Fine-structure spectrum of the FO radical, observed by far-infrared laser magnetic resonance

The fine-structure transition 2∏1/2→ 2∏3/2 of the free radical FO has been detected by far-infrared laser magnetic resonance. All the observed transitions are magnetic dipole in character. The spin-orbit constant A0 has been determined experimentally; its value of -196.108686(50) cm-1 is consistent with previous estimates. The analysis of a set of 290 transitions leads to the determination of a number of molecular parameters including rotational, centrifugal distortion, spin-orbit, lambda-doubling, magnetic hyperfine, and Zeeman terms. All four magnetic hyperfine structure constants a, bF, c, d for the 19F nucleus have been determined and are discussed in terms of the expectation values of the appropriate operators over the electronic wave function. © 1999 American Institute of Physics.