Cross sections and transport properties of negative bromine ions in Kr and Xe

We have used a combination of a simple semi-analytic theory - momentum transfer theory (MTT) and exact Monte Carlo (MC) simulations to develop Br^- in Kr and Xe momentum transfer cross sections based on the available data for reduced mobility at 300K as a function of E/N. At very low energies, we extrapolated obtained cross sections using Langevin´s cross section and supplemented it by the total detachment cross section. Other possible reactive processes have not been taken into account. A good agreement for the mean energy and diffusion coefficients is an independent proof of the validity of the cross sections that were derived for the negative ion mobility data.