The analyses of some geological materials (rocks, soils, plant ash, etc.) by emission spectroscopy methods often require various arrangements of filter settings. For total energy methods, we found that using 100 % transmission for the first 30 sec of the burn improves the detection limits for the volatile elements. Mosier described a split slit technique for the analysis of plant ashes in which (1) the sample is arced for 15 sec using a split slit having 15 % transmission in one area and 100 % in the remainder, (2) the arc is stopped to insert a Hartmann diaphragm to block out the 100 % portion of the spectrum, and (3) the arc is restarted recording only the 15% transmission portion throughout the remaining 81 sec of burn time.
Kenneth J. Curry, Elmo F. Cooley, and John A. Dietrich, "An Automatic Filter Positioner Device for Emission Spectroscopy," Appl. Spectrosc. 29, 274-275 (1975)