Faculté des sciences

Electron spectra for associative detachment in low-energy collisions of Cl⁻ and Br⁻ with H and D

Živanov, Svetlana ; Cížek, M. ; Horáček, J. ; Allan, Michael

In: Journal of Physics B: Atomic, Molecular and Optical Physics, 2003, vol. 36, no. 16, p. 3513-3531

Energy spectra of electrons detached in collisions of Cl⁻ and Br⁻ with atomic hydrogen and deuterium have been measured for laboratory frame ion energies between 0.2 and 8.0 eV. Their shapes agree very well with the predictions of nonlocal resonance theory. Both types of structure predicted by the theory are observed. They are the 'v steps', at ro-vibrational thresholds, and the 'S... Plus

Ajouter à la liste personnelle
    Summary
    Energy spectra of electrons detached in collisions of Cl⁻ and Br⁻ with atomic hydrogen and deuterium have been measured for laboratory frame ion energies between 0.2 and 8.0 eV. Their shapes agree very well with the predictions of nonlocal resonance theory. Both types of structure predicted by the theory are observed. They are the 'v steps', at ro-vibrational thresholds, and the 'S steps', which are a consequence of interchannel coupling, which raises the cross section when a higher vibrational channel closes. They exhibit the behaviour predicted by theory both when the collision energy is varied and upon isotope substitution. The 'v steps' move to higher electron energies with higher collision energy and when hydrogen is substituted by deuterium, reflecting the higher maximum energy available to the electron. The positions of the S steps do not depend on collision energy, and are essentially equal to differences of vibrational energies of the product molecules HCl, DCl, HBr and DBr. The relative cross sections for formation of low vibrational levels (i.e., emission of fast electrons) are smaller in the deuterated compounds, reflecting the slower motion of D compared to H and consequently preferred detachment at high internuclear separations.