ELECTRONIC SPECTROSCOPY OF JET-COOLED IRON MONOCARBIDE - THE (3)DELTA(I)[--](3)DELTA(I) TRANSITION NEAR 493 NM

We report the first gas phase spectroscopic study of iron monocarbide. FeC molecules generated in a laser vaporization molecular beam source and detected by laser induced fluorescence. Twenty-six vibronic bands have been recorded in the 430-500 nm region. Rotational analyses have been carried out for 22 of the bands. There are three lower states involved, two with Omega''=2 and one with Omega''=3. Based on our experimental observations and the ab initio calculations on RuC [Shim et al. J. Phys. Chem. 91, 3171 (1987)] the observed bands are interpreted as (3) Delta(i)<--(3) Delta(i) and (1) Delta<--(1) Delta transitions. The ground state electronic configuration is assigned to 1 delta(3)9 sigma(1). Evidence for three excited electronic states (one (3) Delta(i) state, one (1) Delta state and another state with Omega'=3) and for perturbations in several of their vibrational levels is presented. (C) 1995 American Institute of Physics.