Continuous electron spectra from 150 keV u C++He, Ne, Ar collisions at electron emission angles from 0 degrees to 180 degrees

Electron spectra in the 20-550 eV energy range and in the full angular rang e of 0-180 degrees were measured by the impact of 150 keV/u C+ ions on He, Ne and Ar atoms. Double differential cross sections for electron emission h ave been determined. We observed an unexpected, broad structure around 300 eV electron energy at backward emission angles relative to the beam directi on. Our calculations support the hypothesis that the new structure is due t o double scattering of the target electrons on the screened fields of the p rojectile and the target. The calculations also show that both electron-emi tting partners are multiply ionized in the collision. (C) 1999 Elsevier Sci ence B.V. All rights reserved.