Search results for "Deposit"
showing 10 items of 1447 documents
A Scanning Electron Microscope for Ultracold Atoms
2006
We propose a new technique for the detection of single atoms in ultracold quantum gases. The technique is based on scanning electron microscopy and employs the electron impact ionization of trapped atoms with a focussed electron probe. Subsequent detection of the resulting ions allows for the reconstruction of the atoms position. This technique is expected to achieve a much better spatial resolution compared to any optical detection method. In combination with the sensitivity to single atoms, it makes new in situ measurements of atomic correlations possible. The detection principle is also well suited for the addressing of individual sites in optical lattices.
Epitaxy of thin films of the Heusler compound
2007
Abstract Epitaxial thin films of the highly spin polarized Heusler compound Co 2 Cr 0.6 Fe 0.4 Al are deposited by DC magnetron sputtering. It is shown by XRD and TEM investigations how the use of an Fe buffer layer on MgO(1 0 0) substrates supports the growth of highly ordered Co 2 Cr 0.6 Fe 0.4 Al at low deposition temperatures. The as-grown samples show a relatively large ordered magnetic moment of μ ≃ 3.0 μ B / f . u . providing evidence for a low level of disorder.
Reactivity of Nickel(II) Porphyrins in oCVD Processes—Polymerisation, Intramolecular Cyclisation and Chlorination
2019
Abstract Oxidative chemical vapour deposition of (5,15‐diphenylporphyrinato)nickel(II) (NiDPP) with iron(III) chloride as oxidant yielded a conjugated poly(metalloporphyrin) as a highly coloured thin film, which is potentially useful for optoelectronic applications. This study clarified the reactive sites of the porphyrin monomer NiDPP by HRMS, UV/Vis/NIR spectroscopy, cyclic voltammetry and EPR spectroscopy in combination with quantum chemical calculations. Unsubstituted meso positions are essential for successful polymerisation, as demonstrated by varying the porphyrin meso substituent pattern from di‐ to tri‐ and tetraphenyl substitution. DFT calculations support the proposed radical oxi…
Model emulation to understand the joint effects of ice-nucleating particles and secondary ice production on deep convective anvil cirrus
2021
Abstract. Ice crystal formation in the mixed-phase region of deep convective clouds can affect the properties of climatically important convectively generated anvil clouds. Small ice crystals in the mixed-phase cloud region can be formed by heterogeneous ice nucleation by ice-nucleating particles (INP) and secondary ice production (SIP) by, for example, the Hallett-Mossop process. We quantify the effects of INP number concentration, the temperature dependence of the INP number concentration at mixedphase temperatures, and the Hallett-Mossop splinter production efficiency on the anvil of an idealised deep convective cloud using a Latin hypercube sampling method, which allows optimal coverage…
Peculiarities of imaging one- and two-dimensional structures in an emission electron microscope. 1. theory
2000
Local changes in work function cause deviations of the electrical microfield near a sample surface as a result of the uniform accelerating field distribution between the sample (cathode) and the extractor electrode (anode). This results in a change in the electron trajectories. As a consequence, the microscope image shows remarkable changes in position, size, intensity and lateral resolution of distinct details, which can be quantitatively described by the calculations presented here. Analysing these effects in the image gives an opportunity to determine the real lateral size of the observed structures and the distribution of local contact potentials.
Dopant Contrast in Semiconductors as Interpretation Challenge at Imaging by Electrons
2007
Mechanisms responsible for the contrast between differently doped areas in semiconductors, which is observed in electron micrographs, is discussed as regards the key factors determining the sign and magnitude of the contrast. Experimental data obtained by means of the scanning electron microscope (SEM), scanning low energy electron microscope and photoelectron emission microscope are reviewed together with hints following from them for compilation of a model of the contrast mechanism.
Influence Of The Electrical Parameters On The Fabrication Of Copper Nanowires Into Anodic Alumina Templates
2009
Abstract Metallic copper nanowires have been grown into the pores of alumina membranes by electrodeposition from an aqueous solution containing CuSO 4 . and H 3 BO 3 at pH 3. In order to study the influence of the electrical parameters on growth and structure of nanowires, different deposition potentials (both in the region where hydrogen evolution reaction is allowed or not) and voltage perturbation modes (constant potential or unipolar pulsed depositions) were applied. In all cases, pure polycrystalline Cu nanowires were fabricated into template pores, having lengths increasing with the total deposition time. These nanowires were self-standing, because they retain their vertical orientati…
Sintering of copper nanopowders under hydrogen: an in situ X-ray diffraction analysis.
2003
Abstract The reduction by hydrogen gas of the cuprite layer on copper nanocrystals and the subsequent sintering of the nano-particles were studied using in-situ X-ray diffraction and dilatometry. Spherical nanocrystals produced by evaporation and condensation have an average size of 35 nm, exhibiting a large surface curvature. Each nanoparticle is coated with a 3.5 nm layer of Cu 2 O, which is rough and disordered, as revealed by high-resolution electron microscopy. Reduction by hydrogen of this curved cuprite layer occurs at 363 K, which is ≈65 K lower than is observed on a layer supported by micrometer-sized or bulk copper with a flat surface. The reduction process and its effect on the s…
Nickel-Indium Sulphide Core-Shell Nonostructures Obtained by Spray-ILGAR Deposition
2013
Ni nanowires (NWs) of different lengths were fabricated by pulsed potentiostatic deposition within pores of polycarbonate membranes. After template dissolution, substrates underwent sequential Spray-ILGAR® depositions of thin indium sulphide films. The effect of deposition temperature was also investigated. For low number of deposition cycles, results showed complete and uniform covering of metal over the entire length of NWs, with formation of Ni - In2S3 core-shell structures. However, with increasing number of deposition cycles films became uneven and crusty, especially at higher temperatures, owing to the simultaneous formation of nickel sulfide. This drawback was almost eliminated doubl…
Co-deposition and characterization of hydroxyapatite-chitosan and hydroxyapatite-polyvinylacetate coatings on 304 SS for biomedical devices
2019
During the last decades, biomaterials have been deeply studied to fabricate and improve coatings for biomedical devices. Metallic materials, especially in the orthopedic field, represent the most common materials used for different type of devices thanks to their good mechanical properties. Nevertheless, low/medium resistance to corrosion and low osteointegration ability characterizes these materials. To overcome these problems, the use of biocoatings on metals substrate is largely diffused. In fact, biocoatings have a key role to confer biocompatibility features, to inhibit corrosion and thus improve the lifetime of implanted devices. In this work, the attention was focused on Hydroxyapati…