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Dissociative electron capture of H2+ into H− fragments

Research output: Contribution to Journal/MagazineJournal articlepeer-review

<mark>Journal publication date</mark>15/04/1987
<mark>Journal</mark>International Journal of Mass Spectrometry and Ion Processes
Issue number3
Number of pages15
Pages (from-to)329-343
Publication StatusPublished
<mark>Original language</mark>English


Translational energy spectra of H− ions have been measured for capture dissociation of 6 keV H2+ molecular ions in collision with H2 gas. Voltage separation of the ion spectra has been obtained by the application of a biasing potential to the collision gas cell, allowing the sequence of processes taking place in different regions of the spectrometer to be identified. The energy release distribution of the H− spectra and a correlation with the corresponding component of the H+ spectra indicate that the majority of H− are produced from single electron capture-dissociation of H2+ in a double-collision mechanism, H2+ + H2 → H2* + [H2+] and H2* + H2 → H− + H+ + [H2], in which high Rydberg states of the H2* molecule are involved. The H− and corresponding H+ spectral peaks are narrow, with an FWHM of ∼ 0.14 eV in the centre-of-mass system for the H+ and H− ions released from dissociation of H2*, consistent with the suggested mechanism.