Quartz Substrates (quartz + substrate)

Distribution by Scientific Domains


Selected Abstracts


Hypolithic community shifts occur as a result of liquid water availability along environmental gradients in China's hot and cold hyperarid deserts

ENVIRONMENTAL MICROBIOLOGY, Issue 2 2007
Stephen B. Pointing
Summary Hypolithic cyanobacterial communities occur in hot and cold hyperarid environments but the physical factors determining their diversity are not well understood. Here we report hypolithic diversity and colonization of a common quartz substrate at several hyperarid locations in the ancient deserts of north-western China, that experience varying mean annual temperature, rainfall and concomitant availability of liquid water in soil. Microscopy and enrichment culture resulted only in Chroococcidiopsis morphotypes which were ubiquitous, but community phylogenetic analysis revealed considerable cyanobacterial and heterotrophic bacterial diversity. Species Richness and Shannon's Diversity Index displayed a significant positive linear correlation with availability of liquid water but not temperature or rainfall alone. Several taxonomic groups occurred only in specific climatically defined locations, while for Chroococcidiopsis, Deinococcus and Phormidium location specific lineages within these genera were also evident. Multivariate analysis was used to illustrate pronounced community shifts due to liquid water availability, although these did not significantly affect the predicted functional relationships within any given assemblage in either hot or cold, wet or dry hyperarid deserts. This study clearly demonstrates that availability of liquid water, rather than temperature or rainfall per se is the key determinant of hypolithic diversity in hyperarid locations, and furthermore that functionally similar yet taxonomically distinct communities occur, characterized by the presence of taxa that are specific to defined levels of aridity. [source]


Tris(8-hydroxyquinoline-5-sulfonate)aluminum Intercalated Mg,Al Layered Double Hydroxide with Blue Luminescence by Hydrothermal Synthesis

ADVANCED FUNCTIONAL MATERIALS, Issue 17 2010
Shuangde Li
Abstract Blue luminescent hybrid materials (DDS,AQS(x%)/LDH) are successfully prepared by co-intercalating tris(8-hydroxyquinoline-5-sulfonate)aluminum anions (AQS3,) and dodecyl sulfonate (DDS,) with different molar ratios into Mg,Al layered double hydroxides (LDHs) by the hydrothermal and solution co-precipitation methods. A film of the material on a quartz substrate is obtained by the solvent evaporation method. The results show the blue luminescence is remarkably different from the pristine Na3AQS, which has cyan luminescence (ca. 450,470 nm vs. 495 nm). Furthermore, the hydrothermal product of DDS,AQS(66.67%)/LDH exhibits optimal luminous intensity and a significantly enhanced fluorescence lifetime. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy indicate that the cyan,blue luminescence transition is due to the isomerization of meridianal to facial AQS via ligand flip caused by a host,guest electrostatic interaction, in combination with the dispersion and pre-intercalation effect of DDS. The hydrothermal conditions can promote a more ordered alignment of the intercalated fac -AQS compared with alignment in the solution state, and the rigid LDHs environment can confine the internal mobility of AQS to keep the facial configuration stable. This stability allows a facile preparation of large amounts of blue luminous powder/film, which is a new type of inorganic,organic hybrid photofunctional material. [source]


Crinkling Ultralong Nanotubes: Crinkling Ultralong Carbon Nanotubes into Serpentines by a Controlled Landing Process (Adv. Mater.

ADVANCED MATERIALS, Issue 41 2009
41/2009)
A rational approach to crinkling ultralong CNTs into serpentine geometries by controlling their landing on a quartz substrate is demonstrated by Jin Zhang and co-workers on p. 4158. Using this method, the length, density, and number of parallel CNT segments in the serpentine CNTs were significantly increased. When incorporated into ultrahigh-current devices, the performance of the devices could be improved by increasing the number of parallel segments in the serpentine CNT arrays. [source]


A simple K-band waveguide-to-microstrip probe transition

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 7 2007
Alessandro Navarrini
Abstract We describe the design, construction, and test of a simple K-band waveguide-to-microstrip transition based on a radial-shaped probe patterned on a quartz substrate. From 16 to 28 GHz, the measured reflection coefficient at the coaxial SMA input, used for test purposes of the adapter, was less than ,14 dB, and the dissipative loss was ,0.30 dB. The estimated loss of the waveguide to microstrip transition only, with coaxial connector effects removed, is ,0.08 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1597,1600, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22558 [source]


Boron nitride phosphide thin films grown on quartz substrate by hot-filament and plasma-assisted chemical vapor deposition

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 13 2004
X. W. Zhang
Abstract Boron nitride phosphide films are, for the first time, grown on transparent quartz substrate by hot filament and radio-frequency plasma co-assisted chemical vapor deposition technique. XPS, XRD, SEM, and UV measurements are performed to study the chemical composition, crystallization, microstructure, and optical absorption, respectively. A "centipede-like" microstructure and undulating ground morphology on the film surface are observed, and their growth mechanism is speculated upon. The chemical composition is determined as BN1,xPx, whose characteristic XRD peak is preliminarily identified. The optical band gap can be modulated between 5.52 eV and 3.74 eV, simply by adjusting the phosphorus content in BN1,xPx through modifying the PH3 flux during the film-deposition process. The merits of the BN1,xPx film, such as high ultraviolet photoelectric sensitivity with negligible sensitivity in the visible region, modifiable wide optical band gap, and good adhesion on transparent substrate, suggest potential applications for ultraviolet photo-electronics. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Refractive index-modulated grating in two-mode planar polymeric waveguide produced by two-photon polymerization

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 7 2007
Yi Dong
Abstract A polymeric waveguide film was manufactured by spinning the materials on quartz substrate. Two-photon-initiated photopolymerization was carried out by tight-focusing femtosecond laser pulses in the two-mode planar waveguide. A typical index-modulated grating of 2.5,×,2,mm areas without morphology was fabricated. The results show that peak-to-peak modulation depth of the surface profile of grating region was only about 7,nm. The diffraction efficiency (DE) of the grating with a spacing period 2,µm was 0.17% and the corresponding index modulation reached 5.7,×,10,3. Copyright © 2007 John Wiley & Sons, Ltd. [source]


Directional Surface Plasmon-Coupled Emission from a 3 nm Green Fluorescent Protein Monolayer

BIOTECHNOLOGY PROGRESS, Issue 6 2005
Yordan Kostov
High-sensitivity detection schemes are of great interest for a number of applications. Unfortunately, such schemes are usually high-cost. We demonstrate a low-cost approach to a high-sensitivity detection scheme based on surface plasmon-coupled emission (SPCE). The SPCE of a monomolecular layer of green fluorescent protein (GFP) is reported here. The protein was electrostatically attached to a thin, SiO2 -protected silver film deposited on a quartz substrate. The visible, directional emission of GFP was observed at a sharp, well-defined angle of 47.5° from the normal to the coupling prism, and the spectrum corresponded to that of GFP. The SPCE resulting from the reverse Kretschmann configuration showed a 12-fold enhancement over the free space fluorescence. The directional emission was 97% p-polarized. The directionality and high polarization can be coupled with the intrinsic spectral resolution of SPCE to be used in the design miniaturized spectrofluorometers. The observation of SPCE in the visible region of the spectrum from a monolayer of protein opens up new possibilities in protein-based sensing. [source]


Optical investigations on the existence of phase transition in ZnO:Li thin films prepared by DC sputtering method

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 3 2008
A. Abu EL-Fadl
Abstract We investigated the effect of temperature on the absorption spectra of Zn0.8Li0.2O thin films (ZnO:Li), deposited at 573 K, in the wavelength range 190-800 nm. The films were deposited on sapphire, MgO or quartz substrates by DC sputtering method. The results show a shift of the optical energy gap (Eg), with direct allowed transition type near the fundamental edge, to lower wavelengths as the temperature increases. The temperature rate of Eg changes considerably showing an anomaly around 320 K depending on type of substrate. The founded results indicated that replacement of Zn ions with Li ions induces a ferroelectric phase in the ZnO wurtzite-type semiconductor. The exponential dependence of the absorption coefficient on the incident photon energy suggests the validity of the Urbach rule. (© 2007 WILEY -VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Fabrication and Characterization of DNA/QPVP-Os Redox-Active Multilayer Film

ELECTROANALYSIS, Issue 23 2004
Jianyun Liu
Abstract Calf thymus DNA was immobilized on functionalized glassy carbon, gold and quartz substrates, respectively, by the layer-by-layer (LBL) assembly method with a polycation QPVP-Os, a quaternized poly(4-vinylpyridine) partially complexed with osmium bis(2,2,-bipyridine) as counterions. UV-visible absorption and surface plasmon resonance spectroscopy (SPR) showed that the resulting film was uniform with the average thickness 3.4,nm for one bilayer. Cyclic voltammetry (CV) showed that the total surface coverage of the polycations increases as each QPVP-Os/DNA bilayer added to the electrode surface, but the surface formal potential of Os-centered redox reaction shifts negatively, which is mainly attributed to the intercalation of redox-active complex to DNA chain. The electron transfer kinetics of electroactive QPVP-Os in the multilayer film was investigated by electrochemical impedance experiment for the first time. The permeability of Fe(CN) in the solution into the multilayer film depends on the number of bilayers in the film. It is worth noting that when the multilayer film is up to 4 bilayers, the CV curves of the multilayer films display the typical characteristic of a microelectrode array. The nanoporous structure of the multilayer film was further confirmed by the surface morphology analysis using atomic force microscopy (AFM). [source]


Self-Assembly of m -Diethynylbenzene Macrocycles Containing Exoannular Chiral Side Chains,

ADVANCED FUNCTIONAL MATERIALS, Issue 12 2006
Y. Tobe
Abstract Induced circular dichroism (CD) spectra of the m -diethynylbenzene macrocycles (S)- 2 and (R)- 2 that have exoannular chiral side chains are observed in a methanol/chloroform (8:2) solution, indicating the formation of chiral, helical aggregates in solution. Solid films prepared on the surface of quartz substrates by spin-coating solutions of (S)- 2 also exhibit CD signals that are remarkably dependent on the solvent used for the spin-coating. The relationship between the CD spectra and the morphology of the solid films observed by atomic force microscopy is discussed. [source]


Structural characterization of undoped and Sb-doped SnO2 thin films fired at different temperatures

JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003
Alessandro P. Rizzato
SnO2 thin films were obtained by the sol-gel method starting from inorganic precursor solutions. In this work, we compare the structure of undoped and Sb-doped SnO2 films prepared by dip-coating. The films were deposited on quartz substrates and then fired at different temperatures ranging from 383 up to 1173 K. The density and the thickness of the films were determined by X-ray reflectivity (XRR) and their porous nanostructure was characterized by grazing-incidence small angle X-ray scattering (GISAXS). XRR results corresponding to undoped and Sb-doped samples indicate a monotonous decrease in film thickness when they are fired at increasing temperatures. At same time, the apparent density of undoped samples exhibits a progressive increase while for Sb-doped films it remains invariant up to 973 K and then increases for T = 1173 K. Anisotropic GISAXS patterns of both films, Sb-doped and undoped, fired above 573 K indicate the presence of elongated pores with their major axis perpendicular to the film surface. For all firing temperatures the nanopores in doped samples are larger than in undoped ones. This suggests that Sb-doping favours the pore growth hindering the film densification. At the highest firing temperature (1173 K) this effect is reversed. [source]


Wettability of Silica Substrates by Silver,Copper Based Brazing Alloys inVacuo

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2000
Jorge López-Cuevas
The sessile drop method has been used to determine the time dependence of the contact angle at 850°C in vacuo for Ag,28 wt% Cu, Ag,35 wt% Cu,1.5 wt% Ti, and Ag,27 wt% Cu,12 wt% In,2 wt% Ti on vitreous and devitrified fused quartz substrates. Nonwetting behavior (, > 90°) was observed for Ag,28 wt% Cu on both substrates with no evident effect of time at temperature. The silica substrate structure, whether crystalline or amorphous, as well as its surface condition, whether smooth or rough, made no significant difference. In contrast, with Ag,35 wt% Cu,1.5 wt% Ti and Ag,27 wt% Cu,12 wt% In,2 wt% Ti the contact angle continuously decreased with time for both silica substrates, and the structure and surface condition of the substrates had a negligible effect in the case of Ag,27 wt% Cu,12 wt% In,2 wt% Ti, which produced essentially the same contact angles on both silica substrates at a given time of hold at 850°C. The contact angles produced by Ag,35 wt% Cu,1.5 wt% Ti on devitrified fused quartz were consistently higher than those produced on the vitreous substrates, with increasing holding time at 850°C. This is attributable to the presence of extensive cracks in the ,-cristobalite layer at the surface of the devitrified substrates, which obstruct wetting and spreading. These results, when correlated with the wettability of preoxidized silicon carbide by the same alloys reported in previous work, could account for the adverse effect on wetting of the high-temperature silica films formed on the surface of the SiC in that work. [source]


Dielectric modeling of transmittance and ellipsometric spectra of thin In2O3:Sn films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2010
Zhaohui Qiao
Abstract Thin ITO films with thickness between 0.05 and 0.4,µm were deposited on quartz substrates by direct-current magnetron-sputtering. The films' ellipsometric and transmittance spectra between 280 and 2500,nm were simulated simultaneously with a computer program based on dielectric modeling. The dielectric function used is the sum of three types of electronic excitations: intraband transitions of free electrons (extended Drude model), band gap transitions, and interband transitions into the upper half of the conduction band. A successful fit of the simulated to the experimental curves was obtained with a two-layer model (bulk and surface layers) and applying the Bruggeman effective-medium approach. From the simulation, film thickness, refractive index, band gap, and free carrier density can be obtained. The thickness of the surface layer is comparable with the surface roughness determined by AFM measurements. [source]


Optical and magnetic properties of c -oriented ZnCoO films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006
Huijuan Zhou
Abstract We investigated ZnCoO thin films prepared via sol-gel methods and dip-coating techniques. The Co concentrations range from 0.5% to 5%. The films show the wurtzite crystal structure of ZnO and are highly c -axis oriented grown on the quartz substrates. They have a typical grain size of 20 to 50 nm and a thickness between 300 nm and 1 µm. The fine structures of the Co (3d7) internal absorptions are well resolved, all zero-phonon lines (ZPL) and phonon replica related to the 4T1(F) , 4A2 are observed, demonstrating the good crystalline quality of the layers and the incorporation of the Co2+ on Zn2+ lattice sites. The films show paramagnetic behaviour. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Thin film formation by rf sputtering with EuGa2S4 target and photoluminescence of the prepared films

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 8 2006
M. Dohi
Abstract Thin films were deposited on Si and fused quartz substrates by rf sputtering with EuGa2S4 target. The deposited films were annealed in the mixed atmosphere of S and He, which led crystallization of the film from amorphous phase. Photoluminescence of the annealed films, characteristic to the Eu2+ ion, was observed with room temperature quantum efficiency of 17%. Decay time constants at room temperature and liquid nitrogen temperature were measured to be 140 ns, and 430 ns, respectively. The latter value is close to the reported radiative lifetime of the EuGa2S4 crystal. Construction possibility of a surface-emitting laser is discussed with data on behaviour of excitation intensity dependent time-resolved spectra under pulsed laser excitation and on surface roughness of the film. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


Optical and Structural Analysis of GaN Grown by Remote Plasma Enhanced Laser Induced Chemical Vapour Deposition

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2003
Afifuddin
Abstract High quality polycrystalline gallium nitride (GaN) films have been grown by remote plasma enhanced laser induced chemical vapour deposition (RPE-LICVD) on sapphire, silicon, and quartz substrates at temperatures below 600 °C. Transmission spectra of the films indicate excellent properties with band gap 3.38 ± 0.02 eV. A yellow band-to-band transition at 2.2 eV is observed. X-ray diffraction patterns reveal the (0002) wurtzite reflection at 2, = 34.6° is dominant. Raman spectra of the films are discussed with respect to the phonon frequencies and strain-related phenomena. Compositional analysis with heavy ion Elastic Recoil Detection shows stoichiometric nitrogen to gallium ratios and relatively small amounts of incorporated oxygen. [source]


Measuring Tg in ultra-thin polymer films with an excimer fluorescence technique

POLYMER ENGINEERING & SCIENCE, Issue 9 2001
C. C. White
An excimer fluorescence technique has been applied to the measurement of Tg of ultra-thin polystyrene films. This technique utilizes an excimer-forming molecule with fluorescent emission in two wavelength bands. The intensity ratio of these bands is a sensitive measure of local viscosity. This technique has been applied to five polystyrene films in the thickness range of 25 nm to 200 nm supported on quartz substrates. The observed Tg for the five ultra-thin polymer films was similar to the bulk Tg with no observed dependence upon thickness. Additionally, the Tg determined for each film did not show any dependence upon thermal history. [source]


Growth of Hafnium Dioxide Thin Films by MOCVD Using a New Series of Cyclopentadienyl Hafnium Compounds,

CHEMICAL VAPOR DEPOSITION, Issue 11 2007
G. Carta
Abstract Thin films of HfO2 are grown by metal-organic (MO)CVD on Si(001) and fused quartz substrates in the temperature range 400,500,°C, using a new series of bis-cyclopentadienyl bis-amino-alkoxide hafnium precursors, namely [(C5H5)2Hf{OC(CH3)2CH2N(CH3)2}2] and [(C5H5)2Hf{OCH(CH3)CH2N(CH3)2}2], stable in air because of their strong coordination to the metal center. The films obtained are investigated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Rutherford backscattering spectroscopy (RBS), and atomic force microscopy (AFM). Monoclinic phase HfO2 (baddeleyite) films, characterized by a correct stoichiometric ratio and a granular surface morphology with a roughness/thickness ratio that decreases with increasing deposition rate, are obtained. [source]


Effects of Processing Parameters in the MOCVD Growth of Nanostructured Lanthanum Trifluoride and Oxyfluoride Thin Films,

CHEMICAL VAPOR DEPOSITION, Issue 12 2006
G. Malandrino
Abstract Using metal,organic (MO)CVD, lanthanum trifluoride (LaF3) and oxyfluoride (LaOF) films are deposited on Si(100), glass, and quartz from a La(hfa)3diglyme single-source precursor. The films are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). They are found to be crystalline with a high degree of fiber texture even when deposited on glass or quartz substrates. The SEM indicates very homogeneous surfaces with grain dimensions decreasing upon increasing the deposition temperature and the oxygen flow. The AFM data indicate a very smooth surface with a root mean square (rms) roughness of 0.96,nm for films deposited at high temperature/high oxygen flow. [source]


Cell Adhesion onto Highly Curved Surfaces: One-Step Immobilization of Human Erythrocyte Membranes on Silica Beads

CHEMPHYSCHEM, Issue 7 2003
Stefan Kaufmann
Abstract This paper deals with single-step, orientation-selective immobilization of human erythrocyte membranes on bare silica beads with different topographies: 1) solid (nonporous) silica beads with a diameter of 3 ,m and 2) porous silica beads with a diameter of 5 ,m. Erythrocyte membranes were immobilized onto beads simply by incubation, without sonication or osmotic lysis. Membrane orientation before and after immobilization was identified with two immunofluorescence labels: 1) the extracellular part of glycophorin can be labeled with a first monoclonal antibody and a second polyclonal antibody with fluorescence dyes (outside label), while 2) the cytoplasmic domain of Band 3 can be recognized with a first monoclonal antibody and a second fluorescent polyclonal antibody (inside label). Adherent erythrocytes on the beads all ruptured, inverted the asymmetric orientation of the membrane, and selectively exposed their cytoplasmic domain. The surface topography did not influence the orientation or the amount of immobilized membrane. On the other hand, the fact that no adsorption or rupture of erythrocytes could be observed on planar quartz substrates suggests a significant influence of contact curvature on adhesion energy. [source]