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Physical Review A

Observation of an isotope effect in state-selective mutual neutralization of lithium with hydrogen

Alice F. Schmidt-May, Stefan Rosén, MingChao Ji, Gustav Eklund, Henning Zettergren, H. Cederquist, Henning T. Schmidt, P. S. Barklem, Jon Grumer

Published Oct 16, 2023• 10 citations
Publisher

Abstract

We report on mutual neutralization measurements between $^{7}\mathrm{Li}^{+}$ and $^{1}\mathrm{H}^{\ensuremath{-}}$ at effective center-of-mass collision energies in the range of 100 to 350 meV. We find that final states of lithium with principal quantum number $n=3$ dominate with $3s$ separated from the unresolved $3p$ and $3d$ states. We measure the $3s$ branching fraction to be 0.665(12) at 100(16) meV and no significant dependence on collision energy is observed in the studied range. Comparing to previous results on mutual neutralization between $^{7}\mathrm{Li}^{+}$ and $^{2}\mathrm{H}^{\ensuremath{-}}$ [G. Eklund et al., Phys. Rev. A 102, 012823 (2020)], we find that $^{7}\mathrm{Li}^{+}$ collisions with $^{1}\mathrm{H}^{\ensuremath{-}}$ result in a significantly higher $3s$ branching fraction than collisions with $^{2}\mathrm{H}^{\ensuremath{-}}$. The difference is 0.087(14). The $3s$ branching fraction of $^{7}\mathrm{Li}^{+} + ^{1}\mathrm{H}^{\ensuremath{-}}$ and the determined isotope difference are in agreement with results from extended full quantum calculations based on the same input data and numerical method as in Croft et al. [H. Croft, A. S. Dickinson, and F. X. Gad\'ea, J. Phys. B 32, 81 (1999)]. These calculations reveal strong Stueckelberg oscillations of the $3s$ branching fraction for both isotopes.

DOI
10.1103/physreva.108.042810

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