Abstract
The processes of formation and the properties of ethanol recondensates, formed from a nitrogen cryomatrix during its evaporation, are investigated. Ethanol molecules create matrix-isolated polyagregates due to co-condensation with nitrogen. The matrix evaporation at 35 K is accompanied by recondensation of ethanol from the matrix onto a substrate. This leads to a formation of a highly-dispersive film (recondensate) consisting of agregates of different size including dimers and monomers. IR-spectroscopic investigations of recondensed samples were performed. The condensation temperature was Tc = 12 K. The gas phase pressure in the cryodeposition process was P = 10–5 Torr. The ethanol concentration in nitrogen was from 0.5 to 10%. The film thickness was varied from 1 to 30 μm. The spectral range of measurements was 400–4200 cm–1. From a comparative analysis of oscillatory spectra of samples of ethanol cryocondensates, matrix-isolated ethanol in a nitrogen cryomatrix and ethanol recondensates, we concluded that both polyagregates located previously in a matrix and recondensed onto a substrate are in a glass state. A film heating near the glass point of ethanol (97 K) leads to transitions, which take place in a few steps at different temperatures. Such a character of a warming-up curve is explained by a highly-dispersive composition of recondensates and by a dependence of the glass point of polyagregates on their size. The character of warming-up curves of recondensates allows to speak about grouping of elements of recondensates by their size. In other words, in the process of recondensation and possible further coalescence, polyagregates with preferential sizes, which are energetically optimal for these conditions, are formed. In the considered case it is reasonable to speak about existence of three such sets, involved sequentially in a glass transition.