Ion dissociation dynamics of the chlorine azide cation (ClN3+) investigated by velocity map imaging

The velocity map imaging technique was applied to study the unimolecular dissociation dynamics of the chlorine azide cation (ClN3+) fragmenting into N-2 and NCl+ and the results have been compared to quantum chemical calculations. The ClN3+ ion was produced in a molecular beam by two-photon ionization of chlorine azide (ClN3) with laser light at lambda approximate to 202 nm. Rotationally resolved REMPI spectra and velocity map images of state selected N-2(X (1)Sigma(g)(+), upsilon,J) quantify the energy deposition into N-2 and NCl+ products. Photoelectron velocity map images show near zero-energy electron production. Angular distributions of the photo-fragments suggest we are witnessing the influence of the ions first excited (A') electronic state on its decomposition. The N-2(X (1)Sigma(g)(+)) dissociation products are mainly in the vibrational ground state, but rotationally excited with J up to similar to60. An unusual vibrational distribution in the NCl+ (X (2)Pi, upsilon = 1-12) product was observed, which is evidence of nonstatistical ion decomposition. This work also provides an accurate determination of the energetics for the reaction, ClN3+ --> N-2(X (1)Sigma(g)(1)) + NCl+ (X (2)Pi)(DeltaE < -0.2 eV), from which one may use prior photoionization threshold data to derive the energetics of the ClN3 -> N-2(X (1)Sigma(+)(g)) + NCl(a (1)Delta)(DeltaE < 0.3 eV) dissociation. (C) 2003 American Institute of Physics.