Analysis of Vibrational Spectra of Tetrafluoroethane Glasses Deposited by Physical Vapor Deposition.

Abstract

This paper presents the results obtained in the study of structural phase transitions in thin films of R134A. The samples were condensed on a substrate by physical deposition of R134A molecules from the gas phase. Structural phase transformations in samples were investigated by observing the changes in characteristic frequencies of Freon molecules in the mid-infrared range with the help of Fourier-transform infrared spectroscopy. The experiments were carried out in the temperature range from 12 to 90 K. A number of structural phase states, including glassy forms, were detected. The changes in thermogram curves at fixed frequencies of half-widths of absorption bands of R134A molecules were revealed. These changes indicate a large bathochromic shift of these bands at frequencies of ν = 842 cm-1, ν = 965 cm-1, and ν = 958 cm-1 and a hypsochromic shift of the bands at frequencies of ν = 1055 cm-1, ν = 1170 cm-1, and ν = 1280 cm-1 at temperatures from T = 80 K to T = 84 K. These shifts are related to the structural phase transformations in the samples.