Raman intensities of the internal and external modes of solid nitrogen in the α- and γ-phases

Abstract

Relative Raman intensities of the internal and external modes of solid nitrogen under hydrostatic pressure up to 9 kbar† at 4·2 K have been measured in the two phases α and γ. These are compared with the results of calculations within the oriented gas model and the approximation of the additivity of the molecular polarizabilities. For the internal modes it has been possible to verify experimentally the general relation for the intensity ratios of the Davydov components, I(sym. mode)/I(non-sym.) for a cubic phase < I(sym. mode)/I(non-sym.) for any non-cubic phase. For the external modes simple modifications of the polarizability theory are proposed for improving agreement with experiment.