Induced infrared absorption of molecular hydrogen in solidC60

We report on the observation of induced infrared absorption in a molecular species trapped within a ${\mathrm{C}}_{60}$ lattice. Infrared spectra for interstitial ${\mathrm{H}}_2$ show distinct rotational and translational side-bands superimposed on the ${\mathrm{H}}_2$’s highly redshifted $\left(54\mathrm{}\hspace{0.5em}{\mathrm{cm}}^{-1}\right)$ fundamental vibrational mode. Data indicate that the hydrogen is rotating almost completely freely while at the same time undergoing localized three-dimensional translational motion within the “box” formed by the ${\mathrm{C}}_{60}$ molecules.