A STUDY OF THE FO RADICAL BY FAR-IR LMR

Abstract

The fine-structure transition $^{2}\Pi_{1/2} \leftarrow ^{2}\Pi_{3/2}$ of the free radical FO has been detected by far-infrared Laser Magnetic Resonance. The spectrum is entirely magnetic dipole and several pure rotational transitions ranging between $J = \frac{1}{2}$ and $J = 20 \frac{1}{2}$ have been recorded in both perpendicular and parallel polarization. These data form the most accurate spectroscopic information available for FO. A set of 272 transitions have been analyzed using a linear least-squares fit. The Hamiltonian, which contains rotational, centrifugal distortion, spin-orbit. A-doubling, magnetic hyperfine and Zeeman terms, was set up in a decoupled basis set. The spin-orbit coupling constant $A_{0}$, the magnetic hyperfine parameters $a, b_{P}, c, d$ and a number of g-factors have been derived experimentally for the first time. The value of $A_{0}$ obtained from the fit is: $A_{0} = -196.108690(50) cm^{-1}$.