THEORY OF THE INFRARED AND RAMAN SPECTRA OF SOLID PARAHYDROGEN

Abstract

The theory of the rotational and vibrational energy bands in solid hydrogen, developed previously, is applied to the interpretation of the infrared and Raman spectra of solid parahydrogen. A comparison of the theory with the experimental results yields information about the nature of the rotational and vibrational motions of the molecules in the solid, and about the anisotropic intermolecular forces. A calculation of the intensity of the infrared rotational and vibrational lines is given, which is based on the induction mechanisms introduced previously to explain the induced absorption in gaseous hydrogen. Satisfactory agreement with the experimental values is obtained. The importance of the interaction between other than nearest neighboring molecules, and of the interference effects affecting the single transitions, is pointed out. A frequency analysis is given of the infrared and Raman rotational and vibrational lines in the solid, and a consistent theory of the shifts and splittings of the various lines is obtained. Empirical values of the rotational and vibrational coupling constants are derived and compared with the theoretical values.