Scintillators are materials that absorb a high energy particle (α,β,γ radiation) and convert it into a short pulse of visible or near-visible light. CsBa₂I₅:Eu²⁺,Sm²⁺ has a remarkably high energy resolution of 3.2% at 662 keV gamma excitation and a scintillation decay time of 2.1 µs.
Sm²⁺ co-doping shifts the emission wavelength to 755 nm and eliminates the Eu²⁺ self-absorption. The novel double-doping principle opens up an entirely new class of near-infrared (NIR) scintillators.

This work was carried out in the groups of Prof. Pieter Dorenbos (TU Delft) and PD Dr. Karl Krämer.

References:

• W. Wolszczak, K. W. Krämer, P. Dorenbos;
  "CsBa₂I₅:Eu²⁺,Sm²⁺ - The First High-Energy Resolution Black Scintillator for γ-Ray Spectroscopy"
  Phys. Status Solidi RRL, 2019, 13(9), 1900158; doi:10.1002/pssr.201900158
• P. Dorenbos, K. Krämer, M. Alekhin;
  "Scintillator material comprising a crystalline alkaline-earth halide doped with an activator and co-doped with Sm²⁺"
  PCT Int. Patent Application, WO 2019137961;
  https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2019137961
• P. Dorenbos, K. Krämer, M. Alekhin;
  "Scintillator material comprising a crystalline cation halide doped by Eu²⁺ and co-doped by Sm²⁺"
  PCT Int. Patent Application, WO 2019137962;
  https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2019137962