Knowledge Bank

A method is described for correcting the observed intensity of a Raman band for the convergence error in terms of the observed depolarization ratio. Further, a correction to the intensity for the reflection loss as a function of the dimensions of the irradiation set-up, sample holder, and refractive index of the sample has been applied and an empirical curve found for liquids of refractive index < 1.47. The effect of slit width on the band shape is discussed, and the extent of the error introduced by measuring $Imax$ instead of integrated intensity is estimated. Reduction of observed intensity in the light of the above considerations and also taking due account of other corrections discussed in the literature leads to a standard intensity scale. The standard intensities of the Raman bands of the chloroethanes (Et; 1, 1; 1, 1, 1; 1, 1, 1, 2; penta, and hexa) have been measured in the liquid phase with a photoelectrically recording grating Raman spectrometer. Vibrational assignments are proposed which are consistent with the depolarization data, infrared contours and a vibrational sum rule.