Confinement Narrowing of the R(0) Line in the 13CO Fundamental Band Broadened by Helium from Room Temperature down to 40 K

Abstract

The R(0) line profile of the 13CO fundamental band is studied at low concentration in helium from room temperature (296.7 K) to 40 K. A narrowing effect due to molecular confinement (Dicke effect) is observed and analyzed using the Galatry soft collision model. The narrowing parameter is found to be in good agreement with the dynamic friction coefficient deduced from the diffusion coefficient over the entire temperature range.