Electron Microprobe Analysis by Wavelength Dispersive Spectrometry on JEOL JXA-8200 Superprobe
Usually in mid-July. Application form.
Purpose This is an intermediate to advanced level, lab-oriented course for Electron Microprobe operators working with WDS. It is intended to familiarize the operator with the basic principles of X-ray Microanalysis and provide "hands-on" training and practical tips to efficiently operate an Electron Microprobe.
Course Outline
- Uses of the Electron Microprobe (EPMA)
- Signal types (electron, x-ray, and light)
- Parts of an EPMA
- Electron optics
- Electron emitting source
- Electron beam column and lens aberrations
- Electron probe parameters
- Filament saturation
- Electron probe diameter
- Objective lens apertures
- Electron gun brightness
- Comparison of electron emitting sources
- Working distance and depth of focus
- Column modes
- Spatial resolution
- Electron interaction volume and depth (range)
- Production volume for different signals
- Electron-specimen interactions
- Elastic and inelastic scattering
- Backscattered electron (BSE) generation
- Electron backscatter coefficient
- Backscattered electron detector
- Compositional and topographic imaging with the BSE detector
- Secondary electron (SE) generation
- Everhart-Thornley detector
- BSE and SE detection with the Everhart-Thornley detector
- Cathodoluminescence (CL)
- CL spectrometer: the xCLent system
- CL spectrometry and hyperspectral imaging
- CL image display modes
- X-ray generation
- Electromagnetic spectrum
- Energy-wavelength relation
- Characteristic x-ray generation
- Critical excitation energy and overvoltage
- K-alpha, K-beta, L-alpha, L-beta, M-alpha, etc. x-rays
- X-ray production depth (Castaing’s formula)
- Electron range versus x-ray range
- Continuum x-ray generation
- Typical x-ray spectrum
- X-ray background (Bremmstrahlung)
- Energy Dispersive Spectrometer (EDS)
- Lithium-drifted silicon (Si-Li) detector
- Spectral resolution (FWHM)
- Wavelength Dispersive Spectrometer (WDS)
- Focusing geometry (Rowland circle)
- Bragg’s law of diffraction
- Diffracting crystals and layered structures (LIF, PET, TAP, LDE, etc.)
- WDS operation: detecting a specific wavelength
- L-value
- Limits of spectrometer movement
- Diffraction angle
- Order of diffraction (1st, 2nd, etc.)
- Curved diffracting crystals and x-ray focusing ellipsoid
- Spectral resolution of WDS vs. EDS
- Spectrometers with 140 mm and 100 mm focusing circle
- Proportional counter
- Counter window
- Counter gas efficiency and absorption edges
- Single channel analyzer (SCA) and pulse height analysis (PHA)
- Escape peaks in SCA scan
- Standard pulse height voltages and SCA configurations
- Detector slit openings and mylar film covered slits
- Standard crystal, counter and slit combinations
- Electron probe microanalysis with WDS
- Analytical procedure
- Sample preparation and carbon coating
- Setting up the electron microprobe
- Qualitative analysis with BSE and EDS
- Qualitative and semi-quantitative analysis with WDS
- Standard x-ray intensity measurement (calibration)
- X-ray intensity measurement: peak minus background
- Peak overlap and resolution
- Minimizing overlap and overlap correction
- Quantitative analysis and matrix corrections
- Quantitative analysis equation
- ZAF matrix corrections
- X-ray absorption and mass absorption coefficient
- Depth-distribution of x-rays: the phi-rho-z function
- Phi-rho-z corrections
- Fluorescence
- Matrix correction flowchart
- Compositional imaging (x-ray elemental mapping) with WDS
- Beam-raster mode
- Stage-raster mode
- Background in x-ray image
- Defocusing in beam-raster mode
- Image quality: resolution and signal
- Simultaneous BSE, CL, and x-ray (with WDS and EDS) mapping
Location MIT is located on the northern bank of Charles River in the city of Cambridge. The Electron Microprobe Facility is in the Department of Earth, Atmospheric and Planetary Sciences. The instruments are housed on the twelfth floor.
Accommodation Participants are responsible for arranging their own accomodation. For a list of hotels near MIT campus, click here.
Registration The registration fee is to be announced. To register, please complete and submit application form. Please send your payment only after registration is confirmed.
MIT Electron Microprobe Facility
Massachusetts Institute of Technology
Department of Earth, Atmospheric & Planetary Sciences
Room: 54-1221, Cambridge, MA 02139
Phone: (617) 253-1995; Fax: (617) 253-7102
E-mail: e-probe-www@mit.edu
Web: http://web.mit.edu/e-probe/www/
