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Updated: Oct 13, 2025

High Resolution Phonon-assisted Quasi-resonance Fluorescence Spectroscopy
Published on: June 28, 2016
Structure-Dependent Accessibility of Phonon-Coupled Radiative Relaxation Pathways Probed by X-ray-Excited Optical
Malsha Udayakantha1, S Sameera Perera2, Rachel D Davidson1
1Department of Chemistry, Department of Materials Science and Engineering, Texas A&M University, College Station, Texas 77843, United States.
Abstract:
Rare-earth scheelites represent a diverse family of compounds with multiple degrees of freedom, which enables the incorporation of a wide range of lanthanide color centers. Precise positioning of quantum objects is attainable by the choice of alkali cations and lattice connectivity of polyanion units. Herein, we report the structure-dependent energy transfer and lattice coupling of optical transitions in La3+- and Dy3+-containing scheelite-type double and quadruple molybdates NaLa1-Dy(MoO4)2 and Na5La1-Dy(MoO4)4. X-ray excitation of La3+ core states generates excited-state electron-hole pairs, which, upon thermalizing across interconnected REO8 polyhedra in double molybdates, activate a phonon-coupled excited state of Dy3+. A pronounced luminescence band is observed corresponding to optical cooling of the lattice upon preferential radiative relaxation from a "hot" state. In contrast, combined X-ray absorption near-edge structure and X-ray-excited optical luminescence studies reveal that such a lattice coupling mechanism is inaccessible in quadruple molybdates with a greater separation of La3+-Dy3+ centers.
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