Reaction ClO + ClO → products:: Modeling and parameterization for use in atmospheric models

The interaction of two ClO radicals is important in the Antarctic stratosphere. Current models assume a single ClOOCl product and use the parameters suggested in the NASA/JPL or IUPAC compilations to describe the rate constant as a function of temperature and pressure (in air). it has been noted that these parameters suggest an inordinately high energy transfer efficiency and perhaps a somewhat high negative temperature dependence at the high pressure limit. Recent potential energy surface calculations reveal the possibility of the formation of ClOClO. In this study RRKM/master equation modeling of this surface was performed. Rational input parameters confirm that the formation of ClOClO in 10-15% yields may be important, but they do not conform with the shape and temperature dependence of the data. The simplest best representation of the extant data remains the single channel NASA/JPL format with parameters k(0) (cm(6) molecules(-2) s(-)!) = 1.6 x 10(-32)(T/300)(-4.5) and k (cm(3) molecules(-1) s(-1)) = 2.0 x 10(-12)(T/300)(-2-4). However, the data can be represented as the sum of the two pathways as well. (C) 2003 Wiley Periodicals, Inc.