Raman spectroscopy is a non-destructive chemical analysis technique that provides detailed information about chemical structure, phase, polymorphism, and molecular interactions. It was discovered in 1928 by Sir Chandrasekhara Venkata Raman and is based on inelastic scattering of light. Raman spectroscopy involves exciting a sample with a laser and analyzing the spectrum of scattered light to determine the molecular vibrations within the material. It has advantages such as being non-contact, non-destructive, and requiring little to no sample preparation. However, fluorescence from impurities can interfere with the Raman spectrum. Applications include detection of pesticides in fruits using surface-enhanced Raman spectroscopy.

1. RAMAN SPECTROSCOPY
HEMA MALINI.S
2017694709
M.TECH(FST)

2. INTRODUCTION
• Raman Spectroscopy is a non-destructive
chemical analysis technique which
provides detailed information about
chemical structure, phase and polymorphy,
crystallinity and molecular interactions.
• It is based upon the interaction of light
with the chemical bonds within a material.

3. HISTORY
• This inelastic scattering of light was predicted
theoretically by Adolf Smekal in 1923.
• This was first observed experimentally by Sir
Chandrasekhara Venkata Raman in 1928,
which is why this inelastic scattering is called
Raman scattering (Raman effect).
• Noble prize in 1930.

4. PRINCIPLE

5. (a) An electron is excited from the ground level and falls to
the original ground level. (b) An electron is excited from the
ground level and falls to a vibrational level. (c) An electron is
excited from a vibrational level and falls to the ground level.

6. MOLECULAR VIBRATIONS
SYMMETRIC
ASYMMETRIC
BENDING

7. DISPERSIVE RAMAN

8. 8
S.No. Laser wavelength
01 Nd:YAG 1064nm
02 He:Ne 633nm
03 Argon ion 488nm
04 GaAlAs diode 785nm
05 Co2 10600nm
06 Ti-Sapphire 800nm
LASER

9. 9
SAMPLE HOLDER
FILTER
•Optical filter
•Notch filter
•Edge filter
• Glass and silca tubes
• Water is regarded as good solvents for the
study of inorganic compounds in raman
spectroscopy

10. DETECTORS
• Photomultipler tube
• Charge coupled device

14. RAMAN SHIFT

15. Advantages :
• Non-contact and non-destructive analysis
• High spatial resolution up to sub-micron scale
• No sample preparation needed.
• Both organic and inorganic substances can be
measured
• Samples in various states such as gas, liquid,
solution, solid, crystal, emulsion can be
measured
• Samples in a chamber can be measured
through a glass window

16. Disadvantages :
• The Raman effect is very weak. The detection
needs a sensitive and highly optimized
instrumentation.
• Fluorescence of impurities or of the sample
itself can hide the Raman spectrum. Some
compounds fluoresce when irradiated by the
laser beam.
• Sample heating through the intense laser
radiation can destroy the sample

17. APPLICATION

18. • The use of SERS to detect and monitor the
chemical fungicide thiabendazole (TBZ) which
is used in the food industry against mold and
blight on citrus fruit and bananas.

19. Detection of pesticides in fruits by surface-
enhanced Raman spectroscopy coupled with
gold nanostructures

20. REFERENCE
• Jin, H., Lu, Q., Chen, X., Ding, H., Gao, H. and Jin, S. (2015). The use of
Raman spectroscopy in food processes: A review. Applied Spectroscopy
Reviews, 51(1), pp.12-22.
• Mabrouk, P. (2005). Modern Raman SpectroscopyA Practical Approach By
Ewen Smith (Strathclyde University, Glasgow, U.K.) and Geoffrey Dent
(Intertek ASG and UMIST, Manchester, U.K.). John Wiley & Sons,
Ltd: Chichester. 2005.Journal of the American Chemical Society, 127(33),
pp.11876-11877.

21. Thank you