Velocity Dependence of the Ionization Cross Section of Methyl Chloride Molecules Ionized by Metastable Argon Atoms

The ionization of methyl chloride molecules by metastable argon atom collisions is studied in a crossed beam experiment. The relative cross sections exhibit a decreasing trend in the investigated collision energy range, 0.04-0.3 eV. The results have been analyzed in terms of the potential energy interaction between the two colliding partners, using the optical potential model. The effect of the potential energy anisotropy has also been investigated by the use of a simple sudden approximation within the semiclassical framework. The experimental cross-sections appear to be rather well reproduced by the theoretical calculation with a spherically average potential and very close to the calculation performed using the potential for a perpendicular orientation between the C-Cl axis and the approaching direction of the excited atom.