The Raman Effect and the Spectrum of the Zodiacal Light

Abstract

IN a recent address (Indian Journal of Physics, vol. 2, part 3, p. 387) Prof. C. V. Raman announced the interesting discovery that when monochromatic light is diffused by the molecules of a liquid, the spectrum of the scattered light contains, besides the incident lines, also other new lines of increased wavelength. The Raman effect, as it may be called, is less easily observed in the case of scattering by gases and vapours. Nevertheless, I have succeeded in photographing a satisfactory spectrum of the light scattered by the vapour of ether showing the effect. For this purpose, a specially constructed spectrograph of small dispersion and very large light-gathering power was used. With a 3000 c.p. mercury vapour lamp as the source, an exposure of 186 hours on the light scattered by a flask of ether vapour brought out the most prominent line of increased wave-length very clearly. The intensity of this line in relation to the incident line which excites it is considerably less in the case of the vapour than in the case of the liquid.