ABSOLUTE PARTIAL CROSS-SECTIONS FOR ELECTRON-IMPACT IONIZATION OF CO2FROM THRESHOLD TO 1000 EV

Absolute partial cross sections for the production of CO2+, CO+, CO22, O+, C+, O2+, and C2+ from electron-impact ionization of CO2 are repo rted for electron energies from threshold to 1000 eV. The product ions are mass analyzed using a time-of-flight mass spectrometer and detect ed with a position-sensitive detector whose output provides clear evid ence that all product ions are completely collected. The overall uncer tainty in the absolute cross section values is +/-3.5% for singly char ged parent ions and is slightly greater for fragment and doubly charge d ions. For the fragment ion cross sections, all but one of the previo us measurements are observed to be significantly lower than the presen t results. (C) 1996 American Institute of Physics.