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Updated: Feb 26, 2026
Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
Large Differences in the Optical Spectrum Associated with the Same Complex: The Effect of the Anisotropy of the
José Antonio Aramburu1, Pablo García-Fernández1, Juan María García-Lastra2
1Departamento de Ciencias de la Tierra y Física de la Materia Condensada, Universidad de Cantabria , Avenida de los Castros s/n, 39005 Santander, Spain.
Abstract:
Transition-metal complexes with a well-defined geometry are usually considered to display almost the same properties independently of the system where they are embedded. Here we show that the above statement is not true depending on the anisotropy of the host lattice, which is revealed in the form of the electric field created by the rest of lattice ions over the complex. To illustrate this concept we analyze the origin of the surprisingly large differences in the d-d optical transitions of two systems containing square-planar CuF42- complexes, CaCuF4, and center II in Cu2+-doped Ba2ZnF6, even though the Cu2+-F-distance difference is just found to be 1%. Using a minimalist first-principles model we show that the different morphology of the host lattices creates an anisotropic field that red-shifts the in vacuo complex transitions to the 1.25-1.70 eV range in CaCuF4, while it blue-shifts them to the 1.70-3.0 eV region in Ba2ZnF6:Cu2+. This particular example shows how the lattice anisotropy strongly alters the optical properties of a given transition-metal complex. This knowledge opens a new path to tune the spectra of this large family of systems.
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