VIBRATIONALLY RESOLVED ELECTRON-ATTACHMENT TO OXYGEN CLUSTERS

Highly monochromatized electrons (with 30 meV FWHM) are used in a cros sed beam experiment to investigate electron attachment to oxygen clust ers (O-2)(n) at electron energies from approximately 0 to 2 eV. At ene rgies close to zero, the attachment cross section for the reaction (O- 2)(n) + e --> O-2(-) rises strongly with decreasing electron energy co mpatible with s-wave electron capture to (O-2)(n). Peaks in the attach ment cross section present at higher energies can be ascribed to vibra tional levels of the oxygen anion. The vibrational spacings observed c an be quantitatively accounted for by model calculations.