A method is described for the measurement of depolarization factors in Raman spectra which utilizes the spectral intensity traces obtained directly on a recording monochromator. A dry ice-refrigerated multiplier photo-tube is used as a detector with additional d.c. amplification. The initial photo-current, amplified some 108-fold, is continuously traced on a galvanometer deflection recorder of sensitivity 10−9 amp./mm. Analysis of the partially polarized scattered Raman light is made by means of a Polaroid oriented to obtain one record each for the parallel and perpendicular intensities. The instrument responds to the parallel and perpendicular intensities in the ratio of 0.82 to 1.00. Thus, the apparent depolarizations determined by this method were divided by 0.82 to correct for the in equivalence of transmission by the instrument for the two types of polarization. Values thus obtained for the principal Raman lines of benzene, chloroform, carbon tetrachloride, and symmetrical tetrachloroethane are tabulated together with results published by other authors. Values obtained for the depolarization factors ρ agree satisfactorily with the values for the same molecules using the generally accepted method of Cabannes and Rousset.
© 1943 Optical Society of AmericaFull Article | PDF Article