High-resolution inverse Raman experiments for ${\mathrm{H}}_2$ diluted in Ar have revealed unusual Q-line profile features at various concentrations which have been interpreted in terms of speed-changing collisions. A more general approach including both speed- and phase-changing collisions has led to an alternative interpretation of these features. In order to further analyze the role of these various collisional mechanisms, new experiments have been performed. Pure ${\mathrm{H}}_2$ and ${\mathrm{H}}_2$ perturbed by Ne, Ar, and Xe have been investigated at various temperatures between 295 and 800 K.

• Received 7 September 1993

DOI:https://doi.org/10.1103/PhysRevA.49.3396