Considerable confusion can exist when one looks to the literature for guidance in the selection of crystals for the determination of light elements by x-ray fluorescence. At least five different crystals have been recommended for the detection of elements chlorine (Z = 17) through magnesium (Z = 12). In some cases generalized claims of superiority are made by vendors of crystals without respect to background signal or sample matrix. It is then a disappointment to the spectroscopist to find the crystal unsuitable for the intended application. As an assistance to analytical problems in this laboratory, an experiment established the relative merits of several commercial crystals for the detection of light elements 1) as major constituents and 2) as minor constituents in a matrix of iron.
J. C. Wagner and F. R. Bryan, "On the Choice of Crystals for the Detection of Light Elements by X-Ray Fluorescence," Appl. Spectrosc. 18, 157-158 (1964)