title: The rotational and fine-structure spectrum of FeH, studied by far-infrared laser magnetic resonance.
abstract: Transitions between the spin-rotational levels of the FeH radical in the upsilon=0 level of the X (4)Delta ground state have been detected by the technique of laser magnetic resonance at far-infrared wavelengths. Both pure rotational and fine-structure transitions have been observed; lambda-type doubling is resolved on all the observed transitions. The energy levels of FeH are strongly affected by the breakdown of the Born-Oppenheimer approximation and cannot be modeled accurately by an effective Hamiltonian. The data are therefore fitted to an empirical formula to yield term values and g factors for the various spin-rotational levels involved. Many of the resonances show a doubling that arises from the proton hyperfine structure. These splittings are analyzed in a similar manner.
authors.affiliation: The Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, United Kingdom. jmb@physchem.ox.ac.uk
authors.forename: John M
authors.initials: JM
authors.lastname: Brown
authors.forename: Helga
authors.initials: H
authors.lastname: Körsgen
authors.forename: Stuart P
authors.initials: SP
authors.lastname: Beaton
authors.forename: Kenneth M
authors.initials: KM
authors.lastname: Evenson