Determination of the Depolarization Factors of Highly Polarized Raman Lines*

The errors arising in the measurement of the depolarization factor of highly polarized Raman lines are discussed. Particular attention is given to the error introduced by the convergence of the incident light. It is shown that the ratio of the intensity of the parallel component of the scattered light when incident light is polarized along the direction of observation of the sample to the intensity of the parallel component when the incident light is polarized perpendicular to this, gives a value of the depolarization factor ρs that is very nearly free from convergence errors. ρs is related to the depolarization factor in unpolarized light ρs by ρn=2ρs/(1+ρs). Using this method, the depolarization factors of some highly polarized lines have been measured with a photoelectric spectrograph. They were found to be considerably below previously accepted values. The depolarization factor ρn for the most highly polarized lines of carbon tetrachloride and benzene were found to be 0.013 and 0.038, respectively. It is shown that the depolarization factor is not constant across the width of the line for many Raman lines.