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The main objective of this paper was to assess three leaded brass samples (pending application with Copper Development Association) using optical microscopy and mass spectrometry to compare the distribution of lead. Based on the mass spectrometry data, a great deal of variation was not found within each of the samples based on five different sample locations. Optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that the lead was homogenously distributed in brass.

We investigate the carrier dynamics of thin films of black silicon, amorphous hydrogenated silicon which under laser annealing forms a microstructured surface with extremely high broadband optical absorption. We use Raman spectroscopy to determine the degree of crystallinity of the annealed surfaces, and investigate the dependence on crystallinity and fabrication method of the photoconductivity. Time-resolved THz spectroscopy is used to determine the evolution of the carrier scattering time and confinement of carriers on the picosecond time scale. We conclude that a fabrication method with high energy leading edge of the annealing laser results in black silicon with the largest photon-to-electron conversion efficiency, largest mobility, and longest carrier lifetime.

Black silicon is produced by laser annealing of a-Si:H films. During annealing, silicon microstructures are formed on the surface. We use time-resolved terahertz spectroscopy to study the photoconductivity dynamics in black silicon. We find that when a copper film is deposited on top of the a-Si:H layer prior to laser annealing, the carrier lifetime of black silicon is significantly reduced.

Electron Field Emission (FE) properties of various laser annealed thin silicon films on different substrates were investigated. HWCVD microcrystalline and PECVD amorphous silicon films were irradiated with Nd : YAG and XeCl Excimer lasers at varying energy densities. Encouraging FE results were mainly from XeCl Excimer laser processed PECVD and HWCVD films on metal backplanes. FE measurements were complemented by the study of film surface morphology. Geometric field enhancement factors from surface measurements and Fowler-Nordheim Theory (FNT) were compared. FE properties of the films were also found to be particularly influenced by the backplane material.

Thin films of off-stoichiometric NdBaCuO (NBCO) and Ca-doped NdBaCuO were grown on (10 mm)/sup 2/ strontium titanate substrates by pulsed laser deposition. The statistical methods of Experimental Design and regression analysis were used to correlate the electrical and morphological properties with the growth parameters. The surface morphology of the films was studied using atomic force microscopy and scanning tunnelling microscopy.

This study examines the thermal decomposition of 1,5-cyclooctadiene platinum (II) chloride organometallic films, deposited by thermal evaporation. The thin film samples were annealed both in air and hydrogen with well-controlled temperature regimes. After annealing, the decomposed thin films were examined by AFM and STM scanning probe, XPS and TEM microbeam analytical techniques. The experimental results confirm that the thermal decomposition products on silicon substrates are composed predominantly of metallic platinum. Annealing in hydrogen can reduce substantially the decomposition temperature of the material from around 250 to 160 °C but the surface morphology of the decomposed films is significantly different to those annealed in air. The metallic nature of the thermally decomposed films was confirmed by bonding configuration recognition, electronic property probing and microstructure analysis.

A study of the surface electronic configuration and surface morphology of excimer laser irradiated organo-platinum films [cis-dichlorobis(triphenylphosphine)platinum(II)] is presented. The films were deposited by thermal evaporation to a thickness of approximately 1 µm. The organo-platinum films were irradiated in air with 248 nm UV light in order to produce metallic deposits. The irradiation source used was a krypton fluoride excimer laser with a pulse length of approximately 20 ns. After irradiation, the surface morphology of the films was studied by atomic force microscopy, which yielded information concerning the effect of exposure dose on the surface roughness. The composition of the deposits was investigated using X-ray photoelectron and Fourier-transform infrared spectroscopy. The effect of annealing the deposits has also been studied. XPS analysis of the annealed samples has provided evidence for the formation of platinum silicide (PtSi).

The characteristics of the interface microstructures between a CVD diamond film and the silicon substrate have been studied by transmission electron microscopy and electron energy loss spectroscopy. The investigations are performed on plan-view TEM specimens which were intentionally thinned only from the film surface side allowing the overall microstructural features of the interface to be studied. A prominent interfacial layer with amorphous-like features has been directly observed for CVD diamond films that shows a highly twinned defective diamond surface morphology. Similar interfacial layers have also been observed on films with a growth texture but having the {100} crystal faces randomly oriented on the silicon substrate. These interfacial layers have been unambiguously identified as diamond phase carbon by both electron diffraction and electron energy loss spectroscopy. For the CVD diamond films that exhibit heteroepitaxial growth features, with the {100} crystal faces aligned crystallographically on the silicon substrate, such an interfacial layer was not observed. This is consistent with the expectation that the epitaxial growth of CVD diamond films requires diamond crystals to directly nucleate and grow on the substrate surface or on an epitaxial interface layer that has a small lattice misfit to both the substrate and the thin film material.

Thin films of YBa2Cu3O7−δ and NdBa2Cu3O7−δ were grown by pulsed laser deposition. The statistical methods of experimental design and regression analysis were used to correlate the electrical and morphological properties of the films to the growth conditions. For optimised transition temperatures the deposition parameter settings of target–substrate distance, oxygen pressure and laser energy density were found to differ significantly for YBa2Cu3O7−δ and NdBa2Cu3O7−δ. While the maximum transition temperatures obtained were similar (∼90 K) for the two materials, all NdBa2Cu3O7−δ films had a roughness comparable to the c-axis unit cell dimension whereas the YBa2Cu3O7−δ films had a surface roughness which varied between 5–17 nm depending on the growth conditions. In addition, there were differences in the average size and density of non-stoichiometric outgrowths on the two types of film. These differences we relate to a difference in growth mode. Our atomic force microscope and scanning tunnelling microscope studies suggest a 3D screw dislocation mediated growth for YBa2Cu3O7−δ and a 2D layer-by-layer process for NdBa2Cu3O7−δ.

Artificial biomimetic substrates provide useful models for studying cell adhesion, signaling, and differentiation. This article describes biological interactions with a new type of tunable, micro-nanotextured silicon substrate, generated by irradiation of a hydrogenated amorphous silicon film with a large beam, excimer laser (248 nm). In this study, we demonstrate that BV-2 microglial cells can sense differences in laser processed silicon surface topology over the range of 30 nm to 2 μm, where they undergo marked morphogenic changes with increasing feature size. The cells adopt a more elongated shape in the presence of the modified surface structure and exhibit increased levels of actin-rich microdomains, suggesting enhanced adhesion. The excimer laser modification of hydrogenated amorphous silicon to generate micro-nanostructures realizes large area benefits as well as providing a biomaterial where the external and internal structure can be altered and tuned for various applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 99A: 135–140, 2011.

The ultrafast photoconductivity dynamics of black silicon is measured by time-resolved terahertz spectroscopy. Black silicon is produced by laser annealing of an a-Si:H film. We show that the decay time of the photoconductivity depends on the annealing method and fluence used in the production process.

We present experimental and theoretical work on excimer laser microstructuring of hydrogenated amorphous silicon (a-Si∶H) films on molybdenum coated glass substrates, in the form of sharp and conical poly-Si spikes, for electron field emission applications.

The hydrogenated amorphous silicon (a-Si:H) films on molybdenum coated glass substrates were microstructured by irradiating the films using KrF excimer laser with a slope beam profile. By varying the laser processing parameters i.e., the laser pulse energy, the number of laser pulses and the laser energy distribution along the sample scan directions, the homogeneous, high density, and conical polycrystalline silicon features can be fabricated on the thin film surfaces. The electron field emission measurement results show that this kind of laser processed a- Si:H films possess good field emission characteristics with a low turn on electric field of less than 15 V/�� m and a larger saturation emission current. The diode configured field emission display devices have been demonstrated by using the laser irradiated a- Si:H films as the electron cold cathode emitters.

Most parameters that control the solidification of castings, and consequently, microstructure and mechanical properties, are: chemical composition, liquid metal treatment, cooling rate and temperature gradient. In this work, characterization of the influence of water flow rate, casting speed, alloying element and pull distance on tensile strength, elongation percentage and microstructure of continuous cast copper alloys has been carried out. A significant different in tensile strength, elongation percentage and grain structure has been investigated and it was also found that these parameters could improve the physical and mechanical properties of samples. As a particular example, water flow rate could improve the elongation of samples from 10% to 25%.

The main processing factors that control the solidification of castings, and consequently, microstructure and mechanical properties, are: chemical composition, liquid metal treatment, cooling rate and temperature gradient. In this work, the influence of melt temperature; cleanout cycle, continuous casting direction (horizontal / vertical) and super-cooler size on tensile strength and elongation percentage of continuous cast copper alloys has been characterized by tensile machine and confirmed by microstructure examination. A significant difference on tensile strength and elongation percentage has been observed by changing the processing parameters. By optimizing these parameters, the mechanical properties of continuous copper alloys can be substantially improved. As a particular example, super cooler size could improve the elongation of samples from 38% to 45% or cleanout cycle could improve the tensile strength of samples from 532 MPa to 561 MPa.

Various functions of the cell-to-cell movement protein (MP) of Groundnut rosette virus (GRV) were analysed. The GRV ORF4-encoded protein was shown by immunofluorescence microscopy to generate tubular structures that protrude from the surface of the protoplast. The protein encoded by ORF4 was assessed also for RNA-binding properties. This protein was tagged at its C terminus with six histidine residues, produced in Escherichia coli using an expression vector and purified by affinity chromatography. Gel retardation analysis demonstrated that, in contrast to many other viral MPs, including the 3a MP of Cucumber mosaic virus (CMV), the ORF4-encoded protein bound non-cooperatively to viral ssRNA and formed complexes of low protein:RNA ratios. Competition binding experiments showed that the ORF4-encoded protein bound to both ssRNA and ssDNA without sequence specificity, but did not bind to dsDNA. UV cross-linking and nitrocellulose membrane-retention assays confirmed that both the GRV and the CMV MPs formed complexes with ssRNA and that these complexes showed similar stability in NaCl. Probing the MP–RNA complexes by atomic force microscopy demonstrated that the ORF4-encoded protein bound RNA incompletely, leaving protein-free RNA segments of varying length, while the CMV 3a protein formed highly packed complexes. The significance of the two properties of limited RNA binding and tubule formation of the umbraviral MP is discussed.

The YBa 2 Cu 3 O 7-x (YBCO) superconducting thin films with Tc(R equals 0) of 84 K and Jc of 2 X 10 3 A/cm 2 at 77 K, on polycrystalline Ni-based alloys with buffer layers of Yttria-Stabilized-Zirconia (YSZ), have been prepared in situ by excimer laser. The orientation of laser-deposited YSZ buffer layers on NiCr alloys can be improved by choosing the suitable preparing parameters. The microstructure of YBCO thin films, investigated with a scanning tunneling microscopy, shows that the spiral growth structure may be an important characteristic of the high quality YBCO superconducting thin films.

In-situ laser deposition was used to fabricate YBa2Cu3O7-x superconducting films on YSZ substrates. The surface topography of YBa2Cu3O7-x thin films has been studied with both atomic force microscopy (AFM) and scanning tunneling microscopy (STM). A stepped surface is clearly observed on the mounds with a single step edge the originates from a screw dislocation at the center of the mound and moves out to the edge in a spiral fashion. The experimental result show that the spiral growth structure is an intrinsic character of superconductor films. The existence or absence of the spiral growth structure and the quality of the spiral structures may have significant implications for properties of the high temperature superconducting thin films. The new visual details may lead to improvements of YBCO films.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The optimum conditions required to obtain a stable image and reliable morphological information for YBa2Cu3O7-x (YBCO) high Tc superconducting thin films are summarised. Some typical morphological images of YBCO thin films prepared by the conventional laser ablation technique are presented. By analysing the STM images, three growth modes i.e. spiral growth, layer-by-layer growth and step propagation growth have been identified. Scanning tunneling spectroscopy has been used to study the local area tunneling behaviour for different regions of the YBCO thin films. Distinct and representative I-V curves for spiral growth crystal grains, particulates and non-spiral growth islands have been obtained. Some initial experiments show nanometre scale modification and structure fabrication on the YBCO thin film surface obtained by scanning the tip.

High T c and J c YBa2Cu3O7-x (YBCO) superconducting thin films have been prepared by DC oxygen discharge plasma assisted excimer laser ablation on MgO (100), SrTiO3 (100) and yttria-stabilized ZrO2 (100) substrates. The main improvement obtained with this laser ablation scheme is that laser deposition can be carried out in the oxygen discharge environment. This is achieved by two ring-shaped electrodes which have been placed in the middle between the target and substrate. X-ray diffraction (XRD), atomic force microscopy (AFM) and scanning tunnelling microscopy (STM) techniques have been used to characterise the as-deposited films. A set of narrow (001) peaks in the x-ray diffraction patterns from these films indicate film growth with a preferential c-axis orientation. AFM image observations show that the number of the particulates observed on thin films prepared by this new laser ablation scheme is reduced by comparison with films prepared by the conventional laser ablation method. The majority of growth islands have merged and connected with each other and have formed much larger, denser and smoother flat plateaus. Similar to films fabricated by the conventional laser ablation scheme, STM surface characterisation reveals that the films prepared by oxygen plasma assisted laser ablation are also formed mainly by screw dislocation generated spiral growth.

This paper is aimed at discussing the basic principles of light-induced drift (LID) and estimating the characteristic of the effect, produced by quasi-black-body radiation. Many astrophysical objects as well as laser-produced plasmas may be described by that model in the first approximation. The feasibility is analyzed of converting the radiation of the most efficient cw laser (a technological CO2 laser) via laser-produced plasma into a broad-band radiation to be used as a source of LID of a wide range of substances.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The paper studies the process of photostimulated aggregation of ultradispersoidal silver particles into fractal clusters observed in some colloidal solutions irradiated by different types of pulsed and continuous-wave lasers and by a nonmonochromatic light. A photoaggregaton mechanism has been proposed, based on mutual charging of different-size particles in a conducting medium when the Fermi potentials become equal because of their dimensional dependence.

Surface morphology and tunneling behaviour of the growth spirals and particulates on laser ablated YBa 2 Cu 3 O 7−x (YBCO) thin films have been studied by scanning tunneling microscopy (STM) and spectroscopy (STS). STM image observations confirm that material removal by laser ablation undergoes an explosive process and most of particulates on film surfaces are a direct products of this process. STS studies show that the electronic properties of these particulates differ from that of the surrounding growth spirals.

High Tc superconducting films with zero resistance temperature of 91 K and critical current density about 10 5 A/cm 2 at 77 K have been reproductively fabricated using oxygen discharge plasma-assisted excimer laser ablation method. Scanning electron micrographs and x-ray diffraction patterns of the films showed that these kinds of in situ prepared films had excellent epitaxial quality with its C axis oriented perpendicular to the substrate surface.

High quality particle-free YBa 2 Cu 3 O 7−x superconducting films have been fabricated by laser ablated plasma collision deposition techniques. X-ray diffraction, atomic force microscopy and scanning tunneling microscopy analysis show that both the particle density and the particle size in the prepared c-axis oriented films have been greatly reduced, and the films are dominantly formed by screw dislocation generated spiral growth.

Systematic atomic force and scanning tunneling microscopic studies of the growth mechanisms of YBa 2 Cu 3 O 7−x films prepared by laser ablation have been carried out. In addition to the well known spiral growth features, layer-by-layer growth of crystal grains has been observed on c-oriented films frown mainly on ZrO 2 substrates. The majority of measured single terrace steps in the spiral growth grains correspond to c-axis unit cell. While, most of the layer heights for layer-by-layer growth grains are close to a half or a multiple of the unit cell. The changes of spiral growth pattern with the film thickness have also been studied.