Photoelectron spectroscopy of the oxygen dimer and clusters

✍ Scribed by Frank Carnovale; J. Barrie Peel; Richard G. Rothwell

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 757 KB
• Volume: 26
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210260406

✦ Synopsis

The He I photoektron spectra of gas-phase oxygen dimer and oxygen clusters have been measured in a pulsed beam, The spectrum of the dimer (Oz), is characterized by broad bands which show 1 : 1 correspondence with those of the monomer 0,. The vertical ionization energies are 0.2 f 0.1 eV lower than those of the monomer. The photoelectron bands observed for mixtures of small clusters are identical to the dimer bands except for further shifts of up to -0.3 eV to lower ionization energies. The clusters spectra show bandwidths and bandshapes which are effectively the same as those measured for thin films of condensed 0, , indicating that the oxygen dimer (Oz)z is the ionization chromophore in each case. This supports the dimer-ion hypothesis proposed for the ionization of van der Waals clusters of closed-shell molecules. Ab initio calculations on (Oz)z+ show good agreement with the experimental data, and suggest that the ground dimer-ion electronic state is of rectangular rather than trans-planar geometry.