Photolysis of phenol and para-chlorophenol by UV laser excitation

The photolysis of phenol and para-chlorophenol by irradiation with the four th harmonic of a neodymium laser was examined using electronic absorption s pectroscopy, fluorescence, and quantum-chemical techniques. It was found th at the introduction of a chlorine atom into the phenol molecule increases t he efficiency of photolysis of para-chlorophenol by excitation in the long- wavelength absorption band. The O-H and C-Cl bonds in the test compounds ar e ruptured via a predissociation mechanism in triplet states localized at t he breaking bonds.