Investigating asymmetries in the HD⁺(1sσ) branching ratio following electron impact at energies from threshold to 100 eV

I. Ben-Itzhak
James R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS, USA

J.B. Williams, A.L. Landers
Auburn University

E. Wells
Augustana College

We present preliminary results where momentum-imaging is used to investigate e^- + HD collisions at energies from near threshold to 100 eV. Single ionization proceeding to the ground (1sσ) electronic state usually results in the production of HD⁺, but a small fraction of the ionization events reach the vibrational continuum, leading to H⁺+D(1s) or, via charge transfer to the 2pσ state, H(1s) + D⁺. The H(1s) + D⁺ final state is 3.7 meV higher than the H⁺ + D(1s) state at the separate atom limit. When initiated by fast ion impact, this energy difference leads to a measurable asymmetry in the ground state dissociation process [1]. Fast electron impact is expected to produce a similar result, but as the electron energy is reduced toward threshold, this asymmetry may increase and have significant astrophysical implications.

[1] E. Wells, B.D. Esry, K.D. Carnes, and I. Ben-Itzhak, Phys. Rev. A, 62, 062707 (1999).

This work was supported by the Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, and by the National Science Foundation.

Presented at DAMOP, May 2008, in State College, PA.

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