화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.117, No.46, 12138-12145, 2013
Ultraviolet Photodissociation Dynamics of the o-Pyridyl Radical
Ultraviolet (UV) photodissociation dynamics of jet-cooled o-pyridyl radical (o-C5H4N) was studied in the photolysis region 224-246 nm using the high-n Rydberg atom time-of-flight (HRTOF) technique. The o-pyridyl radicals were produced from 193 nm photolysis of 2-chloropyridine and 2-bromopyridine precursors. The Hatom photofragment yield (PFY) spectrum contains a broad peak in this wavelength region and reveals the UV absorption feature of o-pyridyl for the first time. The translational energy distributions of the H-atom loss product channel, P(E-T)'s, peak at similar to 7 kcal/mol, and the fraction of average translational energy in the total excess energy, (f(T)), is nearly constant at similar to 0.18 in the region 224-242 nm. The P(E-T) distribution indicates the production of the lowest energy dissociation products,.H + cyanovinylacetylene. The H-atom product angular distribution is isotropic. The dissociation mechanism is consistent with unimolecular dissociation of the hot o-pyridyl radical to H + cyanovinylacetylene after internal conversion from the electronically excited state.