ChemInform Abstract: Properties of the HCl/Ice, HBr/Ice, and H2O/Ice Interface at Stratospheric Temperatures (200 K) and Its Importance for Atmospheric Heterogeneous Reactions

Autor: Michel J. Rossi, Benoit Fluckiger, Laurent Chaix
Rok vydání: 2001
Předmět:
Zdroj: ChemInform. 32
ISSN: 1522-2667
0931-7597
DOI: 10.1002/chin.200108014
Popis: The properties of the interface region of bulk, vapor-deposited, and single-crystal ice have been studied in a Knudsen cell flow reactor in the range 190−210 K using repetitive pulse experiments (RPEs) at variable frequency. Fluxes of surface-to-bulk loss in ice on single-crystal and bulk ice vary from 5 × 1011 to 1 × 1013 and from 5 × 1012 to 5 × 1014 molecule s-1 cm-2 for HCl and D2O, respectively. A positive activation energy for diffusional loss of EA = 3.0 ± 0.5 kcal/mol for HCl/ice and 5.3 ± 0.7 kcal/mol for D2O/ice has been measured. Complementary measurements (“dope and probe” experiments) of the HCl/ice interface region using the titration reaction of ClONO2 + HCl → Cl2 + ΗΝΟ3 are in good agreement with the diffusional loss measurements from RPEs. These experiments allowed the evaluation of the thickness h of the interfacial region, defined as the near-surface region of the ice where HCl is immediately available for titration at a high rate. We measured h = 100 ± 10 nm for single-crystal ice, 200...
Databáze: OpenAIRE
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