Ir-spectrometric investigation on cluster composition of two-component solid films of nitrogen-ethanol

Abstract

Studies that were carried out previously investigating the properties of the cry condensed films of weak two-component solutions of ethanol in nitrogen found that the state of the film is not stable. A slight increase in temperature of solid nitrogen cryomatrix leads to changes in the vibrational spectrum of ethanol. This article is a continuation of this research and is aimed at studying the cluster composition of thin films of ethanol cry vacuum condensates in weak solutions with nitrogen. Measurements were carried out in a temperature range from 12 to 40 K, the pressure in the vacuum chamber was less than 5 × 10-8Torr. The concentration of ethanol in nitrogen was varied in the range from 0.5% to 3%. Based on the analysis of the vibrational spectra, it is assumed that the two-component nitrogen-ethanol film contains clusters of various compositions, from dimers to polyaggregates. An increase in cryomatrixtemperature leads to transformations in these polyaggregates with formation of more stable forms, as demonstrated by changes in the fine structure of the considered bands. The presence in the spectra of the absorption bands, which frequencies correspond to the existence of ethanol dimers and monomers in nitrogen matrix, can be explained as follows. Part of the ethanol molecules forming polyaggregates may not be combined via hydrogen bonds with neighboring molecules, forming a broken chain. Thus, they form a set of quasi-free molecules with corresponding absorption bands of these states. It is assumed that the quasi-free unbound molecules are preferably arranged in the surface area of the clusters.