Spectroscopic Properties and Local Structure of Eu ³⁺ in Ge–Ga–S–CsBr (or CsCl) Glasses

Spectroscopic properties and local structure of Eu 3+ in Ge–Ga–S–CsBr (or CsCl) glasses were investigated using fluorescence measurements and several spectroscopic methods. Fluorescence from Eu 3+ : 5 D 0 → 7 F 2 was observed only from glasses with CsBr/Ga ratios greater than unity and disappeared at temperatures above 140 K. Phonon sideband (PSB) spectra revealed that Eu 3+ ions are located next to halogen ions, which form part of well‐structured complexes such as EuCl 3 , tetrahedral [GaS 3/2 Cl] − , subunits and/or Ga 2 Cl 6 . These new bonds showed reduced coupling strength compared with Eu 3+ –S bonds in Ge–Ga–S glass. Fluorescence line narrowing experiments showed little site‐to‐site variation of Eu 3+ ions.