First observation of the OIO molecule by time-resolved flash photolysis absorption spectroscopy

In the time-resolved flash photolysis of I-2 in O-3, in addition to the IO electronic bands between 21500 and 26000 cm(-1), a new absorption spectrum has been observed between 15000 and 21500 cm(-1), which is attributed to the (A) over tilde-(X) over tilde electronic bands of the OIO radical. A number of spectroscopic constants of the (A) over tilde state of OIO were determined by linear least-squares fitting the observed spectrum: nu(1) (symmetric I-O stretch) omega(1) = 631 cm(-1), nu(1) anharmonicity constant omega(1)X(1) = 2.6 cm(-1), nu(2) (O-I-O angle bend) omega(2) = 177 cm(-1), electronic energy with respect to the ground state T-c = 14553 cm(-1). These values are in good agreement with those expected from measurements of the same electronic bands in OClO and OBrO.