LOW-ENERGY ELECTRON-SCATTERING FROM HALOMETHANES .1. ELASTIC DIFFERENTIAL CROSS-SECTION FOR E-CF4 SCATTERING

In a crossed-beam experiment, we have studied vibrationally elastic and inelastic scattering of electrons by CF4 in the energy range 0.3-20 eV. The angular range covered by the measurements is from 10-degrees to 105-degrees. In the present paper, we report our results for elastic scattering. Absolute values of the differential cross section (DCS) are determined with reference to the total cross section measured by Jones. For energies above 10 cV, the experimental results are well described by the 'static-exchange' multichannel Schwinger variational principle (SMC) calculations of Huo. At lower energies, the measurements show strong deviations from the calculated results which are attributed to neglect of the polarization effects in the calculations. The elastic e-CF4 scattering shows a Ramsauer-Townsend effect below E = 0.5 eV. The data have been evaluated by means of a modified effective range theory (MERT) analysis, and the resulting integral cross sections are compared with results from swarm experiments.