Low-energy electron scattering by methane, arsine and phosphine

We present cross sections for the elastic scattering of low-energy electrons by phosphine (PH_3) and arsine (AsH_3), and for electron-impact excitation of the (1t_2 → 3sa_1)^3T_2 and ^1T_2 states in methane (CH_4). These results were calculated using the Schwinger multichannel method as implemented on distributed-memory parallel computers. The PH_3 and AsH_3 cross sections show a pronounced low-energy shape resonance which may provide a pathway to dissociative attachment. The ^(1,3)T_2 cross sections for CH_4 correlate fairly well with recent measurements of CH_2 production via electron-impact dissociation of methane