THEORETICAL AND EXPERIMENTAL STUDY OF THE ROVIBRATIONAL SPECTRA OF CO$_2$-({\em para}-H$_2$)-He TRIMERS
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Date
2011
Journal Title
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Publisher
Ohio State University
Abstract
Clusters of {\em p}-H$_2$ had been predicted to exhibit superfluid behavior twenty years ago, {\bf 67}, 1871 (1991).} but direct observation of this phenomenon was elusive until our recent work {\bf 105}, 133401 (2010)} combining experimental measurments and theoretical simulations of the non-classical rotational inertia and superfluid response of {\em p}-H$_2$ clusters doped with CO$_2$. However, the size-dependent superfluid response of those clusters reached a maxmum at $N\!=\!12$, and the clusters become frozen at larger $N$. It is therefore interesting to examine the effect of adding helium atoms to a pure {\em p}-H$_2$ shell around a CO$_2$ chromophore, and to investigate their effect on the superfluid response of CO$_2$-({\em p}-H$_2$)$_N$ for $N\!>\!12$. This will help us understand the role of helium as a `second solvent' species, and help explain experiments that had been presented as evidence of superfluidity of doped hydrogen clusters embedded in helium nanodroplets. {\bf 289}, 1532 (2000).} Exact quantum calculation of infrared and microwave spectra for dopant molecules attached to two pure He atoms or two pure {\em p}-H$_2$ molecules, respectively, have been reported by Wang and co-workers and by Li {\em et al}.\ {\bf 87}, 417 (2009); {\em J.\ Phys.\ Chem.} {\bf A 113}, 13331 (2009); {\em Can.\ J.\ Phys.}\ {\bf 88}, 779 (2010); \,H.\ Li, P.-N.\ Roy and R.J.\ Le Roy, {\em J.\ Phys.\ Chem.}\ (2011, {\em submitted}).}~ To date, however, no such calculations have been reported for mixed {\em p}-H$_2$/He solvent species. The present paper therefore extends such work to the case of one {\em p}-H$_2$ and one He atom attached to one CO$_2$ dopant molecule. Three-dimensional {\em p}-H$_2$ and helium densities in the body-fixed frame are presented, and compared with those for the analogous CO$_2$--(He)$_2$ and CO$_2$--({\em p}-H$_2$)$_2$ trimers.
Description
Author Institution: Institute of Theoretical Chemistry, State Key Lab. of; Theoretical \& Computational Chemistry, Jilin Univ., 2519 Jiefang Rd; Changchun 130023, P.R.China; Chemistry Dept., Univ. of Waterloo, Waterloo, Ontario N2L 3G1, Canada; Chemistry Dept., Univ. of Waterloo, Waterloo; Ontario N2L 3G1, Canada; Steacie Institute for Molecular Sciences, NRCC, Ottawa, Ontario K1A OR6, Canada