Electron Microprobe Laboratory

microprobe labChemical analyses, elemental mapping, and scanning electron imaging of geological and man-made materials.

Contact: Dr. Marty Yates

Cameca SX-100

Column Configuration

  • Self-biasing LaB6 cathode
  • Two stage electromagnetic condenser lens
  • Fully automated alignment, focus, astigmatism correction, electron gun, beam current, beam scanning, and beam diameter
  • Double aperture beam regulation of beam current from .5 to 300 nA
  • Retractable Faraday cup for direct beam current measurement
  • Electron absorbing column liner tube

X-ray Spectrometers

  • 5 vertical wavelength dispersive spectrometers
  • 1 Röntec XFlash 2000 energy dispersive spectrometer
  • 160 mm spectrometer Rowland circle
  • 40 degree x-ray take-off angle
  • .22 to .83 sin-theta spectrometer range
  • Spectrometer resolution 1E-5 sin-theta
  • Programable scanning pulse height analyzers

Spectrometer Configuration

Crystal 2d Formula K-Shell Range L-Shell Range M-Shell Range
Spectrometer 1 LTAP 2.7745 nm C8H5O4TI F-P Mn-Nb Ag-Ir
1 Atm P10 mylar window LPET 0.8742 nm C5H12O Si-Mn Sr-Tb Ta-U
Spectrometer 2 TAP 2.7745 nm C8H5O4TI F-P Mn-Nb Ag-Ir
1 Atm P10 mylar window LPET 0.8742 nm C5H12O Si-Mn Sr-Tb Ta-U
Spectrometer 3 LPET 0.8742 nm C8H5O4TI Si-Mn Sr-Tb Ta-U
3 Atm P10 mylar window LLIF 0.4027 nm LiF Sc-Rb Te-U Ag-Ir
Spectrometer 4 LPET 0.8742 nm C5H12O Si-Mn Sr-Tb Ta-U
3 Atm P10 mylar window LLIF 0.4027 nm LiF Sc-Rb Te-U Ag-Ir
Spectrometer 5 TAP 2.7745 nm C8H5O4TI F-P Mn-Nb Ag-Ir
1 Atm P10 polypropylene window PC1 60 nm W/Si Multilayer C-F
PC2 95 nm Ni/C Multilayer B-O
PC3 200 nm Mo/B4C Multilayer Be-B

Energy Dispersive Spectrometer

  • Röntec XFlash 2000 Detector
    • LN2-free operation
    • Analysis of element ranging in atomic number from Na to U
    • Resolution <159eV at 1000 counts/sec and < 170eV at 30,000 counts/sec
  • Röntec EDS Software
    • Spectrum acquisition and processing
    • Quantitative ZAF analysis
    • Standardless quanitative analysis
    • Bremsstrahlung modeling
    • Integrated expert system

Sample Handling

  • Sample change airlock
  • Stage movement: X-axis 50mm; Y-Axis 80mm; Z-axis 1.5mm
  • Stage positioning via linear optical encoders
  • Stage reproducibility: 1 micrometer
  • Stage minimum step size: 100 nanometers
  • Stage speed 15 mm/sec
  • Two sample holders

Vacuum System

  • Magnetic bearing turbomolecular pump
  • Direct drive roughing and backing mechanical pumps
  • Electron gun pumping by ion pump

Anticontamination System

  • Oxygen gas jet
  • LN2 cold plate
  • Magnetic bearing turbomolecular pump
  • .2%/min. contamination rate without anticontamination
  • .025%/min. with LN2 cold plate only
  • Near zero contamination with combined gas jet and LN2 cold plate

Imaging Capability

  • Secondary Electron Imaging
    • 40X to 400,000X magnification
    • Images up to 2048 x 1536 pixels
    • Automated and manual photomultiplier voltage and collector bias
    • Raster rates from 20 msec to 245 sec per frame
  • Backscattered Electron Imaging
    • Topographical, compositional, and orientation image modes
    • 6 BSE detector sectors coinciding with x-ray spectrometer ports
    • 15 nm spatial resolution
  • Cathodoluminescence
  • X-ray compositional images
    • Images up to 2048 x 1536 pixels
    • Acquisition of up to 13 x-ray channels; 8 EDS and 5 WDS
  • Light optical images
    • Continuous zoomed view from .25mm to 1.75mm
    • Transmitted light with polarizer and analyzer
    • High resolution color CCD camera
    • Optical resolution .7 micrometers
    • Real-time optical image frame grabber
    • Dedicated CRT monitor

Analytical Capability

  • Analysis of elements ranging in atomic number from Be to U
  • Analysis of elements ranging in concentration from 100% to 10 ppm
  • Automated full matrix corrections using the PAP, Pouchou & Pichoir (1987) or X-Phi, Merlet(1995) models
  • Analysis of up to 13 elements simultaneously
  • Analysis of up to 40 elements per analytical point

Automation Hardware

  • Computer Workstation
  • Dual 18″ LCD monitors
  • Video frame acquisition board
  • Color Laserwriter printer

Software

  • Windows-based Peak Sight software
  • Cameca Expert Assistant
  • Monazite Geochronology Analysis
  • Geological Sample Quantification
  • Sample Navigation
  • Multiple Phase ID
  • High Performance Phase Mapping
  • Dynamic Beam Tracking
  • Profile Reconstruction