Excitation of atomic hydrogen by protons and multiply charged ions at intermediate velocities

We have investigated the collisional excitation of hydrogen atoms by protons and multiply charged ions at intermediate velocities applying the optical method. The population of the np levels (n=2,...,6) has been determined for a variety of projectiles with charge states q ranging from 1+ to 11+ and scaled velocities nu / square root (q between 0.7 and 5.6 au. The cross sections are shown to fulfil the scaling relation sigma /q=f( nu 2 /q) with respect to the projectile charge g and velocity nu for q>or=3. The relevance of scaled intermediate velocities for a classification of excitation mechanism is pointed out.