Raman Effect in Rock-salt
Abstract
IN a recent communication1, R. S. Krishnan rejects the explanation of the Raman spectrum of rock-salt given by Miss Bradburn and myself2. He repeats the contention that the photomicrographs taken by Fermi and Rasetti3 and by himself4 represent a line spectrum. The Italian physicists themselves have interpreted their results as a continuous band, and there is no reason to doubt the opinion of such experienced observers. Krishnan's own photograph is of exactly the same type, namely, a continuous intensity maximum rising high above the average background, on which some small peaks are discernible. The latter are regarded by Krishnan as representing lines. If this were true, there are two possibilities: (1) If the lines are sharp, then the background between them should not be stronger than outside the region; as it is in fact much stronger, almost of the same intensity as the maxima of the lines, it must represent a separate phenomenon connected with the Raman effect: in this case the line-theory given by Raman is incomplete. (2) If the lines are broad so that their overlapping constitutes the raised background, then they are not lines, but maxima of continuous bands, which is our own interpretation. In both cases Krishnan ought to give the explanation of the characteristic feature. In the first case, how a monochromatic primary beam could produce scattered light which has, apart from a line spectrum, a continuous intensity distribution over the same range; in the second case, how the abnormal width of the lines can be understood.
- Publication:
-
Nature
- Pub Date:
- June 1946
- DOI:
- 10.1038/157810a0
- Bibcode:
- 1946Natur.157Q.810B