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Rotational spectra of the van der Waals complexes of molecular hydrogen and OCS.
- Source :
- Journal of Chemical Physics; 8/3/2007, Vol. 127 Issue 5, pN.PAG, 8p, 1 Diagram, 3 Charts, 2 Graphs
- Publication Year :
- 2007
-
Abstract
- The a- and b-type rotational transitions of the weakly bound complexes formed by molecular hydrogen and OCS, para-H<subscript>2</subscript>–OCS, ortho-H<subscript>2</subscript>–OCS, HD–OCS, para-D<subscript>2</subscript>–OCS, and ortho-D<subscript>2</subscript>–OCS, have been measured by Fourier transform microwave spectroscopy. All five species have ground rotational states with total rotational angular momentum J=0, regardless of whether the hydrogen rotational angular momentum is j=0 as in para-H<subscript>2</subscript>, ortho-D<subscript>2</subscript>, and HD or j=1 as in ortho-H<subscript>2</subscript> and para-D<subscript>2</subscript>. This indicates quenching of the hydrogen angular momentum for the ortho-H<subscript>2</subscript> and para-D<subscript>2</subscript> species by the anisotropy of the intermolecular potential. The ground states of these complexes are slightly asymmetric prolate tops, with the hydrogen center of mass located on the side of the OCS, giving a planar T-shaped molecular geometry. The hydrogen spatial distribution is spherical in the three j=0 species, while it is bilobal and oriented nearly parallel to the OCS in the ground state of the two j=1 species. The j=1 species show strong Coriolis coupling with unobserved low-lying excited states. The abundance of para-H<subscript>2</subscript>–OCS relative to ortho-H<subscript>2</subscript>–OCS increases exponentially with decreasing normal H<subscript>2</subscript> component in H<subscript>2</subscript>/He gas mixtures, making the observation of para-H<subscript>2</subscript>–OCS in the presence of the more strongly bound ortho-H<subscript>2</subscript>–OCS dependent on using lower concentrations of H<subscript>2</subscript>. The determined rotational constants are A=22 401.889(4) MHz, B=5993.774(2) MHz, and C=4602.038(2) MHz for para-H<subscript>2</subscript>–OCS; A=22 942.218(6) MHz, B=5675.156(7) MHz, and C=4542.960(7) MHz for ortho-H<subscript>2</subscript>–OCS; A=15 970.010(3) MHz, B=5847.595(1) MHz, and C=4177.699(1) MHz for HD–OCS; A=12 829.2875(9) MHz, B=5671.3573(7) MHz, and C=3846.7041(6) MHz for ortho-D<subscript>2</subscript>–OCS; and A=13 046.800(3) MHz, B=5454.612(2) MHz, and C=3834.590(2) MHz for para-D<subscript>2</subscript>–OCS. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 00219606
- Volume :
- 127
- Issue :
- 5
- Database :
- Complementary Index
- Journal :
- Journal of Chemical Physics
- Publication Type :
- Academic Journal
- Accession number :
- 26222228
- Full Text :
- https://doi.org/10.1063/1.2756534