Advances in Scanning Electron Microscopy

Abstract

IntroductionScanning électron microscopes offer several unique advantages and they hâve evolved into complex integrated instruments that often incorporate several important accessories. Their principle advantage stems from the method of constructing an image from a highly focused électron beam that scans across the surface of a spécimen. The beam générâtes backscattered électrons and excites secondary électrons and x-rays in a highly localized "spot." Thèse signais can be detected, and the results of the analysis are displayed as a spécifie intensity on a screen at a position that represents the position of the électron spot. As with a télévision image, after a given period, information about the entire field of view is displayed on the screen, resulting in a complète image. If the spécimen is thin, the same type of information can be gathered from the transmitted électrons, and a scanning transmission image is thus constructed.The scanning électron microscope is highly versatile and widely used. The quality of the image is related to its resolution and contrast, which, in turn, dépend on the diameter of the focused beam as well as its energy and current. Because électron lenses hâve inherently high aberrations, the usable aperture angles are much smaller than in a light microscope and, therefore, the électron beam remains focused over a relatively large distance, giving thèse instruments a very large depth of focus.Scanning électron microscopes are versatile in their ability to detect and analyze a lot of information. As a resuit, modem versions of thèse instruments are equipped with a number of detectors. Developments are sometimes related to placing the detectors in a geometrically attractive position close to the spécimen.

Neural Network for Nanoscience Scanning Electron Microscope Image Recognition

“…A scanning electron microscope (SEM) is a versatile instrument which is routinely used in nanoscience and nanotechnology to explore the structure of materials with spatial resolution down to 1 nm. Advances in SEM technology, particularly the complete computer control of the instrument and the increased ease of operation, have enabled users to independently operate the microscope and to acquire images with limited training 7 . In most research and industrial centers, SEMs work as multi-user facilities, and generate large numbers of images per user and per field of application.…”

The role of the environmental scanning electron microscope in the investigation of cement‐based materials

“…As drying progressed, much of the finer microstructure collapsed and drying cracks appeared. Sujata and Jennings (1991a) also studied early hydration in C 3 S as well as cement paste. For C 3 S, a sample paste of water/C 3 S ratio= 0.5 (by weight) was studied at a variety of times.…”

“…In order to study portland cement, Sujata and Jennings (1991a) condensed water on several dry cement particles using a cooling stage and high pressure in the microscope chamber. Within 30 min, an amorphous layer of product formed on the surface of the grains.…”

Polymer interfaces on a molecular scale: Comparison of techniques and some examples

“…A more conventional technique is scanning electron microscopy (SEM) which can also be used to obtain the surface topography and chemical composition on molecular to micrometer scale [40,41]. With modern electron microscopes it is not only possible to record the backscattered or secondary electrons, but also to perform an energy analysis of Auger electrons for chemical surface analysis or to detect the element-characteristic X-ray fluorescence (with /am-resolution).…”

“…with platinum. A recent development is environmental SEM where specimens can be observed at high pressure (20 Torr) and in different environments including wet surfaces [41].…”