RESONANT INELASTIC-SCATTERING OF ELECTRONS FROM GAS-PHASE AND PHYSISORBED N-2 - A TIME-DEPENDENT APPROACH

We report the results of a theoretical study in which time-dependent q uantum wave-packets have been used to simulate the resonant vibrationa l excitation of N-2 by electron impact. We have studied the dynamics o n model potential energy surfaces (PESs) explicitly including both the electron-molecule and the intramolecular coordinates. Resonance param eters for the (IIg)-I-2 State in N-2(-) were chosen to agree with thos e obtained from fixed nuclei ab initio calculations, and the resulting vibrational-excitation cross sections are in excellent agreement with experiment. For the case of an N-2 molecule physisorbed on a metal su rface, the metallic image potential is known to broaden the resonance and lower its energy. The degree of broadening is estimated by fitting calculated cross sections to those obtained experimentally for N-2 on Ag.