Electron impact spectra of methane, ethane, and neopentane have been obtained at scattering angles of 0deg; and 90deg; and at impact energies from quest;30 to 250thinsp;eV. The data are consistent with the lowest excitation in all of these systems to involve promotion of an electron to a 3sRydberghyphen;like orbital. Differences between 0deg; and 90deg; onsets are attributed to largehyphen;angle intensity enhancements of transitions to the 3sRydberg triplets. At 90deg; all of the spectra exhibit very similar intensity redistributions with strong enhancement of transitions in the 12 and 15 eV region as compared to lowerhyphen;lying transitions. Assignments of the spectra and possible origins of the angular dependence are discussed.
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