NCEM National Center for Electron Microscopy: Microscopes and Facilities: AEM

AEM

The Analytical Electron Microscope is optimized for elemental microanalysis. The basic instrument is a JEOL 200CX microscope with a side-entry double-tilt goniometer stage and an assortment of specimen holders. This machine can be operated at between 80 and 200 kV in the TEM or STEM mode. Electron energy loss and x-ray signals for elemental microanalysis or spectral imaging can be collected either separately or simultaneously using probe diameters from 6nm to 100nm. Diffraction modes include convergent beam diffraction for three-dimensional structure information and micro-diffraction with a minimum probe size of 20nm.

For updates or details, contact Zonghoon Lee or Velimir Radmilovic.

The instrument is equipped with two Kevex EDXS detectors and a Gatan PEELS spectrometer coupled to a Microsoft Windows NT computer system running Emispec analytical software. This system can acquire and quantify EDX and PEELS spectra, generate X-ray maps and elemental line profiles, and perform microstructural and spectral imaging. Data can be saved internally and exported in a range of formats to 1.5 MB floppy, 100MB zip drive or transferred over a network. Optionally, the Gatan PEELS spectrometer is interfaced with a Macintosh computer running Gatan EL/P software. A Gatan model 673 wide-field video camera is available for dynamic in-situ studies and video recording. The column vacuum has been improved by replacing the diffusion pumps with cryopumps running at 2x10-7 Torr.

All AEM users are requested to fill out the AEM Data Sheet as part of their proposal to help us assess sample preparation, compatibility with instrument vacuum, and the possibility of elemental overlaps. Microscopists planning to use a heating specimen holder should consult the heating holder guidelines [BROKEN LINK - FILE NOT ONLINE] and should bring a supply of VHS video tapes if dynamic recording of the experiment is planned. Users must bring 2 empty Iomega Zip drives per session to store X-ray acquisition data.

Detectors

High-angle energy-dispersive X-ray detector with a resolution of 165eV for Mn K-alpha radiation. High-angle energy-dispersive X-ray detector with a resolution of 165eV for Mn K-alpha radiation.

Ultra-thin window energy-dispersive x-ray detector with a resolution of 109eV for F K-alpha radiation, for elements with Z > 6.

Gatan 666 electron energy loss spectrometer for parallel detection with 2.0eV energy resolution.

Specimen Holders
Gatan 636 double-tilt analytical	170/+150°C	±60/±30°
JEOL BST double-tilt	-	± 60/±45°
JEOL SCSH single-tilt, (bulk, graphite inserts)	-	±60°
JEOL SQH10 single-tilt, double-specimen	-	± 60°
JEOL BSR single-tilt / rotation holder	-	± 60°
Gatan 628Ta single-tilt heating	<1300°C	± 60°
Gatan 652Ta double-tilt heating	<1000°C	± 60/±30°
Single-tilt	-	±60°
Double-tilt	-	±60/±45°
Single-tilt heating	<1300°C	±60°
Double-tilt heating	<1000°C	±60/±30°
Double tilt cooling/heating	-170/+150°C	±60/±30°
Double-tilt electrical biasing Two electrical contacts to top surface of specimen.; maximum voltage 100V; maximum current 1Å.	-	±40/±15°
Single tilt electrical biasing heating: Two electrical contacts to top surface of specimen.; maximum voltage 100V; maximum current 1A.	950°C	±40°
Electrochemical biasing Enclosed electrolyte reservoir, 3mmx2mmx1mm. Two electrical contacts, one to the top surface of the sample, the other to the reservoir; maximum voltage 150V; maximum current 1A.	-	±35°

Spectral imaging characterization of Synroc, a material being considered for possible use in the storage of nuclear waste. Synroc is a man-made material containing three distinct mineral phases, Zirconolite, Perovskite, Hollandite. All three of these phases occur naturally on earth and are quite stable. It is believed that the heavy elements contained in waste will be concentrated and contained in the Zirconolite and Perovskite phases.

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