Line intensity and background measurements were made on the K lines for the elements with atomic numbers 16 to 60, L lines for the elements above atomic number 42, and M lines for elements above atomic number 80. Three general classes of samples were investigated: (1) infinitely thick, (2) microgram deposits, and (3) thin layers.

These studies show that longer-wavelength L radiation may be preferable to the K series lines from the same element in the range of elements with atomic numbers 42 to 60, In particular the Lα lines are more intense than the K series lines from Class 2 and 3 samples. With Class 1 samples the Lα lines are weaker than the K series but their line-to-background ratio is superior to the K series.

M series lines show little promise for spectrochemical analysis except for elements with atomic numbers 90 to 92; for example, with uranium samples in Class 2 and 3, the very high line-to-background ratio of the UMβ1 line may have limited application.

Elements with atomic numbers from 16 to 22 are more sensitive than expected due to the very high line-to-background ratios and the reduced collimation requirements in this longwavelength region.