A model for spectral diffusion induced by resonant energy migration applied to the 4A2 → 2E transition of Cr3+ in [Cr(ox)3]3- (ox = C2O42-)

In the 3D oxalate networks [NaCr(ox)(3)][Rh(bpy)(3)]ClO4 and [NaCr(ox)(3)][Ru(bpy)(3)] (ox=oxalite, bpy = 2.2'-bipyridine) three different types of energy migration within the (4)A(2) -> E-2 transition can be identified One is a resonant process between spectral members spaced by the ground-state zero-field splitting (ZFS). This leads to the sequential appearance of additional sharp lines spaced by the ground-state ZFS in the fluorescence line narrowing spectrum across the inhomogeneous line. The second one is a quasi-resonant process between spectral neighbours and manifests itself by rapid spectral diffusion. The third one is the well-known phonon-assisted process setting in at higher temperature (C) 2009 Elsevier B V All rights reserved.