ELECTRON-CAPTURE FROM ORIENTED ELLIPTIC RYDBERG ATOMS

Electron capture cross sections for coherent elliptic Rydberg states h ave been measured as a function of eccentricity. The ion impact veloci ty was parallel to the minor axis of the associated, classical ellipti c orbit and both clockwise and anticlockwise orbital motion of the ele ctron were studied. The incoming ions were 2.5 keV Na-23+ and the Rydb erg target, with principal quantum number n = 25, was formed by laser excitation of Li atoms with subsequent adiabatic switching of crossed, external electric and magnetic fields. A strong dependence on eccentr icity and sense of orbital motion was found.