To put Raman effect at par with Compton effect may be a bit misleading. In Raman effect, the emission is that of light, while in CE, it is electron. But, more fundamentally, in CE, the electron emission occurs from loosely bound electrons vecause of interaction with the incident light. On the other hand, RE is primarily because of molecular vibrations affecting the polarizability. It is more appropriate to talk about CE in relation to the photoelectric effect. In the latter, the emission of the ELECTRON takes place from deep inside, at the nucleus and that is why the work function is involved. Both CE (1923) and PE (1905) are considered the forerunners of Quantum Mechanics, especially the wave-particle duality. In contrast, RE can be explained by vibrational relaxations or fluctuations, occasionally coupled with rotational motion, rendering it a molecular phenomenon.
Sushanta Da, thank you for listening to the play with attention and sharing your thoughts. Raman himself had erroneously compared his "modified radiation" with Compton Effect and called it an optical analogue of Compton Effect. We have quoted him verbatim from his letter to Nature that he sent on 16th Feb. So the onus of comparison with Compton Effect is on Raman. Not us.
Raman called his effect 'Optical analogue of Compton Effect'! - This is there in G. Venkataraman's book Journey into Light. Venkataraman also writes that Raman was wrong in this comparison.
My opinion is, errors should have been corrected in a documentary done almost a century later .... as the public at large should not be kept guessing (irrespective of what Raman or Krishnan said around 1930's). Like GV corrected Raman
It is difficult to make these corrections in a dramatized version set in a certain period in history. But the corrections can definitely be made in a discussion arising out of the drama. I think we should create a platform for such a discussion.
There is a conversation towards the end of the play that goes like this:
Little girl: Uncle, explain to me what is Raman Effect.
Krishnan: Come dear, I will explain. You must have seen your brother playing cricket. Suppose he is holding the bat straight and the bowler is bowling. The ball will bounce off his bat at almost the same speed. But now suppose he is swinging his bat towards the ball as the ball hits the bat.
Girl: The ball will bounce off at a higher speed
Krishnan: And if he swings his bat away from the ball as the ball hits the bat?
Girl: The ball will bounce back with a lower speed.
Krishnan: Now imagine that the ball is a bundle of light and the bat is an electron – you get Raman Effect
I am not comfortable with the last line. I would have preferred 'bat is a molecule' instead of 'bat is an electron'. But my resource person insisted on 'electron'.
That is the point -- Raman effect has to do with molecule, which has three degrees of freedom -- translational, rotational and vibrational. Neglecting the translational part related to the motion of the center of mass, the other two d.e.f. define the molecular polarizability, the dynamics of which decides the inelastic Raman effect -- it has nothing to do with electron! In fact, while Rayleigh scattering deals with elastic scattering, R.E. connotes to inelastic part, yielding Stokes and anti-Stokes lines. Actually, Raman never invoked quantum phenomena, though of course, the effect was later analyzed by quantum theory, just as J. C. Bose's work on photosynthesis was.
On the other hand, Compton Effect, like P. E., deals directly with Q. M., because the emitted electron is ascribed wave property. Mind you, Rayleigh and Raman scattering involve light only, whose wave nature was explained threadbare by Maxwell in 1960. The polarizability fluctuations can be entirely understood from classical considerations. (In fact, Raman, after 1930, never worked on quantum mechanics though through 1920 -- 1928, the subject was well developed -- he only dealt with color of minerals and flowers after he moved to Bangalore! His paper with Bhagavantham in which he claimed that S. N. Bose had told him that photons have intrinsic spin, was proved to be incorrect, according to his biographer G. Venkataraman.)
I am not sure if Raman invoked Quantum Mechanics to explain his results. The reference to Kramers-Heisenberg should be checked.
Krishnan’s diary entry on Feb 7:
Prof. suddenly came to the house and called for me. When we went down, we found that he was much excited and had come to tell me that what we had observed that morning must be the Kramers-Heisenberg effect that we had been looking for all these days. We therefore agreed to call the effect ‘modified scattering’.
