Electron microprobe

A Cambridge Scientific Instrument Company "Microscan" electron probe microanalyzer based on a design by Peter Duncumb.[1] This model is housed at the Cambridge Museum of Technology

An electron microprobe (EMP), also known as an electron probe microanalyzer (EPMA) or electron micro probe analyzer (EMPA), is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials. It works similarly to a scanning electron microscope: the sample is bombarded with an electron beam, emitting x-rays at wavelengths characteristic to the elements being analyzed. This enables the abundances of elements present within small sample volumes (typically 10-30 cubic micrometers or less) to be determined,[2] when a conventional accelerating voltage of 15-20 kV is used.[3] The concentrations of elements from lithium to plutonium may be measured at levels as low as 100 parts per million (ppm), material dependent, although with care, levels below 10 ppm are possible.[4] The ability to quantify lithium by EPMA became a reality in 2008.[5]

  1. ^ Cosslett, V. E., and P. Duncumb. "Micro-analysis by a flying-spot X-ray method." Nature 177, no. 4521 (1956): 1172-1173.
  2. ^ Wittry, David B. (1958). "Electron Probe Microanalyzer", US Patent No 2916621[dead link], Washington, DC: U.S. Patent and Trademark Office
  3. ^ Merlet, C.; Llovet, X. (2012). "Uncertainty and capability of quantitative EPMA at low voltage–A review". IOP Conference Series: Materials Science and Engineering. 32 (2): 012016. doi:10.1088/1757-899X/32/1/012016.
  4. ^ Donovan, J.; Lowers, H.; Rusk, B. (2011). "Improved electron probe microanalysis of trace elements in quartz" (PDF). American Mineralogist. 96 (2–3): 274–282. Bibcode:2011AmMin..96..274D. doi:10.2138/am.2011.3631. S2CID 15082304.[permanent dead link]
  5. ^ Fukushima, S.; Kimura, T.; Ogiwara, T.; Tsukamoto, K.; Tazawa, T.; Tanuma, S. (2008). "New model ultra-soft X-ray spectrometer for microanalysis". Microchim Acta. 161 (3–4): 399–404. doi:10.1007/s00604-007-0889-6. S2CID 94191823.