ELECTRON-IMPACT EXCITATION CROSS SECTIONS OF LOWEST-LYING TRIPLET STATES OF BENZENE

Calculations of electron-impact excitation cross sections of the lowest-lying triplet states 3B 3B2u of benzene are carried out, using the Ochkur and Ochkur-Rudge approximations. Electronic wavefunctions are constructed from the LCAO molecular orbitals for TT electrons in benzene, and nuclear motions are dis-regarded. It is found that the differential cross section has a peak at a large scattering angle in the low-energy region. The angular distribution for the excitation of the 3Biu, 3Eiu states shows a broad subsidiary peak at a larger scattering angle. As the incident energy is lowered, the position of the peak in the angular dis-tribution shifts towards larger scattering angles, and the subsidiary peak tends to vanish. The total excitation cross section for the lowest-lying triplet states is about πa 0ao2 at low incident energy. Results of calculations are discussed and compared with experimental findings.