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Updated: May 16, 2026

Cooling an Optically Trapped Ultracold Fermi Gas by Periodical Driving
Published on: March 30, 2017
Internal state thermometry of cold trapped molecular anions
Rico Otto1, Alexander von Zastrow, Thorsten Best
1Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstrasse 25, A-6020 Innsbruck, Austria.
Abstract:
Photodetachment spectroscopy of OH(-) and H(3)O(2)(-) anions has been performed in a cryogenic 22-pole radiofrequency multipole trap. Measurements of the detachment cross section as a function of laser frequency near threshold have been analysed. Using this bound-free spectroscopy approach we could demonstrate rotational and vibrational cooling of the trapped anions by the buffer gas in the multipole trap. Below 50 K the OH(-) rotational temperature shows deviations from the buffer gas temperature, and possible causes for this are discussed. For H(3)O(2)(-) vibrational cooling of the lowest vibrational quantum states into the vibrational ground state is observed. Its photodetachment cross section near threshold is modelled with a Franck-Condon model, with a detachment threshold that is lower, but still in agreement with the expected threshold for this system.
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