VIBRATIONAL-EXCITATION OF H-2 D-2 N-2 AND O-2 BY LI+ IMPACT IN THE ENERGY-RANGE FROM 100-EV TO 1200-EV

Cross sections for vibrational excitation of H2, 22, N2 and O2 by Li+ impact are measured with an ion energy-loss spectrometer. The cross sections are obtained from relative height of the loss peaks in a spectrum. The absolute cross sections are obtained above a few hundred eV. The maximum values of the measured cross sections for v=0→1 excitation of H2, D2, N2 and O2 are 7.5×10−18 cm2, 1.0×10−17 cm2, 3.3×10−18 cm2 and 1.6×10−17 cm2, respectively. For H2 and D2, v=0→2 excitation is observed, while, it does not appear for N2 and O2. The measured cross sections are compared with the first Born approximation assuming that the exctiation occurs only through polarization force. The contribution of the polarization force to the vibtational excitation of infrared active molecules is estimated. © 1979, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.