Z, Velocity, and Charge Dependence of Zero-Degree Electron "Cusps" from Charge Transfer to Continuum States of Bare and Highly Ionized Projectiles

Data on continuum electron capture and loss for bare and highly ionized Cq+, Oq+ ions traversing Ar at energies 1.6-2.8 MeV/A reveal striking disagreements with corresponding theories. We demonstrate a velocity-independent (~Z^2.2±0.2) scaling for continuum capture by bare ions, a Z-independent velocity scaling, and an approximately q-independent ($q=6, 7, 8$) equality of continuum electron-capture and-loss cross sections at velocities corresponding to {~}2 MeV/A.