Cliff-Lorimer method

The Cliff-Lorimer method is a qualitative measurement method of elements in spectroscopic analysis of characteristic X-rays (EDS). It is also called the thin-film approximation method. The method is applied when a specimen thickness is 10 nm or less (though depending on measured elements). For example, when a substance is composed of two elements A and B, characteristic X-ray intensities I_A and I_B are measured. Then, the concentration ratio of element A to element B (C_A/C_B) is obtained from equation C_A/C_B = k・I_A/I_B, where k is a proportionality factor, which is determined by ionization cross sections, fluorescent yields etc. of the elements. If a specimen is thin, quantitative measurements can be performed with a relatively high accuracy even when corrections for the atomic-number effect, the absorption effect and the fluorescence excitation effect are neglected. On the other hand, if a specimen is thick, the corrections must be executed for the measured intensities (ZAF correction).

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