The Independent-Electron Model Applied to 100–600 KeV Sulfur Beam-Foil Population Functions

Abstract

We have recently had some success in describing relative beam-foil population curves ( viz. relative beam-foil population of selected levels as function of the projectile energy ) for He¹, Li² and Be³ in terms of two probability factors, one accounting for Rydberg state populations, and the other describing core vacancies. This has motivated the proposal of an independent-electron model for bea-foil populations and charge-state distributions², and surprisingly good agreement exists between the model and experiments. For a further test of the model, it was felt desirable to apply it to beam-foil measurements on an element with many electrons outside a closed core, since, according to the model, population functions for all level schemes of all charge states of the element should be linked by only one parameter, as long as ionization of the core can be ignored. For this purpose, sulfur was chosen, since it from earlier measurements is known⁴ that transitions between levels belonging to the first six spectra of sulfur can be observed at projectile energies accessible to us, and also, ionization of the 1s²2s²2p⁶ core is very unlikely even up to 1 MeV.