Configuration interaction effects in the [formula omitted] rydberg series of neutral indium investigated with a frequency-doubled dye laser

Abstract

The 5s 25p 2P built3 2 − 5s 2ns 2S built1 2 , 5s 2nd 2D built3 2 , built5 2 Rydberg series (25 ⩽ n ⩽ 107) in indium have been investigated with high precision. The atoms were excited in an atomic beam by a frequency-doubled pulsed dye laser ( λ ≈ 225 nm). The highly excited atoms were detected using the field ionization technique. The ionization limit has been determined at 46 670.107 ± 0.010 cm -1 from the 2 series. The perturbation of the series due to configuration interaction with the 2D term of the 5s5p 2 configuration has been studied. Discrepancies with previous observations of these series are discussed. The fine structure splitting of the 2D levels could be determined up to n 2D up to n = 70. It is found to be almost proportional to n ∗-3 over the range observed, but the size of the splitting is strongly affected by the perturbation. A description of the effects is presented in the framework of perturbation theory with Hartree-Fock values as a first order approximation. Level values for the 5 s5 p 2 2 D built3 2 , built5 2 levels are predicted and compared with observations.