Rotational Spectrum and Internal Dynamics
of the Ne–H2S van der Waals Complex.
Yaqian Liu and Wolfgang Jäger
Department of Chemistry, University of Alberta, Edmonton AB T6G 2G2, Canada
Rotational spectra of several isotopomers of the Ne–H2S van der Waals dimer were measured in the frequency range from 4 to 22 GHz, using a pulsed molecular beam Fourier transform microwave spectrometer. Two K = 0 progressions were recorded for the symmetrical isotopomers (with H2S/D2S). This doubling is attributed to an internal rotation motion of the H2S moiety within the complex. The two states can be correlated to the 000 and 101 internal rotor states of free H2S and D2S. Only one K = 0 progression was measured for Ne–DSH. The excited internal rotor state is no longer metastable since the symmetry constraints no longer apply. An anomalous isotope effect observed in Ar–H2S, where the substitution of hydrogen by deuterium causes an increase in the ground state B rotational constant,1 was not observed here, in agreement with the ab initio study by Dykstra and co-workers.2 Nuclear quadrupole hyperfine structure was resolved or partially resolved for isotopomers containing 33S and D, respectively, and the corresponding quadrupole coupling constants were determined. These were used to derive information about the intermolecular dynamics. The results are compared with those of Ar–H2S and Ar–H2O.
1 H. S. Gutowsky, T. Emilsson, and E. Arunan, J. Chem. Phys 106, 5309 (1997).
2 G. de Oliveria and C. Dykstra, J. Chem. Phys 110, 289 (1999).