Optical and mobility measurements of alkali earth atoms and ions in superfluid helium

Abstract

This article is devoted to optical measurements of alkali earth atoms and mobility measurements of alkali earth ions in superfluid helium. Four topics serve as examples. The optical excitation spectrum of implanted Ca atoms is quantitatively explained with the bubble model. The lack of optical transitions in the recombination process of implanted ions with electrons is discussed for the case of Ba. In case of the Mg triplet system a prolonged lifetime and an unexpected emission profile of the lowest triplet states have been measured. Mobility measurements of the alkali earth ions Be+, Mg+, Ca+ Sr+ and Ba+ are reported. These results raise the question if the defect structure of Be+ may be a snowball like defect in contrast, to the bubble like defect of the heavier alkali earth ions.KeywordsLiquid HeliumRecombination ProcessHelium AtomMobility MeasurementAlkali EarthThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.