Energetics and dissociative photodetachment dynamics of superoxide – water clusters : O 2 À „ H 2 O ... n , n Ä 1 – 6

The dissociative photodetachment of O2 (H2O)n51 – 6 was studied at 388 and 258 nm using photoelectron–multiple-photofragment coincidence spectroscopy. Photoelectron spectra for the series indicate a significant change in the energetics of sequential solvation beyond the fourth water of hydration. Photoelectron–photofragment kinetic energy correlation spectra were also obtained for O2 (H2O)1 – 2 , permitting a determination of the first and second energies of hydration for O2 2 to be 0.8560.05 and 0.7060.05 eV, respectively. The correlation spectra show that the peak photofragment kinetic energy release in the dissociative photodetachment of O2 (H2O) and O2 (H2O)2 are 0.12 and 0.25 eV, respectively, independent of the photon and photoelectron kinetic energies. The molecular frame differential cross section for the three-body dissociative photodetachment: O2 (H2O)21hn→O212H2O1e is also reported. The observed partitioning of momentum is consistent with either a sequential dissociation or dissociation from a range of initial geometries. © 2001 American Institute of Physics. @DOI: 10.1063/1.1342221#