This document provides an overview of Raman spectroscopy. It discusses Raman scattering, which is the inelastic scattering of monochromatic light, usually from a laser, by molecules or atoms excited to higher vibrational or rotational energy levels. There are two types of Raman scattering: Stokes Raman scattering where the material absorbs energy and anti-Stokes Raman scattering where the material loses energy. Raman spectroscopy can be used to identify molecules and provide information about chemical bonds and molecular symmetry. It has various applications including medical use, detection of explosives, and investigation of historical documents.

2. S. No. Topic Slide no.
1. What is spectroscopy 3
2. Raman Spectroscopy 4
3. Raman Scattering 5
4. Theory of Raman Spectroscopy 7
5. Stokes and Anti Stokes scattering 9
6. Selection Rules 11
7. Instrumentation 13
8. Difference Between Raman and IR
Spectroscopy
16
9. Applications 17
10. References 18

3. The study of the interaction of electromagnetic
radiation in all its forms with matter.
When a beam of white light strikes a triangular
prism it is separated into its various components
(VIBGYOR). This is known as a spectrum.
The optical system which allows production and
viewing of the spectrum is called a spectroscope.

4. A spectroscopic technique used to observe
vibrational, rotational, and other low-frequency modes
in a system.
Commonly used in chemistry to provide a fingerprint
by which molecules can be identified.
It relies on inelastic scattering, or Raman
scattering, of monochromatic light, usually from
a laser in the visible, near infrared, or near
ultraviolet range.

5. The inelastic scattering of
a photon by molecules which
are excited to higher
vibrational or rotational energy
levels.
It was discovered by C.V.
Raman and K. S. Krishnan
Dr. c.v. Raman
Dr. k.s. Krishnan

7. Phenomenon of inelastic light scattering.
Scattering of light at the same frequency as
incident light is called RAYLEIGH SCATTERING
Light scattered with different frequency is called
RAMAN SCATTERING

8. 1.
There are two theories:-
2. Quantum theory of Raman effect

10. Two possible outcomes:
The material absorbs energy and the emitted photon
has a lower energy than the absorbed
photon Stokes Raman scattering
The material loses energy and the emitted photon
has a higher energy than the absorbed photon
Anti Stokes Raman scattering

12. Primary selection rule: Molecular polarizability must
change during the molecular vibration
The specific selection rules state that the allowed
rotational transitions are
Δ J = ± 2,
where J is the rotational state.
The allowed vibrational transitions are Δ ν = ± 1,
where ν is the vibrational state.

14. Three main components-
1. The laser
Small form factor, low power consumption, narrow
linewidth, a stable power output, and a stable
wavelength output.
2. The sampling interface
Block the laser wavelength as much as possible so
that the raman shift can be observed
3. The spectrometer
Small form factor, high resolution, low power
consumption, and low noise.

16. Raman Infrared
1. Scattering of light by vibrating
molecules
1. Absorption of light
2. Due to change in polarisability 2. Due to change in dipole
moment
3. Permanent dipole moment
not necessary
3. Vibrating molecules must
posess dipole moment
4. Water as a solvent 4. Water not solvent due to
intense absorption in IR region
5. Tells about covalent nature 5. Tells about ionic nature

17. To determine the nature of chemical bonds and
symmetry of molecules
As a fingerprint to identify molecules
In solid state physics to crystallographic orientation of
sample
To detect explosives for airport security
To investigate chemical composition of historical
documents
In medicine

18. https://en.wikipedia.org/wiki/Raman_spectrosco
py
https://en.wikipedia.org/wiki/Raman_scattering
https://www.slideshare.net/ajamilan12/raman-
spectroscopy-13063160
https://www.slideshare.net/krishslide/raman-
spectroscopy-39462565
https://www.slideshare.net/tzhang1999/Raman
online