The Microwave and Millimetre Wave Spectrum, Molecular Constants, Dipole Moment, and Structure of Isocyanic Acid, HNCO
Citations Over TimeTop 10% of 1975 papers
Abstract
The microwave and millimetre wave spectra of six isotopic species of isocyanic acid, HNCO, have been measured. The molecule is a very slightly asymmetric prolate rotor. Besides the a type R branches, previously reported for two species, we have assigned for the first time a type Q branches and also some intense b type P and R branch transitions. Accurate values of the rotational constants have been determined. The rotational constant A 0 is particularly large, with the result that the molecule undergoes very large centrifugal distortion, and terms up to the 12th power in the angular momentum are required to fit the spectrum. 14 N nuclear quadrupole hyperfine splitting has been measured and accurate values for both χ aa and (χ bb − χ cc ) have been obtained, the latter for the first time. From the Stark effect of the b type transitions we have found the b component of the dipole moment to be 1.35 ± 0.1 D, an order of magnitude larger than previously supposed, and have used it to reinterpret earlier data indicating a variation of the a component with K a . An improved molecular structure has been obtained. Astrophysical consequences of the large b component of the dipole moment are discussed. A table of transitions of potential astrophysical interest is presented.
Related Papers
- → Fine and hyperfine structure in theX2Σ+-state of AlO(1989)30 cited
- → Phosphorus and silicon analogs of isocyanic acid: Microwave detection of HPCO and HNSiO(2014)18 cited
- → The Lamb-dip spectrum of phosphine: The nuclear hyperfine structure due to hydrogen and phosphorus(2006)24 cited
- → High-resolution laser-rf spectroscopy on the AΠ-XΠ system of lodine oxide (IO)(1983)54 cited
- → Hyperfine structure of the J= 1 ? 0 and J= 2 ? 1 transitions of D35Cl and D37Cl(2004)10 cited