k factor

A factor used for the Cliff-Lorimer method in EDS analysis. For the determination of the k factor, a substance composed of two elements A and B, whose composition is similar to the target substance, is used as a standard specimen. Characteristic X-ray intensities I_A and I_B of the standard specimen are measured. And then the k factor is determined by equation k = C_A/C_B・I_B /I_A using the known compositions C_A and C_B. The k factor is theoretically given by equation k = （M_AQ_Bω_Bα_B）/（M_BQ_Aω_Aα_A）, where M, Q, ω and α are atomic weight, ionization cross section, fluorescent yield and the ratio of Kα line to the total K lines of a substance, respectively. It is noted that the accuracies of Q and ω are low. In actual cases, the absorption due to the window material is also needed to be taken into account. For the elements up to 3d metals, it is said that the error between the quantitative analysis using experimental k factor and that with the theoretical k factor is about 10%. For a substance composed of elements with greatly different atomic numbers, the accuracy of the analysis is low.

Related Term(s)