Search results for "PHOTOELECTRON"

Pulsed Direct liquid Injection ALD of TiO2 Films Using Titanium Tetraisopropoxide Precursor

2013

Abstract TiO 2 thin films are grown by pulsed direct liquid injection atomic layer deposition with rapid thermal heating using titanium tetraisopropoxide and water vapor as precursors. The ALD growth rate is constant in the saturation zone range 35-47 ms at the temperature deposition of 280 °C. The TiO 2 growth rate of 0.018 nm/cycle was achieved in a self-limited ALD mode. SEM and AFM analysis showed the as-deposited films have a smooth surface with a low roughness. XPS analysis exhibited the stoichiometry of TiO 2 in the homogenous depth composition.

Graphene and graphene oxide on Ir(111) are transparent to wetting but not to icing

2021

Anti-icing coatings reduce the freezing onset temperature for water by changing the chemical and physical environment at the water-substrate interface to prevent ice nucleation and growth. Graphene oxide has several attributes that make it attractive as an anti-icing coating and it has been theoretically predicted that graphene oxide has a lower freezing onset temperature than pristine graphene. Here, we test this hypothesis using carefully prepared, well-characterized graphene oxide substrates. We compare the water contact angle for graphene and graphene oxide coatings, both prepared on iridium(111) surfaces. The results show both materials to be transparent to wetting, but indicate a lowe…

Symmetry of valence states of Heusler compounds explored by linear dichroism in hard-x-ray photoelectron spectroscopy.

2011

This study reports on the linear dichroism in angular-resolved photoemission from the valence band of the Heusler compounds ${\mathrm{NiTi}}_{0.9}{\mathrm{Sc}}_{0.1}\mathrm{Sn}$ and NiMnSb. High-resolution photoelectron spectroscopy was performed with an excitation energy of $h\ensuremath{\nu}=7.938\text{ }\text{ }\mathrm{keV}$. The linear polarization of the photons was changed using an in-vacuum diamond phase retarder. The valence band spectra exhibit the typical structure expected from first-principles calculations of the electronic structure of these compounds. Noticeable linear dichroism is found in the valence band of both materials, and this allows for a symmetry analysis of the cont…

Role ofp-dands-dinteractions in the electronic structure and band gap of Zn1−xMxO (M=Cr, Mn, Fe, Co, Ni, and Cu): Photoelectron and optical spectrosc…

2012

We report an investigation on the effect of $p$-$d$ and $s$-$d$ interactions in the electronic structure, and especially in the band-gap value, of wurtzite wide-gap diluted magnetic semiconductors Zn${}_{1\ensuremath{-}x}$${M}_{x}$O ($M=\mathrm{Cr}$, Mn, Fe, Co, Ni, Cu). Thin films prepared by pulsed laser deposition are investigated by means of optical absorption at low-temperature and photoelectron spectroscopy. Pure wurzite phase is shown to be maintained for Co and Mn concentrations up to 25$%$ and for Cr up to 10$%$, while in the case of Fe, Ni, and Cu, other phases are present for concentrations higher than 5, 2, and 1$%$, respectively. The band gap of the Zn${}_{1\ensuremath{-}x}$${M…

Influence of Sn Low Doping on the Morphological, Structural and Optical Properties of ZnO Films Deposited by Sol Gel Dip-Coating

2014

In this work, Undoped Zinc Oxide (ZnO) and Sndoped Zinc Oxide (ZnO:Sn) films have been deposited by sol-gel dip coating method, where the Sn/Zn atomic ratio was 3% and 5% in the solution. The effects of Sn incorporation on morphological, structural and optical properties of ZnO films were investigated. The Scanning Electron Microscopy (SEM) showed that the morphological surface of the films was affected by Sn low doping. The X-Ray Diffraction (XRD) patterns showed that all films have polycrystalline structures, and the doping incorporation has not lead to substantial changes in the structural characteristics of ZnO films. The crystallite size was calculated using the well-known Scherrer’s f…

Influence of the chemical dissolution of MnS inclusions on the composition of passive films and the local electrochemical behaviour of stainless stee…

2006

Abstract Immersion of stainless steel containing MnS inclusions in aqueous electrolytes leads to the chemical dissolution of these heterogeneities. Chemical dissolution of MnS inclusions in 1M NaCl, pH=3 was studied using in-situ AFM and the dissolution rate of MnS was estimated between 0.04 and 0.19 μm 3 /min. The local electrochemical measurements reveal that the chemical dissolution of MnS inclusions promotes pitting corrosion. Similary, chemical dissolution of MnS inclusions in IM NaClO 4 , pH=3 solution modified the surface close to the inclusions by the presence of FeSO 4 in the passive film.

2014

Hard x-ray photoelectron spectroscopy (HAXPES) is used to investigate the intrinsic electronic properties of single crystal epitaxial CdO(100) thin films grown by metal organic vapor phase epitaxy (MOVPE). The reduced surface sensitivity of the HAXPES technique relaxes stringent surface preparation requirements, thereby allowing the measurement of as-grown samples with intrinsically higher carrier concentration (n=2.4×1020cm−3). High-resolution HAXPES spectra of the valence band and core levels measured at photon energy of 6054 eV are presented. The effects of conduction band filling and band gap renormalization are discussed to explain the observed binding energy shifts. The measured bandw…

ELECTRODEPOSITION OF NOVEL POLY(NAPHTHALENEDIIMIDE-QUATERTHIOPHENE) THIN FILMS AND APPLICATIONS IN PLASTIC OPTOELECTRONICS DEVICES

2013

A novel symmetric naphthalenediimide-quaterthiophene derivative (NDIT4d) has been polymerized on different substrates including glassy carbon and ITO/PET electrodes by means of electrochemical methods. XPS and UV-VIS spectroscopy as well as cyclic voltammetry have been employed for characterizing the thin film chemical features, the band gap and the HOMO and LUMO levels. DFT computational studies were in close agreement with the experimental observables also showing intriguing geometrical effects on the band gap energy values. The comparison of the energy levels locations of the electrodeposited poly(naphthalenediimide-quaterthiophene) derivative (e-PNDIT4) and P3HT thin films transferred b…

Physical chemistry of the powder metallurgy of beryllium: Chemical characterization of the powder in relation to its granularity

1996

Combining the systematic quantitative chemical analysis of the light impurities H, C, N, and O, the quantitative thermal desorption of molecular H2O and H2, and X ray diffractometry of various size fractions of a commercial Be powder (SP-65 grade from Brush-Wellman) allowed the precise de-termination of the mean composition and equivalent mean thickness of the surface impurity phases in the passivation-contamination layer on the surface of the particles. The overall surface stoichi-ometry is as follows: 0.2 BeOcrystallized, 0.8 [BeO - 0.59 H2O]amorphous, 0.14 H2Oads The result of the elemental analysis by X-ray photoelectron spectroscopy of the unetched surface of a powder pellet is compare…

XPS and SIMS study of aluminium native oxide modifications induced by Q-switched Nd:YAG laser treatment

2006

Publié suite au congrès ECASIA: 11th European Conference on Applications of Surface and Interface Analysis, 25-30 September 2005, Vienna, Austria; International audience; During laser cleaning of aluminium in ambient atmosphere, modifications of the metal surface can be induced by transient thermal effects. This work aims to characterize the modification of the aluminium oxide layer on pure aluminium for a wide range of power per area using a Q-switched Nd :YAG (1064 nm) laser with two pulse durations, 10 and 180 ns. Experiments were carried out with single laser shots in ambient air at fluences (e.g. energy per area) below the ablation regime. For 10-ns pulses with fluences between 0.7 and…