Matrix isolation spectroscopy of H2O, D2O, and HDO in solid parahydrogen

Abstract

Public reporting burlenror this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information ABSTRACTWe present infrared (IR) absorption spectra over the 800-7800 cm"1 region of cryogenic parahydrogen (pH 2 ) solids doped with H20, D 2 0 and HDO molecules. Analysis of the rovibrational spectra of the isolated H 2 0, D 2 0 and HDO monomers reveals their existence as very slightly hindered rotors, typically showing only 2 to 5 % reductions in rotational constants relative to the gas phase. The nuclear spin conversion (NSC) of metastable J = 1 ortho-H 2 0 (oH20) and para-D 2 0 (pD 2 0) molecules follow first order kinetics, with single exponential decay lifetimes at T = 2.4 K of 1900±100 s, and 860±50 s, respectively. We report without discussion some absorptions of water clusters produced during sample annealing. We report and assign a number of absorptions to oH2-water pairs or "complexes." The main features of the oH 2 -H 2 0 and oH 2 -D 2 0 spectra are explained qualitatively by assuming a semi-rigid C 2 , structure with the oH2 acting as a proton donor to the 0 atom. Surprisingly, NSC of oH 2 -water complexes proceeds at very nearly the same rate as for the corresponding water monomer. We report unassigned spectra of larger (oH2)n-water clusters, and the even more surprising observation of the prolonged survival of 01-20 and pD 2 0 molecules clustered with several o0-2 molecules. We report and assign a number of water dopant-induced IR absorption features of the pH2 host, along with cooperative water-pH 2 transitions in which the vibrational excitation of the pH2 solid is accompanied by a pure rotational transition of the water dopant.

Collisional cross-section of water molecules in vapour studied by means of 1H relaxation in NMR

“…Our measurements are useful to refine intermolecular potentials for water vapour. These may be compared with water confined in matrices3334 or in fullerene cages2135 where a gas-phase like behaviour can be observed.…”

Infrared spectroscopy of solid normal hydrogen doped with CH3F and O2 at 4.2 K: CH3F:O2 complex and CH3F migration

“…In solid pH 2 , dopant molecules such as H 2 O [5,6], CH 4 [7][8][9][10] and HCl [11], trapped in high-symmetry single substitutional sites with 12 nearest neighbors, undergo almost free rotation. The CH 3 F molecule rotates only about its C 3 axis [12], and always carries a nonzero total nuclear spin (I = 3/2 or 1/2).…”