Life Sciences Commons^™

Image Simulation For Secondary Electron Micrographs In The Scanning Electron Microscope, David C. Joy

Scanning Microscopy

The interpretation of high resolution secondary electron images, and quantitative measurements of micrometer size features on integrated circuits, both require accurate modelling of the process of image formation in the scanning electron microscope. A Monte Carlo model, based on the semi-empirical theory of Salow, has been developed which permits the simultaneous computation of the secondary and backscattered yields. The physical constants necessary to apply this model can be derived from straightforward measurements of the total electron yield as a function of beam energy. On the basis of simplifying assumptions line profiles and images can then be simulated for specimens of …

The Root Surface: An Illustrated Review Of Some Scanning Electron Microscope Studies, Sheila J. Jones

Scanning Microscopy

This review paper highlights how the advent of a new type of surface microscopy in the late 1960s, scanning electron microscopy (SEM), was responsible for a fresh appraisal of the structure of the root surface. Details of the formation, resorption and repair of cementum, all surface phenomena, and the varied relationships and mineralization patterns of the two sets of fibres within cementum - the hall mark of the tissue - could be seen in a way and at a range of magnifications hitherto impossible. The major interpretational advances were made rapidly using secondary electron imaging of anorganic normal, exposed, carious …

Scanning Microscopic Observations On Dental Caries, Sheila J. Jones, Alan Boyde

Scanning Microscopy

This paper presents findings made using special techniques of imaging and/or of specimen preparation to investigate the changes in tooth structure which occur in caries. We have studied both coronal and root caries in enamel, dentine and cementum using scanning electron and confocal scanning optical microscopy.

In preparation for backscattered electron (BSE) imaging in the SEM, teeth were stored in 70% ethanol until further dehydration in ethanol and embedding in polymethylmethacrylate (PMMA). Longitudinally cut surfaces were diamond polished and coated with carbon or silver before BSE imaging. Important changes in the distribution of densities in both enamel and dentine occurred …

Scanning Electron Microscope Solid State Detectors, Zbigniew J. Radzimski

Scanning Microscopy

Solid state detectors (SSD) are the most commonly used backscattered electron (BSE) detectors in scanning electron microscopy (SEM). They have been used for at least 20 years and many types are described in the literature. These detectors can be designed in many shapes and forms but in commercially available SEMs two semiconductor detectors (A and B) are usually placed below the polepiece where they are used for compositional (A+B) and topographic (A-B) contrast enhancement. The range of SSD applications available from BSE is quite extensive. The kind and quality of information depend strongly on the shape and position of the …

Secondary Electron Emission Induced By Electron Bombardment Of Polycrystalline Metallic Targets, R. Bindi, H. Lanteri, P. Rostaing

Scanning Microscopy

The aim of the present paper is the analysis of the backward secondary electron emission phenomenon, under electron bombardment, on the basis of experimental and theoretical results. Among the theoretical models, we will mention the phenomenological models, those which use a Monte-Carlo type simulation method, and those based on the numerically solved Boltzmann transport equation.

To correlate experimental and theoretical results on all the data characterizing this phenomenon, it is necessary to use an appropriate description for the excitation process of the internal secondary electrons; it also needs a complete description of the transport process for the excited electrons, which …

A Ring Scintillation Detector For Detection Of Backscattered Electrons In The Scanning Electron Microscope, J. Hejna

Scanning Microscopy

A backscattered electron detector with a cylindrical detecting surface has been constructed and installed in a scanning electron microscope. The detector surrounds the specimen and accepts electrons emitted into a specific range of zenith angles. In the case of untilted specimens it collects electrons emerging from the specimen surface at low exit angles relating to it. This enables us to obtain a good resolution of images of untilted specimens. Moreover, the detect or gives very high level of topographic contrast and good three-dimensional impression of the specimen shape.