The presence of an unfilled inner electron shell in the rare earth elements is manifested in x‐ray absorption effects that are unique to the energy region including the Mα and Mβ lines of these elements. In contrast to the normal edge‐type absorption, this anomalous absorption appears as an absorption line. A method is presented here for the quantitative determination of the extent of this anomalous absorption. Solid bulk metal samples, excited with a monoenergetic electron beam, were examined with a wavelength‐dispersive x‐ray spectrometer. The discussed method makes the experimentally determined absorption independent of both the detection efficiency and atomic data such as the fluorescence yield and transition probabilities. A simple empirical model is proposed to explain the dependence of the absorption of the Mα line on the absorption path length, which was varied by the primary beam energy. Normal and anomalous absorption are treated as independent and competing processes in this model. Atomic data such as the mass absorption coefficients pertinent to the anomalous absorption of the Mα lines were also determined and are presented.
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