ArF laser flash photolysis of phenol and anisole

Absorption spectra of phenoxy radical in the gas phase are observed in the range of 210–300 nm in the ArF excimer laser (193 nm) flash photolysis of phenol and anisole. An intense absorption band is obtained around 230 nm and a broad band around 270–300 nm. In the photolysis of anisole, simultaneous formation of methyl and phenoxy radicals makes it possible to determine the molar extinction coefficient of phenoxy radical which is determined to be 7800 M−1 cm−1 at 230 nm. The phenoxy radicals are produced in the time range of shorter than 1 ns from phenol, anisole, pentafluorophenol, and pentafluoroanisole on irradiation with the ArF laser light. The photodissociation is not explained in terms of the hot molecule mechanism but of predissociation.