Energy Transfer in Antiferromagnetic Alkali Manganese Halide Crystals
Energy transfer has been investigated in pure and Er3+ and Nd3+ doped crystals of CsMnBr3 Rb2MnCl4, RbMnC13 and CsMnCl3. These compounds adopt different structures, m which the manganese ions are coupled one-, two-or three-dimensionally. Evidence of efficient energy transfer is given by the intense Lanthanide luminescence on excitation into the manganese absorption bands, the time dependence of the Lanthanide emission as well as the shorter decay times of the manganese emission in the doped samples. Quantitative information on transfer rates is obtained from the temperature and concentration dependence of the decay times. In all compounds the energy transfer within the manganese hosts is a thermally activated process. The activation energies however differ markedly and they are related to the splitting of the manganese 4T1g state due to an axial crystal field. It has not been possible to eltablish the low dimensional character of the energy transfer in both compounds with strongly anisotropic crystal structures, CsMnBro3 and Rb2MnCl4.