The microwave spectrum of the PF2radical in theXtilde;thinsp;2B1ground vibronic state

摘要

The microwave spectrum of the PF2radical in theXtilde;thinsp;2B1ground vibronic state was observed by using a source modulation spectrometer. The radical was produced in a freehyphen;space absorption cell by a dc glow discharge in a mixture of PH3and CF4, and 260 spectral lines were observed in the frequency region of 63ndash;181 GHz and were assigned to 37 rotational transitions. The observed lines were leasthyphen;squares analyzed to determine the rotational constants, centrifugal distortion constants, spinhyphen;rotation coupling constants with centrifugal distortion correction terms, and magnetic hyperfine coupling constants for both the phosphorus and fluorine nuclei. The egr;aaspinhyphen;rotation coupling constant was found to be very small: minus;30.041 MHz, suggesting that excited electronic states contributing to egr;aaare all high lying or their contributions have canceled each other. Ther0structure of PF2was calculated from the observed rotational constants:r0(Pndash;F)=1.5792(18) Aring; and thgr;0(FPF)=98.48 (21)deg; with uncertainties in parentheses. The vibrational frequencies were estimated from the observed centrifugal distortion constants to be ohgr;1=864(14), ohgr;2=365.3(11), and ohgr;3=848(24) in cmminus;1. TheTccdipolar hyperfine coupling constants give the spin density of the unpaired electron orbital to be 92.1percnt; and 8.1percnt; at P and each of F, respectively, whereas theaFFermi coupling constants lead to thescharacters of 1.64percnt; and 0.18percnt; at the two atoms.