Why scanning electron microscope is used

For instance, some products, like stainless steel, must be evenly coated with special chemicals for optimal performance. Scanning electron microscopy can help identify cracks, imperfections, or contaminants on the surfaces of coated products. Industries, like cosmetics, that work with tiny particles can also use scanning electron microscopy to learn more about the shape and size of the small particles they work with.

For instance, particles that are too large or jagged might not flow or mix as well as particles that are small and round. Particles that are the wrong size or shape may have an impact on the consistency or performance of the product.

Scanning electron microscopy can be used to identify problems with particle size or shape before products reach the consumer. Finally, industries that use small or microscopic components to create their products often use scanning electron microscopy to examine small components like fine filaments and thin films. A Secondary Electron SE detector is placed at the side of the electron chamber, at an angle, in order to increase the efficiency of detecting secondary electrons which can provide more detailed surface information.

The key difference between electron and optical microscopy is right there in the name. SEMs use a beam of electrons rather than a beam of light. An electron source located at the top of the microscope emits a beam of highly concentrated electrons.

In SEMs, there are three different types of electron sources :. Looking for the perfect analytics instrument for YOUR next big discovery? Speak with the ATA Scientific team today to get expert advice on the right instruments for your research. In modern materials science, investigations into nanotubes and nanofibres, high temperature superconductors, mesoporous architectures and alloy strength, all rely heavily on the use of SEMs for research and investigation. In fact, just about any material science industry, from aerospace and chemistry to electronics and energy usage, have only been made possible with the help of SEMs.

Researchers are exploring new ways nanowires can be used as gas sensors by improving existing fabrication methods and developing new ones. Electron microscopy is vitally important in helping characterise nanowires and understanding their gas sensing behaviour. Reliable performance of semiconductors requires accurate topographical information. The high resolution three dimensional images produced by SEMs offers a speedy, accurate measurement of the composition of the semiconductor.

In fact, in just about all wafer manufacturing processes, SEMs are one of three essential quality control tools used. In the case of repetitive daily quality control tests, larger monitors 19 inches have been shown to reduce visual fatigue for inspectors.

Microchip production is increasingly relying on SEMs to help gain insight into the effectiveness of new production and fabrication methods. The SEM is also capable of performing analyses of selected point locations on the sample; this approach is especially useful in qualitatively or semi-quantitatively determining chemical compositions using EDS , crystalline structure, and crystal orientations using EBSD.

The design and function of the SEM is very similar to the EPMA and considerable overlap in capabilities exists between the two instruments. Accelerated electrons in an SEM carry significant amounts of kinetic energy, and this energy is dissipated as a variety of signals produced by electron-sample interactions when the incident electrons are decelerated in the solid sample.

These signals include secondary electrons that produce SEM images , backscattered electrons BSE , diffracted backscattered electrons EBSD that are used to determine crystal structures and orientations of minerals , photons characteristic X-rays that are used for elemental analysis and continuum X-rays , visible light cathodoluminescence--CL , and heat.

Secondary electrons and backscattered electrons are commonly used for imaging samples: secondary electrons are most valuable for showing morphology and topography on samples and backscattered electrons are most valuable for illustrating contrasts in composition in multiphase samples i. X-ray generation is produced by inelastic collisions of the incident electrons with electrons in discrete ortitals shells of atoms in the sample.

As the excited electrons return to lower energy states, they yield X-rays that are of a fixed wavelength that is related to the difference in energy levels of electrons in different shells for a given element. Thus, characteristic X-rays are produced for each element in a mineral that is "excited" by the electron beam. SEM analysis is considered to be "non-destructive"; that is, x-rays generated by electron interactions do not lead to volume loss of the sample, so it is possible to analyze the same materials repeatedly.

The specific capabilities of a particular instrument are critically dependent on which detectors it accommodates. The SEM is routinely used to generate high-resolution images of shapes of objects SEI and to show spatial variations in chemical compositions: 1 acquiring elemental maps or spot chemical analyses using EDS , 2 discrimination of phases based on mean atomic number commonly related to relative density using BSE , and 3 compositional maps based on differences in trace element "activitors" typically transition metal and Rare Earth elements using CL.

Precise measurement of very small features and objects down to 50 nm in size is also accomplished using the SEM. Backescattered electron images BSE can be used for rapid discrimination of phases in multiphase samples. SEMs equipped with diffracted backscattered electron detectors EBSD can be used to examine microfabric and crystallographic orientation in many materials. There is arguably no other instrument with the breadth of applications in the study of solid materials that compares with the SEM.

The SEM is critical in all fields that require characterization of solid materials. While this contribution is most concerned with geological applications, it is important to note that these applications are a very small subset of the scientific and industrial applications that exist for this instrumentation.

Most SEM's are comparatively easy to operate, with user-friendly "intuitive" interfaces. Many applications require minimal sample preparation.