Excitons in scintillator materials: Optical properties and electron-energy loss spectra of NaI, LaBr3, BaI2, and SrI2

A. Schleife, X. Zhang, Q. Li, P. Erhart, and D. Åberg
Journal of Materials Research 32, 56 (2016)
doi: 10.1557/jmr.2016.395

Materials for scintillator radiation detectors need to fulfill a diverse set of requirements such as radiation hardness and highly specific response to incoming radiation, rendering them a target of current materials design efforts. Even though they are amenable to cutting-edge theoretical spectroscopy techniques, surprisingly many fundamental properties of scintillator materials are still unknown or not well explored. In this work, we use first-principles approaches to thoroughly study the optical properties of four scintillator materials: NaI, LaBr3, BaI2, and SrI2. By solving the Bethe-Salpeter equation for the optical polarization function we study the influence of excitonic effects on dielectric and electron-energy loss functions. This work sheds light into fundamental optical properties of these four scintillator materials and lays the ground-work for future work that is geared toward accurate modeling and computational materials design of advanced radiation detectors with unprecedented energy resolution.