The HD⁺ dissociative recombination rate coefficient at low temperature

¹ Max-Planck-Institut für Kernphysik, 69117 Heidelberg, Germany
² Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
³ Laboratoire Ondes et Milieux Complexes UMR-6294 CNRS and Université du Havre, 25, rue Philippe Lebon, BP. 540, 76058 Le Havre, France
⁴ LPF, UFD Mathémathiques, Informatique Appliquée et Physique Fondamentale, University of Douala, PO Box 24157, Douala, Cameroun
⁵ Laboratoire Aimé Coton, CNRS-UPR-3321, Univ. Paris-Sud et Ecole Normale Supérieure de Cachan, 91405 Orsay, France

^a Corresponding author: A.Wolf@mpi-hd.mpg.de

Published online: 29 January 2015

Abstract

The effect of the rotational temperature of the ions is considered for low-energy dissociative recombination (DR) of HD⁺. Merged beams measurements with HD⁺ ions of a rotational temperature near 300 K are compared to multichannel quantum defect theory calculations. The thermal DR rate coefficient for a Maxwellian electron velocity distribution is derived from the merged-beams data and compared to theoretical results for a range of rotational temperatures. Good agreement is found for the theory with 300 K rotational temperature. For a low-temperature plasma environment where also the rotational temperature assumes 10 K, theory predicts a considerably higher thermal DR rate coefficient. The origin of this is traced to predicted resonant structures of the collision-energy dependent DR cross section at few-meV collision energies for the particular case of HD⁺ ions in the rotational ground state.