Reaction dynamics of Y O2→ YOX,A′,A O3PJ studied by the crossed-beam technique

The dynamics of the reaction, Y O2→ YO O was studied by using the crossed-beam technique at several collision energies from 10.3 to 52.0 kJ mol−1. The Y atomic beam was generated by laser vaporization and crossed with the O2beam at a right angle. Among the energetically accessible electronic states of YO, the formation of the A2Π and A′2Δ states was observed by their chemiluminescence at all collision energies. By analyzing the chemiluminescence spectra of YOA2Π12,32–X2Σ, vibrational state distributions and relative populations of spin–orbit states were determined for YOA2Π12,32. At low collision energies, the vibrational distributions agree quite well with those expected from the statistical energy partitioning, while a little deviation from the statistical expectation was observed at the highest energy, 52.0 kJ mol−1. The populations of two spin–orbit states are in good agreement with the statistical expectations at all collision energies. The vacuum ultraviolet laser-induced fluorescence VUV-LIF technique was employed to determine the distributions of spin–orbit states of the product O3PJ at two collision energies, 20.7 and 52.0 kJ mol−1. The line shapes of the O atom transitions were analyzed to determine relative branching ratio of the ground state to the excited states of YO, i.e.YOX2Σ O3PJvs. YOA2Π and A′2Δ O3PJ. The results showed that the electronically excited YO was formed with comparable amount with the ground state which is statistically more favorable, and suggested the occurrence of two mechanisms taking place in the title reaction.