Propane, Propene and Their Radical Cations. Part 2: The structure of propane radical cation.
The ionization of propane, by electron impact ionization for example, removes one electron from one of the sigma bonds. Notice how different the C-C bond lengths are: One is 189.3 pm long (much longer than in propane) while the other remains short at 146.5 pm (even a bit shorter than in propane).