Elastic and vibrational excitation cross sections for electron collisions with propane

Absolute, elastic differential cross sections (DCS) for electron-propane collisions have been measured over a range of scattering angles from 10 degrees to 130 degrees and at incident kinetic energies from 2 to 100 eV. The angular distributions were extrapolated to 0 degrees and 180 degrees by a nonlinear phase shift fit and integrated numerically to obtain the integral elastic and momentum transfer cross sections. The observed DCS agree approximately with a continuum multiple scattering calculation that uses only local potentials and also with a multichannel Schwinger variational calculation. The vibrationally inelastic DCS reveal a shape resonance with a peak at 7.5 eV that is characteristic of trapping by valence orbitals with C-H antibonding character and is identical with peaks encountered in electron-methane and electron-ethane scattering.