SYNTHESIS OF DIOXYGEN IN A CO2 MATRIX - POSITIVE-ION DESORPTION AT THE SOLID IONIZATION THRESHOLD

O-2(+) ion desorption as a reaction product from solid CO(2)( )ice has been observed for the first time. The desorption threshold is at the ionisation potential for solid CO2, similar to 6 eV below that for O-2 (+) production in the gas phase. The threshold for CO+ ions is also su bstantially below the gas phase threshold. No positive ion desorption has been seen at or below the solid ionisation threshold in any conden sed gas before. Both solid threshold energies are a result of multiele ctron excitations. (C) 1998 Elsevier Science B.V. All rights reserved.