Raman spectroscopy

IT IS a slide for raman spectroscopy

1. RAMAN SPECTROSCOPY Submitted to- XYZ Submitted by- ABC

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 contents

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 ( V I B G Y O R ). This is known as a spectrum . The optical system which allows production and viewing of the spectrum is called a spectroscope. What is spectroscopy

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.  Raman spectroscopy

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 Raman scattering Dr. c.v. Raman Dr. k.s . Krishnan

6. Theory of raman spectroscopy 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

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

8. Fate of light after striking a surface

9.   Two possible outcomes : T he material absorbs energy and the emitted photon has a lower energy than the absorbed photon   Stokes Raman scattering T he material loses energy and the emitted photon has a higher energy than the absorbed photon Anti  Stokes Raman scattering Stokes and anti-Stokes scattering

10. TRANSITION FOR RAMAN AND RAYLEIGH SCATTERING

11. Selection rules 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.

12. The raman instrument

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

14. A MODERN RAMAN SPECTROMETER

15. 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 Differnces between

16. Applications of raman spectroscopy 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

17. https://en.wikipedia.org/wiki/Raman_spectroscopy 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/Ramanonline References