For more than 40 years, electron probe microanalysis (EPMA) has played a central role in the on-going research activities at the Carnegie Institution of Washington. Carnegie staff, postdoctoral fellows and external collaborators utilize EPMA for a wide range of scientific research, such as analyzing natural and synthetic samples to understand the chemistry of Earth and the geological processes that have formed it and related planetary materials. This award will permit the acquisition of a state-of-the-art field emission (FE) electron microprobe system to conduct automated, high resolution, quantitative elemental microanalysis, multi-spectral imaging, and low-energy x-ray emission measurements that will improve scientific throughput and enable future cutting-edge research.
The system is designed for high productivity and reliability, with easy operating procedures that enable precise and sensitive in situ analyses by researchers of variable skill levels. It will be housed in a user-friendly facility, with a dedicated facilities manager, that will be utilized by staff, postdoctoral fellows, visiting scientists, graduate students, and summer interns at Carnegie. The instrument will have significant impact on the research programs in a number of fields including experimental petrology and geophysics, high-pressure physics and mineral physics, inorganic geochemistry, solar system origins, and astrobiology, thereby promoting interdisciplinary collaborations.
The funds from this project have been used to purchase a state-of-the-art field emission electron microprobe to replace the 22-year-old electron microprobe currently used by the Geophysical Laboratory and Department of Terrestrial Magnetism at the Carnegie Institution of Washington (CIW). For more than 40 years, electron microprobe analysis has played a central role in the on-going research activities at CIW. Carnegie staff, postdoctoral fellows and external collaborators utilize the electron microprobe for a wide range of scientific research, such as analyzing natural and synthetic samples to understand the chemistry of Earth and related planetary materials. Our 20+ year-old microprobe has been the primary tool for the elemental characterization of natural and synthetic samples. Literally tens of thousands of accurate analyses have been performed, hundreds of publications have reported data it collected, and scores of new researchers have been trained in its use – many of whom have gone on to set up their own electron microprobe laboratories. The old instrument, however, has reached the end of its reliable life and no longer meets the analytical needs of the CIW research community. The new field emission electron microprobe, which was installed during March and April 2015 in a newly completed laboratory which exceeds its stringent environmental specifications, provides markedly enhanced performance – with greatly improved imaging and analytical resolution. Our initial testing results on this instrument, as well as the results of performance tests we conducted on a recently installed field emission-microprobe at another institution, confirm that we are able to increase our analytical resolution by almost an order of magnitude over that obtainable on our old electron microprobe– accurately and quantitatively analyzing regions in geological specimens < 250 nanometers in diameter (one 40th the width of a human hair). An electron beam extracted by high magnetic fields in a ‘field emission’ electron microprobe is much more finely focused and can deliver to the sample a much greater number of electrons in the same area as a conventional source which boils electrons off of a heated tungsten wire, like an incandescent light bulb. Field emission sources on electron microprobes have only become available in the last few years. In addition to having higher spatial resolution, our new electron microprobe has significantly better sensitivity in analyzing element concentrations, particularly of low atomic number elements. The more sophisticated computer control and better integration of the various components of the instrument allow for much more efficient and versatile operation, making it much easier to tackle difficult analytical problems. The P.I. and his colleagues are working on developing new analytical and data processing procedures to best utilize the new capabilities this improved instrumentation provides. These new features will open doors for new research opportunities that are made possible only with the field emission-source. In addition to accurately determining the phase compositions of samples of interest in CIW research projects, the microprobe will play a critical role in identifying appropriate specimen areas for characterization by other analytical techniques employed by Carnegie staff, including synchrotron-based x-ray techniques at national laboratories. As with our current instrument, the new system will be a community and de facto regional and national facility. The system is designed for high productivity and reliability, with easy operating procedures that enable precise and sensitive analyses by researchers of variable skill levels. It will be a user-friendly facility, with a dedicated facilities manager, that will be utilized by staff, postdoctoral fellows, visiting scientists, graduate students, and summer interns at Carnegie. Over 75% of the scientific staff and postdoctoral fellows of the Geophysical Laboratory and the geochemistry groups at the Department of Terrestrial Magnetism have used our current electron microprobe and this will only increase due to the capabilities of the new instrument. The benefit of the new instrument will extend to the entire mineral physics and high-pressure communities and to researchers and students from other institutes and universities in the region, as well as our numerous international visiting scientists. The instrument will have significant impact on the research programs in a number of fields including experimental petrology and geophysics, high-pressure physics and mineral physics, inorganic geochemistry, solar system origins, and astrobiology, thereby promoting much interdisciplinary collaboration.
