Scintillation mechanisms in inorganic scintillators: an excitonic and alkali halides focused review

Abstract

Scintillation mechanisms in inorganic scintillators were reviewed and reorganized in a more comprehensive way, from excitonic to activator-based, charge transfer luminescence, to Auger-free core-valance luminescence as well as selfactivation and donor-acceptor recombination. The focus is on excitonic mechanisms since this is the class with many subcategories (free exciton, self-trapped exciton (STE), exciton bounds to donor/acceptor/trapping centers…) that published articles fail to cover the most, despite the fact that excitonic mechanism tends to be the dominant mechanism in ultra-fast semiconductor scintillators highly sought-after nowadays as in ZnO. Focus will also be on alkali halide scintillators such as NaI(Tl) and CsI(Tl), both doped and undoped since they are still referenced standards despite having 70 years in the making. The review is unique in the sense that its purpose is to clarify and enrich existing literatures and hence provide a more comprehensive collection of inorganic scintillation mechanisms known to date. Despite the focuses, the reorganized classification was attempted to cover all classes of inorganic scintillators include various forms of halides to oxides, chalcogenides and the more recent trend in nanocomposite ceramic scintillators. Topics such as STE, color centers and general exciton dynamics will be presented more in-depth.