State-selective one-electron capture by slow state-prepared N²⁺(²P) ground-state ions in collisions with hydrogen atoms

Abstract

The technique of double translational energy spectroscopy (DTES), recently successfully developed in this laboratory for use with targets of atomic hydrogen, has been used to study one-electron capture by ground-state N2+(2s22p)2Po ions in collisions with hydrogen atoms at energies within the range 0.8-6.0 keV. Cross sections for the formation of the main excited product channels have been determined. The measurements allow a re-evaluation of our previous TES measurements carried out with N2+ primary beams containing an admixture of metastable N2+(2s2p2)4P ions. The main findings of these earlier measurements are confirmed and the DTES measurements now remove any ambiguity in interpretation of the experimental data. While recent theoretical studies correctly predict the two main N+ 3Do and 3Po product channels, the quantitative agreement with experiment is only partially satisfactory.

Experimental study of the collision mechanisms involved in one-electron capture by slow N5 ions in atomic and molecular hydrogen

“…The basic experimental arrangement and measurement procedure were similar to those used in our previous TES studies of He 2+ -H 2 collisions, so that only a brief description need be given here. Our measurements in atomic hydrogen have been carried out using our recently developed (Voulot et al 2001) aluminium target cell fed with highly dissociated hydrogen from a microwave-driven discharge source. This replaces the tungsten tube furnace target used in our many previous studies of collisions in atomic hydrogen at higher impact energies.…”

“…The measurements in atomic hydrogen followed the procedure described in our previous paper (Voulot et al 2001). Energy change spectra in pure atomic hydrogen were derived from the measured spectra in highly dissociated hydrogen (typically 75%) by careful subtraction of the appropriate fraction of the molecular contribution from the spectrum obtained in the highly dissociated hydrogen target.…”

State-selective electron capture in collisions of ground and metastable O2 ions with H(1s)

“…Recently, double-translational energy techniques have allowed the measurement of EC cross sections for ions in both ground and metastable states (see e.g. the data for C 2+ + H and N 2+ + H collisions of Voulot et al 2000Voulot et al , 2001. Similarly, O 2+ beams from usual ion sources are, in principle, a mixture of unknown proportions of ground state (1s 2 2s 2 2p 2 3 P) and metastable (1s 2 2s 2 2p 2 1 D and 1s 2 2s 2 2p 2 1 S) ions, and accordingly, the following EC reactions can take place in O 2+ + H experiments: O 2+ (1s 2 2s 2 2p 2 3 P) + H(1s) → O + + H + (1) O 2+ (1s 2 2s 2 2p 2 1 D) + H(1s) → O + + H + (2) O 2+ (1s 2 2s 2 2p 2 1 S) + H(1s) → O + + H + .…”

Studies of Electron Capture by Multiply Charged Ions from Molecules using Translational Energy Spectroscopy

“…We have developed an experimental system that makes it possible to produce pure primary ion beams in either ground or metastable states using double translational energy spectroscopy (DTES) [14]. This technique has been used to identify the significant capture channels and determine their relative importance, of a wide variety of multiply charged ions in both ground and metastable states in atomic and molecular targets (see [15], [16]). A particular feature of the DTES technique is its ability, in the case of molecular targets, to determine the relative importance of capture involving both dissociative and non-dissociative processes where the projectile is left in either a ground or metastable state.…”