Convoy electrons accompanying neutral ejectiles in ion-solid interactions

Electron energy spectra (θ=0deg) induced by H+ (150 keV) and He+ (200 keV/u) impinging on thin carbon and copper foils (100-500 A) have been measured in coincidence with the emergent charge states qf(H)=0, 1 and qf(He)=0, 1, 2. The experiments were carried out in an ultrahigh vacuum chamber (P=1.5x10-9 hPa), in order to minimise the charge changing of the ejectiles between the target and their detection in the novel charge state analysing detector UHLAND. The charge states were separated electrostatically and extreme care was taken to prevent them from overlapping. Convoy electrons accompanying the projectiles in low-lying continuum states were detected in coincidence not only with emerging charged ions, but also with neutral ejectiles. These measurements may help to clarify the discrepancies between recent data published by different groups. (orig.)