On theJ-dependence of the odd (ns′,J=0,1) autoionization resonances of the rare gases Ne, Ar, Kr, and Xe

Abstract

Using resonant two-photon ionization of metastable rare gas atoms Rg(mp ⁵(m + 1)s ³ P _2,0) in a collimated beam by two transverse cw dye lasers, we have performed a comprehensive high resolution study of the odd Rg(ns′,J=0,1) autoionization resonances of all the heavier rare gases Rg=Ne, Ar, Kr and Xe. In this way, we have determined the variation of the nearlyn-independent reduced resonance widths Γ _r =n*³ · Γ _n (n*=effective quantum number) with atomic size and — for the first time — with the angular momentumJ for all Rg. The reduced widths for the Rg(ns′,J=1) resonances vary by about a factor of three, being lowest for Ne(371 cm⁻¹) and largest for Kr(1185 cm⁻¹). Compared toJ=1, the Rg(ns′,J=0) resonances are three times narrower for Ne, but up to two times broader for Ar, Kr, and Xe. The results of ab initio calculations for the widths are reported, in which the relevant transition matrix elements are carefully evaluated. Good overall agreement of the calculated widths with the experimental data is achieved. For Rg(ns′,J=0), the first orders′−d coupling amplitude provides a satisfactory description only for Rg=Ne, whereas for Rg=Ar−Xe, correlation effects are important. For Rg(ns′,J=1), the additional amplitudes due tos′−d exchange coupling and due tos′−s decay are found to be of varying importance with atomic number. Destructive interference between the different amplitudes and the influence of Rg(ns′,J=1)−Rg(nd′,J=1) coupling are responsible for the fact that the (ns′,J=1) resonances are narrower than the (ns′,J=0) resonances for Ar, Kr, and Xe.