O n + clusters produced by the sputtering of solid oxygen

A brief survey is provided of the formation of cluster ions in the sputtering of frozen gases with keV-range energy rare gas atoms or ions, and of radiation damage in the residual solid. The sputtering of solid oxygen produces cluster ions, primarily the series O _3n+2 ⁺ . The constitution of these clusters has been investigated by observing collision-induced dissociation, laser-induced photo-dissociation, and metastable decay in a triple quadrupole mass spectrometer. It is proposed that the dominant clusters contain O ₅ ⁺ as the central ion, surrounded by molecules of ozone. Upon electronic excitation of one of the ozone molecules, its departure from the cluster competes with more extensive disintegration, presumably preceded by excitation energy transfer from the excited ozone to O ₅ ⁺ .