15min:

MASATO HAYASHI, TOSHIHIDE HIKIDA, KENSUKE HARADA, KEIICHI TANAKA AND TAKEHIKO TANAKA, Department of Chemistry, Faculty of Science, Kyushu University 33, Hakozaki, Higashiku, Fukuoka 812-8581, Japan.

Rotational spectrum of the CoCO radical generated by ultraviolet photolysis of Co(CO)₃NO was measured in the millimeter wave region to determine rotational and hyperfine interaction constants. Rotational transitions ranging from J = 29.5 - 28.5 to 34.5 - 33.5 were assigned in the = 3/2 and = 5/2 spin substates of the X² _i ground vibronic state as well as in the vibrationally excited states ₂, ₃, and 2 ₂ of the = 5/2 spin substate. Each rotational transition was split into 8 hyperfine components due to the ⁵⁹Co nucleus. Molecular constants, including the rotational constant B, centrifugal distortion constant D, nuclear spin-orbit interaction constant a, Fermi contact interaction constant b_F, magnetic dipolar interaction constant c, and nuclear quadrupole interaction constant eQq, were determined for the vibrationally ground state by least squares fitting of the observed spectrum. The equilibrium rotational constant B_ riptsizee was determined to be 4435.7510(18) MHz and the internuclear distance between Co and C was evaluated to be 1.688 Å. The a and c values are consistent with the values estimated from the hyperfine constants of the ⁵⁹Co atom. The b_F value is nearly equal to zero.