Structural effects of ice grain surfaces on the hydrogenation of CO at low temperatures

TL;DR

This study investigates how the surface structure of ice influences CO hydrogenation at low temperatures, revealing that CO coverage and desorption dynamics are key factors affecting reaction rates.

Contribution

It demonstrates that CO coverage, rather than ice surface structure, primarily controls the hydrogenation rate of CO on ice surfaces at 15 K.

Findings

Higher effective H addition rate on amorphous ice

Greater CO depletion on crystalline ice after prolonged exposure

CO coverage dominates reaction rate over surface structure

Abstract

Experiments on the hydrogenation of CO on crystalline and amorphous ice at 15 K were carried out to investigate the structural effects of the ice surface. The effective rate of H atom addition to CO on the amorphous ice was found to be larger than that on the crystalline ice, while CO depletion on crystalline ice became larger after long exposure.We demonstrated that the CO-coverage on the ice surfaces dominates the effective reaction rate rather than the surface structure. The larger depletion of CO on crystalline ice, as compared to amorphous ice, suggests easier desorption of CO and/or products by the heat of the reaction.