Structure and phase transition peculiarities in solid nitrous oxide and attempts at their explanation

Cryogenic vacuum deposited films of nitrous oxide were studied for the following conditions: a mirror-like silver-coated copper substrate; deposition temperature 16 K; gas phase pressure during deposition 10(-3) Pa. Analysis of IR-spectroscopic and thermal desorption data leads to the following conclusion. The transition from the amorphous to the crystalline state in the vicinity of 40 K proceeds in several steps that reflect the relaxation processes related to different molecular vibrations. The differences in the temperature intervals of the transitions are determined by the activation energies of the relevant vibrations. It was shown that cryocondensation at 16 K is accompanied by the appearance of flashes on the condensate surface. Based on the uniform nature of the observed processes, a model based on several possible isomorphic molecular states of nitrous oxide is suggested. (C) 2013 AIP Publishing LLC.