Knowledge Bank

Cryogenic solid molecular hydrogen is a unique condensed phase environment due to a variety of quantum mechanical effects such as large amplitude translational zero point motion of the individual H$2$ molecules, the presence of ortho and para nuclear spin manifolds, and that in the solid phase the individual molecules retain good vibrational and rotational quantum numbers. Equally intriguing is that a variety of non-classical dynamics occur within the crystal at liquid helium temperatures. This talk will highlight some of these dynamics as elucidated from high-resolution FTIR spectroscopy of chemically doped parahydrogen crystals. Some examples of the types of phenomena that have been studied are: ortho-H$2$ spin diffusion and cluster growth, nuclear spin relaxation of ortho-H$2$ to para-H$2$ catalyzed by the presence of a closed shell impurity molecule, and the loss of chemically reactive species introduced into the crystal via tunneling reactions with the surrounding H$2$.