We present in situ measurements of temperatures inside multi-atmosphere spin-exchange optical pumping cells using Raman scattering from the ${\mathrm{N}}_2$ quenching gas. Under conditions usually prevailing in spin-exchange optical pumping experiments, we find that gas temperatures can be elevated hundreds of degrees above ambient, and that convection plays a very important role in the heat transport of the system.

• Received 15 December 2000

DOI:https://doi.org/10.1103/PhysRevLett.86.3264