A linear variation of the thermal expansivity with frequency shifts for the translational mode in ammonia solid II near the melting point

Abstract

We examine here our spectroscopic modification of the Pippard relation which is a linear variation of the thermal expansivity α p with the frequency shifts (1/ ν)(∂ ν/∂ p) T close to the melting point in ammonia solid II. For this we use our calculated frequencies for the Raman mode of ν (51 cm −1) in ammonia solid II for the pressures of 3.65, 5.02 and 6.57 kbars. We establish this linearity between α p and (1/ ν)(∂ ν/∂ p) T for the pressures studied in ammonia solid II close to the melting point. The observed behaviour of ammonia solid II is explained in terms of our spectroscopic relation given here.