Scanning electron microscopy conductive coatings

This technique can be applied to samples prepared for study by scanning electron microscopy (SEM). When subject to impact by electrons, atoms emit characteristic X-ray line spectra, which are almost completely independent of the physical or chemical state of the specimen (Reed, 1973). To analyse samples, they are prepared as required for SEM, that is they are mounted on an appropriate holder, sputter coated to provide an electrically conductive surface, generally using gold, and then examined under high vacuum. The electron beam is focussed to impinge upon a selected spot on the surface of the specimen and the resulting X-ray spectrum is analysed. 

Scanning electron microscopy (SEM) seems to have been used only scarcely for the characterization of solid lipid-based nanoparticles [104], This method, however, is routinely applied for the morphological investigation of solid hpid microparticles (e.g., to smdy their shape and surface structure also with respect to alterations in contact with release media) [24,38,39,41,42,80,105]. For investigation, the microparticles are usually dried, and their surface has to be coated with a conductive layer, commonly by sputtering with gold. Unlike TEM, in SEM the specimen is scanned point by point with the electron beam, and secondary electrons that are emitted by the sample surface on irradiation with the electron beam are detected. In this way, a three-dimensional impression of the structures in the sample, or of their surface, respectively, is obtained. 

Scanning electron microscopy is an important tool when examining the mode of wear of any sample. The surface of the sample is coated with a very thin layer (only several atoms thick) of a conductive material such as gold. The surface is scanned using a beam of electrons and the image magnified and recorded. 

The surface structure of thicker samples can be examined using scanning electron microscopy (SEM). Here a fine beam of electrons is scanned across the surface of the specimen, and the scattered secondary electrons emitted from the surface of the sample are detected electronically. Secondary electrons are best produced by electron collision with conduction electrons in a metal surface (by analogy with the photoelectric effect), so samples for SEM are usually coated by evaporation with a thin film of gold in order to make them more visible. This naturally limits the fine detail that can be seen. 

Scanning Electron Microscopy (SEM) with magnification capability of up to 20,000X was used for the study of the polymer composite fracture surfaces. The freshly fractured surfaces were coated with a 250 thick Au-Pd conducting layer. 

Scanning Electron Microscopy. Samples of unweathered and weathered untreated and formaldehyde-treated wools were mounted or specimen stubbs using conducting silver paint and coated with two thin layers of silver. Scanning electron micrographs of the samples were prepared and examined for changes In the fiber surface (Fig. 1). 

The particle morphology is normally assessed by scanning electron microscopy (SEM). The sample preparation depends, in the first instance, on the type of equipment and normally requires the use of aluminum stubs with a carbon conductive tape and coating with gold-palladium layer. Sometimes the particles are placed on a double-sided carbon tape that is attached to aluminum stubs, without coating requirement. The analyses are carried out by applying to sample a difference of potential between 2 and 20 kV. 

FIGURE 3.2 (A) Schematic illustration of the fabrication process of conductive polymer-coated hollow sulfur nanospheres. RT means room temperature. (B) and (D) Scanning electron microscopy (SEM) and (C) and (E) transmission electron microscopy (TEM) images of the hollow sulfur nanospheres before and after coating with polypyrrole (PPy). 

Yoon et al. used Palladium (Pd) to modify Nafion membranes by coating them with a different thickness of Pd film, using as puttering method (Yoon et al. 2002). The scanning electron microscopy (SEM) micrographs showed that the 10 and 30 nm Pd films were dense and appeared to be well attached to the membrane. However, some cracks were found on the surface of the 100 nm Pd film. It was believed that the cracks were caused by the difference between the Nafion membrane and the Pd film in the expansion that took place when the composite membrane was immersed in water. The Nafion membrane swells more than the Pd film, which eventually develops cracks in the Pd film. Therefore, the sputtering procedures for a membrane thicker than 100 nm apparently need to be improved. From this research, a trade-off between proton conductivity and methanol crossover was noted similar to the results... 

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