Scanning Electron Microscope
A scanning electron microscope (SEM) is an analytical instrument that uses an electron beam to scan over an area of a specimen’s surface and produces an image from electron-electron surface interactions. SEM images can be produced from two types of electron sources: (1) secondary or (2) back-scattered electrons. Secondary electron (SE) imaging allows for the characterization of a specimen’s topographical features due to the large depth of field and high magnifications (up to 200,000X) associated with an SEM. Back-scattered electron (BSE) imaging allows for characterization of a specimen’s elemental composition as the intensity of a BSE image is strongly dependent on to the atomic number (Z) of the area under analyzed; BSE imaging allows for identification of elemental changes at the surface of geological, metal, plastic, and ceramic specimens. The interaction volume (IV) from a specimen’s surface that produces the different signals that can be created and detected by an SEM (such as SE, BSE, and characteristic X-rays) is approximately 1 cubic micrometer in size; as a result, scanning electron microscopy is considered a surface analysis technique.
Energy-dispersive X-ray spectroscopy (EDS)
Energy-dispersive X-ray spectroscopy (EDS) is an analytical technique that is used in conjunction with an SEM in order to provide qualitative, semi-quantitative information about the elemental composition of a specimen’s surface. EDS uses electrons in order to induce X-ray excitation of the interaction volume (IV) from a specimen’s surface; the X-ray excitation signal of every element is different and unique, which allows for elemental characterization and identification of the most prominent spectrum peaks in the spectra data that is gathered during this analysis
The SEM services offered at CMS, in conjunction with the experience of an operator that has accumulated over 30 years in producing and interpreting SEM/EDS results, give our customers the utmost value for their investment in the investigative and analytical testing capabilities of the CMS facility/laboratory.