Die erlaubten und verbotenen Resonanzübergänge der Mn2+ -Ionen in CeO2/ The Allowed and Forbidden Resonance Transitions of Mn2+-Ions in CeO2

The absorption behaviour of Mn2+ -ions in CeO2 has been investigated and interpreted for the first time. Beside the hyperfine-multiplett with selection rules ΔM =1 and Δm = 0 we observed forbidden transitions with ΔM = 1 and Δm=± 1 At T = 29Q K the line width is rather small and amounts to 2.5 G. The entire spectrum can be described by an isotropic spin-Hamilton operator with g=1.9989 and A = 86.36·10-4 cm -1 . It is shown for Mn2+ in the crystal-field of oxygen-ions that there is a linear relationship between the hyperfine coupling constant A and the coordination number.