title: A unique dosing system for the production of OH under high vacuum for the study of environmental heterogeneous reactions.
abstract: A unique dosing system for the production of hydroxyl radicals under high vacuum for the study of environmental heterogeneous reactions is described. Hydroxyl radicals are produced by the photodissociation of a hydrogen peroxide aqueous gas mixture with 254 nm radiation according to the reaction H2O2+hnu (254 nm)-->OH+OH. Under the conditions of the current design, 0.6% conversion of hydrogen peroxide is expected yielding a hydroxyl number density on the order of 10(10) molecules/cm3. The flux distribution of the dosing system is calculated using a Monte Carlo simulation method and compared with the experimentally determined results. The performance of this unique hydroxyl dosing system is demonstrated for the heterogeneous reaction with a solid surface of potassium iodide. Coupling of the hydroxyl radical dosing system to a quantitative surface analysis system should help provide molecular level insight into detailed reaction mechanisms.
authors.affiliation: Department of Chemistry and Institute for Surface and Interface Science, University of California, Irvine, 1102 Natural Science II, Irvine, California 92697, USA. mabrown@uci.edu
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Brown
authors.forename: Viktor
authors.initials: V
authors.lastname: Johánek
authors.forename: John C
authors.initials: JC
authors.lastname: Hemminger