![]() Msall, M.E., Dietsche, W., Beane, R., Wichard, R.Using the scanning electron microscope for discovery based learning in undergraduate courses. Origin and mechanical significance of honeycomb garnets in high-pressure metasedimentary rocks from the Tauern Window, Eastern Alps. Hawkins, A.T., Selverstone, J., Brearley, A.J., Beane, R.J., Carlson, W.D.Kyanite deformation in whiteschist of the UHPM Kokchetav Massif, Kazakhstan. Clast-based kinematic vorticity gauges: the effects of slip at matrix/clast interfaces. Johnson, S.E., Lenferink, H.J., Price, N.A., Marsh, J.H., Koons, P.O., West, D.P., and Beane, R.J., accepted.Chopinite-sarcopside solid solution, (PO_4 )_2, in GRA95209, a transitional acapulcoite: Implications for phosphate genesis in meteorites. Grew, E.S., Yates, M.G., Beane, R.J., Floss, C.Data are post-processed by removing wild spikes, removing observed systematic misindexing, and by extrapolating zero solutions based on 4 neighbors (if required). Mean angular deviations between the detected Kikuchi bands and the simulations are less than 1.3 degrees (and often less than 0.8 degrees). Operating parameters for collecting EBSD patterns are an accelerating voltage of 20kV, working distance of 25 mm, and probe current of 2.2nA.Ĭhannel 5 acquisition and indexing settings vary by phase, but typical values are 2x2 or 4x4 binning, high gain, Hough resolution=75, 7 bands, and 80 reflectors. Thin sections are not carbon coated charging is minimized by using a chamber pressure of 10-15 Pa, combined with the 70° tilt. Cheadle, personal communication) and polishing an additional six hours in a non-crystallizing colloidal silica suspension on a Buehler Vibromet2 vibratory polisher (SYTON method of Fynn and Powell, 1979). Samples are prepared by taking standard polished thin sections weighted with halved brass rods (M. Specific projects will vary from these methods.Įlectron backscatter diffraction (EBSD) analyses are conducted at Bowdoin College on a LEO 1450VP SEM outfitted with an HKL Nordlys II detector and Channel 5 software. The typical methods this lab uses for collection and processing of EBSD data follow. The scanning and mapping capabilities of the system permit rapid acquisition of data, from polished rock thin sections, at sub-micron resolutions.Īmong other uses, these data may be applied to evaluate crystallographic preferred orientations (CPO) of mineral fabrics, and to examine misorientation axes and angles that may signify processes such as subgrain development and dislocation creep. The EBSD system uses backscattered electrons (BSE) emitted from a specimen in a SEM to form a diffraction pattern that is imaged on a phosphor screen.Īnalysis of the diffraction pattern allows identification of the phase and its crystal lattice orientation. The system is attached to a LEO 1450VP SEM (variable pressure scanning electron microscope) with an EDAX energy dispersive spectrometer (EDS) for mineral chemistry. The EBSD system, by HKL Technology Inc., includes a Nordlys II EBSD Detector, forescatter detectors and software for orientation mapping (stage and beam control), texture determination, and phase identification (using the American Mineralogist Geological Phase database). EBSD is a relatively new analytical capability that allows geologists to test existing nucleation, growth, and deformation models for minerals and rocks, and to develop new ones.Bowdoin College's electron backscatter diffraction (EBSD) system was purchased with funds awarded through the NSF Major Research Instrumentation program (proposal 0320871 funded to Rachel Beane ). Among other uses, these data may be applied to evaluate crystallographic preferred orientations (CPO) of mineral fabrics, and to examine misorientation axes and angles that may signify processes such as subgrain development and dislocation creep. The scanning and mapping capabilities of the system permit rapid acquisition of data from polished rock thin sections at sub-micron resolutions. Analysis of the diffraction pattern of backscattered electrons from crystalline materials allows identification of phase and its crystal lattice orientation. The EBSD will be installed on an existing modern scanning electron microscope (SEM) equipped with an energy-dispersive spectrometer (EDS) in the Department of Geology at Bowdoin College. Primary Place of Performance Congressional District:Ġ320871 Beane This Major Research Instrumentation (MRI) Program grant supports the acquisition of an electron backscattered diffraction system (EBSD), provides limited PI salary support and travel costs associated with instrument training, and supports the acquisition of related consumables, sample preparation equipment and software. Rachel Beane (Principal Investigator) Sponsored Research Office:.Russell Kelz (703)292-4747 EAR Division Of Earth Sciences GEO Directorate For Geosciences Acquisition of an Electron Backscatter Diffraction System NSF Org: ![]()
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