Heavy Metal Layer Research Articles

Effect of additional heavy metal layer on ZnO-Si monolithic SAW devices

Enhancement of electromechanical coupling has been shown in numerical calculations with an additional massive and conducting layer, such as Au, which makes the velocity of SAW slow between a ZnO thin film and an Si substrate. It is also shown that the electromechanical coupling factor can be increased without deterioration of the temperature coefficient of phase velocity.

Application of the thiocarbohydrazide-osmium coating technique to scanning electron microscopy of the inner ear.

The application of the thiocarbohydrazide-osmium coating technique to scanning electron microscopy of the inner ear is described. In this procedure specimens which have been prepared for electron microscopy (fixation in buffered glutaraldehyde or in Karnovsky's fixative followed by post fixation in osmium tetroxide) are twice exposed to solutions of thiocarbohydrazide and osmium tetroxide with water rinses in between each treatment. This method binds osmium to the specimen and so eliminates the need to coat the surface of the material with a layer of heavy metal. Initial observations indicate that this is a convenient and reliable method which is capable of yielding good results.

Method of obtaining clear images of biological objects in the scanning electron microscope

The quality of the image is affected not only by fixation of the material, but also by the conditions of its study in the scanning electron microscope. If the sprayed layer of carbon or heavy metal is thin there is the risk of charging the specimen during rapid scanning with the electron beam, and this interferes with the quality of the image. The study of biological objects is best carried out at two nominal values of the accelerating voltage (for example, 10 and 4 kV), for in this way errors during interpretation of the results can be avoided. Neither the thickness of the layer of carbon or heavy metal or different nominal values of the accelerating voltage can affect the reliability of the information obtained if in each concrete case the physical basis of image formation and the experimental conditions are allowed for in the analysis. Museum material fixed in ordinary formalin can be used for study in the scanning electron microscope.

A new penetrating-radiation image converter

A NEW practical penetrating-radiation television camera tube, termed the Metallonicon, has been built. It operates at X-ray frequencies, and a discernible image is obtained with two mr. s−1 incident on the target, which is comprised of a heavy metal layer in intimate contact with a secondary electron enhancing storage layer.

Unstained Biological Specimens in High Resolution Electron Microscopy

Negative staining and high resolution shadowing have been extensively used for structural studies in electron microscopy. However, these techniques cover the specimen with a layer of heavy salt or metal, and hence do not allow determination of true mass distribution or localization of specific sites using heavy atom markers. A prerequisite for such structural studies is an examination of unstained specimens. For thin specimens dark field microscopy must be used to obtain adequate contrast. The scanning transmission electron microscope is preferred for such studies since elastic, energyloss, and unscattered electrons can be recorded and analyzed quantitatively to form images with a minimum of beam-induced damage.

Transmission Secondary Electron Multiplication for High-Speed Pulse Counting

A new type of high-speed electron multiplier employing transmission secondary electron emission from thin insulating films is described. Electrons from a photosurface are multiplied in a series of plane-parallel dynodes consisting of a thin scattering layer of a heavy metal followed by a layer of a pure crystalline insulating material of high secondary emission yield. The characteristics of such dynodes are described, and the dc and pulse performance of an experimental seven-stage device employing this principle is presented.