ENERGY DISTRIBUTIONS IN RESONANT CHARGE TRANSFER ION-RYDBERG COLLISIONS D. S. Fisher, C. W. Fehrenbach, s. R. Lundeen, E. Hessels, and B. D. DePaola Department of Physics, Colorado State University, Fort Collins, CO 80523, USA Department of Physics & Astronomy, York University, North York, ON M3J1P3 Canada J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, KS 66506-2604 Charge transfer collisions between slow ions of charge q=1-11 and Rydberg states of rubidium with principal quantum number n=7-26, have been studied using selective laser excitation to determine both the initial Rydberg binding energy and the final binding energy of the transferred electron. The result is a comprehensive and precise determination of both the position and the width of the capture resonance.