UV-VISIBLE SPECTRUM OF THE PHENYL RADICAL AND KINETICS OF ITS REACTION WITH NO IN THE GAS-PHASE

Pulse radiolysis transient UV-visible absorption spectroscopy was used to study the UV-visible absorption spectrum (225-575 nm) of the pheny l radical, C6H5(.), and kinetics of its reaction with NO. Phenyl radic als have a strong broad featureless absorption in the region of 225-34 0 nm. In the presence of NO phenyl radicals are converted into nitroso benzene. The phenyl radical spectrum was measured relative to that of nitrosobenzene. Based upon sigma(C6H5NO)(270nm) = 3.82 x 10(-17) cm(2) molecule(-1) we derive an absorption cross-section for phenyl radical s at 250 nm, sigma(C6H5(.))(250nm) = (2.75 +/- 0.58) x 10(-17) cm(2) m olecule(-1). At 295 K in 200-1000 mbar of Ar diluent k(C6H5(.) + NO) = (2.09 +/- 0.15) x 10(-11) cm(3) molecule(-1) s(-1). (C) 1998 Elsevier Science B.V. All rights reserved.