Dihydrogen in zeolite CaXAn inelastic neutron scattering study

We report an inelastic neutron scattering (INS) study of the rotational-vibrational spectrum of dihydrogen sorbed by zeolite CaX. In the low energy (<200 cm(-1)) INS spectrum of adsorbed H-2 we observe the rotational-vibrational spectrum of H-2, where the vibration is that of the H-2 molecule against the binding site (i.e. H-2-X, not H-H). We have observed for the first time the vibrational overtones of the hydrogen molecule against the adsorption surface up to sixth order. These vibrations are usually forbidden in INS spectroscopy because of the selection rules imposed by the spin flip event required. In our case we are able to observe such a vibration because the rotational transition J(1