Brief idea about Mass spectrophotometry & Raman spectrophotometry (include principle, applications).

1. LADY AMRITBAI DAGA COLLEGE & Smt. RATNIDEVI
PUROHIT COLLEGE
SHANKAR NAGAR NAGPUR
[RAMABAI BARLINGAY SCHOOL OF BIOTECHNOLOGY]
Topic: Basic Introduction To Raman & Mass
spectrophotometry
Presented By:
Vaishnavi R Ghugal
M.Sc. Sem 1
Batch:2021-22

2. CONTENTS
[A]RAMAN SPECTROPHOTOMETRY
 Introduction
 Principle
 Applications
[B]MASS SPECTROPHOTOMETRY
 Introduction
 Principle
 Conclusion

3. [A]Raman Spectrophotometry
Introduction
o Raman effect was discovered by Sir
Chandrasekhara Venkata Raman in
1928.
o Raman spectroscopy is based on light
scattering phenomenon.
o Raman spectroscopy is the
measurement of the wavelength and
intensity of inelastically scattered light
from molecules.
o The Raman scattered light occurs at
wavelengths that are shifted from the
incident light by the energies of
molecular vibrations.

4. Principle
o When incident light is scattered by intervening sample
molecules, the frequency of light scattered is the same as that of
the frequency of the incident photon. This phenomenon is
Rayleigh scattering.
o During scattering of monochromatic light by molecules, a small
fraction of the scattered light is observed to have a different
frequency from that of the incident photon. This phenomenon is
known as the Raman effect.
o All molecules vibrate at all times in different modes. If any
external energy interferes with the vibrational motion.
o In case of Raman spectroscopy, photon causes a change in the
polarizability of the molecule with respect to its vibrational
motion, which induces dipole moment.
o Radiations are emitted due to this dipole moment, which are of
both Rayleigh and Raman type.

5. Cont.
o When the radiation is absorbed, a molecule jumps to
a higher vibrational or rotational energy level .
o If the emitted radiation is of lower frequency than the
incident radiation, then it is called Stokes scattering.
o If it is of higher frequency, then it is called anti-
Stokes scattering.
https://www.researchgate.net/publication/304341022/figure/fig3/AS:669038971744263@
1536522729466/Schematic-showing-the-difference-between-Stokes-and-anti-Stokes-
Raman-scattering-Notes.png

6. Block Diagram
https://www3.nd.edu/~kamatlab/images/Facilities/raman%20spectroscopy.jpg

7. Applications
o Indispensable tool for elucidation of molecular
structures.
o Identification of unknown substances.
o Provide information about frequencies of molecular
vibrations.
o Give conformation of molecule.

8. [B] Mass Spectrophotometry
Introduction
o Mass spectroscopy[MS] is used to determine
molecular mass of the compounds.
o It is the most accurate method amongst all other
spectroscopic techniques.
o Signal will appear in the form of mass to charge
ratio[m/e ]
o Generally charge will be +1 in most of the cases,
rarely it will be +2.
E.g :
Molecular weight=72
m/e=72/1=72

9. Principle
o Mass spectroscopy [MS] is a technique whereby
materials are ionized and dissociated into fragments
characteristics of the molecule[s] or element[s]
present in the sample.
o The numbers of ions of each mass provide
information for qualitative and quantitative analysis.
o In Mass spectroscopy [MS] only positive [+] charge
will be detected.

11. Block Diagram
https://www.researchgate.net/profile/Falah_Al-
Fartusie/publication/317350914/figure/download/fig12/AS:525107026198541@15022066
79303/Block-diagram-showing-the-main-parts-of-a-mass-spectrometer.png

12. Conclusion
o In conclusion, monoisotopic mass is used when it is
possible experimentally to distinguish the isotopes,
whereas the average mass is used when the isotopes
are not distinguishable.
o The use of nominal mass is not recommended and
should only be used for low mass compounds
containing only the elements C, H, N, O and S to
avoid to making mistakes.

13. Reference
o Biophysical chemistry principles and techniques by UPADHYAY
and UPADHYAY NATH chapter 8 page no.220
o Mass Spectroscopy Third Edition Edmond de Hoffmann and
Vincent Stroobant page no.4
o Analytical Chemistry D. Kealey & P. J. Haines chapter 14 page
no.270
o https://www.researchgate.net/profile/Falah_Al-
Fartusie/publication/317350914/figure/download/fig12/AS:5251070261985
41@1502206679303/Block-diagram-showing-the-main-parts-of-a-mass-
spectrometer.png