Analysis of memory and nonadditivity effects on the far infrared spectra of HCl in rare gas liquids

Abstract

The far-infrared spectra of HCl in noble gas liquids Ar ( T = 105 K), Kr (125 K) and Xe (175 K) have been analyzed by applying a non Markovian theory in which both memory and nonadditivity effects are explicitly considered. Using only two phenomenological parameters, we find that both effects are of great significance in the considered spectra. The importance of the memory effects shows the necessity of using non-Markovian theories in order to make a theoretical description of these types of spectra, while the importance of the nonadditivity effects shows the existence of a strong overlapping between adjacent rotational transition lines. Qualitatively, the influence of both effects in the considered spectra mainly consists in a enhancement (reduction) of the absorption in the low-frequency (high-frequency) side. Quantitatively, the nonadditivity effects are larger than the memory effects.