Photoionization of (O 2) 2, (O 2) 3, and Ar·O 2 in the 50–100 nm region: state selective ionization of O 2 in a framework of van der Waals molecules

Abstract

Photoionization processes of the van der Waals molecules (O 2) 2, (O 2) 3, and ArO 2, produced in a supersonic expansion were studied in the 50–100 nm region of synchrotron radiation using mass spectrometry. In the photoionization efficiency (PIE) curves, a large number of autoionization structures of O 2 in the 70–100 nm region were almost completely diminished in these clusters, except for the structure due to the c 4Σ u − (3sσ g) Rydberg state of O 2. Molecular rearrangement seemed to be very important in the formation of O 3 + and ArO +. Selective photoionization into the O 2 + (b 4Σ g −) state was observed in the PIE spectrum of ArO +.