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1 +
2 -
2 HOT BAND OF THE FeCO RADICAL PRODUCED BY THE ULTRAVIOLET LASER PHOTOLYSIS OF Fe(CO)5.
KEIICHI TANAKA, T. HIKITA AND T. TANAKA, Department of Chemistry, Kyushu University, Fukuoka, 812-8581 Japan.
Time-resolved infrared diode laser spectroscopy was applied to the observation of the
1 +
2 -
2 hot band of the iron carbonyl (FeCO) radical. The FeCO radical was produced by the ArF excimer laser photolysis of iron pentacarbonyl Fe(CO)5. Although the FeCO radical has the 3
- electronic ground state, the
2 bending vibrational excited state has vibronically the 3
symmetry, which allows the vibronic interaction with the 3
electronic state located very closely, 6400 cm-1, to the ground electronic state .
In the frequency region of 1930-1950 cm-1, more than 50 R- and P-branch lines were identified which split into triplet (P = 0, 1, and 2) due to the spin-spin interaction. Each spin component split further into doublet, as
-type doubling, because of the vibraonic interaction with the nearby 3
electronic state. The band origin
0 = 1941.54573 (50) cm-1 was determined as well as the molecular constants for the
1 +
2 state, fixing the molecular constants for the
2 state to those of the millimeter-wave . results. The effective spin-orbit constant Aeff and the
-type doubling constants for the
1 +
2 state are much different from those of the
2 state indicating that the effect of vibronic interaction with the 3
electronic state has increased due to the excitation of the
1 vibration.