a b s t r a c tThe oblique angle configuration has emerged as an invaluable tool for the deposition of nanostructured thin films. This review develops an up to date description of its principles, including the atomistic mechanisms governing film growth and nanostructuration possibilities, as well as a comprehensive description of the applications benefiting from its incorporation in actual devices. In contrast with other reviews on the subject, the electron beam assisted evaporation technique is analyzed along with other methods operating at oblique angles, including, among others, magnetron sputtering and pulsed laser or ion beam-assisted deposition techniques. To account for the existing differences between deposition in vacuum or in the presence of a plasma, mechanistic simulations are critically revised, discussing well-established paradigms such as the tangent or cosine rules, and proposing new models that explain the growth of tilted porous nanostructures. In the second part, we present an extensive description of applications wherein oblique-angle-deposited thin films are of relevance. From there, we proceed by considering the requirements of a large number of functional devices in which these films are currently being utilized (e.g., solar cells, Li batteries, electrochromic glasses, biomaterials, sensors, etc.), and subsequently describe how and why these nanostructured materials meet with these needs.

Copper and copper oxides (Cu2O and CuO) have been deposited by evaporation of copper and subsequent oxidizing treatments, on the surface of flat SiO2 and ZrO2 substrates. Large variations of several eVs have been found in the values of the Cu 2p3/2 binding energy (BE) and Auger parameter (α‘) of copper as a function of the amount of deposited metallic copper or copper oxides. The magnitude of the changes was also dependent on the type of support upon which the experiment was carried out. These changes have been attributed to modifications in the factors contributing to the initial and final state effects of the process, according to the dispersion degree and the nature of the interactions between the copper oxide moieties and the support. All of these changes can be systematized with the help of chemical state plots. Experiments carried out with real catalysts stress the need of such plots, which summarize the results obtained with the model systems, for a proper characterization of the supported oxide phases in this kind of real materials.

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A detailed study of ammonia synthesis from hydrogen and nitrogen in a planar dielectric barrier discharge (DBD) reactor was carried out. Electrical parameters were systematically varied, including applied voltage and frequency, electrode gap, and type of ferroelectric material (BaTiO 3 versus PZT). For selected operating conditions, power consumption and plasma electron density were estimated from Lissajous diagrams and by application of the Bolsig + model, respectively. Optical emission spectroscopy was used to follow the evolution of plasma species (and * 2 2 ) as a function of applied voltage with both types of ferroelectric material. PZT gave both greater energy efficiency and higher ammonia yield than BaTiO 3 : 0.9 g NH 3 kWh −1 and 2.7% single pass N 2 conversion, respectively. This performance is substantially superior to previously published findings on DBD synthesis of NH 3 from N 2 and H 2 alone. The influence of electrical working parameters, the beneficial effect of PZT and the importance of controlling reactant residence time are rationalized in a reaction model that takes account of the principal process variables

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Plasma treatment is recognized as a suitable technology to improve germination efficiency of numerous seeds. In this work Quinoa seeds have been subjected to air plasma treatments both at atmospheric and low pressure and improvements found in germination rate and percentage of success. Seed water uptake by exposure to water vapor, although slightly greater for plasma treated seeds, did not justify the observed germination improvement. To identify other possible factors contributing to germination, the chemical changes experienced by outer parts of the seed upon plasma exposure have been investigated by X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM-EDX). XPS revealed that the outer layers of the Quinoa plasma treated seeds were highly oxidized and appeared enriched in potassium ions and adsorbed nitrate species. Simultaneously, SEM-EDX showed that the enrichment in potassium and other mineral elements extended to the seed pericarp and closer zones. The disappearance from the surface of both potassium ions and nitrate species upon exposure of the plasma treated seeds to water vapor is proposed as a factor favoring germination. The use of XPS to study chemical changes at seed surfaces induced by plasma treatments is deemed very important to unravel the mechanisms contributing to germination improvement.