THE LASER SPECTROSCOPY OF DEHYDROAZEPINE

Abstract

Thionylaniline (Ph-N=S=O) is photodissociated at 193 and 248 nm, to produce ground state SO $(X^{3}\sum^{-})$ The nascent vibrational state distribution of the SO $(X^{3}\sum^{-})$ radical is observed by laser induced fluorescence (LIF) on the B-X transition. The vibrational state distribution of the SO photofragment provides insight into the cleavage of the N=S bond of thionylaniline. A gas phase LIF excitation spectrum of a transient species in the region of 440-520 nm is also obtained following the same photodissociation. The carrier of this spectrum is attributed to dehydroazepine, based on kinetic and chemical reactivity studies. This hypothesis is further confirmed by ab initio calculations of the UV spectrum.