Electron impact total cross sections of CHx, NHx and OH radicals vis-a-vis their parent molecules

Various total cross sections for the impact of electrons on free radicals CH,, NH, and OH are calculated at intermediate to high energies. The known ionization data on the parent molecules CH4, NH3 and H2O are employed to extract total ionization cross sections of the respective radicals using total inelastic cross sections, which we have calculated through a complex optical potential. The results give an upper bound of the total ionization cross section in the energy region around 100 eV, and are in suitable harmony with available experimental data at higher energies.