Heterogeneous reactions of HOI on substrates of atmospheric importance

Experiments were conducted in a Knudsen cell flow reactor in order to investigate the heterogeneous interaction of HOI on water ice and sulfuric acid at temperatures relevant to the lower stratosphere. They reveal a nonreactive uptake on ice whose rate is temperature-independent in the range 180-200...

Full description

Saved in:
Bibliographic Details
Published in:Journal of Geophysical Research 1999-08, Vol.104 (D15), p.18
Main Authors: Allanic, A, Rossi, M J
Format: Article
Language:English
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Experiments were conducted in a Knudsen cell flow reactor in order to investigate the heterogeneous interaction of HOI on water ice and sulfuric acid at temperatures relevant to the lower stratosphere. They reveal a nonreactive uptake on ice whose rate is temperature-independent in the range 180-200 K, whereas a negative temperature dependence were observed in the range 195-250 K on liquid sulfuric acid. Two processes take place at the interface, namely, decomposition of HOI, resulting in the formation of I2, and partial loss of HOI in the condensed phase without the apparent formation of a product. This latter fraction of HOI could not be retrieved by conversion to ICI or IBr upon addition of HCI or HBr. The heterogeneous reactions of HOI with alkali salts at ambient temperature were also studied. HOI was found to interact reactively with KBr with an uptake coefficient of (6 +/- 2) x 10 exp -2. I2 was observed as the main product, but IBr was also detected at a branching ratio of approximately 6:1. Implications for atmospheric chemistry are briefly discussed. (Author)
ISSN:0148-0227