Geology and Geophysics

YALE ELECTRON MICROPROBE & SEM LABORATORY
Kline Geology Laboratory Room 327, P.O. Box 208109, New Haven, CT 06520-8109 203-432-3181

NSF Instrument Upgrade (IF/EAR-0744154) and Yale University Fund Installation of JEOL JXA-8530F
The JEOL JXA-8530F (FEG) "Hyperprobe" now is installed. provisionally, though testing toward appropriate behavior and consistency continues. This electron probe microanalyzer (EPMA; aka electron microprobe analyzer, EMPA) permits imaging of features as small as 5-10 nanometers and quantitative analytical (chemical) resolution of features perhaps as small as 200 nm. This analytical resolution applies to both quantitative analysis and extremely high-resolution chemical mapping. UPDATE: Removal/decommissioning of the JXA-8600 is complete; renovation of KGL 327 is essentially complete, and installation of the JEOL JXA-8530F is mostly complete, though testing toward appropriate behavior and consistency continues. . We currently have moved into the testing/verification stage as well as having re-commenced analytical sessions. Imaging and chemical analyses Schedule updates and current constraints can be found here. Thanks for your interest, and please stay tuned for details...

THE YALE MICROPROBE FACILITY
(GEOLOGY AND GEOPHYSICS)

USES OF THE MICROPROBE, 1. IMAGING:

USES OF THE MICROPROBE, 2. MICROSCALE CHEMISTRY

Qualitative and semi-quantitative microscale chemistry can be assessed rapidly using EDS spectrometry. This can benefit phase identification and recognition of compositional variability in a sample. This allows rapid imaging and compositional mapping, as well as storage of images and data in readily transferable formats. With either the native JEOL acquisition software or with Probe for Windows, we also can accommodate integration of EDS data into the quantitative-analysis package.

QUANTITATIVE ANALYSIS

Quantitative microscale chemical analysis, using wavelength dispersive spectrometry (WDS), requires both a stable, well-tuned instrument and standards for comparison that are both well characterized and appropriate for a given specimen. The JXA-8530F is proving to be a very stable instrument, and the Yale suite of available standards is quite diverse and extensive. Typical operating conditions for the electron beam are an accelerating voltage of 15 kV beam currents of 5 to 20 nanoamps, and beam diameter of 5 to 10 microns. However, these parameters can be varied widely (0.5 - 30 kV, ~10 pA to ~1500 nA) to address various questions. Many of the Yale standards, a collection begun by Horace Winchell in the 1960's, are appropriate representatives of their mineral group. These generally high quality standards, which include both synthetic and naturally occurring varieties, have been graciously provided by a wide variety of esteemed scientists over several decades. Nonetheless, alternative standards for less traditional projects also can be applied.

Quantitative analysis can address all elements heavier than beryllium (boron and higher). Each analysis takes several minutes to count the X-rays and perform related calculations. Ultimate WDS detection limits for sodium and heavier elements are about 50 to 100 ppm (0.005 to 0.01 wt%, elemental); for lighter elements, the instrument is somewhat less sensitive. Automated analysis allows the operator to assign locations for analysis during a session, then acquire data automatically (unattended) at those stored locations. Thus, the operator may concentrate on other tasks while the time-consuming X-ray counting and data reduction are completed. Data can be transferred via network or USB connections for rapid accommodation into reports and manuscripts.

APPROPRIATE SPECIMENS

• solid and dry
• stable in a vacuum and under a high-voltage electron beam (some less stable materials can be evaluated under less intense voltage and current)
• polished on the flat upper surface (for quantitative analysis) - this can be completed in the lab here, if needed
• mounted on either:
  1) 25.4 mm (1") diameter cylindrical blocks, plates, or discs;
  2) 27 mm wide (standard petrographic {U.S.}) glass slides or thin (~1 mm) plates up to 80 mm long (45 mm standard);
  3) another substrate no more than 100 mm X 100 mm and 25 mm thick (high)
• able to conduct an electrical current or coated with a thin layer of conductive carbon (coating typically performed in the lab here).

ACCESS

For the Upcoming Schedule, Yale-Microprobe Calendar, click here

Training

Other Microprobe Resources

Contact:

JAMES O. ECKERT, JR., Ph.D.
Laboratory Manager, Electron Microprobe and XRD Facilities
Office: KGL 327 Voice: 203-432-3181
Alt.#1 (@probe) 436-9182 Alt.#2 (@XRD) 432-5169 FAX: 203-432-3134

email: Jim Eckert

Designated a "Links2Go Key Resource" Laboratory Site (July 2000)