UV–visible spectrum of the phenyl radical and kinetics of its reaction with NO in the gas phase

Abstract

Pulse radiolysis transient UV–visible absorption spectroscopy was used to study the UV–visible absorption spectrum (225–575 nm) of the phenyl radical, C 6H 5(⋅), and kinetics of its reaction with NO. Phenyl radicals have a strong broad featureless absorption in the region of 225–340 nm. In the presence of NO phenyl radicals are converted into nitrosobenzene. The phenyl radical spectrum was measured relative to that of nitrosobenzene. Based upon σ(C 6H 5NO) 270 nm =3.82×10 −17 cm 2 molecule −1 we derive an absorption cross-section for phenyl radicals at 250 nm, σ(C 6H 5(⋅)) 250 nm =(2.75±0.58)×10 −17 cm 2 molecule −1. At 295 K in 200–1000 mbar of Ar diluent k(C 6H 5(⋅)+NO)=(2.09±0.15)×10 −11 cm 3 molecule −1 s −1.