ELECTRON-EXCITATION OF THE H-2(A (3)SIGMA(G)(+)-]B(3)SIGMA(U)(+)) CONTINUUM IN THE VACUUM ULTRAVIOLET

The electron excitation function for the H-2(a 3SIGMA(g)+ --> b 3SIGMA(u)+) continuum emission has been measured from 11 to 30 eV at 195.0 nm. The emission cross section data have been combined with electron energy loss cross section measurements (Khakoo & Trajmar 1986) to extend the experimental data to 60 eV. The excitation cross section has been estimated by normalizing the data to the electron energy loss cross section at 20 eV and using a model to account for emission from the entire band system (120-500 nm). The spin forbidden excitation of the a 3SIGMA(g)+ state is a major dissociative channel of H-2 at low energy with a peak cross section of 1.7 +/- 0.85 x 10(-17) cm2 at 15.5 eV. The full width at half-maximum (FWHM) of the cross section is 7 eV. The high energy dependence of the cross section has a rapid 1/E3 fall off with electron energy, E, above 50 eV. A modified Born approximation analysis was applied to the data to provide an analytic model.