Knowledge Bank

$CH3Cl$ doped solid parahydrogen $(p-H2)$ crystals have been studied using high-resolution FT-IR. Similar to related studies of $CH3F$ in solid $p-H2$, multiplet structures are observed in the C-Cl stretch region, which are assigned to clustering of the $CH3Cl$ with ortho-$H2$ molecules present in the sample. In this study individual vibrational absorptions are observed for clusters in the size range of $n=0-5$. In contrast with the $CH3Fstudies,a$ at low temperature $(T=1.8K)$ absorptions features $2.8cm-1$ to the blue of the main features are observed to grow in intensity. These low temperature absorption features are believed to be due to $CH3Cl$ in a new structurally distinct crystal environment that must occur by reorganization of the solid hydrogen around the $CH3Cl$ impurity at low temperature. Experimental results and analysis will be presented to support this hypothesis.