Raman Spectroscopy

1. Uka Tarsadia University
Tarsadia Institute of Chemical Science
Raman Spectroscopy: Instrumentation & Application in Research
Presented by: Pinalkumari Sanjaykumar Bhavsar
Enrollment No: 202108100910004
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2. Content
Introduction
History of Raman spectroscopy
Principle
Instrumentation
Application in Research
Topes modal of Raman instruments
How to plot Raman spectrum?
References
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3. Sir Chandrasekhara Venkata Raman
Awarded Noble Prize in Physics in 1930.
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4. Principle
When monochromatic radiation is incident upon a sample then this light
will interact with the sample. It may be reflected, absorbed or scattered in
some manner. It is the scattering of the radiation that occurs which gives
information about molecular structure.
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5. Raman is based on scattering. Most of the radiation is elastically scattered
(called the Rayleigh scatter).
A small portion is inelastically scattered (Raman scatter, composed of stoke
and anti-stokes portion)
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7.  Instrumentation for Raman spectroscopy consist of four components:
1.Laser or source of light
2.Filter
3.Sample holder
4.Detector
1. Laser or source of light:
 The sources used in modern raman spectrometry are nearly always laser
because their high intensity is necessary to produce Raman scattering of
sufficient intensity to be measured with a reasonable signal-to-noise ratio.
Instrumentation 7

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List of various Laser source for Raman spectroscopy:

9.  Band pass filters are used to isolate a single laser beam. A combination of
notch filter and high quality grating monochromator is mostly employed in
dispersive instruments.
 Double or even triple grating monochromators, super notch filters,
rejection filters, holographic notch or edge filters and holographic filters are
used to separate relatively weak Raman lines from intense Rayleigh
scattered radiations.
2. Filter
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10. 3. Sample holder
 For the study of Raman effect the type of sample holder to be used depends
upon the intensity of sources, the nature and availability of the sample.
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11. 4. Detector
 Thermoelectrically cooled photomultiplier tubes and photodiode array
detectors were used in early models of dispersive Raman
spectrophotometers.
 Advances in instrumentation and technology replace these detectors with
more sensitive charge transfer devices (CTDs) such as charge-coupled
devices (CCDs) and charge-injection devices (CIDs). These devices act as a
detector and used in the form of arrays.
CCD
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12. Instrumentation 12

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Types of Raman Spectroscopy
• Resonance Raman Spectroscopy (RRS)
• Surface-enhanced Raman Spectroscopy (SERS)
• Micro-Raman Spectroscopy.
• Non-linear Raman Spectroscopic Techniques

14. Application
 Raman spectroscopy is used in chemistry to identify molecules and study chemical
bonding and intramolecular bonds. Because vibrational frequencies are specific to a
molecule's chemical bonds and symmetry.
 In solid-state physics, Raman spectroscopy is used to characterize materials,
measure temperature, and find the crystallographic orientation of a sample.
 In nanotechnology, a Raman microscope can be used to analyze nanowires to better
understand their structures, and the radial breathing mode of carbon nanotubes is
commonly used to evaluate their diameter.
 Raman spectroscopy has a wide variety of applications in biology and medicine.
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Advantage
• Can be used with solid, liquid & gas.
• No sample preparation is needed.
• Not interfered by water
• Non-destructive
• Highly specific like a chemical fingerprint of a material
• Samples can be analyzed through glass or polymer packaging.
• Laser light and Raman scattered light can be transmitted by optical fiber for
long distances for remote analysis
• Raman spectra can be collected from a very small volume (<1 micrometer)
• Inorganic materials are normally analyzed by Raman.

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Disadvantage
• Can not be used for metals or alloys.
• The Raman effect is very weak. The detection needs a sensitive and highly
optimized instrument.
• Fluorescence of impurities or of the sample itself can hide the Raman
spectrum.
• Sample heating through the intense laser radiation can destroy the sample
or cover the Raman spectrum.

18. Raman Instrument
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19. How to plot Raman spectrum?
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References
• Skoog, Douglas A., F. James Holler and Timothy Nieman. Principles of
Instrumental Analysis. Fifth Edition. New York, 1998.
• https://studiousguy.com/raman-spectroscopy-uses/
• https://www.mt.com/in/en/home/applications/L1_AutoChem_Appli
cations/Raman-Spectroscopy.html
• Basic Concepts Of Analytical Chemistry - S M Khopkar

24. Thank yo
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