This grant will fund the acquisition of a new Electron Probe Micro-Analyzer (EPMA), which will replace an aging and malfunctioning instrument and thus greatly enhance the capabilities of a facility critical to research and scientific training in the Earth and Materials Sciences. This instrument focuses a narrow beam of electrons onto the surface of a solid material such as a rock or mineral, an experimental product, or an electronic component. It then analyzes the emitted X-rays and provides precise chemical analyses on spots as small as one micrometer. Images and maps of composition can also be produced to visualize the complex spatial variations that are captured in both natural and laboratory-grown materials, which reveal details of processes and history. A fully-functioning EPMA with state-of-the-art capabilities will be essential to a wide range of research programs in the Earth sciences, ranging from experimental studies of the minerals of the planet's deep interior, to samples obtained from the mantle and crust that reveal the intricate processes of the growth of continents and ocean basins, to studies of fluid flow in fractures near the surface and chemical weathering. In the fields of Applied Physics and Materials Science, the EPMA will provide critical and unique data for a variety of research on complex electronic and superconducting materials, on ceramics, and on glasses for applications such as display screens and solar cells. In all of these fields, most of the research is funded by grants from NSF or other U.S. government agencies. The EPMA facility will be synergistic with a number of other world-class analytical instruments at Stanford such as ion microprobes, electron microscopes, and geochronology labs. Besides being a major contribution to the research infrastructure of the University, and being key to the research of at least five women faculty in our Department of Geological and Environmental Sciences, the new EPMA will provide wonderful opportunities for scientific training of undergraduate, graduate, and postdoctoral students.
Measurements of the chemical compositions of the minerals that make up the solid Earth, and of samples produced in experimental laboratories in the geosciences, materials sciences, and applied physics, provide essential information to understanding processes in nature and in advanced technologies. In many types of materials, containing multiple kinds of minerals, zonation caused by chemical reactions "caught in the act" before completion, and built-in multi-phase microstructures, composition can change rapidly on very short length scales. One of the best types of instruments to make such measurements is the "electron microprobe (EPMA)", which bombards a solid sample with a tiny, focused electron beam and images the scattered electrons as well as X-rays that are produced. The latter are specific to each element in the periodic table, and, for elements heavier than beryllium, can be analyzed to give accurate concentrations to levels as low as 10’s of parts per million. This can be done on spots as small as a millionth of a meter, and combined to make maps of chemical composition from this scale up to a couple of centimeters. This Major Research Infrastructure grant (and associated matching funds) was intended to fund a new electron microprobe at Stanford to support a wide range of research on solid materials in the geosciences and other fields. Stanford researchers have relied for decades on an aging instrument that was far overdue for modernization and in fact ceased to operate shortly after the award was made. We have successfully acquired a new, state-of-the-art instrument, and it is installed and fully functional as of January 2013. It is already being used by a rapidly growing research community to provide data for projects ranging from the evolution of the Earth’s crust to large scale geochemical processes in the mantle, to the formation of ore deposits, fluid flow pathways for oil and water in rocks, toxic metals in the environment, high tech materials for optical systems, computer displays, and superconductor technologies. Its elemental sensitivity is far better than the old instrument, and its capabilities for imaging of x-rays and of visible light produced by electron bombardment ("cathodoluminescence") are producing beautiful, high resolution chemical pictures of natural rocks and minerals as well as complex synthetic materials. This instrument should serve a large and varied research community at Stanford and nearby institutions for many years to come. The students who learn to use the instrument, and whose research depends on analyzing the data and images that it produces, are being benefited enormously from this hands-on experience, which will have major significance in their scientific training and career development.
