Imaging the electron transfer reaction of Ne2+ with Ar using position-sensitive coincidence spectroscopy

A new experiment, employing position-sensitive detection coupled with time-of-flight mass spectrometry, has been used to investigate the single-electron transfer reaction between Ne(2+) and Ar by detecting the resulting pairs of singly charged ions in coincidence. The experimental technique allows the determination of the individual velocity vectors of the ionic products, in the centre-of-mass frame, for each reactive event detected. The experiments show that forward scattering dominates the reactivity, although a bimodal angular distribution is apparent. In addition, the spectra show that at laboratory frame collision energies from 4-14 eV the reactivity is dominated by Ne(2+) (2p(4), (3)P) accepting an electron from an argon atom to form the ground state of Ne(+) together with an Ar(+) ion in an excited electronic level, predominantly arising from the Ar(+) (3s(2)3p(4)3d) configuration. The form of this reactivity, and the differences between the reactivity observed in these experiments and those performed at higher collision energies, are well reproduced by Landau-Zener theory.