Oxidation of Si(100)2x1 and Gex Si1−x (100)2x1

High resolution electron energy loss Spectroscopy (HREELS), X-ray photoelectron Spectroscopy (XPS) and low energy electron diffraction (LEED) have been used to characterize initial stages of oxidation of Si(100)2x1 and Ge_x Si_1−x (100)2x1 surfaces. Different oxidation stages of Si were identified by measuring Si 2p core level shifts and characteristic vibrations of Si-O-Si complexes. The latter may be described in the framework of continuous random network models.Then,from the experimentally determined frequencies, force constants,average bond angles and bond lengths are determined. Complementary,marker experiments with atomic hydrogen as a probe in conjunction with HREELS were used to determine the local, atomic structure for different stages of oxidation from chemical shifts of Si-H and Ge-H stretching mode intensities, respectively.     

Deposition behaviour of single Si adatom on p(2×2) Si(100) surface

The deposition of a single Si adatom on the p(2×2) reconstructed Si(100) surface has been simulated by an empirical tight-binding method. Using the perfect and defective Si surfaces as the deposition substrates, the deposition energies are mapped out around the research areas. From the calculated energy plots, the binding sites and several possible diffusion paths are achieved. The introduced defects will make the deposition behaviour different from that on the perfect surface.     

A NEW utilization of 11B ion beams: Hydrogen analysis by 1H 11B,α)α α nuclear reaction

It is proposed that the characteristic depth of origin of sputtered atoms in the spike regime, as for other collisional regimes, is given by the mean free path of atoms moving, at low energy, towards the surface.     

Direct synthesis of β-FeSi2 by ion beam mixing of Fe/Si bilayers

The iron di-silicide #-FeSi₂ is a promising direct band gap semiconductor but difficult to produce. Here, the successful direct synthesis of this phase by ion beam mixing of Fe/Si bilayers at temperatures in the range of 450 to 550 °C is reported. The obtained single-phase #-FeSi₂ layers and their structure are confirmed by Rutherford backscattering spectrometry, X-ray diffraction and conversion electron Mössbauer spectroscopy.     

Synthesis of Ag metallic nanoparticles by 120 keV Ag− ion implantation in TiO2 matrix

TiO₂ thin film synthesized by the RF sputtering method has been implanted by 120 keV Ag^? ion with different doses (3?×?10¹⁴, 1?×?10¹⁵, 3?×?10¹⁵, 1?×?10¹⁶ and 3?×?10¹⁶ ions/cm²). Further, these were characterized by Rutherford back Scattering, XRD, X-ray photoelectron spectroscopy (XPS), UV–visible and fluorescence spectroscopy. Here we reported that after implantation, localized surface Plasmon resonance has been observed for the fluence 3?×?10¹⁶ ions/cm², which was due to the formation of silver nanoparticles. Ag is in metallic form in the matrix of TiO₂, which is very interestingly as oxidation of Ag was reported after implantation. Also, we have observed the interaction between nanoparticles of Ag and TiO₂, which results in an increasing intensity in lower charge states (Ti³⁺) of Ti. This interaction is supported by XPS and fluorescence spectroscopy, which can help improve photo catalysis and antibacterial properties.     

C (2) N+1 Ruijsenaars–Schneider Models

We define the notion of C ⁽²⁾ _N+1Ruijsenaars–Schneider models and construct their Lax formulation. They are obtained by a particular folding of the A _2N+1 systems. Their commuting Hamiltonians are linear combinations of Koornwinder–van Diejen external fields Ruijsenaars–Schneider models, for specific values of the exponential one-body couplings but with the most general two double-poles structure as opposed to the formerly studied BC _N case. Extensions to the elliptic potentials are briefly discussed.     

Surface phonon dispersion of Cu(100)c(2×2)N

The Cu(100) surface covered with atomic nitrogen has been studied with low energy electron diffraction (LEED), Auger electron spectroscopy (AES) and inelastic electron scattering (EELS). Atomic nitrogen, formed by thermal dissociation of NH₃ adsorbed at 100 K, forms a c(2×2) overlayer on the Cu(100) surface. The dispersion of adsorbate and substrate associated modes of the Cu(100) surface covered with a c(2×2) nitrogen overlayer has been measured along the two dimensional Brillouin zone in the - by inelastic electron scattering. The experimental data are compared to a lattice dynamical slab calculation. The Rayleigh-mode (S₄-phonon) is only slightly changed by the N-overlayer. An optimum fit for the perpendicular and parallel nitrogen modes (=320 cm^–1 and =740 cm^–1 at =0.1) is obtained when the nitrogen atom is placed 0.6 Å above the first copper layer.     

Energy Band Structure of Be–(C,Si, Ge,Sn)–N2 Crystals

Russian Physics Journal - For the BeMN2 (M = C, Si, Ge, Sn) crystals with the chalcopyrite lattice, model calculations of the electronic structure are performed, equilibrium parameters of the...     

Modification of the Structure of Ti–Al–Si–Cu–N Gradient Coatings by Mechanical Tests

Technical Physics - The structural state in the zones of indentation and scratch testing of Ti–Al–Si–Cu–N gradient coatings has been studied using dark-field electron...     

Enhancement in electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes by 100 MeV Si9+ swift heavy ion irradiation

Swift heavy ion (SHI) irradiation has been used as a tool to enhance the electrochemical properties of ionic liquid-based nanocomposite polymer electrolytes dispersed with dedoped polyaniline (PAni) nanorods; 100 MeV Si⁹⁺ ions with four different fluences of 5?×?10¹⁰, 1?×?10¹¹, 5?×?10¹¹, and 1?×?10¹² ions cm^?2 have been used as SHI. XRD results depict that with increasing ion fluence, crystallinity decreases due to chain scission up to fluence of 5?×?10¹¹ ions cm^?2, and at higher fluence, crystallinity increases due to cross-linking of polymer chains. Ionic conductivity, electrochemical stability, and dielectric properties are enhanced with increasing ion fluence attaining maximum value at the fluence of 5?×?10¹¹ ions cm^?2 and subsequently decrease. Optimum ionic conductivity of 1.5?×?10^?2 S cm^?1 and electrochemical stability up to 6.3 V have been obtained at the fluence of 5?×?10¹¹ ions cm^?2. Ac conductivity studies show that ion conduction takes place through hopping of ions from one coordination site to the other. On SHI irradiation, amorphicity of the polymer matrix increases resulting in increased segmental motion which facilitates ion hopping leading to an increase in ionic conductivity. Thermogravimetric analysis (TGA) measurements show that SHI-irradiated nanocomposite polymer electrolytes are thermally stable up to 240–260 °C.     

Deposition of ultrahard Ti–Si–N coatings by pulsed high-current reactive magnetron sputtering

We report on the results of investigation of properties of ultrahard Ti–Si–N coatings deposited by pulsed high-current magnetron reactive sputtering (discharge pulse voltage is 300–900 V, discharge pulse current is up to 200 A, pulse duration is 10–100 μs, and pulse repetition rate is 20–2000 Hz). It is shown that for a short sputtering pulse (25 μs) and a high discharge current (160 A), the films exhibit high hardness (66 GPa), wear resistance, better adhesion, and a lower sliding friction coefficient. The reason is an enhancement of ion bombardment of the growing coating due to higher plasma density in the substrate region (10¹³ cm^–3) and a manifold increase in the degree of ionization of the plasma with increasing peak discharge current (mainly due to the material being sputtered).     

Effect of nitrogen partial pressure on Al–Ti–N films deposited by arc ion plating

AlTiN films with different nitrogen partial pressures were deposited using arc ion plating (AIP) technique. In this study, we systematically investigated the effect of the nitrogen partial pressure on composition, deposition efficiency, microstructure, macroparticles (MPs), hardness and adhesion strength of the AlTiN films. The results showed that with increasing the nitrogen partial pressure, the deposition rate exhibited a maximum at 1.2 Pa. Results of X-ray photoelectron spectroscopy (XPS) analysis revealed that AlTiN films were comprised of Ti–N and Al–N bonds. XRD results showed that the films exhibited a (1 1 1) preferred growth, and AlTi₃N and TiAl_x phases were observed in the film deposited at 1.7 Pa. Analysis of MPs statistics showed MPs decreased with the increase in the nitrogen partial pressure. In addition, the film deposited at 1.2 Pa possessed the maximum hardness of 38 GPa and the better adhesion strength.     

Charge state effect on K-shell ionization of aluminum by 600–3400 keV xenonq+ (12 < q < 29) ion collisions

K-shell X-ray spectra of Al were measured by the interaction of 600–3400 keV Xe ^q+ (q = 12–29) ions with Al surface. The X-ray yields per incident ion were deduced and the K-shell ionization cross-sections were obtained from the experimental yield data. With the same incident energy, the K-shell ionization cross-sections of Al excited by Xe ^q+ (q < 26) ions were of the same order of magnitude, while for q = 26 and 29 Xe ion collisions, they were, respectively, about two and ten times larger. Taking into account the binding-energy-modification and the recoil effect of target atoms, the binary encounter approximation (BEA) theory was consistent with the experimental data for q < 26 Xe ion collisions, but it underestimated those excited by q = 26 and 29 Xe ions. This indicates that the K-shell ionization of target induced by Xe ^q+(q < 26) ions was mainly due to the direct Coulomb excitation. However for q = 26 and 29 Xe ions collisions, the transfer of 3d vacancies of projectile to the 1s orbital of target via rotational coupling of the 3dπ, δ-3dσ molecular orbitals, which were formed in the ion-atom quasi-molecule, may cause a considerable contribution to the enhancement of ionization. In addition to the well known Auger and X-ray transition, our experiments proved that the molecular orbital transition (“side-feeding”) mechanism is also a significant channel for de-excitation of hollow atoms formed below the surface.     

Sensing of Zn2+ion by N-Furfurylsalicylaldimine Based on CHEF Process†

The recognition ability of N-Furfurylsalicylaldimine (HL) toward various cations (Pb²⁺, Hg²⁺, Ba²⁺, Cd²⁺, Ag⁺, Zn²⁺, Cu²⁺, Ni²⁺, Co²⁺, K⁺, Sr²⁺, and Na⁺) has been studied by UV–Vis and fluorescence spectroscopy. The compound showed highly selective fluorescence signaling behaviour for Zn²⁺ ions in methanol-water medium based on CHEF process and is capable of distinguishing Zn²⁺ from Cd²⁺ ion. From single crystal X-ray analysis it is revealed that a Zn²⁺ ion binds two ligand molecules through imine nitrogen and phenolate oxygen atom.

Mechanism of H2 desorption from monohydride Si(100)2 × 1H

Most recent experimental work on H₂ desorption from the monohydride Si(100) surface seems to point to a pairwise desorption mechanism involving the concerted desorption of two hydrogen atoms on different Si atoms of a single dimer. Using ab initio SCF and CI theory and a cluster model of the surface, the present work finds that the lowest energy pathway is symmetric rather than asymmetric. The desorption energy barrier is calculated to be 3.7 eV. Compared with an experimental value of 2.6 eV, the large barrier suggests that this direct desorption mechanism is not applicable. A multi-step desorption mechanism which involves a delocalized process in the formation of dihydride SiH₂ and a localized desorption of H₂ is proposed and is shown to explain the experimental observations.     

Theoretical and experimental analysis of N2–H2 stimulated Raman spectra

The paper reports on a detailed study of the N₂–H₂ collisional line broadening coefficient. High resolution stimulated Raman spectra of nitrogen–hydrogen mixtures have been recorded at liquid nitrogen and room temperatures. Corresponding linewidth calculations have been performed at temperatures between 77 and 500?K using the semiclassical Robert and Bonamy model for J rotational quantum numbers varying between 0 and 11. Comparison between experimental data and calculated results shows good agreement at room temperature using an adjusted value for the kinetic diameter.