Resonant ion-pair formation in the recombination ofNO+with electrons: Cross-section determination

Resonant ion-pair formation from the collisions of ${\mathrm{NO}}^{+}$ ions with electrons was studied using the heavy-ion storage ring CRYRING at the Manne Siegbahn Laboratory of Stockholm University. The total cross section is measured for the formation of ${\mathrm{N}}^{+}{+\mathrm{O}}^{\mathrm{\ensuremath{-}}}$ for electron energies 8--18 eV, and the results are compared with ion-pair formation in photoionization work. A peak in the cross section is observed at 12.5 eV, with a magnitude of $8.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}{\mathrm{cm}}^{2}.$ An attempt to extract the cross section for the reverse process of associative ionization is made.