Interactions of N2O5 and Related Nitrogen Oxides with Ice Surfaces: Desorption Kinetics and Collision Dynamics

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• 作者：Liza S. E. Romero Lejonthun ; Patrik U. Andersson ; Mattias Hallquist ; Erik S. Thomson ; Jan B. C. Pettersson
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：November 26, 2014
• 年：2014
• 卷：118
• 期：47
• 页码：13427-13434
• 全文大小：409K
• ISSN：1520-5207

文摘

The detailed interactions of nitrogen oxides with ice are of fundamental interest and relevance for chemistry in cold regions of the atmosphere. Here, the interactions of NO, NOub>2ub>, Nub>2ub>Oub>4ub>, and Nub>2ub>Oub>5ub> with ice surfaces at temperatures between 93 and 180 K are investigated with molecular beam techniques. Surface collisions are observed to result in efficient transfer of kinetic energy and trapping of molecules on the ice surfaces. NO and NOub>2ub> rapidly desorb from pure ice with upper bounds for the surface binding energies of 0.16 卤 0.02 and 0.26 卤 0.03 eV, respectively. Above 150 K, Nub>2ub>Oub>4ub> desorption follows first-order kinetics and is well described by the Arrhenius parameters Eub>aub> = 0.39 卤 0.04 eV and A = 10up>(15.4卤1.2)up> sup>鈥?up>, while a stable Nub>2ub>Oub>4ub> adlayer is formed at lower temperatures. A fraction of incoming Nub>2ub>Oub>5ub> reacts to form HNOub>3ub> on the ice surface. The Nub>2ub>Oub>5ub> desorption rates are substantially lower on pure water ice (Arrhenius parameters: Eub>aub> = 0.36 卤 0.02 eV; A = 10up>(15.3卤0.7)up> sup>鈥?up>) than on HNOub>3ub>-covered ice (Eub>aub> = 0.24 卤 0.02 eV; A = 10up>(11.5卤0.7)up> sup>鈥?up>). The Nub>2ub>Oub>5ub> desorption kinetics also sensitively depend on the sub-monolayer coverage of HNOub>3ub>, with a minimum in Nub>2ub>Oub>5ub> desorption rate at a low but finite coverage of HNOub>3ub>. The studies show that none of the systems with resolvable desorption kinetics undergo ordinary desorption from ice, and instead desorption likely involves two or more surface states, with additional complexity added by coadsorbed molecules.