Abstract
The absorption and fluorescence of Yb3+ in yttriumgalliumgarnet and yttriumaluminumgarnet have been investigated to locate the levels of the ground manifold2 F 7/2. From the temperature dependence of absorption in the gallium compound, it is concluded that the levels lie at 0, 112, 308, and 550 cm—1. For the aluminumgarnet, the fluorescencespectrum can be interpreted in terms of a ground manifold with levels at 0, 140, 490, and 620 cm—1.