A single-channel x-ray spectrometer has been converted to a two-channel instrument. Two separate planes in a single lithium fluoride crystal are employed to reflect, simultaneously, two portions of the x-ray spectrum. The instrument has been used to measure trace quantities of lead in the form of particulate matter as an air pollutant. One crystal plane was used to reflect the lead Lα emission line while the second plane reflected background radiation near that line.
E. B. Buchanan and Thomas D. Schroeder, "Trace Lead Analysis Employing a Dual-Channel Single-Crystal X-Ray Spectrometer," Appl. Spectrosc. 24, 100-103 (1970)