Transient hole-burning and homogeneous linewidth of Eu 3+ in sol–gel-produced corundum

Abstract

In α-Al 2O 3, small-grain ceramics prepared by annealing of sol–gel-produced γ-Al 2O 3, it is possible to obtain trivalent rare earth ions at a single regular site despite the large difference in RE 3+ and Al 3+ ionic radii. Transient spectral holes, generated by a redistribution of the population among the hyperfine levels of the two isotopes of Eu 3+, were burned in the inhomogeneously broadened lineshape of the 7F 0– 5D 0 transition of Eu 3+. This observation gives additional evidence for the regular structure of Eu 3+ 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 5D 0– 7F 1 transition, obtained by single frequency excitation of the 7F 0– 5D 0 transition.