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Pulsednozzle Fouriertransform microwave spectroscopy of laservaporized metal oxides: Rotational spectra and electric dipole moments of YO, LaO, ZrO, and HfO J. Chem. Phys. 92, 4724 (1990); 10.1063/1.457690 An investigation of the trimethylammonium chloride molecule in the vapor phase by pulsednozzle, Fourier transform microwave spectroscopy J. Chem. Phys. 90, 6867 (1989); 10.1063/1.456260 Optothermalinfrared and pulsednozzle Fouriertransform microwave spectroscopy of rare gas-CO2 complexes J. Chem. Phys. 88, 6157 (1988); 10.1063/1.454454An investigation of the hydrogenbonded dimer H3NHBr by pulsednozzle, Fouriertransform microwave spectroscopy of ammonium bromide vaporThe high sensitivity of pulsed-nozzle, Fourier-transform microwave spectroscopy has been used to observe the rotational spectra of the isotopic species H/ 4 S···HF, H2 33S···HF, and H2 32S···DF of the hydrogen sulphide-hydrogen fluoride complex. The hyperfine coupling constants D~: = -236 (7) kHz, Xaae 3 S) = 32.785(9) MHz, and X ~ = 274(6) kHz, respectively, have thereby been determined together with (Bo + Co) and D J values. TheK_ 1 = 1, J = 2+-1 transitions ofH 2 32S ... HF, which are very weak because of the low effective temperature of the supersonically expanded gas, have also been detected. Their frequencies, when combined with those of the 202+-101 and 1 01 +-0 00 transitions, then allow the spectroscopic constants (Bo -Co) = 8.768(2) MHz, (Bo + Co) = 7672.413(2) MHz, D J = 15.10(22) kHz, and DJK = 473.3 kHz to be obtained. The values of the various spectroscopic constants have been interpreted in terms of the geometry and internal dynamics of the complex.

The ground state rotational spectrum of a hydrogen-bonded heterodimer formed from water and hydrogen cyanide has been detected and measured by using the technique of pulsed-nozzle, Fourier-transform microwave spectroscopy. Rotational constants ( B 0 , C 0 ) centrifugal distortion constants ( ∆ J , ∆ JK ) and, where appropriate, 14 N-, D- or 17 O-nuclear quadrupole coupling constants have been determined for the following isotopic species; H 2 16 O· · · HC 14 N, H 2 18 O· · · HC 14 N, H 2 16 O· · · HC 15 N, HD 16 O· · · HC 15 N, D 2 16 O· · · HC 15 N, H 2 16 O· · · DC 15 N, HD 16 O· · · DC 15 N and H 2 17 O· · · HC 15 N. An analysis of these spectroscopic constants indicates that the heterodimer is effectively planar, with a pair of equivalent protons and the arrangement H 2 O· · · HCN. The intermolecular interaction is through a hydrogen bond between HCN and H 2 O and the distance between the O and C nuclei r (O· · · C) is 3.157 Å (1Å = 10 -10 m). An interpretation of the nuclear quadrupole coupling constants leads to the conclusion that arccos <cos 2 Φ > ½ ≈ 51°, where Φ is the angle between the local C 2 axis of H 2 O and the a -axis of the complex; and that arccos <cos 2 θ > ½ ≈ 10°, where θ is the angle between the HCN axis and the a -axis. The intermolecular stretching force constant k σ = 11 Nm -1 has been determined from ∆ J .