DISSOCIATION OF ALIPHATIC-HYDROCARBONS BY CONTROLLED ELECTRON-IMPACT - VIBRATIONAL AND ROTATIONAL ENERGY-DISTRIBUTIONS OF THE EXCITED CH RADICALS

Emission spectra of CH(A(2) Delta-X(2) Pi) produced in collisions of a cetylene, ethylene and ethane with electrons (17-100 eV) have been mea sured and the rovibrational distributions of CH(A(2) Delta) have been obtained. The rovibrational distributions of CH(A(2) Delta) apparently depended on the incident electron energy, indicating the existence of more than two dissociation processes. The ratio of the vibrational po pulations, (P(upsilon' = 1)/P(upsilon' = 0)), varied from 0.45, 0.3 an d 0.3 at 17 eV to 0.8, 0.75 and 0.7 at 100 eV, and the rotational temp eratures, T-r(upsilon' = 0), varied from 3200, 5000 and 4300 K at 17 e V to 2500, 3800 and 3800 K at 100 eV for acetylene, ethylene and ethan e, respectively. Component 1, which has the lowest threshold, is vibra tionally cooler and rotationally hotter than components 2 and 3. The i ntermediate states for the formation of component 1 are sigma(c-c) bon ding Rydberg states. The emission and formation cross sections of CH(A (2) Delta) separated into each vibrational level were determined.