On electron transfer

The tunneling transfer of electrons between two sites, appropriate to biological intermolecular electron transfer, contains physical considerations which are not important in the tunneling transfer between two metals. Analyses (such as the recent one by Hales) based on the well-known formula for the latter but applied to the former case are quantitatively and qualitatively misleading.     

Pulmonary mineral dust. A study of ninety patients by electron microscopy, electron microanalysis, and electron microdiffraction

The results of a study of 90 patients are presented. Intrapulmonary mineral deposits were characterized by electron diffraction and electron probe microanalysis. Using this method, pneumoconioses may be distinguidhed from other pneumopathies. In cases of pneumoconiosis, there exists a specific relationship between the etiology of the dust exposure and the crystallographic characteristics of the intrapulmonary deposits. The nature of the deposits may be indicative of a specific type of pneumoconiosis. This method is particularly useful in differentiating between asbestos bodies and ferruginous bodies. The value of the method in general and its importance in the study of pneumoconiosis are discussed.     

Image processing based on the combination of high-resolution electron microscopy and electron diffraction

A method of crystal structure determination by electron crystallographic image processing based on the combination of high-resolution electron microscopy (HREM) and electron diffraction is introduced. It consists of two stages: image deconvolution and resolution enhancement. In the first stage an image taken at an arbitrary defocus condition is transformed into the structure image with the resolution depending on the resolution of the electron microscope. In the second stage the image resolution is enhanced to the diffraction resolution limit by combining the electron diffraction data and using the phase extension technique so that in the final image most unoverlapped atoms can be resolved individually. The experimental diffraction intensities are corrected for approximating to square structure factors. The principle of the image processing and the procedure of diffraction intensity correction are briefly described and the results of applications are illustrated. Since the method is based on the weak phase object approximation (WPOA), the validity of WPOA is discussed by introducing an approximate image contrast theory named pseudo weak phase object approximation (PWPOA) to demonstrate the image contrast change with the crystal thickness for very thin crystals.     

Characterization of palladium hydride films by electron energy loss spectroscopy and electron diffraction

Electrolytic charging is used to hydrogenate Pd films to full stoichiometry PdH, which is checked by making use of the relation between the lattice constant of the Pd-H system and its hydrogen content. The role of the surface barrier in preventing hydrogen escape from fully charged specimens is studied with EELS technique. Electron energy loss spectra collected at different collector aperture deviation angles in a STEM are used to separate the volume loss component from the surface loss component. The results are compared with those of Pd metal and results of PdH obtained with other techniques.