Knowledge Bank

Solid para-hydrogen (pH$2$) crystals doped with part per million concentrations of rare gas (Rg) atoms display a new zero phonon absorption feature which correlates with the pH$2$ pure vibrational Q$1$(0) transition. This Rg induced Q$1$(0) absorption has been studied at high resolution for Ne, Ar, Kr, and Xe doped pH$2$ crystals. The more polarizable the Rg atom, the more intense and red shifted is the induced pH$2$ Q$1$(0) feature. The frequency and lineshape of the transition provides information on how localized the vibron is around the Rg impurity. Comparison of the experimental data with a recent theoretical model is very favourable.} In addition, the Rg atom perturbs the S$1$(0) pH$2$ transition resulting in peaks that show fine structure which is interpreted as a lifting in the $m$ degeneracy of this $J$=2 upper state. Preliminary studies of Xe atom doped ortho-deuterium will also be presented and discussed.