Raman Spectrum of Benzene Vapour

Abstract

MUCH interest is attached to the structure of benzene, and a series of important papers¹ dealing with this subject and based mainly on Raman, infra-red and emission spectra have recently appeared from University College, London. In this connexion it is very desirable to possess a knowledge of the Raman spectrum of benzene vapour, but no data are yet available. Fig. 1 (upper spectrum) shows the Raman spectrum of benzene vapour obtained by us at a pressure of 15 atm. and a temperature of 200° C,; the lower spectrum is the Raman spectrum of the liquid taken alongside, keeping the conditions regarding slit width, etc., unaltered but reducing the time of exposure. Fig. 2, a and b, are photometric records of the wings accompanying the 4077 and 4046 lines respectively in the vapour. Fig. 2, c, is the record of the wing accompanying the line 4046 in the liquid taken under identical conditions. Among other notable features, the following changes which take place as we pass from the liquid to the vapour are of special significance.