Velocity map ion imaging of chlorine azide photolysis:: Evidence for photolytic production of cyclic-N3

The method of velocity map imaging was applied to study the photodissociation dynamics of ClN3 near 235 nm under collision-free conditions. Derived kinetic energy distributions of state-selected Cl (P-2(J)) provide a medium-resolution energy spectrum of the N-3 fragment. Markedly bimodal distributions are observed that suggest simultaneous formation of the linear-N-3 ((X) over tilde (2)Pi) isomer as well as an energetic form of N-3, consistent with recent theoretical predictions of a cyclic isomer, resembling an isosceles triangle. Angular distributions of the photofragments indicate that 2(1)A' <-- 1(1)A' excitation is the most important pathway to photoproducts. Branching ratio measurements between the dominant spin-orbit excited-state Cl* (P-2(1/2)) and the spin-orbit ground-state Cl (P-2(3/2)) showed Cl*/Cl approximate to 0.8/0.2. The branching ratio between linear-N-3 and cyclic-N-3 formation was determined to be approximate to 0.8/0.2.