DOMINANCE OF THE THOMAS MECHANISM FOR ELECTRON-CAPTURE FROM ORIENTATED RYDBERG ATOMS

We investigate electron capture from initially oriented circular Rydberg atoms by proton impact at collision speeds comparable to the electron orbital speed. The Thomas double scattering mechanism is observed even at these low relative speeds. Furthermore, we find evidence for the dominance of a quasi Thomas capture mechanism in the form of not a single peak, but a double-peaked structure in the differential cross section when the plane of the circular orbit is nearly perpendicular to the incident direction of the projectile.