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United States Department of Agriculture

Agricultural Research Service

SEM 3700
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Scanning Electron Microscopy















The Hitachi 3700 Variable Pressure SEM permits the imaging of materials without having to coat the samples with metal. Specimens can be simply placed inside the spacious 300mm diameter x 110mm high specimen holder. By varying the pressure within a VP-SEM, specimens can be imaged with reduced dehydration. In order to overcome dehydration this SEM has a Deben Cool Stage with a temperature range of -50oC to + 50oC. By cooling a wet/biological specimen, water evaporation may be slowed or depending on chamber pressure, stopped altogether. The vacuum within the SEM can be varied from 6-270Pa with magnification ranging from 5x-300,000x. The electron source is a tungsten filament with 0.3 – 30kV accelerating voltage capabilities. There are 2 detectors using the low pressure setting; backscatter with topographical (3D–like) imaging and secondary electron detector for high contrast imaging. There are also 2 detectors in the high vacuum setting; secondary electron detector and backscatter detector.

Oxford X-ray Spectroscopy (EDS):SEMs produce X-rays and the detection and measurement of this energy permits elemental analysis such as C, P, K, Ca, and is especially effective at detecting metals such as Fe, Cu, Zn, Ni, Mg. EDS can provide rapid qualitative, or with adequate standards, quantitative analysis of elemental composition. X-rays may also be used to form maps or line profiles, showing the elemental distribution on a sample surface. X-ray microanalysis is a technique that has proved very useful for elemental localization at the cellular or even sub-cellular levels.

Contact: Gary.Bauchan@ars.usda.gov  301-504-6649
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Last Modified: 9/1/2010
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