DOUBLE DETACHMENT OF ELECTRONS FROM C-2(-)

Cross sections have been measured for the double ionization of carbon dimer anions in collisions with rare gas atoms at impact energies in t he range 20-50 keV. Both non-dissociative as well as dissociative doub le detachment occurs. Cross sections for the former are of the order o f 3 x 10(-18) cm(2); they are a factor of five smaller for the latter channel. The ratio of non-dissociative to dissociative double detachme nt is investigated as a function of the voltage on the cathode of the Cs-vapor sputter source of anions; results indicate that carbon dimer anions are overwhelmingly produced in the ground electronic state over a wide range of operating conditions of such a source.