Scintillation and Optical Characterization of CsCu&lt;sub&gt;2&lt;/sub&gt;I&lt;sub&gt;3&lt;/sub&gt; Single Crystals from 10 to 400 K

van Blaaderen, J.J.; van den Brekel, Liselotte A.; Krämer, Karl W.; Dorenbos, P.

doi:10.1021/acs.chemmater.3c01810

Scintillation and Optical Characterization of CsCu₂I₃ Single Crystals from 10 to 400 K

Title

Scintillation and Optical Characterization of CsCu₂I₃ Single Crystals from 10 to 400 K

Author

van Blaaderen, J.J. (TU Delft RST/Luminescence Materials)
van den Brekel, Liselotte A. (Student TU Delft)
Krämer, Karl W. (University of Bern)
Dorenbos, P. (TU Delft RST/Luminescence Materials)

Date

2023

Abstract

Currently only Eu²⁺-based scintillators have approached the light yield needed to improve the 2% energy resolution at 662 keV of LaBr₃:Ce³⁺,Sr²⁺. Their major limitation, however, is the significant self-absorption due to Eu²⁺. CsCu₂I₃ is an interesting new small band gap scintillator. It is nonhygroscopic and nontoxic, melts congruently, and has an extremely low afterglow, a density of 5.01 g/cm³, and an effective atomic number of 50.6. It shows self-trapped exciton emission at room temperature. The large Stokes shift of this emission ensures that this material is not sensitive to self-absorption, tackling one of the major problems of Eu²⁺-based scintillators. An avalanche photo diode, whose optimal detection efficiency matches the 570 nm mean emission wavelength of CsCu₂I₃, was used to measure pulse height spectra. From the latter, a light yield of 36 000 photons/MeV and energy resolution of 4.82% were obtained. The scintillation proportionality of CsCu₂I₃ was found to be on par with that of SrI₂:Eu²⁺. Based on temperature-dependent emission and decay measurements, it was demonstrated that CsCu₂I₃ emission is already about 50% quenched at room temperature. Using temperature-dependent pulse height measurements, it is shown that the light yield can be increased up to 60 000 photons/MeV by cooling to 200 K, experimentally demonstrating the scintillation potential of CsCu₂I₃.