Laser cooling of dense atomic gases by collisional redistribution of radiation and spectroscopy of molecular dimers in a dense buffer gas environment

Abstract

We study laser cooling of atomic gases by collisional redistribution of fluorescence. In a high pressure buffer gas regime, frequent collisions perturb the energy levels of alkali atoms, which allows for the absorption of a far red detuned irradiated laser beam. Subsequent spontaneous decay occurs close to the unperturbed resonance frequency, leading to a cooling of the dense gas mixture by redistribution of fluorescence. Thermal deflection spectroscopy indicates large relative temperature changes down to and even below room temperature starting from an initial cell temperature near 700 K. We are currently performing a detailed analysis of the temperature distribution in the cell. As we expect this cooling technique to work also for molecular-noble gas mixtures, we also present initial spectroscopic experiments on alkali-dimers in a dense buffer gas surrounding.

A Kennard-Stepanov relation study on redistributional laser cooling in dense gaseous ensembles

“…In particular, using thermal deflection spectroscopy, we recently measured an angular deflection profile that can be related to a temperature change of around 500 K, starting from an initial temperature of a dense rubidium argon mixture (p = 220 bar) of T = 680 K, see Ref. 18 We mainly attribute this to higher absorption of the gas mixture, owing to elevated optical density, as well as to the higher intensity of the cooling laser beam employed.…”