BINDING-ENERGY OF THE METASTABLE AR- ION

This paper presents a combined experimental and theoretical investigat ion of the binding energy of the metastable Ar-(3p(5)4s4p S-4(3/2)e) i on. Utilizing the laser-photodetachment threshold technique combined w ith state-selective detection of neutral atoms by resonant ionization spectroscopy, we find a binding energy of 32.5+/-1.0 meV with respect to the 3p(5)4s P-3(2)0 state of neutral argon. Our calculations, based on many-body perturbation theory, yield a binding energy of 24.9 meV. As a test of the present computational method, we also include the re sults of a comparative study of Ca-.