VIBRATIONALLY INELASTIC AND ELASTIC CROSS-SECTIONS FOR E+NF3 COLLISIONS

Absolute elastic cross sections for electron impact on nitrogen triflu oride (NF3) have been recorded for impact energies from 1.5 to 100 eV and scattering angles from 20 degrees to 130 degrees. Because of the s mall dipole moment, estimates of the integrated and momentum-transfer cross sections were obtained by extrapolation of the angular range wit h the help of a modified phase-shift program and subsequent numerical integration under the fits. Vibrational excitation function measuremen ts show a 2 eV wide resonance at 3 eV impact energy. Vibrational loss spectra were measured near this resonance and resolved into their vibr ational components v(1) and v(3). From the angular behaviour of these fundamental modes, the resonance can be assigned to a temporary trappi ng of the impinging electron in the antibonding orbital of irreducible species 'e', the LUMO orbit.