Laser-induced fluorescence and vibrational relaxation of the phenyl nitrene radical

Abstract

Laser-induced fluorescence (l.i.f.) of the phenyl nitrene (PhN) radical has been observed in the wavelength region 360–370 nm following its production by infrared multiple-photon dissociation of phenyl isocyanate. The transition probes the ground ³A₂ state of the species: the upper ³B₁ level has a radiative lifetime of 45 ± 3 ns. Ground-state PhN is born vibrationally hot, and collisional relaxation has been studied in the presence of nine added gases, with the efficiencies of the processes depending upon long-range attractive forces between the colliding species. The dissociation process is compared with that of benzylamine, with l.i.f. detection of the ²A₂–²B₂ transition in the benzyl radical. An upper limit is proposed for the internal energy content of the PhN radical.