Dr. Stavros Christopoulos: Laser cooling of ultra-dense gases

Project summary

This project investigates absorption and emission lines of rubidium vapor subject to a noble buffer gas environment with pressure 100–200 bar, a regime interpolating between usual gas phase and liquid/solid state conditions. Frequent elastic collisions in the dense buffer gas sample cause a large coupling to the environment. A detailed account of recent observations of the Kennard–Stepanov scaling is given; this is a Boltzmann-like thermodynamic frequency scaling connecting absorption and emission profiles, for both atomic and molecular rubidium species in the gaseous environment. This is due to the thermalization of alkali-noble gas sub-manifolds in both ground and electronically excited states, respectively. Both pressure broadening and shift of the high pressure buffer gas D-lines system are determined. Future prospects, include possible advances in collisional laser cooling and optical thermometry.

Project dates

2013 – Ongoing


DFG, grant number We1748-15