Electron Microprobe

The JEOL JXA-8600 is a conventional hairpin filament thermal emission electron microprobe that is more than 20 years old. It is capable of performing qualitative and quantitative X-ray microanalysis and secondary, backscattered, and topographic electron imaging on a wide variety of samples. It operates at currents ranging from 0.1 nA to greater than 2 mA) at accelerating potentials from 0.5 to 50 kV. The 8600 has a conventional energy dispersive X-ray (EDS) detector with resolution of 137 eV (Mn Kα). The probe also has 5 wavelength dispersive spectrometers (WDS) for high resolution (~ 10 eV) qualitative and quantitative analysis of elements from beryllium to uranium (Z = 5 – 92).  Three of the spectrometers have two crystals and two have four crystals. The 6500 is primarily used for surface compositional analysis to a maximum depth of about 4 mm in materials such as metals, alloys, composites, thin films, ceramics, semiconductors, glasses, and minerals. With Probe for Windows software, the instrument can be set up for automated analysis, making it possible to analyze dozens of samples overnight or over the weekend without operator intervention. With the WDS detectors it can be invaluable in the determination of microheterogeneity of materials, especially for those being evaluated as reference standards for microanalysis. EPMA is a highly precise, efficient method for determining the composition of a surface. Samples are often mounted in 2.54 cm (1 in) circular epoxy mounts although larger specimens can be accommodated. Bulk samples must be polished and flat for high quality quantification, and may have a 7 nm layer of carbon deposited onto the surface to improve specimen conductivity since insulating samples cannot be analyzed without a conductive coating. Many samples, particularly those with low atomic numbers may deteriorate under the electron beam, so careful dosing strategies must be employed for biological and insulating materials.