Bacic Group Elucidates Condensed-Phase Effects, in JPC Letters

bacic.jpgNYU Chemistry Professor Zlatko Bačić's group and their Italian collaborators have elucidated the effects of the condensed phase on the quantum dynamics and spectroscopy of a hydrogen molecule in clathrate hydrates. This result was published in the January 21, 2016 issue of J. Phys. Chem. Lett. (volume 7, Issue 2). The article is entitled Impact of the Condensed-Phase Environment on the Translation-Rotation Eigenstates and Spectra of a Hydrogen Molecule in Clathrate Hydrates ( DOI: 10.1021/acs.jpclett.5b02611 ) The authors include NYU Chemistry Professor Mark Tuckerman and Bacic group members Anna Powers, Ondrej Marsalek and Minzhong Xu.

Abstract: We investigate systematically the manifestations of the condensed-phase environment of the structure II clathrate hydrate in the translation-rotation (TR) dynamics and the inelastic neutron scattering (INS) spectra of an H2 molecule confined in the small dodecahedral cage of the hydrate. The aim is to elucidate the extent to which these properties are affected  by the clathrate water molecules beyond the confining cage and the proton disorder of the water framework. For this purpose, quantum calculations of the TR eigenstates and INS spectra are performed for H2 inside spherical clathrate domains of gradually increasing radius and the number of water molecules ranging from 20 for the isolated small cage to more than 1800. For each domain size, several hundred distinct hydrogen-bonding topologies are constructed in order to simulate the effects of the proton disorder. Our study reveals that the clathrate-induced splittings of the j=1 rotational level and the translational fundamental of the guest H2 are influenced by the condensed-phase environment to a dramatically different degree, the former very strongly and the latter only weakly.

This research was supported by the National Science Foundation.

Updated on 04/26/2016