It’s well known that x-ray line profile analysis is a powerful and convenient method to probe the microstructural characteristics of nanocrystalline samples. In the literature well-documented techniques are normally used to obtain crystalline size distributions from x-ray line-broadening analysis. However, it is less considered that the shape of such size distributions may be a means to determine by which mechanism the particles have grown. A simple method is presented here to distinguish between two different growth mechanisms: the coalescence and Ostwald ripening process. An application of the method to platinum nanoparticle electrocatalysts with different size distributions, dispersed on high-surface-area carbon blacks, is discussed.
Research relevant to the understanding of polymer-metal adhesion led us to an oxygen Auger (KLL) study on metal oxide surfaces. This was done in order to aoalyse the ionicity and strength of 'Lewis sites' on oxide surfaces grown on metals as compared to their bulk metal oxide counterparts. Following some suggestions contained in earlier works by Wagner we show that relative Auger (KLL) oxygen energies are a sensitive probe of oxygen valence electron population and hole relaxation. A semi-empirical model is discussed to justify these findings. Furthermore it is shown that this 'observable' feature is also influenced by the metal oxide thickness at the metal surface.
Statistical theory and applications of lock-in carrierographic image pixel brightness dependence on multicrystalline Si solar cell efficiency and photovoltage J. Appl. Phys. 112, 054505 (2012) Signal contrast in coherent Raman scattering: Optical phonons versus biomolecules J. Appl. Phys. 112, 053101 (2012) Indirect optical absorption in silicon via thin-film surface plasmon J. Appl. Phys. 112, 043103 (2012) Strong photoluminescence from diameter-modulated single-walled carbon nanotubes Secondary electron emission from diamond films is studied as a function of the primary electron beam energy and bulk material properties. A formulation of a simple model of the secondary electron emission coefficient, as a function of the primary electron beam energy, has been found to be helpful in defining physical criteria able to guide the optimization of the diamond film electron emission performance. The secondary electron mean escape depth deduced from the model is indeed related to the density of defects in the material and represents the main factor in determining the low energy secondary electron yield. These results are supported by Raman spectroscopy measurements, indicating a lower graphitic content and a higher crystalline quality of the diamond phase in films showing better secondary electron and photoemission yields. We demonstrate that a diamond film, acting as a stable and proportional electron multiplier, can be used as a converter of backscattered electrons into secondary electrons in scanning electron microscopy. It will be shown that the use of a diamond film converter is suitable to improve the signal to noise ratio of images providing an enhanced compositional contrast.
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