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This article is devoted to the study of the effect of ion sputtering on the alloy surface, using the example of martensitic stainless steel AISI 420 with ultrahigh-dose, high-intensity nitrogen ion implantation on the efficiency of accumulation and transformation of the depth distribution of dopants. Some patterns of change in the depth of ion doping depending on the target temperature in the range from 400 to 650 °C, current density from 55 to 250 mA/cm2, and ion fluence up to 4.5 × 1021 ion/cm2 are studied. It has been experimentally established that a decrease in the ion sputtering coefficient of the surface due to a decrease in the energy of nitrogen ions from 1600 to 350 eV, while maintaining the ion current density, ion irradiation fluence and temperature mode of target irradiation increases the ion-doped layer depth by more than three times from 25 μm to 65 µm. The efficient diffusion coefficient at an ion doping depth of 65 μm is many times greater than the data obtained when stainless steel is nitrided with an ion flux with a current density of about 2 mA/cm2.

AbstractCarbon films 50–180 nm thick on nickel substrates are fabricated by the ion sputtering of graphite and the deposition of heavy hydrocarbons from the gas phase with simultaneous electron irradiation. Irradiation results in the formation of bonds in carbon films due to the sp and sp3 hybridization of orbitals (sp and sp3 bonds), mainly, sp3 bonds. A fraction of these bonds does not change with growth in the electron energy; it increases three-fold with a reduction in the temperature and an increase in the electron current density. Electron irradiation enhances the film microhardness which exceeds 12 GPa. The films, prepared by heavy hydrocarbon deposition, contain CHn bonds and a small fraction of sp3 bonds. The maximum value of the microhardness of the hydrocarbon films is no more than 4.5 GPa. The analysis of the proposed model of the kinetics of forming different allotropic phases in a carbon film to be deposited shows that a temperature reduction changes the specific volume of an atom in the lattice, while under conditions of simultaneous electron irradiation, it appreciably increases the content of the phase with sp3 bonds. The effect of spi-bond breakage during electron-beam-assisted deposition weakly depends on the electron energy. The weak excitations of electrons of carbon atoms can also result in the formation of sp3 bonds and increases their concentration with growth in the electron current density.

Hafnium oxide (HfO 2 ) is an important high-refractive-index material used in the optical thin films. Dual beam ion sputtering is one of the most important methods for preparing HfO 2 films. This study systematically investigated the optical, structural, and compositional properties of HfO 2 films by dual ion beam sputtering deposition. The influence and mechanism of the oxygen flow of the assist ion source and vacuum chamber to prepare hafnium oxide film with higher refractive index, lower extinction coefficient, and lower surface roughness were researched. Based on microstructure measurements obtained by atomic force microscopy, scanning electron microscopy and X-ray diffraction, it was found that the film with 15 sccm oxygen flow rate in assisted ion source and zero in vacuum chamber had the smallest root mean square roughness and highest degree of crystallization. Results of optical studies showed that the film exhibited the highest refractive index and lowest extinction coefficient, whereas the oxygen flow rate of the assist ion source and vacuum chamber were 15 sccm and zero, respectively. The film was polycrystalline and comprised monoclinic, tetragonal, and orthorhombic phases. We believe this study was important for choosing proper oxygen flow parameters for the fabrication of hafnium oxide film with different applications.

Changes in the surface composition of silicon carbide under hydrogen ion bombardment were studied based on the method of calculating the component composition and thickness of the layer of two-component targets that changed as a result of stoichiometric sputtering under irradiation with light ions. The thickness of the modified layer and its component composition were calculated. The calculations showed that the surface layers are depleted of carbon, which is consistent with the experimental results.

The paper investigates the dependence of the sputtering yields by light ions bombardment of the surface layers of titanium and tungsten, modified with carbon, on the thickness of the layer. The theoretical study was conducted on the basis of a sputtering model (previously adapted to describe the sputtering of two-component targets and layered-inhomogeneous surfaces), based on two sputtering mechanisms, which allows to analyze the obtained dependencies. Theoretical calculations of the total yields sputtering by helium ions bombardment of the surface layers of titanium and tungsten modified with carbon are given in comparison with the results of computer simulation obtained using the SRIM-2013pro program.

A method is proposed for calculating the component composition and thickness of a layer of two-component targets changed as a result of prolonged (stoichiometric) sputtering when irradiated with light ions. The method is based on a previously tested model of sputtering inhomogeneous two–component materials with light ions. In the case of stationary sputtering of tungsten and tantalum carbides with helium ions, the results of calculations of the component composition and thickness of the modified layer are presented in comparison with experimental data.

The mechanism of formation of self-organized patterns on Si substrate with simultaneous co-sputtering of molybdenum by low-energy ion beam sputtering has been investigated. The experiment was carried out using a 1 keV Ar ion beam at normal incidence with different ion fluence (10 16 –10 18 ions.cm −2 ). To explore the mechanism of pattern evolution in the presence of impurities (Mo atom), the morphological details of the samples with different ion fluence, as well as with respect to the distance from the Mo target were examined by atomic force microscopy (AFM). The evolution of the surface pattern depends on the ion fluence and a pattern transition from ripple to ripple + dot, and dot was observed with distance from the Mo target. RBS, XPS and XRR measurements were also carried out to understand the mechanism of the surface evolution process.

In the present study, the effects of swift heavy ion induced modification on the structural, morphological and optical properties of potassium sodium niobate (KNN) thin films have been investigated. KNN thin films were deposited using RF magnetron sputtering onto Si and quartz substrates. Subsequently, as-deposited films were annealed at 700 °C in air ambience for crystallization. Eventually, these crystalline films were irradiated using 100 MeV Ag ions at various fluences ranging from 1 × 10 12 to 1 × 10 13 ions/cm 2 . The crystalline and irradiated films were characterized using various techniques such as X-ray diffraction (XRD), atomic force microscopy (AFM), Raman spectroscopy, and UV–Vis spectroscopy. XRD results reveal that the crystallinity of films decreases drastically upon irradiation and almost disappeared at 1 × 10 13 ions/cm 2 . Raman spectra show the different vibration modes of NbO 6 octahedra. Raman peaks intensity is decreased and the peaks get broadened due to irradiation which indicates the amorphous nature of films. Variation in surface morphology and roughness of films before and after irradiation is studied using AFM. The minimum value of roughness is observed at 5 × 10 12 ions/cm 2 . Ion beam irradiation results in the variation of transmittance and optical band gap of the films. The optical band gap of crystalline KNN film is found to be 3.82 eV which decreased to 3.72 eV upon irradiation at 5 × 10 12 ions/cm 2 . The monotonous decrease in the refractive index and packing density of films is also observed with ion fluence.

The plasmon resonances of metallic nanoparticles have received considerable attention for their applications in nanophotonics, biology, sensing, spectroscopy and solar energy harvesting. Although thoroughly characterized for spheres larger than ten nanometres in diameter, the plasmonic properties of particles in the quantum size regime have been historically difficult to describe owing to weak optical scattering, metal–ligand interactions, and inhomogeneity in ensemble measurements. Such difficulties have precluded probing and controlling the plasmonic properties of quantum-sized particles in many natural and engineered processes, notably catalysis. Here we investigate the plasmon resonances of individual ligand-free silver nanoparticles using aberration-corrected transmission electron microscope (TEM) imaging and monochromated scanning TEM electron energy-loss spectroscopy (EELS). This technique allows direct correlation between a particle’s geometry and its plasmon resonance. As the nanoparticle diameter decreases from 20 nanometres to less than two nanometres, the plasmon resonance shifts to higher energy by 0.5 electronvolts, a substantial deviation from classical predictions. We present an analytical quantum mechanical model that describes this shift due to a change in particle permittivity. Our results highlight the quantum plasmonic properties of small metallic nanospheres, with direct application to understanding and exploiting catalytically active and biologically relevant nanoparticles. Metal nanoparticles with dimensions below ten nanometres exhibit plasmon resonances governed by quantum mechanical effects, as probed with electron microscopy and spectroscopy Quantum plasmon resonances of metallic nanospheres The oscillations of electrons in tiny metal particles — called localized surface plasmon resonances — have distinct optical properties that make them attractive in a variety of imaging and sensing technologies. Particles less than 10 nanometres in diameter may be particularly relevant to many natural and engineered systems. But as they approach the quantum regime, our knowledge of how particles' plasmonic properties change becomes rather hazy. Jonathan Scholl and colleagues investigate the plasmonic properties of individual silver nanoparticles with dimensions in the quantum size regime. Using electron microscopy and spectroscopy, they correlate a particle's plasmon resonance with its size and geometry for diameters ranging from 20 nm to less than 2 nm. The results demonstrate the quantum-mechanical nature of small metallic nanospheres, with direct applications to catalytically active and biologically relevant nanoparticles.

Localized surface plasmon resonances of an individual silver nanocube are reconstructed in three dimensions using electron energy-loss spectrum imaging, resulting in a better understanding of the optical response of noble-metal nanoparticles. Observing surface excitations for nano-optics Metal nanoparticles exhibit a range of striking and useful optical properties thanks to the excitation of localized surface plasmon resonances (LSPRs). But the precise relationship between the three-dimensional structure of the nanoparticles and the resulting LSPRs can be hard to determine. Paul Midgley and colleagues have developed a spectrally sensitive imaging technique, based on electron energy-loss spectroscopy, that permits three-dimensional visualization of many of the key features associated with these LSPRs. With this technique, the interplay between the LSPRs, nanoparticle structure and substrate–nanoparticle interactions can be directly probed. This study focuses on silver nanocubes, but the method demonstrated is applicable to similar plasmonic phenomena across all metal nanoparticles. The remarkable optical properties of metal nanoparticles are governed by the excitation of localized surface plasmon resonances (LSPRs). The sensitivity of each LSPR mode, whose spatial distribution and resonant energy depend on the nanoparticle structure, composition and environment, has given rise to many potential photonic, optoelectronic, catalytic, photovoltaic, and gas- and bio-sensing applications 1 , 2 , 3 . However, the precise interplay between the three-dimensional (3D) nanoparticle structure and the LSPRs is not always fully understood and a spectrally sensitive 3D imaging technique is needed to visualize the excitation on the nanometre scale. Here we show that 3D images related to LSPRs of an individual silver nanocube can be reconstructed through the application of electron energy-loss spectrum imaging 4 , mapping the excitation across a range of orientations, with a novel combination of non-negative matrix factorization 5 , 6 , compressed sensing 7 , 8 and electron tomography 9 . Our results extend the idea of substrate-mediated hybridization of dipolar and quadrupolar modes predicted by theory, simulations, and electron and optical spectroscopy 10 , 11 , 12 , and provide experimental evidence of higher-energy mode hybridization. This work represents an advance both in the understanding of the optical response of noble-metal nanoparticles and in the probing, analysis and visualization of LSPRs.