Controlled formation of weakly bound atomic negative ions by electron transfer from state-selected Rydberg atoms

¹ Fachbereich Physik der Universität, D-67653 Kaiserslautern, Germany
² Laboratoire de Physique des Lasers, Université Paris-Nord, F-93430 Villetaneuse, France
³ Department of Physics and Astronomy, University of Nebraska, Lincoln, Nebraska 68588-0111, USA

Received: 12 August 1997
Accepted: 4 September 1997

Abstract

Using crossed atomic beams and mass spectrometric ion detection we have studied the formation of negative Ca ions in slow collisions between laser-excited state-selected and Rydberg atoms and ground state Ca atoms. The rate coefficients exhibit resonant behaviour with maxima at an effective principal quantum number n^* of about 11.5 and an estimated peak value of about . Two different theoretical calculations, based on a curve-crossing model and on a modified adiabatic theory, respectively, yield n^*-dependences of the rate coefficients in good agreement with the experimental results.