VIBRATIONAL-EXCITATION OF CARBON-DIOXIDE BY ELECTRON-IMPACT - SYMMETRICAL AND ANTISYMMETRIC STRETCHING MODES

Vibrational excitation of a CO2 molecule by electron impact is studied theoretically. Differential and integral cross sections in the incide nt energy region 4-35 eV for symmetric stretching and 4-50 eV for anti symmetric stretching modes are calculated. The calculation is based on the rotational sudden and vibrationally two-state close-coupling meth od with an ab initio electrostatic potential and approximate exchange and target polarization. The cross sections obtained are compared with experimental data. For symmetric stretching, differential cross secti ons are in a qualitative agreement with experimental data and two reso nance peaks appear at around 14 and 32 eV. These resonances correspond to those found by Tronc et al in 1979 in their relative measurement o f differential cross section at 90 degrees. For antisymmetric stretchi ng, the present cross sections reproduce experimental data well. The e nergy dependence of cross sections shows resonances similar to those s een in the differential cross section for symmetric stretching.