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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
Alert: NSF Instrument Upgrade Proposal Approved! (IF/EAR-0744154)
An order now has been submitted for the JEOL JXA-8530F (FEG) "Hyperprobe", or electron-microprobe analyzer (aka EMPA or EPMA). This machine should permit imaging of nanometer-scale features 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. Substantial downtime is anticipated during laboratory remodeling and instrument installation. UPDATE: Removal/decommissioning of the JXA-8600 is expected to begin in mid-November 2008, with renovation of KGL 327 expected to begin near Thanksgiving. Thus, any projects that need to employ the 8600 before this disruption should plan to proceed ASAP [i.e., immediately]. Instrument installation is expected to begin in February 2009. Occasional schedule disruptions also can be expected as a result of planning efforts for this renovation. Thanks for your interest, and please stay tuned for details...
We invite your interest in our facility described here. For more information,
please contact Jim Eckert using the information at
the bottom of this page. We now have migrated to the Advanced Microbeam automation-hardware interface. For scheduling, operating time may be arranged as available. However, at least 1.5 or 2-week advance scheduling always is recommended, especially if any training or operator assistance may be required. For the most current schedule information, please click here for the Yale-Microprobe Calendar.
PLEASE BE ADVISED: Scheduling "crises", requiring immediate analysis, often cannot be accommodated on short notice; please try to plan ahead. Thank you.
General Features of the ELECTRON MICROPROBE
(If you are not familiar with electron-microprobe
fundamentals, you may wish to follow this link.)
THE YALE MICROPROBE FACILITY
(GEOLOGY AND GEOPHYSICS)
The Yale University microprobe facility houses a JEOL JXA-8600 "Superprobe", installed in 1990, that maintains state-of-the-art analytical capabilities. This probe includes four wavelength-dispersive spectrometers and an EDAX light-element-capable energy-dispersive spectrometer with Windows-2000 processing software ( upgraded in 1998). Hardware and software allow automated operation and data collection, and software accommodates moderately advanced image processing and feature analysis. Part of this EDS system upgrade includes software to assist (qualitatively) with configuring analysis of thin films. Additional instrumental details can be accessed here. Jim Eckert. is available to answer questions and assist users with all forms of analysis. For information on access and scheduling, click here
Instrument upgrades installed from 1998-2001 include the new Phoenix Pro EDS and digital-imaging system from EDAX , the 32-bit Probe for Windows WDS-control software from Advanced Microbeam, and a new turbo-pumped Emitech carbon evaporator/coater, which also includes metal evaporation capability. The EDAX and Advanced Microbeam acquisition systems also permit combined EDS/WDS acquisition. All these components of the instrument upgrade were supported graciously by NSF grant EAR-9810089 and Yale University.
Completed in 2002: Replacement of SESAME automation with the Advanced Microbeam automation package. Acceptance testing now complete. For the most current schedule information, please click here for the Yale-Microprobe Calendar
USES OF THE MICROPROBE, 1. IMAGING:
Since the microprobe functions also as a scanning electron microscope (SEM), in addition to element maps of a specimen, images from secondary electrons (SEI) and back-scattered electrons (BSE) also can be produced. The Yale JXA-8600 rivals most SEMs in the ability to resolve detail and represent with clarity the textural relationships in a specimen. This capability, coupled with the quantitative analysis described below, permits detailed microscale assessment of a specimen. SEM imaging can routinely apply magnification to 10,000X for carbon-coated specimens; for metal-coated specimens, useful magnification to over 50,000X can be achieved. For a brief discussion of imaging resolution, click here.
USES OF THE MICROPROBE, 2. MICROSCALE
CHEMISTRY
QUALITATIVE ANALYSIS
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. In 1998 we upgraded our capabilities to a WIN-NT/2000-based system from EDAX (Phoenix Pro). This allows more rapid imaging and compositional mapping than available with the previous system, as well as storage of images and data in readily transferable formats. With installation of the 32-bit Probe for Windows upgrade, we now 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-8600 has proven to be a very stable instrument, and the Yale suite of available standards is quite diverse and extensive. Typical operating conditions are an accelerating voltage on the electron beam of 15 kV beam currents of 10 to 20 nanoamps, and beam diameter of 5 to 10 microns, though these parameters can be varied considerably to address various questions. Many of the Yale standards, a collection begun by Horace Winchell, 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 are sought continuously.
Quantitative analysis can address all elements heavier than lithium (beryllium 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 to DOS diskettes for rapid accommodation into reports and manuscripts.The automation package we use is the PROBE For Windows software of John Donovan, from Advanced Microbeam.
APPROPRIATE SPECIMENS
Appropriate specimens for microprobe imaging and analysis can be geological, biological, or technical materials of various compositions and textures. To be appropriate, specimens must be:
- 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 here, if needed
- mounted on either:
1) 25 mm (1") diameter cylindrical blocks, plates, or discs;
2) 27 mm wide (standard petrographic) 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 (which we also do here).
ACCESS
Current hourly usage rates are available here. We encourage use by both academic and corporate institutions; please contact Jim Eckert if you have an interest in this facility. Except for the pending automation upgrade (not yet scheduled), operating time may be arranged as available. However, at least 1.5 or 2-week advance scheduling always is recommended, especially if any training or operator assistance may be required.
PLEASE BE ADVISED: Scheduling "crises", requiring immediate analysis, generally cannot be accommodated on short notice; if possible, please plan ahead. Thank you.
For the Upcoming Schedule, Yale-Microprobe Calendar,
click here
Training
Periodically, a training course for the JEOL 8600 will be run; follow the link for current information. Alternatively, training on the machine can be arranged directly with Jim Eckert.
A page listing other microprobe resources and useful links can be found by clicking here.
Contact:
Please send me any comments or
questions. However, please note that the lab schedules often preclude an especially rapid reply; we appreciate your patience and understanding. In regard to scheduling, please note: Operating time again may be arranged as available. However, at least 1.5 or 2-week advance scheduling always is recommended, especially if any training or operator assistance may be required.
PLEASE BE ADVISED: Scheduling "crises", requiring immediate analysis, generally cannot be accommodated on short notice; if possible, please plan ahead. Thank you.
JAMES O. ECKERT, JR., Ph.D.
Laboratory Manager, Electron Microprobe and XRD Facilities, KGL 327
Phone: 203-432-3181, FAX: 203-432-3134
email: Jim Eckert
Designated a "Links2Go Key Resource" Laboratory Site (July 2000)