Low-temperature infrared spectroscopy of H2 in crystalline C60

Diffuse reflectance infrared spectroscopy is used to measure the quantum dynamics of molecular hydrogen trapped within a C60 lattice at temperatures as low as 10 K. Crystal field effects in conjunction with rotational translational coupling lead to a rich spectrum with multiply split peaks that are more than an order of magnitude sharper than at room temperature. The induced redshifts in the vibrational-rotational mode frequencies are explained using a simple model in which the state dependence of the H2 polarizability leads to changes in the C60-H2 interaction potential

Cryogenic apparatus for diffuse reflection infrared spectroscopy with high-pressure capabilities

A cryogenic apparatus for obtaining diffuse reflection infrared spectra at liquid helium temperature is described. The system combines a commercially available reflection accessory and cold finger cryostat with a custom designed vacuum housing and high-pressure sample cell. This enables spectra to be obtained from room temperature to 10 K and at gas loading pressures as high as 100 bars. Initial experiments on H2 in solid C60 show the power of the system to obtain spectra that are significantly enhanced relative to those at room temperature