Gd exp 3+ EPR Probe of the Determination of the Valence States

摘要

The theory of the Gd exp 3+ probe EPR technique is reviewed. This technique was employed to investigate at 9.2 GHz the Gd exp 3+ EPR in 0.1 at. percent GdS in TmS, 1 at. percent GdTe in TmTe, and 1 at. percent GdSe in TmSe. From the temperature dependence of the Gd exp 3+ EPR linewidth, it is concluded that Tm in TmS is trivalent with a singlet-ground-state. The temperature variation of the Gd exp 3+ linewidth in TmTe was interpreted in terms of the ''delocalization'' of the extra electron ''localized'' around Gd exp 3+ . From the linewidth and g-value data, it is shown that Tm in TmTe is divalent. The linewidth and the g-value of the Gd exp 3+ resonance in TmSe were found to be independent of temperature. These striking results were explained in terms of the ''motional narrowing'' effect attributed to the interconfigurational fluctuations of Tm in TmSe. (ERA citation 02:038041)