Momentum transfer effects in near surface electron energy loss

We examine two formulations for the differential surface excitation parameter (DSEP): one provided by Tung et al. and the other given by the Chen–Kwei position‐dependent differential inverse inelastic mean free path integrated over the electron trajectory. We demonstrate that the latter converges to the former provided that the dielectric function of the solid does not depend on the momentum transfer or it depends on just the momentum transfer component parallel to the surface. Tung's DSEP represents therefore an approximation to the Chen–Kwei DSEP calculated for a dielectric function with no restrictions on the momentum dependence. The approximation is shown to work in the limit of small momentum transfer and to imply an error of 4%–5% for electrons traveling through the solid with energy E = 1 keV. Copyright © 2015 John Wiley & Sons, Ltd.     

Formation of gold nanoparticles and their aggregates in a liquid at magnetron deposition

The influence of magnetron deposition conditions on the size of Au nanoparticles and their aggregates obtained by condensation in a neutral liquid is studied experimentally. A model is suggested in which the nanoparticles and aggregates form in a thin subsurface layer, which becomes oversaturated by atoms and resulting nanoparticles when the liquid flows through a localized deposition zone. The process stops when the products leave this zone because of stirring. The size of nanoparticles and aggregates depends on the particle flux density and exposure time in the deposition zone. The final size of nanoparticles depends on the exposure time only slightly, while that of aggregates significantly depends on the exposure time. This allows one to prepare a concentrated solution of almost monodisperse nanoparticles with a low degree of aggregation by properly selecting deposition conditions and multiply passing the liquid through the deposition zone.     

Analysis of the Mo/Mo Nanocrystalline Optical Coating Obtained with the Aid of Simultaneous Deposition and Ion Sputtering

Structure, optical properties, and resistance to sputtering are studied for a reflecting Mo-coating that is fabricated using magnetron deposition with simultaneous low-energy ion sputtering at the deposition rate that is higher than the etching rate. A Mo-polycrystalline mirror is used as a substrate. It is shown that the coating exhibits textured nanocrystalline structure with a relatively low spread of crystallite sizes and high resistance to sputtering. It is also demonstrated that the spectral reflection coefficient of such a Mo-coating differs from the spectral reflection coefficient of polycrystalline and single-crystalline Mo and the difference results from the effect of the structure of coating on its optical properties. A theoretical model of the coating formation is proposed.     

The influence of metal nanoparticle size distribution in photoelectron spectroscopy

We present an innovative approach to characterize small metal nanoclusters embedded in an amorphous carbon matrix. A simple mathematical relation linking binding energy shifts to the mean nanoparticle (NP) dimensions allows determination of the distribution of NP sizes by fitting the Au 4f X-ray photoemission spectrum. The NP size distributions obtained using our method are compared with those obtained from X-ray diffraction spectra.     

Pico-femtosecond electron-optical photography

The progress of ultra high-speed photography using electron-optical devices is surveyed with special reference to recent work in the USSR. In some applications time resolutions of better than 1 ps are obtainable. The ultimate limits of streak camera techniques are discussed. Finally, systems for X-ray chronography are described.     

Finite-size image isochronism

Classical imaging tautochronism implies zero light transit-time variation over paths, connecting the point source with its image point. For a certain imaging class the variation is shown to be zero over two-dimensional objects and corresponding images. The area-isochronous imaging is surely important for pico and subpicosecond photography.