For 10 points, name this non-destructive form of spectroscopy in which elements are detected through their emission of high-energy photons as electrons change energy levels.
Yoneda and Horiuchi's work on this non-IR technique led to its total reflection variant, which allows for increased sensitivity and less scattering, and Rindby et al. developed capillary focusing for this technique.  This technique is often used to measure the sulfur content of oil. Lithium-drifted silicon detectors are often used in energy-dispersive instruments for this technique, while wavelength dispersive instruments use flow counter and scintillation detectors. A helium purge can be used to increase the resolution of this technique, and the effectiveness of this technique is limited by the (*) Auger effect when analyzing light elements. It is often used to determine the elemental composition of rocks and to measure precious metals content, and the response to this technique for a given element is predicted by Moseley's Law. For 10 points, name this non-destructive form of spectroscopy in which elements are detected through their emission of high-energy photons as electrons change energy levels.
Yoneda and Horiuchi's work on this non-IR technique led to its total reflection variant, which allows for increased sensitivity and less scattering, and Rindby et al. developed capillary focusing for this technique.  
X-Ray Fluorescence [or XRF Spectroscopy or Spectrometry. Do not accept or prompt on “X-ray photoelectron spectroscopy” or “XPS.”]