Laser cooling of dense rubidium-noble gas mixtures via collisional redistribution of radiation

Abstract

We describe experiments on the laser cooling of both helium-rubidium and argon-rubidium gas mixtures by collisional redistribution of radiation. Frequent alkali-noble gas collisions in the ultradense gas, with typically 200 bar of noble buffer gas pressure, shift a highly red detuned optical beam into resonance with a rubidium Dline transition, while spontaneous decay occurs close to the unshifted atomic resonance frequency. The technique allows for the laser cooling of macroscopic ensembles of gas atoms. The use of helium as a buffer gas leads to smaller temperature changes within the gas volume due to the high thermal conductivity of this buffer gas, as compared to the heavier argon noble gas, while the heat transfer within the cell is improved.

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

“…8 Recently, our group succeeded in demonstrating relative cooling of dense alkali-noble gas mixtures using collisional redistribution of radiation. [9][10][11][12] Here, we report on current experiments using this technique. Also, we present initial spectroscopic experiments on an alkali-dimer -noble gas mixture which constitutes a promising candidate for redistributional laser cooling of molecules, following an alternative approach for the production of suitable molecules instead of laser ablation.…”

Towards redistribution laser cooling of molecular gases: production of candidtate molecules SrH by laser ablation

“…Efficient cooling is thus possible at high initial temperature T 0 and requires a large rate of atomic collisions that can be achieved at a high buffer gas pressure p. It is also important that the red-detuned laser radiation is strongly absorbed by the gas, which requires a strong collision broadening of the atomic spectral line and a high number density of the absorbing atoms. The cooling effect was demonstrated [1][2][3][4] in alkali-metal (Rb, K) vapors mixed with different noble gases (He, Ar) at the initial temperature of 500-700 K and the buffer gas pressure of 100-200 bar. Under these conditions, the sample is optically dense even at the used detunings of 10-20 nm with respect to the wavelength of the resonant transition of the alkali atom.…”