Hitachi SU 70 Analytical FESEM with Oxford Instruments EDS and WDS

su70fesem Overview:

The scanning electron microscope (SEM) is a type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. The electrons interact with the shells in atoms that make up the sample producing signals that contain information about the sample's surface topography, composition and other properties such as electrical conductivity.

The types of signals produced by an SEM include secondary electrons (SE), back-scattered electrons (BSE), characteristic X-rays, light (cathodoluminescence), specimen current and transmitted electrons (STEM). Generally the most common or standard detection mode is SE imaging. The spot size in a Field Emission SEM is smaller than in conventional SEM and can therefore produce very high-resolution images, revealing details in the range of 1 to 5 nm in size.

The Hitachi SU 70 is a semi in-lens FESEM with a Schottky electron gun. The SU 70 at CREST in the FOCAS Institute has SE, BSE, STEM and deceleration mode imaging capabilities and is also equipped with Oxford Instruments EDS and WDS. These analytical components provide complementary information in terms of elemental analysis, compositional point analysis and mapping. The SU 70 also allows reduced charge-up imaging and low voltage imaging.

Technical Specifications:

-Secondary electron image resolution 1.0nm/15kV
-Magnification 20x - 800,000x
-Probe current 1pA - 200nA
-Sample size 200 maximum diameter.

The SU 70 is equipped with an Oxford Instruments 50mm2 X-Max silicon drift EDS detector. This detector enables analysis to be performed at high count rates. Along with EDS capability, the SU 70 FESEM also has a WDS spectrometer, which is mounted with a horizontal and inclined Rowland circle. Both techniques use the characteristic X-Rays generated from the sample in the FESEM column. Signal processing generates a spectrum, allowing the identification of elemental constituents in the sample. Quantative analysis can be performed on clean, polished, flat samples in which peak heights or areas are compared in the unknown with a standard material. WDS allows lines to be resolved which are obscured by peak overlaps in EDS.

Applications:

-Morphological analysis: Particle shape and size
-Fracture studies
-Coatings thickness
-Cross sectional analysis.
-Atomic number contrast imaging.
-Mapping of elements.