EPMA ANALYSIS OF FLUID INCLUSIONS IN VOLCANIC ROCKS
The development of the Schottky emitter and its implementation as an electron source in the electron microprobe has significantly improved the characterisation of geological specimens. One of the advantages of the field emission (FE) source is to obtain a finely focussed electron beam at low beam voltage (≤10 keV) while maintaining a high and stable beam current. Under these experimental conditions, the penetration depth of the primary electrons, and thus the interaction volume in which electrons are scattered and generate X-rays, decreases to the sub-µm scale (compared to µm-scale of the traditional electron microprobe at 15 or 20 keV). The high beam current capability allows both major element and trace element analysis. Thanks to wavelength-dispersive X-ray spectrometry (WDS) with sub-10eV energy resolution, accurate qualitative and quantitative analysis can be achieved even on sub-µm phases at low beam energy and high lateral resolution using low energy X-ray lines. For the heavier elements this can be achieved by using L- or M-lines.
The analytical capabilities of the new SXFive FE TACTIS are illustrated by the analysis of the corundum (Al2O3) found in Mount Carmel volcanic ejecta.
 Griffin WL, Gain SEM, Adams DT, et al. Geology 2016;44:815–8. (https://doi.org/10.1130/G37910.1)
The authors acknowledge Professor William L. Griffin and his teams at the Macquarie University for the sample courtesy.