Absolute partial cross sections for electron-impact ionization of CO from threshold to 1000 eV

Absolute partial cross sections for electron-impact ionization of CO are re ported far electron energies from threshold to 1000 eV. The product ions ar e mass analysed using a time-of-flight mass spectrometer and detected with a position-sensitive detector whose output unequivocally demonstrates that the various product ions are collected with equal efficiency irrespective o f their initial kinetic energies. Data are presented for the production of CO+, C+, O+ and CO2+, and for the total cross section which is obtained as the sum of these partial cross sections. The overall uncertainty in the abs olute cross section values is +/-5% for singly charged parent ions and +/-6 % for fragment ions. Comparison is made with prior experiments and calculat ions.