DETAILED THEORETICAL AND EXPERIMENTAL-ANALYSIS OF LOW-ENERGY ELECTRON-N-2 SCATTERING

We have carried out a comprehensive theoretical and experimental study of electron scattering from molecular nitrogen at energies below 10.0 eV. In the theoretical component of this project we have generated di fferential and integral cross sections for elastic scattering and vibr ational excitation in converged vibrational close-coupling calculation s. In the experiments, we have measured differential cross sections fo r these processes at scattering angles from 20 degrees to 130 degrees in a crossed-beam experiment at a large number of energies between 0.5 5 and 10 eV and, in a complementary time-of-flight experiment, total c ross sections at energies between 0.08 and 10.0 eV. The measured angul ar distributions have been extrapolated to 0 degrees and 180 degrees u sing a procedure based on a nonlinear least-squares fit constrained by known physical properties of the e-N-2 scattering matrix; numerical i ntegration of the resulting extrapolated distributions yields integrat ed cross sections with almost no error beyond that inherent in the mea sured angular data. We find generally good agreement between the prese nt experimental and theoretical cross section, particularly at energie s near the Pi(g) resonance near 2.39 eV. In previous studies of scatte ring in this region, such comparisons have been made problematical by the difficulty of ascertaining the appropriate theoretical scattering energy. We recommend here a protocol for resolving this problem for bo th elastic scattering and vibrational excitation.