PRODUCTION OF VIBRATIONALLY AUTODETACHING O-2(-) IN LOW-ENERGY-ELECTRON IMPACT ON OZONE

Attachment of electrons with energies of 1.2 to 2 eV to ozone was foun d to lead to the production of O and vibrationally excited O-2(-), the latter subsequently lose electrons by vibrational autodetachment. Thi s type of electron scattering is intermediate between inelastic electr on scattering and dissociative attachment. Spectra of the detached ele ctrons have resolved vibrational structure, which can be assigned to t he individual O-2(-)/O-2 vibronic transitions, providing detailed info rmation on the product state distribution. The absolute integral cross section for the production of O-2(-) in vibrational states v' greater than or equal to 4 was found to be substantial, for example at 1.7 eV it is 0.27 x 10(-16) cm(2) (with an error bar of about +0.2 x 10(-16) cm(2) and -0.12 x 10(16) cm(2)). Measurements of the signal onsets pe rmit an independent determination of the dissociation energy of ozone into O and O-2 with the result D-0 = 1.06+/-0.04 eV. Comparison of the peak width of the electrons detached by O-2(-) in this work with the width of peaks of O-2(-) resonances observed in electron-O-2 scatterin g indicates a moderate degree of rotational excitation in the present process.