Break-up of H2 in singly ionizing collisions with fast protons: channel-selective low-energy electron spectra

DIMOPOULOU, C.; MOSHAMMER, R.; FISCHER, D.; HOHR, C.; DORN, A.; FAINSTEIN, P. D.; CRESPO LÓPEZ URRUTIA, J. R.; SCHROTER, C. D.; KOLLMUS, H.; MANN, R.

PHYSICAL REVIEW LETTERS

AMER PHYSICAL SOC

Año: 2004 vol. 93 p. 123203 - 123203

0031-9007

Dissociative as well as nondissociative single ionization ofH2 by 6MeV proton impact has been studied in a kinematicallycomplete experiment by measuring the momentum vectors of the electronand the H+ fragment or the H+2 targetion, respectively. For the two ionization pathways, the electron spectrareveal the role of autoionization of the doubly and singly excitedstates of H2. The latter explicitly involve the couplingbetween the electronic and the nuclear motion of the molecule. This is aclear manifestation of a breakdown of the Born-Oppenheimerapproximation.