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Analytical Microscopy Group |
Technical Contact: Greg Gillen |
About the GroupThe Analytical Microscopy Group, located in the Surface and Microanalysis Science Division (837) of the Chemical Science and Technology Laboratory, National Institute of Standards and Technology, carries out research in two major areas: 1) the development of techniques of microbeam analysis based primarily on incident ion or photon excitation; and 2) the development of standard practices for the detection of explosive particles. Microbeam analysis refers to analytical techniques that can analyze selected small volumes of a sample, where the size of the region analyzed has dimensions of the order of one micrometer or less, and explosive particle analysis is a relevant application. Group staff members work closely with the Microanalysis Research Group which has a concentrated effort in electron beam excitation methods. Another Group activity spanning all of the microanalysis techniques is the development of methods for compositional mapping, i.e., obtaining images that are based on elemental, isotopic, or molecular information. To learn about ways to work with this Group, see Opportunities. |
About Our Research and FacilitiesGroup research topics are in measurements and standards related to: The Group applies these measurement approaches to solving problems in diverse technology areas, with major efforts in the following:
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About Microbeam AnalysisMicrobeam analysis refers to analytical techniques which can analyze selected small volumes of a sample, where the size of the region analyzed has dimensions of the order of 1 micrometer down to less than a nanometer. This spatial selectivity is achieved by focusing radiation in a scanning beam microscope or a conventional microscope. Depending on the specific technique, the primary excitation radiation may be electrons, photons, or ions, and the secondary analytical radiation may be photons (x-rays or visible light), electrons, or ionized sample atoms. Elemental and molecular microanalysis is achieved by employing an appropriate form of spectrometry to analyze the emitted secondary radiation. An important aspect of the methods employed by the Group is that they combine analysis information with imaging information. Complete characterization of morphology, crystallography, and elemental, isotopic, and molecular composition can be achieved. About Explosive Particle Sampling and Analysis A hundred picograms of an explosive compound is near the lower limit of detection for most field measurement techniques. Since the vapor pressures of many of these compounds are quite low (10 L of air saturated with RDX at room temperature contains 100 pg of RDX), detection by vapor analysis is unfeasible unless the compound is significantly preconcentrated before measurement. Detection by particle analysis, however, is more viable. A 5-micrometer particle of RDX contains over 100 pg, and a single fingerprint may contain over a microgram of material. Hence, the sensitivity of explosives detection may be greatly facilitated by particle collection and analysis. The Group is involved in development and standardization of particle measurements - from sampling, through process, to detection - which are needed to provide reliable benchmarks that may be used for intercomparibility of instrument performance and subsequent improvements to detector technology. See Talks & Presentations on the subject |
Selected Technical Activity Reports
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Last Updated September 26, 2007
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Web Contact micro@nist.gov