Desorption-induced evolution of cubic and hexagonal ices in an ultrahigh vacuum and cryogenic temperatures. Issue 41 (19th October 2021) - Vishwakarma, Gaurav
Abstract : Reflection absorption infrared spectroscopic investigations of multilayer films of acetonitrile (ACN) and water in an ultrahigh vacuum under isothermal conditions showed the emergence of cubic (ice Ic ) and hexagonal (ice Ih ) ices depending on the composition of the film. Abstract : Reflection absorption infrared spectroscopic investigations of multilayer films of acetonitrile (ACN) and water in an ultrahigh vacuum under isothermal conditions showed the emergence of cubic (ice Ic ) and hexagonal (ice Ih ) ices depending on the composition of the film. The experiments were conducted with a mixed film of 300 monolayers in thickness and the ACN : H2 O monolayer ratios were varied from 1 : 5 to 5 : 1. Mixed films were deposited at 10 K and warmed to 130–135 K, where ACN desorbed subsequently and IR spectral evolution was monitored continuously. While the emergence of ice Ic at 130 K has been reported, the occurrence of ice Ih at this temperature was seen for the first time. Detailed investigations showed that ice Ih can form at 125 K as well. Crystallization kinetics and activation energy ( E a ) for the emergence of ice Ih were evaluated using the Avrami equation.