Inelastic neutron scattering of a quantum translator-rotator encapsulated in a closed fullerene cage: Isotope effects and translation-rotation coupling in H2@C60 and HD@C60

Abstract

We report an inelastic neutron-scattering (INS) investigation of coupled quantum translation and rotation of hydrogen molecules trapped inside the closed isotropic cages of C60. The low-lying states that characterize the translation-rotation manifold of the hydrogen molecules are accurately determined in our study of the INS peak energies. A comparison between the spectra of H2 and HD isotopomers provides quantitative insight into the coupling between rotational and translational angular momentum with HD exhibiting the strongest effects due to mixing of the rotational eigenstates. © 2010 The American Physical Society.