Absolute emission cross sections for production of atoms in the n = 2–6 excited states have been determined for dissociative excitation of molecular hydrogen and deuterium by electrons having energies in the range from 0.05 to 6 keV. The excited atoms have been observed by optical detection of their fluorescence, Lyman-α radiation in the case of n = 2 and Balmer-α, β, γ, and δ radiation in the case of the higher states. In general there is more than one possible molecular transition which can lead to dissociation into a particular atomic state. In the case of the n = 2 level, however, it has been possible with the aid of previous investigations to identify some transitions which may lead to both the 2s and 2p atomic states. For the formation of the higher excited states the systematics of the processes has been determined by means of analysis of the data in the Bethe–Born approximation. A strong isotope effect was found for the production of excited atoms from molecular hydrogen and deuterium. Approximately 20% fewer excited atoms are formed in the case of the heavier isotope. This difference arises due to a competition between dissociation and other processes, in particular autoionization.

The proton transfer reactions H2+ + He→HeH++H and HeH+ + H→H2++He have been studied in the laboratory energy range 1–25 eV. The first process, which is endothermic for ground state reactants, has been studied over the indicated energy range with different degrees of vibrational excitation present in the H2+ particles. Below 9 eV, the reaction is found to depend strongly on vibrational energy while above this energy the reaction cross sections appear to depend mainly on the kinetic energy of the reactants. The exothermic reverse reaction exhibits a 1 / ν dependence in the low-energy region indicating an ion-dipole mechanism. Methods of measuring the degree of dissociation obtained in forming the hydrogen atom beam are discussed.

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Cross sections for reactions of atomic. oxygen with the ions H+, 0+ ,N " ,Nt, 0-, and 0, have been measured. The ion energies range from 1 to 500 eV. For all ions, the charge transfer processes have been considered. In addition, for Nt the ion-molecule reaction leading to production of NO+ has been studied. For the charge transfer reactions in which no accidentally resonant pathway exists, cross sections less than 10-17 cm' at 1 eV were measured. Where accidental resonance occurs, cross sections larger than 10-16 cm' at 1 eV were found. For N+, both the ground and excited states of the ion were used in the measurements. The method used to form the atomic oxygen beam is discussed.