Collision cross-sections for low-energy electrons in some simple hydrocarbons

D/µ as a function of E/N is presented for electron swarms in ethane, propane, propylene and cyclopropane, and momentum transfer and vibrational excitation cross-sections for electron energies between about 0.01 and 1.0 eV are evaluated for these molecules. In each species, vibrational excitation is efficient. Ethane, propane and propylene have a minimum in the momentum transfer cross-section at about 0.1 eV. The cyclopropane momentum transfer cross-section resembles that of ethylene, decreasing between about 1 eV to a constant value at low energies.