TUNABLE EXCITING ENERGIES FOR TOTAL-REFLECTION X-RAY-FLUORESCENCE SPECTROMETRY USING A TUNGSTEN ANODE AND BANDPASS FILTERING

The applicability of crystal monochromators, x-ray mirrors and multila yer configurations as filter elements in the primary beam of a total r eflection x-ray fluorescence spectrometer is discussed. The best compr omise between detection limits and multielement capability was found t o be a double multilayer arrangement with variable distance between th e multilayer mirrors. Two multilayers in combination with the respecti ve control units for multilayer distance, tube height and sample posit ioning provide a free choice of isolated x-ray lines and narrow energy bands of the bremsstrahlung continuum. This permits optional excitati on energies in one instrument. Using a tungsten anode at 60 kV, three arbitrarily selected energies of 9.7, 20 and 40 keV were applied. The effect of tunable exciting energies was demonstrated by means of a sta ndard multielement solution.