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Physical Review A

Rovibrational spectroscopy of trapped molecular hydrogen ions at millikelvin temperatures

Bernhard Roth, Jeroen C. J. Koelemeij, H. Daerr, Stephan Schiller

Published Oct 6, 2006• 74 citations
Publisher

Abstract

We report a high-resolution spectroscopic study of molecular ions at millikelvin temperatures. We measured several rovibrational infrared transitions in $\mathrm{H}{\mathrm{D}}^{+}$ molecular ions, stored in a radio-frequency trap and sympathetically cooled to $\ensuremath{\approx}20\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$ by laser-cooled ${\mathrm{Be}}^{+}$ ions. We observed hyperfine splitting of the lines, in good agreement with theoretical predictions. The transitions were detected by monitoring the decrease in ion number after selective photodissociation of $\mathrm{H}{\mathrm{D}}^{+}$ ions in the upper vibrational state. The method described here is expected to be generally applicable.

DOI
10.1103/physreva.74.040501

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We have measured the ro-vibrational infrared transition (v = 0, J = 2) → (v = 4, J = 1) in ultracold HD+ molecular ions embedded inside Be+ Coulomb crystals, by 1+1 REMPI spectroscopy. The molecular ions, trapped in a linear radiofrequency trap, were cooled to temperatures of few tens of mK, via sympathetic cooling using laser-cooled Be+ ions. For detection, we have used secular excitation of the HD+ ions to monitor their loss rate. The transition frequency agrees with a theoretical prediction.
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