Dissociative recombination and excitation of D₅⁺by collisions with low-energy electrons

Abstract

We report results from high-resolution studies of D 5+ cluster ion collisions with low-energy electrons performed in a heavy ion storage ring. Absolute dissociative recombination (DR) and dissociative excitation (DE) cross sections were determined for the energy range from 0.0005 to 20 eV. The DR cross sections were exceedingly large at low energies, and DR resulted in efficient internal energy redistribution and pronounced fragmentation with two main product channels: D 2 + 3D (0.62 ± 0.03) and 2D 2 + D (0.35 ± 0.01). The DR and DE cross sections were comparable in the energy range from 0.2 to 20 eV, which suggest that the two processes follow similar dynamics and are competing outcomes of the ion-electron interaction. A simple picture of the recombination process of D 5 + which captures the essential physics is suggested.

Dissociative recombination of H3+and D5+

“…There are no storage ring results available for the isotopologue H + 5 . Afterglow results for H + 5 and D + 5 are discussed in [28] and found to be resulting not only from binary reactions but probably also from ternary recombination; hence the larger rate coefficient measured in afterglow plasmas as compared with the storage ring result, which is strictly from binary recombination. Singleelectron recombination should not be sensitive to the isotope composition [29]; however, this remains to be tested experimentally.…”

“…Dissociative recombination of H + 5 has been studied in several afterglow experiments; only one storage ring study has been performed, but with D + 5 instead of H + 5 [28]. A single-electron super-dissociative recombination process had been predicted [29] long before the storage ring experiment was performed.…”

Hydrogen molecular ions: H 3 + , H 5 + and beyond

“…The rate of dissociative recombination (DR) of H + 3 was long a subject of controversy, which appears now to be substantially resolved [71]. Conversely measurements of the DR rate H + 5 , or more precisely for D + 5 , suggest that the situation is more straightforward, with a simple picture of the recombination process capturing the essential physics of the problem, as discussed by Larsson [72,73].…”