Differentiate between Raman effect and Compton effect.
Answers
Raman scattering or the Raman effect {{IPAc-en|ˈ|raman| is the inelastic scattering of a photon by molecules which are excited to higher energy levels. The effect was discovered in 1928 by C. V. Ramanand his student K. S. Krishnan in liquids,[1] and independently by Grigory Landsberg and Leonid Mandelstam in crystals.[2] The effect had been predicted theoretically by Adolf Smekal in 1923.[3]
When photons are scattered by a material, most of them are elastically scattered (Rayleigh scattering), such that the scattered photons have the same energy (frequency and wavelength) as the incident photons but different direction. However, a small fraction of the scattered photons (approximately 1 in 10 million) are scattered inelastically, with the scattered photons having an energy different from, and usually lower than, those of the incident photons—these are Raman scattered photons.[4] Because of conservation of energy, the material either gains or loses energy in the process. Typically this is vibrational energy and the incident photons are of visible light, although rotational energy (if gas samples are used) and electronic energy levels (if an X-ray source is used) may also be probed. The Raman effect forms the basis for Raman spectroscopy which is used by chemists and physicists to gain information about materials.
In order to verify compton theory D Broglie and Geiger conducted an experiment in 1905.
A beam of X-rays was made to scatter in hydrogen gas and in order to detect the resulting photons and electrons two Geiger counters were arranged opposite to each other perpendicular to the beam.
One of the counter was closed with platinum foil which is sensitive to photons since the foil absorbs the electrons allowing X-rays alone to enter the chamber while the other counter was sensitive to electrons only.
When a photons enters the chamber, it interacts with the gas in the chamber producing a secondary electron. Actually the photon counter response only to a secondary electron and not to a photon striking it directly as a photon.
According to compton theory for each photon entering the photon counter, there is an electron entering the electron counter. It was observed that for every scattered photon recorded in photon counter. The explanation is that every photon entering the chamber does not produce a secondary electron. About 10% ionization was detected simultaneously in both the counters which can be explained being due to chance and coincidence. The observed coincidence can be taken due to the simultaneous emission of recoil electron and a scattered photon which supports the compton theory as a two particles effect.
Hope this helps u.