Further Investigations on the Microwave Spectrum of NSF: Evaluation of the Molecular Force Field, Centrifugal Distortion Constants, and the Dipole Moment

The measurements of the microwave spectrum of NSF have been extended to include transitions involving J as high as 40 and the centrifugal-distortion effects have been accounted for. By combining the analysis of the vibrational and rotational spectra, the molecular force field for NSF has been calculated and the following quadratic potential constants, in millidynes per angstrom, were obtained: f1=10.703, f2=2.872, Fα/d2=0.411, and f2α/d=0.014. Here 1 refers to the SN bond, 2 to the SF bond, α to the NSF bond angle, and d is the geometric mean of the SN and SF bond distances. It was found that the data were too insensitive to calculate f1α and f12 and these constants were assumed to be zero. The dipole moment was calculated from the Stark effect of the 51,4→42,3 transition and was found to be 1.902±0.012D, where the uncertainty represents the spread in the value of the dipole moment obtained from different methods of treating the data.