Kinetic energies of fragment ions from propane under electron impact were measured. A part of the ions of m/e13, 14, 15, 26, 27and 28 was found to have appreciable kinetic energies ranging from 1.1 eV to 2.5 eV. The lighter a ion is, the higher is the kinetic energy. Assuming conservation of momentum of the ions, reactions producing high-kinetic energy fragment ions were discussed.
