Three-dimensional ion imaging study of PCl3 photodissociation at 235 nm

The dynamics of photodissociation of PCl3 at 235 nm has been studied by monitoring of ground state Cl(2P3/2) and spin-orbitally excited Cl(2P1/2) atoms by REMPI technique. Also, the P+, PCl+, PCl+, and PCl+ photoions have been monitored non-resonantly in parallel with detection of REMPI-produced Cl+ ions. The speed distributions and speed-dependent anisotropy ± parameters β for all these particles have been determined by three-dimensional photofragment ion imaging technique. The β parameters are close to zero for all these particles. The relative yields of excited Cl(2P1/2) atoms for photodissociation of PCl3 is 0.49 0.03. The speed distributions of Cl(2P3/2) and Cl(2P1/2) atoms are bimodal. We explain the bimodal distributions as a result of competition between two REMPI channels. One channel is far-from-resonance one-photon photodissociation, the another channel is near-resonant two-photon ionisation followed by near-resonance one-photon photodissociation.