Cross sections for electron collision with five-membered ring heterocycles

The absolute total cross-section (TCS) for electron scattering from isoxasole, (CH)3NO, molecule has been measured using the linear transmission technique for impact energies ranging from 1 to 400 eV. The measured TCS energy dependence appears typical for highly polar targets; over whole energy range applied, the magnitude of TCS generally decreases as the energy increases. Some narrow features located near 1.2 and 2.7 eV have been observed in the TCS curve as well as a broad enhancement spanned between 5 and 15 eV. The TCS for electron-isoxazole scattering has been compared with TCS data for furan, (CH)4O; differences and similarities in the appearance of both TCSs energy functions are indicated and discussed. In addition, for several five-membered ring heterocycle molecules: isoxazole, pyrrole [(CH)4NH] and tiophene [(CH)4S], integral elastic (ECS) and ionization (ICS) cross sections have been calculated at intermediate and high electron-impact energies in the additivity rule approximation and the binary-encounter-Bethe approach, respectively. For isoxazole and furan the sums of ECS and ICS are in very good agreement with the respective measured TCSs above 50−60 eV.