Calculation methods for quantitative analysis, energy dispersion, and inhomogeneous samples are current areas in x-ray analysis which offer hope of reducing analysis costs. Other areas which extend the capabilities of x-ray analysis include improved analyzer crystals, diffraction gratings, and effects of valence on spectral lines. Electron spectrometry promises to be a valuable technique for low atomic number elements.
L. S. Birks, "Current Trends in X-Ray Fluorescence Spectrometry," Appl. Spectrosc. 23, 303-308 (1969)