Ppt based on raman spectroscopy

1. RAMAN SPECTROSCOPY

2. WHAT IS RAMAN SPECTROSCOPY?
• Raman Spectroscopy is an analytical
technique.
• The term Spectroscopy refers to
analytical technique using light source
and studying interactions.
• Raman Spectroscopy was discovered by
C.V.Raman in 1928 for which he received
Nobel Prize in 1930.
• Raman Spectroscopy is based on
scattering of light.

3. SCATTERING OF LIGHT
• Scattering of light is a phenomenon that occurs
when light passes through a transparent medium
the species present in that medium scatter light.
• The most common example of scattering of light
is tyndall effect.
• Scattering of light occurs in 2 Ways.
1. Elastic Collision/Rayleigh Scattering.
2. Inelastic Collision/Raman Scattering.

4. RAMAN EFFECT
• Raman effect is based on inelastic
scattering of light.
• Inelastic Scattering/Raman Scattering
can occur in 2 Ways :
1. Stokes Scattering: Reduction in
Energy of scattered light due to being
absorbed by sample.
2. Anti Stokes Scattering : Increase in
Energy of scattered light due to
gaining energy from the sample.

5. WHAT EXACTLY IS BEING MEASURED?
• By varying the frequency of the radiation, a
spectrum can be produced, showing the
intensity of the exiting radiation for each
frequency
• Based on the Peaks on the spectroscopy
graph a finger print can be found for a
particular component or a functional
group.

6. INSTRUMENTATION
• A Raman spectrometer includes
three main components :
• Exitation source
• Sampling interface
• Spectrometer

7. EXITATION SOURCES
• The sources used in modern
Raman spectrometry are nearly
always lasers because their high
intensity is necessary to produce
Raman scattering of sufficient
intensity.
• Higher intensity or shorter
wavelength sources like Argon and
Kyrpton yeilds more scattering.

8. SAMPLING INTERFACE
• In many Raman spectrometers, fiber-optic
probe is typically used which offers an
extremely flexible sampling interface.
• The fiber optic probe acts as both
transmitter of light as well as receiving the
scattering light.
• Based on the quality of the probe noise can
be reduced.

9. SPECTROMETER
• The third component is the spectrometer. Here,
important performance factors are small form
factor, high resolution, low power consumption,
and low noise.
• The most commonly used detectors are Charge
Couple Devices(CCD).

10. WHY PREFER RAMAN SPECTROSCOPY?
• Non-contacting and non-destructive.
• Sample preparation Is not required.
• Information on Chemical composition.
• Analyse through transparent containers.
• Less Time Consuming.

11. CHALLENGES OF RAMAN SPECTROSCOPY
• Not suitable for metals and alloys.
• Expensive.
• Fluorescence.
• Phosphorescence.

12. FLUORESCENCE
• Fluorescence is the ability of certain chemicals to
give off visible light after absorbing radiation.
• Fluorescence occurs due to rapid descending of
exited electron to a lower state than normal.
• Fluorescence interfere with Raman Spectroscopy
resulting in abnormalities.

13. PHOSPHORESCENCE
• Phosphorescence is closely associated
with Fluorescence.
• Instead of immediately emitting energy
like in the case of Fluorescence, there is a
time delay.
• In Phosphorescence instead of electron
returing directly to a lower state , it is goes
to a meta stable level and further exitation
is required.

14. CONCLUSION
• Raman Spectroscopy is an important analytical technique used in different
fields like Pharmaceutical, Quality Control, structural ellucidation etc..
• As population increases so does the production of foods, medicines,
chemicals etc.. and an efficient quality checking method needs to be
implemented.
• Raman spectroscopy is able to detect samples from limited quantity as well as
from aqueous samples.

15. REFERENCES
• https://scholar.google.co.in/scholar?q=raman+spectroscopy+instrumentation
&hl=en&as_sdt=0&as_vis=1&oi=scholart#d=gs_qabs&t=1667736695625&u=
%23p%3D3Vi-1N1TtV0J
• https://physicsopenlab.org/2019/02/05/phosphorescence/
• https://www.sciencedirect.com/topics/materials-science/resonance-raman-
spectroscopyhttps://physicsopenlab.org/2019/02/05/fluorescence

16. THANK YOU