Electron Probe Micro-Analysis

Facility description

The MIT Electron Microprobe Facility was established in 1972 and has been in continuous operation since that time. It has been upgraded several times. In its current configuration, the facility consists of two electron microprobes manufactured by JEOL, a JXA-8200 Superprobe and a JXA-733 Superprobe. The JXA-733 was purchased in 1984 with National Science Foundation, Earth Sciences: Instrumentation and Facilities (NSF-EAR I&F) and Keck Foundation funding. In 1992, a second JXA-733 was purchased with funds from NSF and MIT. In 1997, we obtained funding from the NSF-EAR I&F program to carry out a major upgrade for our JEOL instruments. The upgrade was purchased from Geller Microanalytical Lab, and included new automation for the wavelength dispersive spectrometers (WDS) and stage, new quantitative analysis and data reduction software, new digital imaging and stage mapping software, and new electronics and control software for the energy dispersive spectrometer (EDS). In 2005, we upgraded the automation hardware of both instruments by replacing the old Tracor-Northern PAC controllers with control hardware from Geller Microanalytical Lab.

In 2009, we obtained new funding from NSF-EAR I&F to replace one of the old and frequently malfunctioning JXA-733s with a state-of-the-art JXA-8200. This upgrade was completed in 2010 with NSF and MIT funding. The JXA-8200 features a LaB6 electron gun that generates higher beam currents with smaller spot size compared to conventional W electron guns. New WDS spectrometer design and highly sensitive WDS analyzing crystals and detectors allow accurate trace element analysis. The new instrument also features the advance xClent II cathodoluminesence system that has wavelength discrimination capability allowing map acquisition at different light wavelengths and spectroscopy for phase characterization and identification of trace impurities.