TOSHIHIDE HIKIDA, SEIKI IKEDA, KEIICHI TANAKA AND TAKEHIKO TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashiku, Fukuoka 812-8581, Japan.
Rovibrational transitions of the 1 band (C-O stretch) of the CoCO radical produced by the ultraviolet photolysis of Co(CO)3NO were observed in 1949-1991 cm-1 region by the time resolved infrared diode laser spectroscopy. The electronic ground state was confirmed to be X 2 i by the analysis as predicted by the density functional theory calculation. ~ More than 140 absorption lines were assigned to the = 5/2 spin component of the 1 fundamental band in the X 2 i state. No lines of the = 3/2 component were observed due to the large spin-orbit interaction constant A (-500 cm-1 ). Effective molecular constants for the = 5/2 spin component, including the band origin 0 and the rotational constant B, were derived from observed transitions. Hot band lines originated from the 2 (Co-C-O bending) and 3 (Co-C stretch) vibrational excited states were observed. Absorption lines for the 2 hot band were split into two components because of the vibronic interaction between the 2 state and other nearby electronic excited states. The effective equilibrium rotational constant Be and the vibration rotation constants, 1, 2 and 3 were determined from the analysis of the fundamental band and hot bands.