Variable Pressure Scanning Electron Microscope – Hitachi S3200N
The Hitachi S3200N variable pressure scanning electron microscope (VPSEM) is a conventional high resolution thermionic SEM, which allows the operator to control the specimen chamber vacuum level.
For conductive samples, the instrument is typically operated in high vacuum mode and images are collected with the Everhart-Thornley secondary electron detector. For insulating samples, the instrument is typically operated in variable pressure mode and images are collected with the Robinson backscattered electron detector. When operating in variable pressure mode, the chamber is back filled with a gas in order to allow imaging with little or no charging of the sample. Typically, the back fill gas is either N2 or He, but any non-corrosive, non-reactive gas can be used. Elemental analysis using the energy dispersive X-ray detector can be done in either high vacuum or variable pressure mode.
The Hitachi S3200N SEM is equipped with the standard Everhard-Thornley secondary electron detector, a Robinson backscattered electron detector, an Oxford energy dispersive X-ray spectrometer, and a GW specimen current meter. Electrical feedthroughs are also mounted on the chamber to allow powering active electrical devices or observing electron beam induced current (EBIC). A 4Pi Universal Spectral Engine (electronics set) allows for digital data collection from all of the detectors.
Questions? Contact Chuck Mooney at cbmooney@ncsu.edu.
Location: MRC room 321
Equipment Specifications
Detectors |
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Capabilities |
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Accelerating Voltage |
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Magnification |
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Resolution (SE) |
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Resolution (BSE) |
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Working Distance |
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Specimen Stage |
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Specimen Considerations |
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Documentation
S-3200N Checklist Insulating Samples
S-3200N Checklist Conductive Samples
Hitachi3200 Operating Instructions
Images
Example Analysis: EDS spectrum of the darkest part of the dark sphere showing that this region is mostly C.
Pyrite (FeS) “framboids” filling the shell of a foraminifera in sediments from the continental shelf seaward of the North Island, New Zealand. Pyrite forms under reducing conditions in shallowly buried, organic-rich marine sediments.
From the work of Lonnie Leithold.
Lead-tin eutectic imaged with Robinson BSE detector. The BSE detector is sensitive primarily to changes in atomic number with higher atomic number materials having more contrast. In this case, the Pb is brightest and the Sn is darker. The dark particles observed are polishing media that are embedded in the sample. Sample courtesy Lew Reynolds.