Phenyl Azide, Photochemistry of Schuster and Platz

By 1992 Schuster and Platz could write Scheme 1, which economically explained much of the photochemistry of phenyl azide. UV photolysis of PA produces singlet phenylnitrene and molecular nitrogen. In the gas phase, PN is born with excess vibrational energy and isomerizes over a barrier of >30kcal/mol to form cyanocyclopentadiene, the global minimum on the CsHsN surface." This species is also vibrationally excited and sheds a hydrogen atom to form radical 3 (Scheme 1), the species detected in gas-phase absorption and emission measurements. ... 

Schuster, G. B. and Platz, M., Photochemistry of phenyl azide, Adv. Phototochem., 17, 69,1992. Smith, P. A. S., Aryl and heteroaryl azides and nitrenes, in Azides and Nitrenes, Reactivity and Utility, Scriven, E. E, Ed., Academic Press, Orlando, FL, 1984. 

---