Transient hole-burning and homogeneous linewidth of Eu3+ in sol-gel-produced corundum

In alpha -Al2O3, small-grain ceramics prepared by annealing of sol-gel-produced gamma -Al2O3, it is possible to obtain trivalent rare earth ions at a single regular site despite the large difference in RE3+ and Al3+ ionic radii. Transient spectral holes, generated by a redistribution of the population among the hyperfine levels of the two isotopes of Eu3+, were burned in the inhomogeneously broadened lineshape of the F-7(0)-D-5(0) transition of Eu3+. This observation gives additional evidence for the regular structure of Eu3+ centers in small-grain corundum ceramics. The temperature-dependent hole broadening probably results from dephasing of electronic states by two-phonon Raman processes. The results are discussed together with earlier non-resonant fluorescence line narrowing results on the D-5(0)-F-7(1) transition. obtained by single frequency excitation of the F-7(0)-D-5(0) transition. (C) 2001 Elsevier Science B.V. All rights reserved.