Quenching of Rydberg states by atoms with small electron affinities

Abstract

We discuss the theory of quenching of Rydberg states by atoms with small electron affinities and perform calculations for quenching of s and d states of Ne by Ca. There are two contributions to the quenching cross section: the ion-covalent coupling contribution, which is due to the formation of an intermediate ionic state, and the impulse contribution. The first is very sensitive to the electron affinity of the projectile and may be used for studies of weakly bound anions. The ion-covalent coupling contribution is dominant for the process of quenching of Rydberg states with large quantum defects (e.g. s states) at relatively low principal quantum number n, whereas the impulse contribution dominates the process of quenching of states with small quantum defects (e.g. d states of Ne). We present calculations of quenching of s states by Yb atoms with a hypothetical electron affinity of 2 meV and show that experimental studies of quenching of Rydberg states by Yb might help in determining the electron affinity of Yb even if it is negative. In the latter case the quenching cross section as a function of n should exhibit oscillations (Borodin V M and Kazansky A K 1992 J. Phys. B: At. Mol. Opt. Phys. 25 971).