The 275-nm absorption system of phenyl isocyanate

The vapor-phase absorption spectrum of phenyl isocyanate was photographed in the 285- to 250-nm region. The π ^∗ ← π system origin lies at 36 345 cm ^-1. While considerable vibrational structure is apparent in the spectrum, all the observed features are diffuse. A vibrational analysis is presented. Theoretical calculations based on π-SCF and {HAM}/{3} methods give results in good agreement with observations in the electronic and photoelectron spectrum.