Early events in the photochemistry of aryl azides from femtosecond UV/Vis spectroscopy and quantum chemical calculations

The photochemistry of para- and ortho-biphenylyl azides and 1-naphthyl azide is studied by ultrafast spectroscopy. In each case the singlet azide second excited states are observed by transient absorption spectroscopy and are found to have lifetimes of hundreds of femtoseconds. The lifetime of singlet ortho-biphenynitrene is 16 ps in acetonitrite and is not affected by perdeutration of the aryl ring.