Photodetachment, photofragmentation, and fragment autodetachment of [O[sub 2n](H[sub 2]O)[sub m]][sup −] clusters: Core-anion structures and fragment energy partitioning

Building on the past studies of the O2n− and O2−(H2O)m cluster anion series, we assess the effect of the strong hydration interactions on the oxygen-core clusters using photoelectron imaging and photofragment mass spectroscopy of [O2n(H2O)m]− (n=1–4, m=0–3) at 355 nm. The results show that both pure-oxygen and hydrated clusters with n≥2 form an O4− core anion, indicated in the past work on the pure-oxygen clusters. All clusters studied can be therefore described in terms of O4−(H2O)m(O2)n−2 structures, although the O4− core may be strongly perturbed by hydration in some of these clusters. Fragmentation of these clusters yields predominantly O2− and O2−(H2O)l (l