R. F. Stebbings

Charge Transfer in Collisions Involving Symmetric and Asymmetric Resonance

The cross-sections for charge transfer in collisions between atomic hydrogen and O+ and He2+ ions are presented. Unique interest attaches to these processes because they may occur with small or zero energy defect. Theoretical conflict exists regarding the magnitude and energy dependence of the cross-sections for accidental resonance collisions; the present work was prompted by the need for further information. Cross-sections for symmetric resonance charge transfer between protons and atomic hydrogen are also presented for energies down to 20 eV. The experiments were carried out by means of the techniques of modulated crossed beams.

Charge Transfer in Oxygen, Nitrogen, and Nitric Oxide

The cross sections for charge transfer in collisions of N2 and O2 with various atomic and molecular ions have been measured within the energy range 30 to 10 000 eV. Modulated‐crossed‐beam techniques were used and the relative cross sections so obtained were normalized with the aid of absolute measurements made by Stier and Barnett. Some measurements of charge transfer in NO are also reported.

Crossed‐Beam Investigation of N2D+ Production in N2+—D2 Collisions

The reaction N2++D2→N2D++D has been studied in a crossed‐beam experiment. The angular distribution of the secondary ions was determined with a movable quadrupole mass filter. Differential cross sections have been obtained within the energy range 7.5 to 57.5 eV.Total cross sections for this reaction have been determined using another crossed‐beam apparatus in which the product ions are collected in toto. Total cross sections were also derived from the angular measurements, but less reliance is placed in these values.

Charge Transfer between Atomic Hydrogen and N+ and O+

The cross sections for charge transfer in collisions between atomic hydrogen and singly charged atomic ions of nitrogen and oxygen have been measured within the energy range from 400 to 10 000 ev, using modulated‐beam techniques. The results are compared with recent calculations.

Dissociative Charge Transfer in He+–O2 and He+–N2 Collisions

The cross sections for charge transfer between He+ ions and molecules of nitrogen and oxygen have been determined within the energy range 100–7700 eV. A mass spectrometer was used to analyze the secondary ions, and the dissociative and nondissociative charge‐transfer cross sections were separately determined. The observations show that in both reactions the major contribution to the total charge‐transfer cross section comes from collisions involving dissociation.

Charge Transfer between Some Atmospheric Ions and Atomic Oxygen

Cross sections for charge transfer between oxygen atoms and N+, N2+, NO+, and O2+ ions have been measured within the energy range 50 to 10 000 eV, using modulated‐crossed‐beam techniques. The neutral beam effused from a Pyrex tube in which an electrodeless rf discharge could be established. It was determined, by use of a mass spectrometer, that about 40% of the molecules in the beam could be dissociated. The currents of slow ions which resulted from charge transfer between the primary ion beam and both the undissociated and partially dissociated oxygen beams were measured. The atomic cross sections were then evaluated from knowledge of these currents, the dissociation, and the previously determined molecular charge‐transfer cross sections.