Wavelength-Dispersive Micro X-Ray Fluorescence (WDμXRF) Analysis with the microprobe

An Electron Probe Microanalyser (EPMA) determines the element distribution by detection of the electron beam excited characteristic X-rays using wavelength-dispersive spectrometers (WDS). This study evaluates the benefits of implementing a micro-focus X-ray source into the EPMA as an alternative excitation of X-Ray fluorescence (WDuXRF). Since XRF does not generate a Bremsstrahlung background, a higher detection limit is anticipated for elements with atomic numbers greater than 20 [1]. However, differing excitation probabilities and space constraints may result in lower overall signal intensity and a higher signal-to-noise ratio (SNR). This paper reports the mechanical integration of a IFG-IMOX X-ray source into a JEOL JXA-8530F electron microprobe. The signal-to-noise ratio (SNR) shows that WDμXRF performs comparably to conventional WD-EPMA under standard beam conditions of 20 kV and 500 nA. However, when using a fresh electron source with higher beam currents (1.9 μA) or increased accelerating voltages (30 kV), WD-EPMA exhibits superior SNR at identical measuring times, resulting in improved detection limits. We identify key parameters to enhance WDμXRF performance. Additional advantages of WDμXRF are also discussed, including the suitability for insulating materials, layered structures, rough surfaces, and beam-sensitive specimens. These factors make WDμXRF an attractive alternative, even in cases where the signal-to-noise ratio is lower compared to WD-EPMA.