The hydrogen molecules inside nanocavities such as fullerenes, carbon nanotubes, clathrates hydrates and metal-organic frameworks have received wide attention among both experimentalists and theorists recently. In nano-confinement, both the translational center-of-mass and the rotational motions of the caged light molecule are quantized and coupled. Our rigorous quantum treatment of the coupled translation-rotation (TR) dynamics of the H2, D2, and HD inside C60 cage revealed the peculiar degeneracy patterns of the "rattling" eigenstates of the guest molecules. Meanwhile our new methodology for accurate quantum simulation of the inelastic neutron scattering (INS) spectra of a hydrogen molecule in a nanocavity[1] probes directly the TR eigenstates of confined molecule. This new advance predicts the very first INS selection rule for aperiodic system such as H2/HD inside C60 cage[2]. All above predicted spectroscopy features were confirmed subsequtently in both infrared and INS spectra of H2 inside C60. INS experiments confirms the prediction of selection rule for para-H2 in C60 [3]. Recently, the INS selection rule was generalized to cover a much wider range of transitions involving a variety of TR states of para- and ortho-H2, as well as HD, inside a near-spherical nanocavity [4]. [1]. M. Xu, L. Ulivi, M. Celli, D. Colognesi, and Z. Bacic, Phys. Rev. B, 83, 241403 (R) (2011). [2]. M. Xu, S. Ye, A. Powers, R. Lawler, N. J. Turro, and Z. Bacic, J. Chem. Phys. 139, 064309 (2013). [3]. M. Xu, M. Jimenez-Ruiz, M. R. Johnson, S. Rols, S. Ye, M. Carravetta, M. S. Denning, X. Lei, Z. Bacic, and A. J. Horsewill, Phys. Rev. Lett. 113, 123001 (2014). [4]. M. Xu, S. Ye, and Z. Bacic, J. Phys. Chem. Lett. 6, 3721 (2015).

H2, D2, and HD inside C60: The coupled translation-rotation quantum dynamics and the selection rules in the inelastic neutron scattering spectroscopy

251st National Meeting (2016)

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