Doubly differential cross sections of secondary electrons ejected from gases by electron impact: 25 --250 eV on H2

Doubly differential cross sections of secondary electrons ejected from H2 by electron impact have been measured by a crossed-beam method. The incident energies used were 25, 40, 60, 100, 150, and 250 eV. The energy and angular range of secondary electrons measured were from one half of the difference between incident energy and ionization potential to 1.0 eV and from 120 to 1560, respectively. The present results do not agree with those of DuBois and Rudd for slow secondary electrons (<20 eV) ejected by 100-eV primary electrons. The present data lead to total ionization cross sections within 10% of other measurements