Detection of OH Radical in the Photodissociation ofp-Aminobenzoic Acid at 266 nm

Photodissociation of p-aminobenzoic acid at 266 nm was investigated by probing the nascent OH photoproduct employing the laser-induced fluorescence technique. It was found that the nascent OH radical was vibrationally cold and its rotational state distribution conformed to be a Boltzmann behavior, characterized by a rotational temperature of 1040 110 K. The rotational energy of OH was determined to be 8.78 0.84 kJ/mol. Between the two spin-orbit states of OH, 23/2 and 21/2, the former was found to be preferentially populated. The distribution of the (A) state for the -doublet was dominant. Finally, a probable mechanism for the formation of OH produced from the photodissociation of p-aminobenzoic acid is discussed.