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. Modern SEMs generate data in digital formats, which are highly portable. Samples must be solid and they must fit into the microscope chamber. Maximum size in horizontal dimensions is usually on the order of 10 cm, vertical dimensions are generally much more limited and rarely exceed 40 mm. For most instruments samples must be stable in a vacuum on the order of 10 -5 - 10 -6 torr. Samples likely to outgas at low pressures rocks saturated with hydrocarbons, "wet" samples such as coal, organic materials or swelling clays, and samples likely to decrepitate at low pressure are unsuitable for examination in conventional SEM's.
However, "low vacuum" and "environmental" SEMs also exist, and many of these types of samples can be successfully examined in these specialized instruments. Most SEMs use a solid state x-ray detector EDS , and while these detectors are very fast and easy to utilize, they have relatively poor energy resolution and sensitivity to elements present in low abundances when compared to wavelength dispersive x-ray detectors WDS on most electron probe microanalyzers EPMA.
An electrically conductive coating must be applied to electrically insulating samples for study in conventional SEM's, unless the instrument is capable of operation in a low vacuum mode. Sample preparation can be minimal or elaborate for SEM analysis, depending on the nature of the samples and the data required. Minimal preparation includes acquisition of a sample that will fit into the SEM chamber and some accommodation to prevent charge build-up on electrically insulating samples. Most electrically insulating samples are coated with a thin layer of conducting material, commonly carbon, gold, or some other metal or alloy.
This session will focus to review the forefront of scientific achievements and impacts in the field of ceramics, oxides, in addition to natural minerals. Contributions on new imaging techniques with dedicated detectors and Software are also welcome. Instrumentation and methods 2 Phase-related techniques holography, ptychography, phase plate, DPC, COM, beam shaping This session focuses on recent developments and applications of phase contrast and phase retrieval techniques, including pixelated STEM, ptychography, differential phase contrast and electron holography at both atomic resolution and medium resolution.
We also welcome contributions on electron beam shaping in space and time using refractive and diffractive masks and electromagnetic fields, including new directions based on conventional and programmable phase plates for applications in both physical and life sciences. Instrumentation and methods 3 In-situ, environmental, time-resolved electron microscopy This session focusses on the recent methodological and instrumental developments in in-situ electron microscopy.
A broad field is covered, ranging from environmental TEM, development and application of liquid- and gas-cell sample holders, in-situ sample stimuli and fast and ultrafast electron imaging and detection schemes. Main subjects are the quantitative description of diffraction and imaging, new approaches in image simulation, comparison of simulation with experiment, as well as development and application of methods for the atomic-level determination of structure, composition, strain as well as electric and magnetic fields.
Instrumentation and methods 5 Low energy electron microscopy STEM, TEM, SEM and FIB-techniques Topics of the symposium are methodology developments and applications of imaging and diffraction techniques using low electron energies at 80keV and below as well as advances in understanding electron probe-specimen interactions. FIB-related techniques include new developments in imaging with ions, nanostructuring and sample preparation. Instrumentation and methods 6 Spectroscopy EELS, EDX The session covers analytical techniques related to inelastic scattering and subsequent processes as well as the corresponding simulations and data treatment.
Life sciences 1 Single particle, cryo-TEM This session will highlight the recent advances in single particle electron cryomicroscopy, which has emerged as an important tool for the analysis of biomolecular structures.
Electron Diffraction and High-Resolution Electron Microscopy of Mineral Structures Study of Order/Disorder and Structural Heterogeneity in Layer Minerals. Nov 15, Electron Diffraction and High‐Resolution Electron Microscopy of from these patterns are used for a structural analysis of the platy minerals.
We will not only focus on the recent hardware and software development, but also on improvements of sample preparation and novel insights into biological mechanisms. Life sciences 2 Pathology, pathogens and diagnostics The session will have a focus on imaging in the study of infectious diseases e. Contributions on imaging in diagnostics or other fields of pathology are welcome. Life sciences 3 Imaging of large volumes Volume Scanning Electron Microscopy SEM gathers techniques of growing importance in the field of biomedical imaging, as they offer subcellular resolution on a large range of sample scales, from cells to organisms and tissues.
Life sciences 4 Cryo and Plastic Section Tomography on Biological Samples Electron Tomography is a tool that offers unique, three-dimensional insight into biological samples. This session will focus on the application of electron tomography on both plastic and cryo samples to study subcellular compartments, viral particles, and macromolecular structures such as cytoskeletal elements.
Studies using competitive methods to tomography that reach comparable resolution are also welcome. Life sciences 5 Correlative and multimodal microscopy Correlative Microscopy aims at combining different imaging modalities to generate more or better information than can be generated by each modality as a stand-alone technique. Although the combination of light and electron microscopy Correlative Light Electron Microscopy, CLEM is the best-known approach in the Correlative Microscopy field, other imaging modalities and approaches such as X-rays are being introduced into the workflow.
This session will highlight the current state of the field and the latest developments involving new imaging modalities. Life sciences 6 Probes and localization techniques This session focuses on advanced methods for high-resolution localization of bio molecules in cells and tissues, with emphasis on electron microscopy e.
Life sciences 7 Advances in sample preparation The session offers a platform for advanced techniques in imaging strategies, embedding methods as well as labeling and staining procedures for electron microscopy of biological samples including correlative approaches, analytical EM, 3D-EM, in-situ EM. Toggle navigation Navigation. Show more. Scientific program.