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.

References in corpus (4)

• Radiofrequency multipole traps: Tools for spectroscopy and dynamics of cold molecular ions
• Photodetachment of cold OH- in a multipole ion trap
• Chemical probing spectroscopy of H3+ above the barrier to linearity
• How can a 22-pole ion trap exhibit 10 local minima in the effective potential?

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