ABSTRACT
The high-resolution infrared spectrum of the nu(8) band of SO(2)F(2) (nu(as) SF(2)) centered at 887.2 cm(-1) has been recorded with a resolution of 2.4 x 10(-3) cm(-1). More than 8000 transitions of the C-type band with DeltaK(a) = +/-1 (and in addition some DeltaK(a) = +/-3 transitions) have been assigned. Microwave and millimeter-wave spectra of the v(8) = 1 state up to 450 GHz have been recorded, and 177 pure rotational transitions have been measured. Rotational and rovibrational data have been combined, and excited state parameters up to sextic centrifugal distortion constants have been determined using a Watson-type Hamiltonian in S-reduction. No perturbation was indicated. Copyright 2000 Academic Press.
ABSTRACT
The rotational spectrum of the near-spherical top molecule SO(2)F(2) (sulfuryl fluoride) has been investigated by microwave Fourier transform spectroscopy and by millimeter-wave spectroscopy. The ground state spectrum has been measured from 10 to 472 GHz. One of the reasons for studying this molecule is that it is a nearly spherical top and we wanted to verify our theoretical prediction that for such a molecule all six quartic centrifugal distortion constants (and nine sextic distortion constants) should be determinable, while for a standard asymmetric rotor, Watson has shown that only five quartic and seven sextic distortion constants are determinable. The analysis of the spectra confirmed our predictions, because all six quartic constants were well determinable. The results have been confirmed independently by ab initio calculations of the force field and quartic distortion constants. Because the molecule is relatively heavy, contributions of some sextic constants are too small and we have not been able to determine all nine sextic constants predicted by theory. Copyright 2000 Academic Press.
ABSTRACT
The ground state rotational spectra of SiH3CN and its 29Si, 30Si, 13C, 15N, d1, d2, and d3 isotopic species have been measured by Fourier transform microwave spectroscopy and by millimeterwave spectroscopy. Accurate rotational, centrifugal distortion, and 14N and D nuclear quadrupole coupling constants have been derived. The dipole moment of the parent species has also been measured, µ = 3.4400(42) D. The structure, force field, dipole moment, and nuclear quadrupole coupling constants have been calculated ab initio at the SCF, MP2, and B3LYP levels using triple zeta polarized basis sets. The experimental ro, rs, and rz structures have been determined. An approximate equilibrium structure has been obtained by combining the experimental results and the ab initio calculations: re(C&tbond;N) = 1.159 Å, re(Si&sbond;C) = 1.848 Å, re(Si&sbond;H) = 1.470 Å, and angle(HSiC) = 107.4 degrees. Copyright 1998 Academic Press.
