Experimental identification of charge relaxation rates in intermediate-valence compounds by phonon spectroscopy

The charge relaxation rate c of intermediate-valence compounds is identified experimentally by the different behavior of the phonon-mode frequencies for >>c and c. This classification yields a systematic understanding of the occurrence or absence of phonon anomalies in all intermediate-valence compounds investigated so far. A temperature dependence of c could be determined in the case of Sm0.75Y0.25S. © 1986 The American Physical Society.