POLARIZATION QUANTUM BEAT SPECTROSCOPY OF HCF $(A^{1} A^{\prime\prime}): ^{19}$F AND ${^{1}}$H NUCLEAR HYPERFINE STRUCTURE AND THE ZEEMAN EFFECT

Abstract

To investigate the ${^{19}}F$ and ${^{1}}H$ nuclear hyperfine structure and Zeeman effect in the simplest singlet carbene, HCF, we recorded polarization quantum beat spectra (QBS) of ${^{r}}R_{0}(J)$ lines of the pure bending transitions $2^{n}{0}$ and combination bands $1^{1}{0}2^{n}{0}$ and $2^{n}{0}3^{1}{0}$ in the HCF $A^{1} A^{\prime\prime}-X^{1} A^{\prime}$ system. The spectra were measured under jet-cooled conditions using a pulsed discharge source, both at zero-field and under application of a weak magnetic field $(< 30 G)$. Analysis yielded the nuclear spin-rotation constants $(C{aa})$ and weak field Lande $g_{aa}$ factors. Consistent with theoretical expectations, the majority of vibrational levels exhibit a linear correlation of $C_{aa}$ and $g_{aa}$, from which the a hyperfine constants were estimated. The derived values are consistent with expectations based on the known hyperfine constants of related molecules.