Electron Microprobe Laboratory
¶Ù¾±°ù±ð³¦³Ù´Ç°ù/±Ê±õ:ÌýKevin Mahan
Facility Manager: Aaron Bell
Location: Benson 125
Electron microprobe analysis is a sensitive technique for non-destructive quantification of the chemical composition of in situ micrometer volumes of solid mate- rial (minerals, alloys, ceramics, glass, etc.). The electron microprobe laboratory at ¶¶ÒõÂÃÐÐÉä Boulder was first established in 1984 by Dr. John Drexler and Prof. Charles Stern, and for almost 30 years, the lab provided researchers from all around Colorado and from different departments (geology, chemistry, physics, engineer- ing, etc.) with precise and accurate chemical analyses. Unfortunately, the old JEOL JXA-8600 was showing signs of age, and serious analytical limitations were preventing access to the level of precision and accuracy that is required in 21st century science.
Under the directorship of Prof. Kevin Mahan, a new era for the electron micro- probe laboratory began with the hiring of Dr. Julien Allaz to manage the lab in 2012 to succeed after Dr. Drexler retired. The first goal was to seek funds to purchase a new state-of-the-art instrument, a goal reached in 2014 with a $1.24 million grant from the NSF (Major Research Instrumentation program) awarded to PIs Mahan, Allaz, and Farmer. The new instrument, a JEOL JXA-8230 equipped with LaB6 electron gun, was installed in March 2016, and has been fully operational and open to internal and external users since September 2016.
The new JEOL-8230 electron microprobe offers superior-quality analysis, both in term of precision and accuracy. This 5-spectrometer instrument (compared to 4 on the old one) offers higher spatial resolution (electron beam size ca. 0.2-0.7 µm compared to ≥1 µm) and greater analytical capabilities, notably in terms of minor and trace element analysis. A major advantage is the presence of many large-area monochromators, which offers 2 to 3-fold higher count rates, and thus higher sensitivity and lower detection limits. The software capabilities have also immensely improved; as if you were switching from DOS 3.0 to Windows 10! The fully automated instrument offers more accurate and precise results in far less time. Major elements in silicates are analyzed in less than a minute, X-ray element maps can now be quantified, trace element analysis down to 1-10 ppm range of detection limit is reached in just a few minutes, complex minerals with over 25 elements (e.g., REE-bearing minerals) are analyzed in less than 10 minutes, and accurate analysis of beam sensitive materials is easily done without cutting too much on the precision. These updates will certainly foster new collaborations and discoveries for researchers and private customers. For instance, the new instrument now allows us to analyze rare and precious elements (Au, Ag, Te...) in sulfides, trace element analysis in beam sensitive materials, including carbonate, titanium analysis in quartz for thermometry, U-Th-Pb dating of monazite, quick yet accurate and precise homogeneity tests in synthetic materials, etc. The new instrument and lab will be incorporated into a variety of teaching activities including a graduate level course on analytical methods and several undergraduate courses. Activities for the latter will be facilitated by technological enhancements such as a large wall-mounted monitor, a web-cam, and remote access.