Infrared Spectroscopy of Symmetric and Spherical Top Molecules for Space Observation, Volume 2

3Nanocage of Rare Gas Matrix

The spectral profile, shape and width of the spectral lines of a molecule trapped in a condensed medium could be constructed when it was possible to compare the theoretical results to the high-resolution spectroscopy measurements.

Volumes 1 and 2 of this series [DAH 17, DAH 19a] describe the theoretical models developed in order to determine the absorption spectra of (homonuclear or heteronuclear) diatomic molecules and (linear or nonlinear, symmetric or non-symmetric) triatomic molecules trapped in nanocages of inert matrices of rare gases or hydrate clathrates at very low temperatures.

Depending on its size, composition and geometry, the molecule trapped in rare gas matrices can occupy a simple substitution site (only one atom is substituted) or a double substitution site (two atoms are substituted). The distortion of the nanocage is determined by the iterative method based on Green’s functions of the perfect crystal.

3.1. Introduction

A priori analyses of the behavior of molecules trapped in simple matrices such as rare gas matrices of octahedral symmetry can be used to test the quality of the molecule–matrix interaction potential, the symmetry of the inclusion site and the quality of the approximations used in motion decoupling, by reconstructing the bar spectra (frequencies and integrated intensities of the lines) and comparing them to experimental spectra.

In this chapter, the theoretical models developed in Volumes 1 and 2 are mainly applied ...