Zero-degree dσ/dE and ${\mathit{d}}^2$σ/dE dΩ cusp-shape and yield variations indicate substantial electron-loss–to–continuum (ELC) contributions in the electron-capture–to–continuum (ECC) spectra obtained with bare H and He ∼1 MeV/nucleon projectiles on hydrocarbon molecules. An intramolecular geometrical outscattering model of secondary collisions has been developed to calculate the ELC fraction of the cusp ${\mathit{f}}_{\mathrm{ELC}}$, extract the separate ECC and ELC contributions from measured projectile velocity frame cusp contours, and predict a nominal ${\mathit{Z}}_{\mathit{P}}^3$ dependence for ELC yields in agreement with experiments in our velocity range.

• Received 5 August 1991

DOI:https://doi.org/10.1103/PhysRevLett.68.2145