Vibrational excitation functions for inelastic and superelastic electron scattering from the ground electronic state in hot N_2O

摘要

Inelastic and superelastic vibrational excitation functions are extracted from measured energy-loss spectra. The energy range of the incident electrons is 0.65-4.55 eV, with electrons scattered by 90° by nitrous oxide (N _2O) gas at 300 K and at 700 K being detailed. Based on the known vibrational populations and the principle of detailed balance, the intensities of the inelastic and superelastic peaks are decomposed into the contributions from different vibrational transitions involving up to the second bending overtone (030) in the ground electronic state. The ~2Π resonance peak around 2.3 eV is found to shift to lower energies for the higher bending states. This is interpreted as an effect of the bond-angle dependence of the ~2A′ resonance that the ~2Π resonance in the linear N_2O molecule evolves into. Absolute differential cross sections for the same inelastic and superelastic transitions at 2 eV, within the ~2Π resonance region, and at scattered electron angles in the range 45-120° are also determined in the same way. Even via a common resonance, the angular distributions exhibit quite different profiles depending on the vibrational transition.