The heterogeneous surface reaction of OH with dry KI(100) results in iodide

vacancies in the surface lattice sites that were filled with OH to generate a stable

layer of KOH. Under high-vacuum conditions, in which surface ions were not

mobile, the reaction was self-passivating and generates two molecular layers of

potassium hydroxide, releasing 1.6 x 1016 iodide ions/cm2 of surface area. Reaction

rates were identical with those of NaI(100). A similar surface reaction occurred

with alkali bromides (KBr(100)), albeit at a much slower rate to generate

approximately one-tenth of a monolayer of KOH, whereas no observable reaction

occurred with KCl(100) under the conditions of this experiment. The

heterogeneous reaction of OH with alkali halides was found to be dependent solely

on the identity of the halide anion and independent of the alkali metal cation with

the relative reaction rates following the anion ordering, I- > Br- > Cl-. The release

of halide-containing species was expected to impact the chemistry of the marine

boundary layer.

Halide Vacancies Created by the Heterogeneous Reaction of OH with Alkali

Halide Single Crystals. M.A.Brown, T.M.McIntire, V.Johánek, J.C.Hemminger:

Journal of Physical Chemistry A, 2009, 113[12], 2890-5