Rates

• Internal rate: $44.35 per hour / $532.23 per day

• External federal rate: $71.40 per hour / $856.89 per day

• External market rate: $150 per hour / $1800.00 per day

About our microprobe

The JEOL JXA-iHP200F field emission electron probe microanalyzer is a state-of-the art tool for chemical mapping and point analysis of materials from the nanometer to millimeter scale. Our new instrument, currently one of two in the United States, has the following features:

• Thermionic field emission source for fast, high-resolution analyses

• Five wavelength-dispersive spectrometers (WDS) for fast, high-resolution, quantitative chemical analyses of elements from B to U

• JEOL JED-2300 30 mm2 dry energy-dispersive silicon drift detector (SDD EDS) for rapid phase identification.

• User-friendly software for imaging, phase mapping, and WDS data processing

Example applications for microprobe analyses include:

• Chemical imaging of geological materials from nanometer to thin section scales

• Carbon distribution mapping in steel alloys

• Defect imaging in ceramics and metals

• Phase mapping and quantitative mineralogy in geological materials

• Quantitative analyses of Li-doped ceramics

What is EPMA?

Electron probe microanalysis (EPMA) is a conventional term for quantitative chemical analysis performed using wavelength-dispersive x-ray spectroscopy (WDS) with a scanning electron microscope (SEM); a SEM equipped with multiple WDS detectors and specialized electron optics to accommodate them may also be called an electron microprobe (EMP) -- or just a “microprobe."

The WDS detectors involved in EPMA are used to record the spectrum of secondary x-rays produced by a sample being bombarded by a focused electron beam. Unlike detectors used in energy-dispersive spectroscopy (EDS, which may be used to identify X-rays according to their energy), WDS detectors allow characteristic X-rays to be identified based on their wavelength using the principle of X-ray diffraction described by Bragg’s Law. WDS detectors accomplish this by physically moving a crystal with a known atomic unit cell (d-spacing) along a circular path so that only X-rays which satisfy the Bragg equation (nλ = 2dsinθ) are detected. This approach provides superior spectral resolution compared to EDS.

What kinds of samples can be analyzed by EPMA?

Generally, the microprobe can be used to analyze most solid, inorganic material. Samples must be small enough to fit onto a 2.5 cm wide microscope slide or 1-inch diameter sample holder with a vertical profile not exceeding 1 mm. Unlike a visible light microscope, the analyte observed by the microprobe must be loaded into a vacuum chamber to prevent air from interacting with the electron beam. Additionally, the analyte must remain solid and stable when irradiated by the electron beam (15 kV, 5 nA), which precludes analysis of most organic matter. 

What kind of data can be obtained using EPMA?

• Wavelength-dispersive X-ray (WDS) spectra

• Chemical point analyses as small as 5 micrometers

• Chemical line traverses

• Elemental X-ray images (WDS maps)

• Secondary electron images (SEI)

• Backscattered electron (BSE) images

Instrumentation

The Electron Microprobe Lab features three electron-beam instruments and one X-ray beam instrument:

• JEOL IHP200F Electron Probe Microanalyzer

• Two Cameca SX-50 Electron Probe Microanalyzers

• CamScan Series II Scanning Electron Microscope

• PanAlytical Epsilon3 Benchtop X-ray fluorescence spectrometer for bulk sample analysis.