Ultradense Gases: Laser Cooling & Spectroscopy

In earlier work, we demonstrated this novel cooling method with a heated gas cell containing a rubidium argon gas mixture at 200 bar pressure. In our experiment achieving relative cooling, the chilling power approaches 100 mW, which is more than a factor 10000 above the cooling power achieved in experiments on the Doppler cooling of dilute atomic gases. Frequent collisions of rubidium atoms with the argon buffer gas shift rubidium transiently into resonance with the exciting, far red detuned laser field, while the subsequent spontaneous decay occurs near the unperturbed transition frequency. During this process, kinetic energy is extracted from the sample, and the temperature reduces.

In more recent work, we carried out several spectroscopic experiments of both atomic and molecular samples subject to a noble buffer gas environment in the 100 bar pressure regime. The frequent collisions of buffer gas atoms with the optically active species lead to a thermalization of the quasimolecular manifolds. Our aims here are both to provide spectroscopic information for our VUV photon condensation experiment, as well as to potentially allow for laser redistribution cooling starting from room temperature.