman Spectroscopy (SERS).

Direct SERS applied for the first time to the identification of both

th ti d t l i synthetic and natural organic dyes present in a wide variety ofartist materials in various media including a pastel study

polyphenols, rhodamines media, including a pastel study

attributedto the American artist Mary Cassatt Positive identification

rhodamines,azo pigments andanthraquinones. Cassatt. Positive identification

waspossible on a sample as small as a single grain of pigment

anthraquinones.

THE STUDY IS LIMITED

The study of artwork through Raman is limited. Natural dyes are easily damaged by light and

flfluorescence Natural dyes were replace by synthetic dyes not

until the late 1800s and 1900s until the late 1800s and 1900s The usefulness of SERS in the art world is

limited by a need for experienced spectroscopistslimited by a need for experienced spectroscopists.

SIMILAR METHOD

SERRS Surface-Enhanced Resonance Raman

S tSpectroscopy In SERRS, the laser light is absorbed by the

analyte which doesn’t happen in SERSanalyte, which doesn t happen in SERS. SERRS is 1000–1 000 000 times more sensitive

than SERSthan SERS.

Francesco GranacciIn analyzing St John the Baptistbearing witness, it was establishedthat the main red pigment in

Francesco Granacci.

Europeduring the Renaissance came froman insect dye called kermes. Theanalysis also demonstrated for thefirst time that SERRS could detectdyes in glazes of oil paintings.

MARCO LEONA

Director of the Conservation Department at the Met o olitan M e of A t NYCat the Metropolitan Museum of Art, NYC

CONSERVATION

Experimental set-up for the non-destructive Raman spectroscopic investigation of

t til b a textile banner in the National Museum of S tl dScotland

DYES

Plant Dyes: Madder and Lac - Organic plant based pigmentI t D K Insect Dyes: Kermes

Egyptian painted quiver

In SERRS microanalytical samples of materials such as In SERRS, microanalytical samples of materials such as coatings and dyes are dispersed and coupled to a colloidal support material, which has a doubly beneficial effect. Firstly it quenches the fluorescent light which in normal Firstly, it quenches the fluorescent light, which in normal Raman spectroscopy is the major source of noise, and secondly, it enhances the Raman signal itself by a combination of mechanisms that is still the subject of combination of mechanisms that is still the subject of investigation.

OTHER ART WORKSWORKS

Raman Spectroscopy was also Raman Spectroscopy was also used by UCL Professor Robin Clark (UCL Chemistry) and Libby Sheldon (UCL History Libby Sheldon (UCL History of Art) to authenticate the pigments in the painting by Johannes Vermeer (1632-(1675) of a Young Woman Seated at The Virginals, which sold in London July 7th, 2004 for £16,245,600.

IN SHORT

Surface-enhanced Raman spectroscopy (SERS) The technique is non-destructive and can detect

i t t f t l i tminute amounts of natural pigments. Important method for the conservation of

artworkartwork.

SOURCES

http://www.soci.org/Chemistry-and-Industry/CnI-Data/2010/4/An-analytical-renaissancehtt // / t t/106/35/14757 f ll http://www.pnas.org/content/106/35/14757.full

http://www.rsc.org/chemistryworld/restricted/2010/January/TheArtOfRaman asp0/January/TheArtOfRaman.asp

www.chemistryworld.com Spectroscopy in Arthtt // / h i t ld/ t i t d/201 http://www.rsc.org/chemistryworld/restricted/2010/January/TheArtOfRaman