Microscopy is the technical field of using microscopes to view objects and areas of objects that cannot be seen with the naked eye. There are three well-known branches of microscopy: optical, electron, and scanning probe microscopy, along with the emerging field of X-ray microscopy.
A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. The electron beam is scanned in a raster scan pattern, and the position of the beam is combined with the intensity of the detected signal to produce an image. In the most common SEM mode, secondary electrons emitted by atoms excited by the electron beam are detected using a secondary electron detector. The number of secondary electrons that can be detected, and thus the signal intensity, depends, among other things, on specimen topography. Some SEMs can achieve resolutions better than 1 nanometer.
Electron energy loss spectroscopy (EELS) is a form of electron microscopy in which a material is exposed to a beam of electrons with a known, narrow range of kinetic energies. Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected. The amount of energy loss can be measured via an electron spectrometer and interpreted in terms of what caused the energy loss. Inelastic interactions include phonon excitations, inter- and intra-band transitions, plasmon excitations, inner shell ionizations, and Cherenkov radiation. The inner-shell ionizations are particularly useful for detecting the elemental components of a material. For example, one might find that a larger-than-expected number of electrons comes through the material with 285 eV less energy than they had when they entered the material. This is approximately the amount of energy needed to remove an inner-shell electron from a carbon atom, which can be taken as evidence that there is a significant amount of carbon present in the sample. With some care, and looking at a wide range of energy losses, one can determine the types of atoms, and the numbers of atoms of each type, being struck by the beam. The scattering angle can also be measured, giving information about the dispersion relation of whatever material excitation caused the inelastic scattering.
An electron microprobe (EMP), also known as an electron probe microanalyzer (EPMA) or electron micro probe analyzer (EMPA), is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials. It works similarly to a scanning electron microscope: the sample is bombarded with an electron beam, emitting x-rays at wavelengths characteristic to the elements being analyzed. This enables the abundances of elements present within small sample volumes to be determined, when a conventional accelerating voltage of 15-20 kV is used. The concentrations of elements from lithium to plutonium may be measured at levels as low as 100 parts per million (ppm), material dependent, although with care, levels below 10 ppm are possible. The ability to quantify lithium by EPMA became a reality in 2008.
A scanning transmission electron microscope (STEM) is a type of transmission electron microscope (TEM). Pronunciation is [stɛm] or [ɛsti:i:ɛm]. As with a conventional transmission electron microscope (CTEM), images are formed by electrons passing through a sufficiently thin specimen. However, unlike CTEM, in STEM the electron beam is focused to a fine spot which is then scanned over the sample in a raster illumination system constructed so that the sample is illuminated at each point with the beam parallel to the optical axis. The rastering of the beam across the sample makes STEM suitable for analytical techniques such as Z-contrast annular dark-field imaging, and spectroscopic mapping by energy dispersive X-ray (EDX) spectroscopy, or electron energy loss spectroscopy (EELS). These signals can be obtained simultaneously, allowing direct correlation of images and spectroscopic data.
The Department of Materials at the University of Oxford, England was founded in the 1950s as the Department of Metallurgy, by William Hume-Rothery, who was a reader in Oxford's Department of Inorganic Chemistry. It is part of the university's Mathematical, Physical and Life Sciences Division
David John Hugh Cockayne FRS FInstP was Professor in the physical examination of materials in the Department of Materials at the University of Oxford and professorial fellow at Linacre College from 2000 to 2009. He was the president of the International Federation of Societies for Microscopy from 2003 till 2007, then vice-president 2007 to 2010.
The McCrone Research Institute is a not-for-profit educational and research organization for microscopy located in Chicago, Illinois. It was founded by Dr. Walter C. McCrone in 1960. With more than 30,000 enrollments since its incorporation, it is the largest private, independent, nonprofit microscopy and microanalysis institution in the United States dedicated solely to the teaching of microscopists. McCrone Research Institute maintains over one hundred polarized light and various other light microscopes in addition to electron microscopes, spectrometers, and scientific digital imaging systems for use in any of its over 50 intensive one-week courses offered each year.
Nestor J. Zaluzec is an American scientist and inventor who works at the University of Chicago and Argonne National Laboratory. He invented and patented the Scanning Confocal Electron Microscope. and the π Steradian Transmission X-ray Detector for Electron-Optical Beam Lines and Microscopes.
Vernon Ellis Cosslett, FRS was a British microscopist.
Microscopy and Microanalysis is a peer-reviewed scientific journal that covers original research in the fields of microscopy, imaging, and compositional analysis, including electron microscopy, fluorescence microscopy, atomic force microscopy, and live-cell imaging. It is published for the Microscopy Society of America.
Ondrej L. Krivanek is a Czech/British physicist resident in the United States, and a leading developer of electron-optical instrumentation. He won the Kavli Prize for Nanoscience in 2020 for his substantial innovations in atomic resolution electron microscopy.
Elmar Zeitler was a German physicist.
Sergei V. Kalinin is the Weston Fulton Professor at the Department of Materials Science and Engineering at the University of Tennessee-Knoxville.
Peter Duncumb is a British physicist specialising in X-ray microscopy and microanalysis. He is best known for his contribution to the development of the first electron microprobe.
A microscope is an instrument used to see objects that are too small to be seen by the naked eye.
Miaofang Chi is a distinguished scientist at the Center for Nanophase Materials Sciences in Oak Ridge National Laboratory. Her primary research interests are understanding interfacial charge transfer and mass transport behavior in energy and quantum materials and systems by advancing and employing novel electron microscopy techniques, such as in situ and cryogenic scanning transmission electron microscopy. She was awarded the 2016 Microscopy Society of America Burton Medal and the 2019 Microanalysis Society Kurt Heinrich Award. She was named to Clarivate's list of Highly Cited Researchers in 2018 and 2020.
SEM-XRF is an established technical term for adding a X-ray generator to a Scanning Electron Microscope (SEM). Technological progress in the fields of small-spot low-power X-ray tubes and of polycapillary X-ray optics has enabled the development of compact micro-focus X-ray sources that can be attached to a SEM equipped for energy-dispersive X-ray spectroscopy.
Lena Fitting Kourkoutis was an American physicist working in the field of electron microscopy, and a professor of applied and engineering physics at Cornell University. Her research focused on the use of aberration-corrected scanning transmission electron microscope, providing atomic resolution, at cryogenic temperatures (>77K) to study physical processes such as superconductivity and biological structures such as proteins.
Peter David Nellist, is a British physicist and materials scientist, currently a professor in the Department of Materials at the University of Oxford. He is noted for pioneering new techniques in high-resolution electron microscopy.
