Electron-nuclear double-resonance measurements were performed on the F center in this halide, using a stationary method. It was found that five Cs and three Br shells could be resolved. However, the observed super-hyperfine interactions could not be explained in terms of a spherically symmetrical F-center wave-function. Instead, lattice-ion overlaps and a mixture of |g>type functions (L = 4) had to be included in the description of the F-center wave-function.

T.Pawlik, V.Dierolf, J.M.Spaeth: Journal of Physics - Condensed Matter, 1997, 9[8], 1857-62