ROTATIONAL SPECTROSCOPY OF THE COH RADICAL IN ITS GROUND 3-PHI STATE BY FAR-INFRARED LASER MAGNETIC-RESONANCE - DETERMINATION OF MOLECULAR-PARAMETERS

Five rotational transitions of CoH in its ground (3) phi state have be en detected by far-infrared laser magnetic resonance, three in the low est Omega = 4 component and two in the Omega = 3 component. All the Ze eman transitions show an octet hyperfine pattern due to the Co-59 nucl eus (I = 7/2). The much smaller proton doubling was also resolved for most transitions. The data have been fitted to experimental accuracy b y an effective Hamiltonian for a molecule in an isolated (3) phi state . The electron orbital and spin g factors determined by the data confi rm conclusively that the ground state of CoH is a (3) phi state. The a ccurate measurement of the rotational constant allows the equilibrium bond length to be determined: r(e)= 0.15138435(80) nm. A small Delta-t ype doubling was resolved in the (3) phi(3) component, suggesting the proximity of a (3) Sigma state among the low-lying electronic states. The cobalt hyperfine splittings have been fitted to determine magnetic dipole and electric quadrupole parameters, which are interpreted in t erms of the dominant configuration description for the (3) phi ground state. (C) 1994 Academic Press, Inc.