Internal state thermometry of cold trapped molecular anions
Abstract
Photodetachment spectroscopy of OH- and H3O2- 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 H3O2- 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.
Keywords
Cite
@article{arxiv.1408.4968,
title = {Internal state thermometry of cold trapped molecular anions},
author = {R. Otto and A. von Zastrow and T. Best and R. Wester},
journal= {arXiv preprint arXiv:1408.4968},
year = {2014}
}