THERMODESORPTION AND IR SPECTROMETRIC STUDY OF POLYMORPHIC AND POLYAMORPHIC TRANSFORMATIONS IN CRYOVACUUM CONDENSATES OF ETHANOL
Abstract
Simultaneous thermal desorption and IR spectrometric studies of thermally stimulated transformations in thin films of cryovacuum ethanol condensates have been carried out. Samples 0.75 μm thick in the background condensation mode were deposited from the gas phase in the pressure range of 10-5-10-6 Torr onto a silver-plated copper mirror substrate 40 mm in diameter. The minimum condensation temperature was T = 16K. During warming up (Vann.≈0.02 K / s), the signal from the IR spectrometer at a frequency of 3015 cm-1 and the readings of the vacuum gauge at a constant pumping rate were recorded simultaneously.
The studies performed revealed the anomalous behavior of the samples at temperatures preceding sublimation. This is the abrupt behavior of the heating curve, which is accompanied by an extremum in the pressure in the chamber. In our opinion, these experimental data confirm the point of view that a multicomponent system consisting of amorphous and crystalline components, at a fixed temperature, should have different equilibrium pressures of the gas phase corresponding to the partial activation energies of sublimation. The results obtained are in excellent agreement with the data of P. Jenniskens et al. [1-3].
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