Second order Raman spectrum of carbon disulphide in the condensed phase

Abstract

Below 162K, carbon disulphide crystallizes in the space group D_2h¹⁸ with two molecules in the primitive cell. The internal modes v₁, v₂ and v₃ of the isolated CS₂ molecule are split due to static and correlation field splittings. Anderson et al. have extensively studied the Raman and infrared spectra of CS₂ at 79 K and 18 K and have analysed the internal and external modes with a lattice dynamical calculation of the q = 0 phonons. However, their spectra reveal the presence of extensive second order features accompanying the v₁, v₂, v₃ and 2v₁ bands. The present investigation attempts an interpretation of these second order Raman spectra employing Born's theory and the lattice dynamical calculation of phonons at all allowed q points in the Brillouin zone employing the rigid molecule approximation.