Inhomogeneous Broadening: Symmetry of Centers and Disorder in Solid Solutions and Nanocrystals

Abstract

Zero-phonon electronic transitions of Cr3+ impurity ions in solid solutions and nanocrystals are studied. In the series of Lu3xY3-3xAl5O12 (0<x<1) garnet solid solution crystals the modification of zero-phonon R-line (2E–4A2) fluorescence spectra of Cr3+ ions with changing x occurs in a discrete fashion and is not accompanied by strong inhomogeneous broadening. The effect is ascribed to high C3i symmetry of Cr3+(Al3+) sites. The fluorescence line narrowing experiments were performed for the inhomogeneously-broadened R-line of cubic Cr3+ centers in MgO nanocrystals. The inhomogeneous broadening in nanocrystals is attributed to spatial confinement.