A high-current racetrack induction accelerator

International Nuclear Information System (INIS)

Mondelli, A.; Roberson, C.W.

1983-01-01

In this paper, the energy and system scaling laws of the Racetrack Induction Accelerator are determined and its operating principles are discussed. This device is a cyclic accelerator that is capable of multi-kiloamp operation. Long pulse induction linac technology is used to obtain short acceleration times. The accelerator consists of a long-pulse linear induction module and a racetrack beam transport system. For detailed studies of the particle dynamics in a racetrack, a numerical model is required to integrate the fully-relativistic single-particle equations of motion in an externally applied magnetic field. The numerical model is a compromise between the need for a large rotational transform and the need for a reasonable volume within the separatrix

Spinel Li{sub 2}CoTi{sub 3}O{sub 8} nanometer obtained for application as pigment; Espinela Li{sub 2}CoTi{sub 3}O{sub 8} nanometrica obtenida para aplicacion como pigmento

Energy Technology Data Exchange (ETDEWEB)

Costa de Camara, M. S.; Alves Pimentel, L.; Longo, E.; Nobrega Azevedo, L. da; Araujo Melo, D. M. de

2016-05-01

Pigments are used in ceramics, cosmetics, inks, and other applications widely materials. To this must be single and easily reproducible. Moreover, the pigments obtained in the nanoscale are more stable, reproducible and highlight color in small amounts compared with those obtained in micrometer scale. The mixed oxides with spinel structures AB{sub 2}O{sub 4} have important applications, including: pigments, refractories, catalytic and electronic ceramics. In this context, the aim of this work was the preparation of powder Li{sub 2}CoTi{sub 3}O{sub 8} spinel phase with nanometer particle size of the polymeric precursor method (Pechini) and characterization by means of thermal analysis (TG/DTA) X-ray diffraction (XRD), refined by the Rietveld method, BET, transmission electron microscopy (TEM), Raman and colorimetric coordinates. The pigment was obtained by heat treatment of 400 degree centigrade to 1000 degree centigrade after pyrolysis at 300 degree centigrade/1 h for removing the organic material. Li{sub 2}CoTi{sub 3}O{sub 8} desired spinel phase was obtained from 500 degree centigrade, and presenting stability nanometer to about 1.300 degree centigrade. Spinel green phase introduced at temperatures in the range of 400 degree centigrade and 500 degree centigrade, and 600 degree centigrade at temperatures between blue and 1000 degree centigrade. (Author)

Optoelectronic circuits in nanometer CMOS technology

CERN Document Server

Atef, Mohamed

2016-01-01

This book describes the newest implementations of integrated photodiodes fabricated in nanometer standard CMOS technologies. It also includes the required fundamentals, the state-of-the-art, and the design of high-performance laser drivers, transimpedance amplifiers, equalizers, and limiting amplifiers fabricated in nanometer CMOS technologies. This book shows the newest results for the performance of integrated optical receivers, laser drivers, modulator drivers and optical sensors in nanometer standard CMOS technologies. Nanometer CMOS technologies rapidly advanced, enabling the implementation of integrated optical receivers for high data rates of several Giga-bits per second and of high-pixel count optical imagers and sensors. In particular, low cost silicon CMOS optoelectronic integrated circuits became very attractive because they can be extensively applied to short-distance optical communications, such as local area network, chip-to-chip and board-to-board interconnects as well as to imaging and medical...

Sub-nanometer periodic nonlinearity error in absolute distance interferometers

Science.gov (United States)

Yang, Hongxing; Huang, Kaiqi; Hu, Pengcheng; Zhu, Pengfei; Tan, Jiubin; Fan, Zhigang

2015-05-01

Periodic nonlinearity which can result in error in nanometer scale has become a main problem limiting the absolute distance measurement accuracy. In order to eliminate this error, a new integrated interferometer with non-polarizing beam splitter is developed. This leads to disappearing of the frequency and/or polarization mixing. Furthermore, a strict requirement on the laser source polarization is highly reduced. By combining retro-reflector and angel prism, reference and measuring beams can be spatially separated, and therefore, their optical paths are not overlapped. So, the main cause of the periodic nonlinearity error, i.e., the frequency and/or polarization mixing and leakage of beam, is eliminated. Experimental results indicate that the periodic phase error is kept within 0.0018°.

Development of near-field laser ablation inductively coupled plasma mass spectrometry for sub-micrometric analysis of solid samples

International Nuclear Information System (INIS)

Jabbour, Chirelle

2016-01-01

A near field laser ablation method was developed for chemical analysis of solid samples at sub-micrometric scale. This analytical technique combines a nanosecond laser Nd:YAG, an atomic Force Microscope (AFM), and an inductively coupled plasma mass spectrometer (ICPMS). In order to improve the spatial resolution of the laser ablation process, the near-field enhancement effect was applied by illuminating, by the laser beam, the apex of the AFM conductive sharp tip maintained at a few nanometers (5 to 30 nm) above the sample surface. The interaction between the illuminated tip and the sample surface enhances locally the incident laser energy and leads to the ablation process. By applying this technique to conducting gold and tantalum samples, and semiconducting silicon sample, a lateral resolution of 100 nm and depths of a few nanometers were demonstrated. Two home-made numerical codes have enabled the study of two phenomena occurring around the tip: the enhancement of the laser electrical field by tip effect, and the induced laser heating at the sample surface. The influence of the main operating parameters on these two phenomena, amplification and heating, was studied. an experimental multi-parametric study was carried out in order to understand the effect of different experimental parameters (laser fluence, laser wavelength, number of laser pulses, tip-to-sample distance, sample and tip nature) on the near-field laser ablation efficiency, crater dimensions and amount of ablated material. (author) [fr

Sub-nanometer-resolution imaging of peptide nanotubes in water using frequency modulation atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Sugihara, Tomoki; Hayashi, Itsuho; Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Kimura, Kenjiro, E-mail: kimura@gold.kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan); Tamura, Atsuo [Department of Chemistry, Graduate School of Science, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501 (Japan)

2013-06-20

Highlights: ► Peptide nanotubes were aligned on highly oriented pyrolytic graphite surface. ► We visualized sub-nanometer-scale structure on peptide nanotube surface in water. ► We observed hydration structure at a peptide nanotube/water interface. - Abstract: Peptide nanotubes are self-assembled fibrous materials composed of cyclic polypeptides. Recently, various aspects of peptide nanotubes have been studied, in particular the utility of different methods for making peptide nanotubes with diverse designed functions. In order to investigate the relationship between formation, function and stability, it is essential to analyze the precise structure of peptide nanotubes. Atomic-scale surface imaging in liquids was recently achieved using frequency modulation atomic force microscopy with improved force sensing. Here we provide a precise surface structural analysis of peptide nanotubes in water without crystallizing them obtained by imaging the nanotubes at the sub-nanometer scale in water. In addition, the local hydration structure around the peptide nanotubes was observed at the nanotube/water interface.

Racetrack linear accelerators

International Nuclear Information System (INIS)

Rowe, C.H.; Wilton, M.S. de.

1979-01-01

An improved recirculating electron beam linear accelerator of the racetrack type is described. The system comprises a beam path of four straight legs with four Pretzel bending magnets at the end of each leg to direct the beam into the next leg of the beam path. At least one of the beam path legs includes a linear accelerator. (UK)

Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO{sub 2} transformation

Energy Technology Data Exchange (ETDEWEB)

Shanmugam, Ramasamy [Department of Chemistry, Thiagarajar College, Madurai, Tamilnadu 625 009 (India); National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India); Thamaraichelvan, Arunachalam [Faculty of Allied Health Sciences, Chettinad Hospital & Research Institute, Kelambakkam, Tamilnadu 603 103 (India); Ganesan, Tharumeya Kuppusamy [Department of Chemistry, The American College, Madurai, Tamilnadu 625 002 (India); Viswanathan, Balasubramanian, E-mail: bvnathan@iitm.ac.in [National Center for Catalysis Research, Indian Institute of Technology Madras, Chennai, Tamilnadu 600 036 (India)

2017-02-28

Highlights: • On interaction with adsorbate CO{sub 2,} the adsorbent changes its configuration around the metal. • Electron transfer is faster in low coordinative environment of Cu. • CO formation is more favorable on Cu sites with even coordination number. • Cu at coordination number two has a over potential of −0.35 V. - Abstract: Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO{sub 2} to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO{sub 2} to CO at an applied potential of −0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO{sub 2} to various value added chemicals.

Epitaxial Fe{sub 3-x}Ti{sub x}O{sub 4} films from magnetite to ulvöspinel by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Droubay, T.C.; Pearce, C.I.; Ilton, E.S.; Engelhard, M.H.; Engelhard, M.H.; Heald, S.M.; Arenholz, E.; Rosso, K.M.

2011-07-21

Epitaxial films along the Fe{sub 3-x}Ti{sub x}O{sub 4} (titanomagnetite) compositional series from pure end-members magnetite (Fe{sub 3}O{sub 4}) to ulvöspinel (Fe{sub 2}TiO{sub 4}) were successfully grown by pulsed laser deposition on MgO(100) substrates. Spectroscopic characterization including high resolution x-ray diffraction, x-ray photoelectron spectroscopy, and synchrotron-based x-ray absorption and magnetic circular dichroism consistently shows that Ti(IV) substitutes for Fe(III) in the inverse spinel lattice with a proportional increase in lattice Fe(II) concentration. No evidence of Ti interstitials, spinodal decomposition, or secondary phases was found in the bulk of the grown films. At the uppermost few nanometers of the Ti-bearing film surfaces, evidence suggests that Fe(II) is susceptible to facile oxidation, and that an associated lower Fe/Ti ratio in this region is consistent with surface compositional incompleteness or alteration to a titanomaghemite-like composition and structure. The surface of these films nonetheless appear to remain highly ordered and commensurate with the underlying structure despite facile oxidation, a surface condition that is found to be reversible to some extent by heating in low oxygen environments.

A differential Michelson interferometer with orthogonal single frequency laser for nanometer displacement measurement

International Nuclear Information System (INIS)

Yan, Liping; Chen, Benyong; Wang, Bin

2017-01-01

A novel differential Michelson laser interferometer is proposed to eliminate the influence of environmental fluctuations for nanometer displacement measurement. This differential interferometer consists of two homodyne interferometers in which two orthogonal single frequency beams share common reference arm and partial measurement arm. By modulating the displacement of the common reference arm with a piezoelectric transducer, the common-mode displacement drift resulting from the environmental disturbances can be well suppressed and the measured displacement as differential-mode displacement signal is achieved. In addition, a phase difference compensation method is proposed for accurately determining the phase difference between interference signals by correcting the time interval according to the average speed in one cycle of interference signal. The nanometer displacement measurement experiments were performed to demonstrate the effectiveness and feasibility of the proposed interferometer and show that precision displacement measurement with standard deviation less than 1 nm has been achieved. (paper)

27 CFR 6.53 - Advertising in ballparks, racetracks, and stadiums.

Science.gov (United States)

2010-04-01

... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Advertising in ballparks, racetracks, and stadiums. 6.53 Section 6.53 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX... Advertising, Display Or Distribution Service § 6.53 Advertising in ballparks, racetracks, and stadiums. The...

Superconducting racetrack booster for the ion complex of MEIC

Energy Technology Data Exchange (ETDEWEB)

Filatov, Yu [Joint Inst. for Nuclear Research (JINR), Dubna (Russian Federation); Moscow Inst. of Physics and Technology (MIPT), Moscow (Russian Federation); Kondratenko, A. M. [Science and Technique Laboratory ' Zaryad' , 630090, Novosibirsk, Russia; Kondratenko, M. A. [Science and Technique Laboratory ' Zaryad' , 630090, Novosibirsk, Russia; Kovalenko, A. [Joint Inst. for Nuclear Research (JINR), Dubna (Russian Federation); Derbenev, Yaroslav S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Lin, Fanglei [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Morozov, Vasiliy S. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Zhang, Yuhong [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

2016-02-01

The current design of the Medium-energy Electron-Ion Collider (MEIC) project at Jefferson lab features a single 8 GeV/c figure-8 booster based on super-ferric magnets. Reducing the circumference of the booster by switching to a racetrack design may improve its performance by limiting the space charge effect and lower its cost. We consider problems of preserving proton and deuteron polarizations in a superconducting racetrack booster. We show that using magnets based on hollow high-current NbTi composite superconducting cable similar to those designed at JINR for the Nuclotron guarantees preservation of the ion polarization in a racetrack booster up to 8 GeV/c. The booster operation cycle would be a few seconds that would improve the operating efficiency of the MEIC ion complex.

Room temperature magnetism of few-nanometers-thick Fe{sub 3}O{sub 4}(111) films on Pt(111) and Ru(0001) studied in ambient conditions

Energy Technology Data Exchange (ETDEWEB)

Lewandowski, M., E-mail: lewandowski@amu.edu.pl [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Miłosz, Z.; Michalak, N.; Ranecki, R. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Sveklo, I.; Kurant, Z.; Maziewski, A. [Faculty of Physics, University of Białystok, Lipowa 41, 15-424 Białystok (Poland); Mielcarek, S. [Faculty of Physics, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland); Luciński, T. [Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań (Poland); Jurga, S. [NanoBioMedical Centre, Adam Mickiewicz University, Umultowska 85, 61-614 Poznań (Poland)

2015-09-30

Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were epitaxially grown on Pt(111) and Ru(0001) single crystal supports by sequential iron deposition and oxidation in an ultra-high vacuum chamber. The growth of well-ordered magnetite films was confirmed by low energy electron diffraction. The films were covered with a protective Au layer and subjected to magnetic and structural studies in ambient conditions. Magnetic hysteresis loops, recorded using magneto-optical Kerr effect apparatus, confirmed magnetic ordering in both films at room temperature. The Kerr measurements indicated in-plane orientation of magnetization, which was supported by the lack of magnetic contrast in magnetic force microscopy images. Atomic force microscopy revealed significant differences in morphology of the films, tentatively attributed to different lattice mismatch with Pt(111) and Ru(0001) single crystal supports. - Highlights: • Few-nanometers-thick Fe{sub 3}O{sub 4}(111) films were grown on Pt(111) and Ru(0001). • Magnetic properties were studied using MOKE and AFM/MFM in ambient conditions. • The films exhibited in-plane magnetic ordering at room temperature. • Differences in magnetic properties were tentatively assigned to structural differences.

Fabrication of TiNb{sub 2}O{sub 7} thin film electrodes for Li-ion micro-batteries by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Daramalla, V. [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India); Penki, Tirupathi Rao; Munichandraiah, N. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bengalore 560012 (India); Krupanidhi, S.B., E-mail: sbk@mrc.iisc.ernet.in [Materials Research Centre, Indian Institute of Science, Bengalore 560012 (India)

2016-11-15

Graphical abstract: The TiNb{sub 2}O{sub 7} thin film electrodes as anode material in Li-ion rechargeable micro-batteries are successfully demonstrated. The pulsed laser deposited TiNb{sub 2}O{sub 7} thin film electrode delivers high discharge specific capacity of 143 μAh μm{sup −1} cm{sup −2} at 50 μA cm{sup −2} current density, with 92% coulombic efficiency. The thin films are very stable in crystal structure, with good fast reversible reaction at average Li-insertion voltage 1.65 V. - Highlights: • TiNb{sub 2}O{sub 7} thin films fabricated by pulsed laser deposition. • TiNb{sub 2}O{sub 7} as anode thin films demonstrated successfully. • High discharge specific capacity with 92% coulombic efficiency. • Excellent crystal stability and good reversible reaction. - Abstract: Pulsed laser deposited TiNb{sub 2}O{sub 7} thin films are demonstrated as anode materials in rechargeable Li-ion micro-batteries. The monoclinic and chemically pure TiNb{sub 2}O{sub 7} films in different morphologies were successfully deposited at 750 °C. The single phase formation was confirmed by grazing incident X-ray diffraction, micro-Raman spectroscopy, high resolution transmission electron microscopy, field emission scanning electron microscopy and X-ray photoelectron spectroscopy. The oxygen partial pressure during the deposition significantly influenced the properties of TiNb{sub 2}O{sub 7} films. The TiNb{sub 2}O{sub 7} thin films exhibited excellent stability with fast kinetics reversible reaction. The TiNb{sub 2}O{sub 7} films showed initial discharge specific capacity of 176, 143 μAh μm{sup −1} cm{sup −2} at 30, 50 μA cm{sup −2} current densities respectively with 92% coulombic efficiency in a non-aqueous electrolyte consisting of Li{sup +} ions. The high discharge specific capacity of TiNb{sub 2}O{sub 7} thin films may be attributed to nanometer grain size with high roughness which offers high surface area for Li-diffusion during charge and discharge

MUON ACCELERATION WITH THE RACETRACK FFAG

International Nuclear Information System (INIS)

TRBOJEVIC, D.; EBERHARD, K.; SESSLER, A.

2007-01-01

Muon acceleration for muon collider or neutrino factory is still in a stage where further improvements are likely as a result of further study. This report presents a design of the racetrack non-scaling Fixed Field Alternating Gradient (NS-FFAG) accelerator to allow fast muon acceleration in small number of turns. The racetrack design is made of four arcs: two arcs at opposite sides have a smaller radius and are made of closely packed combined function magnets, while two additional arcs, with a very large radii, are used for muon extraction, injection, and RF accelerating cavities. The ends of the large radii arcs are geometrically matched at the connections to the arcs with smaller radii. The dispersion and both horizontal and vertical amplitude fictions are matched at the central energy

Development of a sub-nanometer positioning device: combining a new linear motor with linear motion ball guide ways

International Nuclear Information System (INIS)

Otsuka, J; Tanaka, T; Masuda, I

2010-01-01

A new type of linear motor described in this note has some advantages compared with conventional motors. The attractive magnetic force between the stator (permanent magnets) and mover (armature) is diminished almost to zero. The efficiency is better because the magnetic flux leakage is very small, the size of motor is smaller and detent (force ripple) is smaller than for conventional motors. Therefore, we think that this motor is greatly suitable for ultra-precision positioning as an actuator. An ultra-precision positioning device using this motor and linear motion ball guide ways is newly developed by making the device very rigid and using a suitable control method. Moreover, the positioning performance is evaluated by a positioning resolution, and deviation and dispersion errors. As a result of repeated step response tests, the positioning resolution is 0.3 nm, with the deviation error and dispersion error (3σ) being sub-nanometer. Consequently, the positioning device achieves sub-nanometer positioning. (technical design note)

KINOFORM LENSES - TOWARD NANOMETER RESOLUTION.

Energy Technology Data Exchange (ETDEWEB)

STEIN, A.; EVANS-LUTTERODT, K.; TAYLOR, A.

2004-10-23

While hard x-rays have wavelengths in the nanometer and sub-nanometer range, the ability to focus them is limited by the quality of sources and optics, and not by the wavelength. A few options, including reflective (mirrors), diffractive (zone plates) and refractive (CRL's) are available, each with their own limitations. Here we present our work with kinoform lenses which are refractive lenses with all material causing redundant 2{pi} phase shifts removed to reduce the absorption problems inherently limiting the resolution of refractive lenses. By stacking kinoform lenses together, the effective numerical aperture, and thus the focusing resolution, can be increased. The present status of kinoform lens fabrication and testing at Brookhaven is presented as well as future plans toward achieving nanometer resolution.

Carrier recombination in tailored multilayer Si/Si{sub 1−x}Ge{sub x} nanostructures

Energy Technology Data Exchange (ETDEWEB)

Mala, S.A. [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Tsybeskov, L., E-mail: tsybesko@njit.edu [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Lockwood, D.J.; Wu, X.; Baribeau, J.-M. [National Research Council, Ottawa, ON, Canada KIA 0R6 (Canada)

2014-11-15

Photoluminescence (PL) measurements were performed in Si/Si{sub 1−x}Ge{sub x} nanostructures with a single Si{sub 0.92}Ge{sub 0.08} nanometer-thick layer incorporated into Si/Si{sub 0.6}Ge{sub 0.4} cluster multilayers. Under pulsed laser excitation, the PL decay associated with the Si{sub 0.92}Ge{sub 0.08} nano-layer is found to be nearly a 1000 times faster compared to that in Si/Si{sub 0.6}Ge{sub 0.4} cluster multilayers. A model considering Si/SiGe hetero-interface composition and explaining the fast and slow time-dependent recombination rates is proposed.

Race-track coils for a 3 MW HTS ship motor

Energy Technology Data Exchange (ETDEWEB)

Ueno, E., E-mail: ueno-eisaku@sei.co.jp; Kato, T.; Hayashi, K.

2014-09-15

Highlights: • Sumitomo Electric manufactured the HTS field coils for a 3 MW HTS ship motor. • The motor was developed and successfully passed the loading test by Kawasaki Heavy. • We tested and obtained the basic data to evaluate the 20-year durability of coils. - Abstract: Since the discovery of high-temperature superconductivity (HTS), Sumitomo Electric has been developing silver-sheathed Bi2223 superconducting wire and products. Ship propulsion motors are one of the most promising applications of HTS. Sumitomo Electric Industries, Ltd. (SEI) has recently manufactured 24 large racetrack coils, using 70 km long DI-BSCCO wires, for use in a 3 MW HTS motor developed by Kawasaki Heavy Industries, Ltd. (KHI). The 3 MW HTS motor, using our newly developed racetrack coils, has successfully passed the loading test. It is particularly important that the HTS field coils used in ship propulsion motors can withstand the expansive forces repeatedly applied to them. As racetrack type coils have straight sections, the support mechanism they require to withstand expansive forces is very different from that of circular coils. Therefore, we ran tests and obtained the basic data to evaluate the 20-year durability of racetrack coils against the repeatedly applied expansive forces expected in domestic ship propulsion motors.

Generating Sub-nanometer Displacement Using Reduction Mechanism Consisting of Torsional Leaf Spring Hinges

Directory of Open Access Journals (Sweden)

Fukuda Makoto

2014-02-01

Full Text Available Recent demand on the measurement resolution of precise positioning comes up to tens of picometers. Some distinguished researches have been performed to measure the displacement in picometer order, however, few of them can verify the measurement performance as available tools in industry. This is not only because the picometer displacement is not yet required for industrial use, but also due to the lack of standard tools to verify such precise displacement. We proposed a displacement reduction mechanism for generating precise displacement using torsional leaf spring hinges (TLSHs that consist of four leaf springs arranged radially. It has been demonstrated that a prototype of the reduction mechanism was able to provide one-nanometer displacement with 1/1000 reduction rate by a piezoelectric actuator. In order to clarify the potential of the reduction mechanism, a displacement reduction table that can be mounted on AFM stage was newly developed using TLSHs. This paper describes the design of the reduction mechanism and the sub-nanometer displacement performance of the table obtained from its dynamic and static characteristics measured by displacement sensors and from the AFM images

Nanopore Measurements of Filamentous Viruses Reveal a Sub-nanometer-Scale Stagnant Fluid Layer.

Science.gov (United States)

McMullen, Angus J; Tang, Jay X; Stein, Derek

2017-11-28

We report measurements and analyses of nanopore translocations by fd and M13, two related strains of filamentous virus that are identical except for their charge densities. The standard continuum theory of electrokinetics greatly overestimates the translocation speed and the conductance associated with counterions for both viruses. Furthermore, fd and M13 behave differently from one another, even translocating in opposite directions under certain conditions. This cannot be explained by Manning-condensed counterions or a number of other proposed models. Instead, we argue that these anomalous findings are consequences of the breakdown of the validity of continuum hydrodynamics at the scale of a few molecular layers. Next to a polyelectrolyte, there exists an extra-viscous, sub-nanometer-thin boundary layer that has a giant influence on the transport characteristics. We show that a stagnant boundary layer captures the essential hydrodynamics and extends the validity of the electrokinetic theory beyond the continuum limit. A stagnant layer with a thickness of about half a nanometer consistently improves predictions of the ionic current change induced by virus translocations and of the translocation velocity for both fd and M13 over a wide range of nanopore dimensions and salt concentrations.

Circular lasers for telecommunications and rf/photonics applications

Science.gov (United States)

Griffel, Giora

2000-04-01

Following a review of ring resonator research in the past decade we shall report a novel bi-level etching technique that permits the use of standard photolithography for coupling to deeply-etched ring resonator structures. The technique is employed to demonstrate InGaAsP laterally- coupled racetrack ring resonators laser with record low threshold currents of 66 mA. The racetrack laser have curved sections of 150 micrometers radius with negligible bending loss. The lasers operate CW single mode up to nearly twice threshold with a 26 dB side-mode-suppression ratio. We shall also present a transfer matrix formalism for the analysis of ring resonator arrays and indicate application examples for flat band filter synthesis.

Mechanical design of ultraprecision weak-link stages for nanometer-scale x-ray imaging

Energy Technology Data Exchange (ETDEWEB)

Shu, D [APS Engineering Support Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Maser, J, E-mail: shu@aps.anl.go [Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439 (United States)

2009-09-01

A nanopositioning diagnostic setup has been built to support the Argonne Center for Nanoscale Materials (CNM) nanoprobe instrument commissioning process at the APS. Its laser Doppler interferometer system provides subnanometer positioning diagnostic resolution with large dynamic range. A set of original APS designed ultraprecision PZT-driven weak-link stages with high-stiffness motor-driven stages has been tested with this diagnostic setup. In this paper we present a preliminary test result of the ultraprecision weak-link stage system developed for the CNM hard x-ray nanoprobe instrument at APS sector 26. A test result for a novel laminar weak-link mechanism with sub-centimeter travel range and sub-nanometer positioning resolution is also introduced in this paper as a future work.

Assembly and Tests of SQ02, a Nb3Sn Racetrack Quadrupole Magnet for LARP

Energy Technology Data Exchange (ETDEWEB)

Ferracin, Paolo; Ambrosio, G.; Barzi, E.; Caspi, S.; Dietderich, D.R.; Feher, S.; Gourlay, S.A.; Hafalia, A.R.; Hannaford, C.R.; Lizarazo, J.; Lietzke, A.F.; McInturff, A.D.; Sabbi, G.L.; Zlobin, A.V.

2007-06-01

The US LHC Accelerator Research Program (LARP) consists of four US laboratories (BNL, FNAL, LBNL, and SLAC) collaborating with CERN to achieve a successful commissioning of the LHC and to develop the next generation of Interaction Region magnets. In 2004, a large aperture Nb{sub 3}Sn racetrack quadrupole magnet (SQ01) has been fabricated and tested at LBNL. The magnet utilized four subscale racetrack coils and was instrumented with strain gauges on the support structure and directly over the coil's turns. SQ01 exhibited training quenches in two of the four coils and reached a peak field in the conductor of 10.4 T at a current of 10.6 kA. After the test, the magnet was disassembled, inspected with pressure indicating films, and reassembled with minor modifications. A second test (SQ01b) was performed at FNAL and included training studies, strain gauge measurements and magnetic measurements. Magnet inspection, test results, and magnetic measurements are reported and discussed, and a comparison between strain gauge measurements and 3D finite element computations is presented.

A general approach to homogeneous sub-nanometer metallic particle/graphene composites by S-coordinator

Science.gov (United States)

Wang, Senhao; Wang, Wei; Gu, Shangzhi; Zhang, Guoxin; Song, Ningning

2018-05-01

In this study, sulphur-modified reduced graphene oxide (S-rGO) was employed as substrate to investigate the growth mechanism of metal and metallic nanoparticles (NPs). It is observed that the monodispersed Au, SnO2, FeO(OH) and Co3S4 NPs in sub-nanometer (sub-nm) with narrow size distribution were successfully anchored on S-rGO, respectively. The results indicate that the S contained radicals, viz. the Cdbnd S and Csbnd Ssbnd C functional groups play an important role in determining the homogeneous distribution of NPs on S-rGO by providing active sites for the NPs anchoring and nucleation. In additional, as anode materials for lithium ion batteries (LIBs), the as-synthesized sub-nm sized Co3S4/S-rGO and SnO2/S-rGO composites show excellent Li storage performance. It could be stabilized at ca. 600 mAh/g after formation cycle with the coulombic efficiency of 98%. It is expected that the strategy of growing sub-nm sized metallic component onto graphene by applying sulphur functionalities could be utilized as a general method to prepare monodispersed graphene-based NPs with other metals, especially with transition metals in sub-nm sizes.

Resolving three-dimensional shape of sub-50 nm wide lines with nanometer-scale sensitivity using conventional optical microscopes

International Nuclear Information System (INIS)

Attota, Ravikiran; Dixson, Ronald G.

2014-01-01

We experimentally demonstrate that the three-dimensional (3-D) shape variations of nanometer-scale objects can be resolved and measured with sub-nanometer scale sensitivity using conventional optical microscopes by analyzing 4-D optical data using the through-focus scanning optical microscopy (TSOM) method. These initial results show that TSOM-determined cross-sectional (3-D) shape differences of 30 nm–40 nm wide lines agree well with critical-dimension atomic force microscope measurements. The TSOM method showed a linewidth uncertainty of 1.22 nm (k = 2). Complex optical simulations are not needed for analysis using the TSOM method, making the process simple, economical, fast, and ideally suited for high volume nanomanufacturing process monitoring.

Sub-nanometer resolution XPS depth profiling: Sensing of atoms

Energy Technology Data Exchange (ETDEWEB)

Szklarczyk, Marek, E-mail: szklarcz@chem.uw.edu.pl [Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw (Poland); Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Macak, Karol; Roberts, Adam J. [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Takahashi, Kazuhiro [Kratos XPS Section, Shimadzu Corp., 380-1 Horiyamashita, Hadano, Kanagawa 259-1304 (Japan); Hutton, Simon [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom); Głaszczka, Rafał [Shim-Pol, ul. Lubomirskiego 5, 05-080 Izabelin (Poland); Blomfield, Christopher [Kratos Analytical Ltd, Wharfside, Trafford Wharf Road, Manchester, M17 1GP (United Kingdom)

2017-07-31

Highlights: • Angle resolved photoelectron depth profiling of nano thin films. • Sensing atomic position in SAM films. • Detection of direction position of adsorbed molecules. - Abstract: The development of a method capable of distinguishing a single atom in a single molecule is important in many fields. The results reported herein demonstrate sub-nanometer resolution for angularly resolved X-ray photoelectron spectroscopy (ARXPS). This is made possible by the incorporation of a Maximum Entropy Method (MEM) model, which utilize density corrected electronic emission factors to the X-ray photoelectron spectroscopy (XPS) experimental results. In this paper we report on the comparison between experimental ARXPS results and reconstructed for both inorganic and organic thin film samples. Unexpected deviations between experimental data and calculated points are explained by the inaccuracy of the constants and standards used for the calculation, e.g. emission factors, scattering intensity and atomic density through the studied thickness. The positions of iron, nitrogen and fluorine atoms were determined in the molecules of the studied self-assembled monolayers. It has been shown that reconstruction of real spectroscopic data with 0.2 nm resolution is possible.

Nanoparticle dispersion effect of laser-surface melting in ZrB{sub 2p}/6061Al composites

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yida; Chao, Yuhjin; Luo, Zhen, E-mail: lz-tju@163.com [Tianjin University, School of Material Science and Engineering (China); Huang, Yongxian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology (China)

2017-04-15

Zirconium diboride (ZrB{sub 2p}, 15 vol%)/6061 aluminum (Al) composites were fabricated via in situ reaction. The existence, morphologies, and dispersion degree of the in situ ZrB{sub 2} particles with size from tens to hundreds of nanometers were studied by X-ray diffractometry, energy-dispersive X-ray spectroscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy. As the particle-settlement effect becomes dominant during the composite fabrication process, ZrB{sub 2} nanoparticles agglomerate to a certain extent in some areas of the as-cast composites. A laser-surface melting (LSM) strategy was applied to disperse agglomerated ZrB{sub 2} nanoparticles in as-cast composites, and the ZrB{sub 2} nanoparticle dispersion is affected visibly by LSM. After LSM, nanoparticles tend to distribute along the grain boundary. Particle clusters were dispersed in an explosive orientation and the particle diffusion distance varied in terms of its radius and melt-viscosity vicinity. High-resolution transmission electron microscopy showed the existence of a subgrain structure near the ZrB{sub 2}–Al interface after LSM. This may increase the yield strength when a dislocation tangle forms.

Racetrack coil instability resulting from friction-heat generation at fixtures

International Nuclear Information System (INIS)

Yazawa, T.; Urata, M.; Chandratilleke, G.R.; Maeda, H.

1993-01-01

This paper describes racetrack coil instability resulting from friction-heat generation at fixtures and a preventive measure against it using a thermal barrier. Epoxy impregnated racetrack coils sometimes experience premature quenches due to frictional heat produced by coil slides at fixtures that are essential for the coil straight part to withstand the electromagnetic force. Experimentally, we confirmed for a small-sized racetrack coil that coil slides were actually occurring. The coil movements coupled with acoustic emissions were observed several times when the coil was energized. Each of them was about 10 μm, an equivalent of 20 mJ in frictional heat. This frictional heat was almost comparable with the analytical and experimental coil stability margins when an insulation layer was thin. One of the effective measures against the frictional heat is the thermal barrier, which is a thick insulation layer at the interface between the coil and the fixtures. By thickening the insulation layer from 0.36 to 1.00 mm, the coil stability margin increased from 100 to 200 mJ. (orig.)

Helium Ion Microscopy (HIM) for the imaging of biological samples at sub-nanometer resolution

Science.gov (United States)

Joens, Matthew S.; Huynh, Chuong; Kasuboski, James M.; Ferranti, David; Sigal, Yury J.; Zeitvogel, Fabian; Obst, Martin; Burkhardt, Claus J.; Curran, Kevin P.; Chalasani, Sreekanth H.; Stern, Lewis A.; Goetze, Bernhard; Fitzpatrick, James A. J.

2013-12-01

Scanning Electron Microscopy (SEM) has long been the standard in imaging the sub-micrometer surface ultrastructure of both hard and soft materials. In the case of biological samples, it has provided great insights into their physical architecture. However, three of the fundamental challenges in the SEM imaging of soft materials are that of limited imaging resolution at high magnification, charging caused by the insulating properties of most biological samples and the loss of subtle surface features by heavy metal coating. These challenges have recently been overcome with the development of the Helium Ion Microscope (HIM), which boasts advances in charge reduction, minimized sample damage, high surface contrast without the need for metal coating, increased depth of field, and 5 angstrom imaging resolution. We demonstrate the advantages of HIM for imaging biological surfaces as well as compare and contrast the effects of sample preparation techniques and their consequences on sub-nanometer ultrastructure.

Sub-Nanometer Channels Embedded in Two-Dimensional Materials

KAUST Repository

Han, Yimo

2017-07-31

Two-dimensional (2D) materials are among the most promising candidates for next-generation electronics due to their atomic thinness, allowing for flexible transparent electronics and ultimate length scaling1. Thus far, atomically-thin p-n junctions2-7, metal-semiconductor contacts8-10, and metal-insulator barriers11-13 have been demonstrated. While 2D materials achieve the thinnest possible devices, precise nanoscale control over the lateral dimensions are also necessary. Although external one-dimensional (1D) carbon nanotubes14 can be used to locally gate 2D materials, this adds a non-trivial third dimension, complicating device integration and flexibility. Here, we report the direct synthesis of sub-nanometer 1D MoS2 channels embedded within WSe2 monolayers, using a dislocation-catalyzed approach. The 1D channels have edges free of misfit dislocations and dangling bonds, forming a coherent interface with the embedding 2D matrix. Periodic dislocation arrays produce 2D superlattices of coherent MoS2 1D channels in WSe2. Molecular dynamics (MD) simulations have identified other combinations of 2D materials that could form 1D channels. Density function theory (DFT) calculation predicts these 1D channels display type II band alignment needed for carrier confinement and charge separation to access the ultimate length scales necessary for future electronic applications.

Emerging terawatt picosecond CO{sub 2} laser technology

Energy Technology Data Exchange (ETDEWEB)

Pogorelsky, I V [Accelerator Test Facility, Brookhaven National Lab., Upton, NY (United States)

1998-03-01

The first terawatt picosecond (TWps) CO{sub 2} laser is under construction at the BNL Accelerator Test Facility (ATF). TWps-CO{sub 2} lasers, having an order of magnitude longer wavelength than the well-known table-top terawatt solid state lasers, offer new opportunities for strong-field physics research. For laser wakefield accelerators (LWFA) the advantage of the new class of lasers is due to a gain of two orders of magnitude in the ponderomotive potential. The large average power of CO{sub 2} lasers is important for the generation of hard radiation through Compton back-scattering of the laser off energetic electron beams. We discuss applications of TWps-CO{sub 2} lasers for LWFA modules of a tentative electron-positron collider, for {gamma}-{gamma} (or {gamma}-lepton) colliders, for a possible `table-top` source of high-intensity x-rays and gamma rays, and the generation of polarized positron beams. (author)

Free spectral range adjustment of a silicon rib racetrack resonator

International Nuclear Information System (INIS)

Keča, T; Matavulj, P; Headley, W; Mashanovich, G

2012-01-01

One of the most important parameters that describe the quality of photonic components and devices is the free spectral range (FSR). In this paper, the measured outgoing power of a silicon rib racetrack resonator was compared with calculated transfer functions derived by coupled mode theory. The influence of geometric parameters on the FSR and resonant wavelength has been investigated. By altering the values of the coupling length and racetrack radius, derived transfer functions were adjusted to match experimental data. This procedure gives the possibility of estimating the FSR and resonant wavelength for different geometric parameters and predicting resonator functionality.

Yb{sup 3+}:Sr{sub 5}(VO{sub 4}){sub 3}F: Crystal growth, spectroscopic characterization and laser development; Yb{sup 3+}:Sr{sub 5}(VO{sub 4}){sub 3}F: Crescimento, caracterizacao espectroscopica e desenvolvimento do laser

Energy Technology Data Exchange (ETDEWEB)

Bustamante, Andrea Nora Pino

1999-07-01

Crystal growth, spectroscopic characterization and laser development of Yb{sup 3+}:SVAP [Sr{sub 5}(VO{sub 4}){sub 3}F] was performed to demonstrate for the first time, operation of tunable laser emission centered at 1120 nm. Initially, SVAP crystals were grown with high dopant concentrations, up to 6.0 mol % of Yb{sub 2} O{sub 3} in the melt, in order to investigate the material for potential laser operation at a new laser wavelength. Additional research was performed to alleviate highly doped SVAP crystals of defects previously observed. Basic spectroscopic characterization including absorption and luminescent properties were measured to better understand the behavior of Yb{sup 3+} ions in SVAP. Based upon these studies, discussion of the 1120 nm laser transition is presented as it arises from a ground state vibrational level. Investigations of the charge compensation process and the optical parameters as a function of dopant concentration are also presented. The laser development of Yb{sup 3+}:SVAP included continuous and pulsed modes of operation of the 1044 nm and 1120 nm transitions. Initial laser action of the 1044 nm transition was achieved using a Yi: Saphire laser pump source in order to compare with previously results. Further development of a diode-pumped Yb{sup 3+}:SVAP laser system demonstrated continuously tunable laser operation from 1103 nm for the first time. The laser investigations also proved that this high gain media does provide continuous wave laser action at 1044 nm and 1120 simultaneously without significant gain depletion. (author)

Computational evaluation of sub-nanometer cluster activity of singly exposed copper atom with various coordinative environment in catalytic CO2 transformation

Science.gov (United States)

Shanmugam, Ramasamy; Thamaraichelvan, Arunachalam; Ganesan, Tharumeya Kuppusamy; Viswanathan, Balasubramanian

2017-02-01

Metal cluster, at sub-nanometer level has a unique property in the activation of small molecules, in contrast to that of bulk surface. In the present work, singly exposed active site of copper metal cluster at sub-nanometer level was designed to arrive at the energy minimised configurations, binding energy, electrostatic potential map, frontier molecular orbitals and partial density of states. The ab initio molecular dynamics was carried out to probe the catalytic nature of the cluster. Further, the stability of the metal cluster and its catalytic activity in the electrochemical reduction of CO2 to CO were evaluated by means of computational hydrogen electrode via calculation of the free energy profile using DFT/B3LYP level of theory in vacuum. The activity of the cluster is ascertained from the fact that the copper atom, present in a two coordinative environment, performs a more selective conversion of CO2 to CO at an applied potential of -0.35 V which is comparatively lower than that of higher coordinative sites. The present study helps to design any sub-nano level metal catalyst for electrochemical reduction of CO2 to various value added chemicals.

Nanometer-sized emissions from municipal waste incinerators: A qualitative risk assessment

Energy Technology Data Exchange (ETDEWEB)

Johnson, David R., E-mail: david.r.johnson@ghd.com

2016-12-15

Municipal waste incinerators (MWI) are beneficial alternatives to landfills for waste management. A recent constituent of concern in emissions from these facilities is incidental nanometer-sized particles (INP{sub MWI}), i.e., particles smaller than 1 micrometer in size that may deposit in the deepest parts of the lungs, cross into the bloodstream, and affect different regions of the body. With limited data, the public may fear INP{sub MWI} due to uncertainty, which may affect public acceptance, regulatory permitting, and the increased lowering of air quality standards. Despite limited data, a qualitative risk assessment paradigm can be applied to determine the relative risk due to INP{sub MWI} emissions. This review compiles existing data on nanometer-sized particle generation by MWIs, emissions control technologies used at MWIs, emission releases into the atmosphere, human population exposure, and adverse health effects of nanometer-sized particles to generate a qualitative risk assessment and identify data gaps. The qualitative risk assessment conservatively concludes that INP{sub MWI} pose a low to moderate risk to individuals, primarily due to the lack of relevant toxicological data on INP{sub MWI} mixtures in ambient particulate matter.

Measurements on Subscale Y-Ba-Cu-O Racetrack Coils at 77 K and Self-Field

Energy Technology Data Exchange (ETDEWEB)

Wang, X.; Caspi, S.; Cheng, D. W.; Dietderich, D. R.; Felice, H.; Ferracin, P.; Godeke, A.; Joseph, J. M.; Lizarazo, J.; Prestemon, S. O.; Sabbi, G.

2009-10-19

YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} (YBCO) tapes carry significant amount of current at fields beyond the limit of Nb-based conductors. This makes the YBCO tapes a possible conductor candidate for insert magnets to increase the bore field of Nb{sub 3}Sn high-field dipoles. As an initial step of the YBCO insert technology development, two subscale racetrack coils were wound using Kapton-insulated commercial YBCO tapes. Both coils had two layers; one had 3 turns in each layer and the other 10 turns. The coils were supported by G10 side rails and waxed strips and not impregnated. The critical current of the coils was measured at 77 K and self-field. A 2D model considering the magnetic-field dependence of the critical current was used to estimate the expected critical current. The measured results show that both coils reached 80%-95% of the expected values, indicating the feasibility of the design concept and fabrication process.

Mechanism and Prediction of Gas Permeation through Sub-Nanometer Graphene Pores: Comparison of Theory and Simulation.

Science.gov (United States)

Yuan, Zhe; Govind Rajan, Ananth; Misra, Rahul Prasanna; Drahushuk, Lee W; Agrawal, Kumar Varoon; Strano, Michael S; Blankschtein, Daniel

2017-08-22

Due to its atomic thickness, porous graphene with sub-nanometer pore sizes constitutes a promising candidate for gas separation membranes that exhibit ultrahigh permeances. While graphene pores can greatly facilitate gas mixture separation, there is currently no validated analytical framework with which one can predict gas permeation through a given graphene pore. In this work, we simulate the permeation of adsorptive gases, such as CO 2 and CH 4 , through sub-nanometer graphene pores using molecular dynamics simulations. We show that gas permeation can typically be decoupled into two steps: (1) adsorption of gas molecules to the pore mouth and (2) translocation of gas molecules from the pore mouth on one side of the graphene membrane to the pore mouth on the other side. We find that the translocation rate coefficient can be expressed using an Arrhenius-type equation, where the energy barrier and the pre-exponential factor can be theoretically predicted using the transition state theory for classical barrier crossing events. We propose a relation between the pre-exponential factor and the entropy penalty of a gas molecule crossing the pore. Furthermore, on the basis of the theory, we propose an efficient algorithm to calculate CO 2 and CH 4 permeances per pore for sub-nanometer graphene pores of any shape. For the CO 2 /CH 4 mixture, the graphene nanopores exhibit a trade-off between the CO 2 permeance and the CO 2 /CH 4 separation factor. This upper bound on a Robeson plot of selectivity versus permeance for a given pore density is predicted and described by the theory. Pores with CO 2 /CH 4 separation factors higher than 10 2 have CO 2 permeances per pore lower than 10 -22 mol s -1 Pa -1 , and pores with separation factors of ∼10 have CO 2 permeances per pore between 10 -22 and 10 -21 mol s -1 Pa -1 . Finally, we show that a pore density of 10 14 m -2 is required for a porous graphene membrane to exceed the permeance-selectivity upper bound of polymeric

Validation of a laboratory method for evaluating dynamic properties of reconstructed equine racetrack surfaces.

Directory of Open Access Journals (Sweden)

Jacob J Setterbo

Full Text Available Racetrack surface is a risk factor for racehorse injuries and fatalities. Current research indicates that race surface mechanical properties may be influenced by material composition, moisture content, temperature, and maintenance. Race surface mechanical testing in a controlled laboratory setting would allow for objective evaluation of dynamic properties of surface and factors that affect surface behavior.To develop a method for reconstruction of race surfaces in the laboratory and validate the method by comparison with racetrack measurements of dynamic surface properties.Track-testing device (TTD impact tests were conducted to simulate equine hoof impact on dirt and synthetic race surfaces; tests were performed both in situ (racetrack and using laboratory reconstructions of harvested surface materials. Clegg Hammer in situ measurements were used to guide surface reconstruction in the laboratory. Dynamic surface properties were compared between in situ and laboratory settings. Relationships between racetrack TTD and Clegg Hammer measurements were analyzed using stepwise multiple linear regression.Most dynamic surface property setting differences (racetrack-laboratory were small relative to surface material type differences (dirt-synthetic. Clegg Hammer measurements were more strongly correlated with TTD measurements on the synthetic surface than the dirt surface. On the dirt surface, Clegg Hammer decelerations were negatively correlated with TTD forces.Laboratory reconstruction of racetrack surfaces guided by Clegg Hammer measurements yielded TTD impact measurements similar to in situ values. The negative correlation between TTD and Clegg Hammer measurements confirms the importance of instrument mass when drawing conclusions from testing results. Lighter impact devices may be less appropriate for assessing dynamic surface properties compared to testing equipment designed to simulate hoof impact (TTD.Dynamic impact properties of race surfaces

Effects of a Picture Racetrack Game on the Expressive Vocabulary of Deaf Preschoolers.

Science.gov (United States)

Davenport, Carrie A; Alber-Morgan, Sheila R; Clancy, Shannon M; Kranak, Michael P

2017-07-01

This study examined the effects of a picture racetrack game on the acquisition, maintenance, and generalization of picture labeling for 2 preschool students who are deaf. The game consisted of placing photographs representing individualized target vocabulary around a racetrack board and prompting the participant to sign each photo. A multiple baseline design across picture sets demonstrated that playing the picture racetrack game was functionally related to acquisition of vocabulary to 100% mastery on at least 3 consecutive sessions for each participant. Additionally, both participants maintained most of the vocabulary they acquired for at least 4 weeks after intervention, and they generalized picture labeling to a different presentation mode (i.e., a photo album). © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Pulsed laser deposition of AlMgB<sub>14sub> thin films

Energy Technology Data Exchange (ETDEWEB)

Britson, Jason Curtis [Iowa State Univ., Ames, IA (United States)

2008-11-18

Hard, wear-resistant coatings of thin film borides based on AlMgB<sub>14sub> have the potential to be applied industrially to improve the tool life of cutting tools and pump vanes and may account for several million dollars in savings as a result of reduced wear on these parts. Past work with this material has shown that it can have a hardness of up to 45GPa and be fabricated into thin films with a similar hardness using pulsed laser deposition. These films have already been shown to be promising for industrial applications. Cutting tools coated with AlMgB<sub>14sub> used to mill titanium alloys have been shown to substantially reduce the wear on the cutting tool and extend its cutting life. However, little research into the thin film fabrication process using pulsed laser deposition to make AlMgB<sub>14sub> has been conducted. In this work, research was conducted into methods to optimize the deposition parameters for the AlMgB<sub>14sub> films. Processing methods to eliminate large particles on the surface of the AlMgB<sub>14sub> films, produce films that were at least 1m thick, reduce the surface roughness of the films, and improve the adhesion of the thin films were investigated. Use of a femtosecond laser source rather than a nanosecond laser source was found to be effective in eliminating large particles considered detrimental to wear reduction properties from the films. Films produced with the femtosecond laser were also found to be deposited at a rate 100 times faster than those produced with the nanosecond laser. However, films produced with the femtosecond laser developed a relatively high RMS surface roughness around 55nm. Attempts to decrease the surface roughness were largely unsuccessful. Neither increasing the surface temperature of the substrate during deposition nor using a double pulse to ablate the material was found to be extremely successful to reduce the surface roughness. Finally, the adhesion of the thin films to M2 tool steel

Sb{sub 2}S{sub 3}:C/CdS p-n junction by laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Arato, A. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); Cardenas, E. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Shaji, S. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico); O' Brien, J.J.; Liu, J. [Center for Nanoscience, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri-63121 (United States); Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One University Boulevard, St. Louis, Missouri-63121 (United States); Castillo, G. Alan; Das Roy, T.K. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Krishnan, B. [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia-Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon (Mexico)], E-mail: bkrishnan@fime.uanl.mx

2009-02-02

In this paper, we report laser irradiated carbon doping of Sb{sub 2}S{sub 3} thin films and formation of a p-n junction photovoltaic structure using these films. A very thin carbon layer was evaporated on to chemical bath deposited Sb{sub 2}S{sub 3} thin films of approximately 0.5 {mu}m in thickness. Sb{sub 2}S{sub 3} thin films were prepared from a solution containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} at 27 deg. C for 5 h and the films obtained were highly resistive. These C/Sb{sub 2}S{sub 3} thin films were irradiated by an expanded laser beam of diameter approximately 0.5 cm (5 W power, 532 nm Verdi laser), for 2 min at ambient atmosphere. Morphology and composition of these films were analyzed. These films showed p-type conductivity due to carbon diffusion (Sb{sub 2} S{sub 3}:C) by the thermal energy generated by the absorption of laser radiation. In addition, these thin films were incorporated in a photovoltaic structure Ag/Sb{sub 2}S{sub 3}:C/CdS/ITO/Glass. For this, CdS thin film of 50 nm in thickness was deposited on a commercially available ITO coated glass substrate from a chemical bath containing CdCl{sub 2}, sodium citrate, NH{sub 4}OH and thiourea at 70 deg. C . On the CdS film, Sb{sub 2}S{sub 3}/C layers were deposited. This multilayer structure was subjected to the laser irradiation, C/Sb{sub 2}S{sub 3} side facing the beam. The p-n junction formed by p-Sb{sub 2}S{sub 3}:C and n-type CdS showed V{sub oc} = 500 mV and J{sub sc} = 0.5 mA/cm{sup 2} under illumination by a tungsten halogen lamp. This work opens up a new method to produce solar cell structures by laser assisted material processing.

Effect of laser energy on the electrical transport properties of La{sub 0.67}Ca{sub 0.33}MnO{sub 3}:Ag{sub 0.2} films by pulsed laser deposition technique

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yalin; Chen, Qingming; Jin, Fei; Chen, Xiaohui; Li, Zhiyu; Li, Di; Zhang, Hui [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China)

2017-09-15

La{sub 0.67}Ca{sub 0.33}MnO{sub 3} (LCMO):Ag{sub 0.2} films were grown on LaAlO{sub 3} (LAO) substrates (100) by pulsed laser deposition (PLD) technique with various incident laser energies. The surface morphologies and the thicknesses of the films were studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The crystal structures were analyzed by X-ray, diffraction (XRD), and the temperature dependence of the resistivity (ρ-T) of the films was studied by the standard four-probe method. It can be found that the crystal quality, surface morphology, metal-insulator transition temperature (T{sub p}), and temperature coefficient of resistance (TCR) of the LCMO:Ag{sub 0.2} films are changed with various laser energy. The highest T{sub p} 287 K is obtained with 300 mJ laser energy; meanwhile, the optimal TCR 13.5% K{sup -1} is achieved. The results suggest that the electrical transport properties of LCMO:Ag{sub 0.2} films are affected by the interface-induced compressive stress, the oxygen balance, and the double exchange between Mn{sup 3+}-O-Mn{sup 4+}. (orig.)

Annular-cathode electron gun for in-line injection in a racetrack microtron

International Nuclear Information System (INIS)

Manca, J.J.; Edmonds, D.S. Jr.; Froelich, H.R.

1976-01-01

A compact annular-cathode electron gun which allows direct, efficient injection into the accelerating structure of a racetrack microtron was designed, built, and tested. The gun operates under pulsed conditions with applied high voltages of 40 kV or more and delivers an output current in excess of 1 A. Design and construction details are presented for both a basic gun and a gun with built-in output current monitor. Gun performance in a test chamber and in the multicavity racetrack microtron at the University of Western Ontario is described

Glass ceramic ZERODUR enabling nanometer precision

Science.gov (United States)

Jedamzik, Ralf; Kunisch, Clemens; Nieder, Johannes; Westerhoff, Thomas

2014-03-01

The IC Lithography roadmap foresees manufacturing of devices with critical dimension of digit nanometer asking for nanometer positioning accuracy requiring sub nanometer position measurement accuracy. The glass ceramic ZERODUR® is a well-established material in critical components of microlithography wafer stepper and offered with an extremely low coefficient of thermal expansion (CTE), the tightest tolerance available on market. SCHOTT is continuously improving manufacturing processes and it's method to measure and characterize the CTE behavior of ZERODUR® to full fill the ever tighter CTE specification for wafer stepper components. In this paper we present the ZERODUR® Lithography Roadmap on the CTE metrology and tolerance. Additionally, simulation calculations based on a physical model are presented predicting the long term CTE behavior of ZERODUR® components to optimize dimensional stability of precision positioning devices. CTE data of several low thermal expansion materials are compared regarding their temperature dependence between - 50°C and + 100°C. ZERODUR® TAILORED 22°C is full filling the tight CTE tolerance of +/- 10 ppb / K within the broadest temperature interval compared to all other materials of this investigation. The data presented in this paper explicitly demonstrates the capability of ZERODUR® to enable the nanometer precision required for future generation of lithography equipment and processes.

Racetrack microtron radio-frequency system

International Nuclear Information System (INIS)

Tallerico, P.J.; Mitra, A.K.

1981-01-01

The design and construction progress of a prototype rf system to drive the Los Alamos-NBS racetrack microtron (RTM) electron accelerator is described. The rf system requires 450-kW cw at 2380 MHz from a single klystron. The output from the klystron is split three ways to drive a capture section, a preaccelerator section, and the main accelerator section. The fields in each section are phase- and amplitude-controlled to tight tolerances. Temperature control of the accelerator sections also is linked to the amplitude-control system, because the system's average power is so high

Racetrack lattices for the TRIUMF KAON factory

International Nuclear Information System (INIS)

Servranckx, R.V.; Wienands, U.; Craddock, M.K.; Rees, G.H.

1989-03-01

Separated-function racetrack lattices have been developed for the KAON Factory accelerators that have more flexibility than the old circular lattices. Straight sections with zero dispersion are provided for rf cavities and fast injection and extraction, and with controlled dispersion for H - injection and slow extraction. In addition the new lattices have fewer depolarizing resonances than the old circular lattices

Long-lived CO/sub 2/ lasers with distributed heterogeneous catalysis

Energy Technology Data Exchange (ETDEWEB)

Browne, P G; Smith, A L.S.

1974-12-11

In a sealed CO/sub 2/-N/sub 2/-He system with a clean discharge tube the degree of dissociation of the CO/sub 2/ is greater than 80 percent (with no hydrogen present), and laser action cannot be obtained. If Pt is distributed along the discharge tube walls as a discontinuous film it catalyses back-reactions reforming CO/sub 2/. The degree of dissociation is then less than 40 percent, and efficient laser action at 10.6 ..mu.. is obtained. Using such distributed heterogeneous catalysis, a CO/sub 2/-N/sub 2/-He-Xe laser has operated for more than 3000 h. In this system, both H/sub 2/ and D/sub 2/ are undesirable additives because they decrease the excitation rate of the upper laser level. (auth)

Laser-joined Al{sub 2}O{sub 3} and ZrO{sub 2} ceramics for high-temperature applications

Energy Technology Data Exchange (ETDEWEB)

Boerner, Floriana-Dana, E-mail: floriana.boerner@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany); Lippmann, Wolfgang, E-mail: wolfgang.lippmann@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany); Hurtado, Antonio, E-mail: antonio.hurtado@tu-dresden.d [Dresden University of Technology (TU Dresden), Institute of Power Engineering, Chair of Hydrogen Technology and Nuclear Power Engineering, George-Baehr-Str. 3, D-01062 Dresden (Germany)

2010-10-01

A laser process is presented that has been specially developed for joining oxide ceramics such as zirconium oxide (ZrO{sub 2}) and aluminium oxide (Al{sub 2}O{sub 3}). It details, by way of example, the design of the laser process applied for to producing both Al{sub 2}O{sub 3}-Al{sub 2}O{sub 3} and ZrO{sub 2}-ZrO{sub 2} joints using siliceous glasses as fillers. The heat source used was a continuous wave diode laser with a wavelength range of 808-1010 nm. Glasses of the SiO{sub 2}-Al{sub 2}O{sub 3}-B{sub 2}O{sub 3}-MeO system were developed as high-temperature resistant brazing fillers whose expansion coefficients, in particular, were optimally adapted to those of the ceramics to be joined. Specially designed measuring devices help to determine both the temperature-dependent emission coefficients and the synchronously determined proportions of reflection and transmission. The glass-ceramic joints produced are free from gas inclusions and macroscopic defects and exhibit a homogenous structure. The average strength values achieved were 158 MPa for the Al{sub 2}O{sub 3} system and 190 MPa for the ZrO{sub 2} system, respectively.

Quench tests of Nb3Al small racetrack magnets

International Nuclear Information System (INIS)

Yamada, R.; Kikuchi, A.; Tartaglia, Michael Albert; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Kotelnikov, S.; Lamm, Michael J.; Fermilab; NIMC, Tsukuba; KEK, Tsukuba

2007-01-01

Two Cu stabilized Nb3Al strands, F1 (Nb matrixed) and F3 (Ta matrixed), have been made at NIMS and their Rutherford cables were made at Fermilab in collaboration with NIMS. A Small Race-track magnet using F1 Rutherford cable, the first Nb3Al dipole magnet in the world, was constructed and tested to full current at Fermilab. This magnet was tested extensively to full short sample data and its quench characteristics were studied and reported. The 3-D magnetic field calculation was done with ANSYS to find the peak field. The quench characteristics of the magnet are explained with the characteristics of the Nb3Al strand and Rutherford cable. The other Small Race-track magnet using Ta matrixed F3 strand was constructed and will be tested in the near future. The advantages and disadvantages of these Nb3Al cables are discussed

Quench tests of Nb3Al small racetrack magnets

Energy Technology Data Exchange (ETDEWEB)

Yamada, R.; Kikuchi, A.; Tartaglia, Michael Albert; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Feher, S.; Kashikhin, V.V.; Kotelnikov, S.; Lamm, Michael J.; /Fermilab /NIMC, Tsukuba /KEK, Tsukuba

2007-08-01

Two Cu stabilized Nb3Al strands, F1 (Nb matrixed) and F3 (Ta matrixed), have been made at NIMS and their Rutherford cables were made at Fermilab in collaboration with NIMS. A Small Race-track magnet using F1 Rutherford cable, the first Nb3Al dipole magnet in the world, was constructed and tested to full current at Fermilab. This magnet was tested extensively to full short sample data and its quench characteristics were studied and reported. The 3-D magnetic field calculation was done with ANSYS to find the peak field. The quench characteristics of the magnet are explained with the characteristics of the Nb3Al strand and Rutherford cable. The other Small Race-track magnet using Ta matrixed F3 strand was constructed and will be tested in the near future. The advantages and disadvantages of these Nb3Al cables are discussed.

Humeral stress remodelling locations differ in Thoroughbred racehorses training and racing on dirt compared to synthetic racetrack surfaces.

Science.gov (United States)

Dimock, A N; Hoffman, K D; Puchalski, S M; Stover, S M

2013-03-01

Veterinarians have observed a putative change in the location of humeral stress remodelling in Thoroughbred racehorses with change from dirt to synthetic racetrack surfaces. To determine whether the location and severity of humeral stress remodelling differs between Thoroughbred racehorses exercising on dirt and synthetic racetrack surfaces, the potential significance of different locations of stress remodelling, and the potential usefulness of scintigraphy for prevention of complete humeral fracture. Scintigraphic images of humeri from 841 Thoroughbred racehorses at 3 racetracks during 2 years before and after conversion from dirt to synthetic surfaces were evaluated for location and severity of lesions. The effects of surface on lesion distributions were examined using Chi-square or Fisher's exact tests. Archived fractured humeri were examined to determine the location and severity of stress remodelling associated with complete fracture. Databases were queried to determine whether racehorses with scintigraphic lesions suffered humeral fracture and whether racehorses with a complete humeral fracture had had a scintigraphic examination. Horses at synthetic racetracks had a greater proportion of distal humeral lesions, whereas horses at dirt racetracks had a greater proportion of caudoproximal lesions (Pdirt surfaces, and, by inference, for horses examined using scintigraphy. © 2012 EVJ Ltd.

Low charge state heavy ion production with sub-nanosecond laser.

Science.gov (United States)

Kanesue, T; Kumaki, M; Ikeda, S; Okamura, M

2016-02-01

We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

Low charge state heavy ion production with sub-nanosecond laser

Energy Technology Data Exchange (ETDEWEB)

Kanesue, T., E-mail: tkanesue@bnl.gov; Okamura, M. [Collider-Accelerator Department, Brookhaven National Laboratory, Upton, New York 11973 (United States); Kumaki, M. [Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198 (Japan); Ikeda, S. [Nishina Center for Accelerator-Based Science, RIKEN, Saitama 351-0198 (Japan); Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Kanagawa 226-8503 (Japan)

2016-02-15

We have investigated laser ablation plasma of various species using nanosecond and sub-nanosecond lasers for both high and low charge state ion productions. We found that with sub-nanosecond laser, the generated plasma has a long tail which has low charge state ions determined by an electrostatic ion analyzer even under the laser irradiation condition for highly charged ion production. This can be caused by insufficient laser absorption in plasma plume. This property might be suitable for low charge state ion production. We used a nanosecond laser and a sub-nanosecond laser for low charge state ion production to investigate the difference of generated plasma using the Zirconium target.

Preliminary study of insertion device effect on dynamic aperture using RACETRACK

International Nuclear Information System (INIS)

Chae, Yong-chul; Crosbie, E.A.

1992-01-01

We studied the effects of an insertion device (ID) on the dynamic aperture using the new version of RACETRACK. We found that the nonlinear effect of the ID is the dominant effect on the dynamic aperture reduction compared to the other multipole errors which exist in the otherwise ideal lattice. The previous study of dynamic aperture was based on the assumption that the effect of the fast oscillating terms in L. Smith's Hamiltonian is small, and hence can be neglected in the simulation. The remarkable agreement between the previous study and the current results using RACETRACK, including all effects of the fast oscillating terms, justified those assumptions at least for the APS ring

Part II. Large scale applications of Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.1 {<=} x {<=} 0.35 using laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Ahmed, M.A., E-mail: moala1947@yahoo.com [Materials Science. Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt); Bishay, Samiha T. [Department of Physics, Faculty of Girls for Art, Science and Education, Ain Shams University, Cairo (Egypt); El-dek, S.I.; Omar, G. [Materials Science. Lab (1), Physics Department, Faculty of Science, Cairo University, Giza (Egypt)

2011-07-28

Highlights: >X-ray diffractograms of Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4} samples before and after laser irradiation are characteristic of cubic spinel structure with better crystallinity after irradiation. > The crystal size of the ferrite increases after laser irradiation. > The main conduction mechanism in the investigated system is the correlated barrier hopping and it is the same before and laser irradiation. > The conductivity decreases after laser irradiation. - Abstract: Ni{sub x}Mn{sub 0.8-x}Mg{sub 0.2}Fe{sub 2}O{sub 4}; 0.1 {<=} x {<=} 0.35 was prepared by standard ceramic technique at sintering temperature 1200 deg. C using heating / cooling rate 4 deg. C/min. The samples were irradiated by Nd YAG pulsed laser with energy of the pulse 250 mJ. X-ray diffractograms reveal cubic spinel structure for all the samples before and after laser irradiation. After laser irradiation, better crystallinity was obtained in a form of an increase in the calculated crystal size. This increase was discussed as due to the change in the valence of some ions like Fe{sup 3+}, Ni{sup 2+} and Mn{sup 2+}. The conductivity of all the investigated samples decreases after laser irradiation and becomes temperature independent for a wider range than that before irradiation. This was ascribed to electron rearrangement after laser irradiation. Accordingly, these ferrites are recommended to be useful in electronic devices.

Investigation of scleral buckling by CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Maswadi, S

2001-05-01

This thesis investigates the effect of using the infrared wavelength CO{sub 2} laser (10.6{mu}m) as a localised heat source for inducing scleral buckling on eyes. Retinal detachment disease is a major cause of blindness and the scleral buckling is an important technique used in treatment. A radio-frequency excited 10.6{lambda}m laser source is used to heat collagen in the sclera above its shrinkage temperature so as to produce a localised indentation and deformation in the human eye (in vitro). Basic measurements of the onset shrinkage temperatures of porcine and human sclera are taken. Optical properties of sclera tissue at 10.6{mu}m are also determined to provide information about the interaction of the CO{sub 2} laser with the sclera. It is found that CO{sub 2} laser radiation is highly absorbed by the scleral water. Optical diffraction technique is investigated to quantify in-plane deformation in the sclera tissue as result of heating by producing grating on porcine and human sclera using the ArF laser (193nm). Photothermal deflection technique is also used to investigate scleral ablation by using the TEA and Ultrapulse CO{sub 2} laser. This technique provides a useful guide to the regime where ablation rather than heat shrinkage of collagen in the sclera will dominate using the Ultrapulse CO{sub 2} laser. A quantitative assessment of buckling using the technique of projection moire interferometry is described which allows a non-contact measurement to be made of the out-of-plane displacement by laser radiation. In-plane surface strain (shrinkage) has also been demonstrated using in-situ optical microscopy of the laser treated eye. The moire method is suitable to obtain information on buckling in real time and to obtain a three-dimensional view of the eye surface as laser treatment proceeds. A theoretical heat flow model is described for predicting the temperature profile produced in the sclera using the Ultrapulse CO{sub 2} laser. For appropriate exposure

Ablation of (GeS{sub 2}){sub 0.3}(Sb{sub 2}S{sub 3}){sub 0.7} glass with an ultra-violet nano-second laser

Energy Technology Data Exchange (ETDEWEB)

Knotek, P., E-mail: petr.knotek@upce.cz [University of Pardubice, Faculty of Chemical Technology, Joint Laboratory of Solid State Chemistry of IMC and University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); University of Pardubice, Faculty of Chemical Technology, Department of General and Inorganic Chemistry, Studentska 573, 532 10 Pardubice (Czech Republic); Navesnik, J.; Cernohorsky, T. [University of Pardubice, Faculty of Chemical Technology, Institute of Environmental and Chemical Engineering, Studentska 573, 532 10 Pardubice (Czech Republic); Kincl, M.; Vlcek, M.; Tichy, L. [Institute of Macromolecular Chemistry, AS CR, Heyrovskeho sq. 2, 162 06 Prague (Czech Republic)

2015-04-15

Highlights: • The interaction of (GeS{sub 2}){sub 0.3}(Sb{sub 2}S{sub 3}){sub 0.7} bulk glass and film with UV nanosecond laser. • Ablation process, topography of crater and structure of the material were studied. • Ablation threshold fluencies changed with the spot diameter and number of pulses. • The photo-thermal expansion of the material occurred for low laser fluency. • Laser direct writing process applicable for fabrication of passive optical elements. - Abstract: The results of an experimental study of the laser ablation of bulk and thin films of a GeSbS chalcogenide glass using UV nanosecond pulses are reported. The response of the samples to illumination conditions was studied through the use of atomic force spectroscopy, digital holographic microscopy, Raman scattering and scanning electron microscopy. The multi-pulse ablation thresholds were determined for both the bulk and thin film samples for varying number of pulses and illuminated spot diameter. The possible application of direct laser writing into the bulk and thin films of this material is presented.

Characterization of phase change Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films by laser-irradiation

Energy Technology Data Exchange (ETDEWEB)

Alvi, M.A., E-mail: alveema@hotmail.com [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Zulfequar, M. [Department of Physics, Jamia Millia Islamia, New Delhi 110025 (India); Al-Ghamdi, A.A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

2013-02-15

Highlights: Black-Right-Pointing-Pointer Effect of laser-irradiation on structure and optical band gap has been investigated. Black-Right-Pointing-Pointer The amorphous nature has been verified by X-ray diffraction and DSC measurements. Black-Right-Pointing-Pointer Laser-irradiation causes a decrease in optical band gap in Ga{sub 15}Se{sub 77}Ag{sub 8} thin films. Black-Right-Pointing-Pointer The decrease in optical band gap can be interpreted on the basis of amorphous-crystalline phase transformation. Black-Right-Pointing-Pointer Optical absorption data showed that the rules of the non-direct transitions predominate. - Abstract: Phase change Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films were prepared by thermal evaporation technique. Thin films were then irradiated by Transverse Electrical Excitation at Atmospheric Pressure (TEA) nitrogen laser for different time intervals. The X-ray structural characterization revealed the amorphous nature of as-prepared films while the laser irradiated films show the polycrystalline nature. Field Emission Scanning Electron Microscope (FESEM) has been used to study the structural changes. The results are discussed in terms of the structural aspects and amorphous to crystalline phase change in Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films. The observed changes are associated with the interaction of the incident photon and the lone-pairs electrons which affects the band gap of the Ga{sub 15}Se{sub 77}Ag{sub 8} chalcogenide thin films. The optical constants of these thin films are measured by using the absorption spectra measurements as a function of photon energy in the wavelength region 400-1100 nm. It is found that the optical band gap decreases while the absorption coefficient and extinction coefficient increases with increasing the laser-irradiation time. The decrease in the optical band gap has been explained on the basis of change in nature of films, from amorphous to polycrystalline state. The dc

A compact, all-optical, THz wave generator based on self-modulation in a slab photonic crystal waveguide with a single sub-nanometer graphene layer.

Science.gov (United States)

Asadi, R; Ouyang, Z; Mohammd, M M

2015-07-14

We design a compact, all-optical THz wave generator based on self-modulation in a 1-D slab photonic crystal (PhC) waveguide with a single sub-nanometer graphene layer by using enhanced nonlinearity of graphene. It has been shown that at the bandgap edge of higher bands of a 1-D slab PhC, through only one sub-nanometer graphene layer we can obtain a compact, high modulation factor (about 0.98 percent), self-intensity modulator at a high frequency (about 0.6 THz) and low threshold intensity (about 15 MW per square centimeter), and further a compact, all-optical THz wave generator by integrating the self-modulator with a THz photodiode or photonic mixer. Such a THz source is expected to have a relatively high efficiency compared with conventional sources based on optical methods. The proposed THz source can find wide applications in THz science and technology, e.g., in THz imaging, THz sensors and detectors, THz communication systems, and THz optical integrated logic circuits.

[Electronic and structural properties of individual nanometer-size supported metallic clusters

International Nuclear Information System (INIS)

Reifenberger, R.

1993-01-01

This report summarizes the work performed under contract DOE-FCO2-84ER45162. During the past ten years, our study of electron emission from laser-illuminated field emission tips has taken on a broader scope by addressing problems of direct interest to those concerned with the unique physical and chemical properties of nanometer-size clusters. The work performed has demonstrated that much needed data can be obtained on individual nanometer-size clusters supported on a wide-variety of different substrates. The work was performed in collaboration with R.P. Andres in the School of Chemical Engineering at Purdue University. The Multiple Expansion Cluster Source developed by Andres and his students was essential for producing the nanometer-size clusters studied. The following report features a discussion of these results. This report provides a motivation for studying the properties of nanometer-size clusters and summarizes the results obtained

Helium Ion Microscope: A New Tool for Sub-nanometer Imaging of Soft Materials

Science.gov (United States)

Shutthanandan, V.; Arey, B.; Smallwood, C. R.; Evans, J. E.

2017-12-01

High-resolution inspection of surface details is needed in many biological and environmental researches to understand the Soil organic material (SOM)-mineral interactions along with identifying microbial communities and their interactions. SOM shares many imaging characteristics with biological samples and getting true surface details from these materials are challenging since they consist of low atomic number materials. FE-SEM imaging is the main imagining technique used to image these materials in the past. These SEM images often show loss of resolution and increase noise due to beam damage and charging issues. Newly developed Helium Ion Microscope (HIM), on the other hand can overcome these difficulties and give very fine details. HIM is very similar to scanning electron microscopy (SEM) but instead of using electrons as a probe beam, HIM uses helium ions with energy ranges from 5 to 40 keV. HIM offers a series of advantages compared to SEM such as nanometer and sub-nanometer image resolutions (about 0.35 nm), detailed surface topography, high surface sensitivity, low Z material imaging (especially for polymers and biological samples), high image contrast, and large depth of field. In addition, HIM also has the ability to image insulating materials without any conductive coatings so that surface details are not modified. In this presentation, several scientific applications across biology and geochemistry will be presented to highlight the effectiveness of this powerful microscope. Acknowledgements: Research was performed using the Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at PNNL. Work was supported by DOE-BER Mesoscale to Molecules Bioimaging Project FWP# 66382.

Sub-Doppler laser cooling of potassium atoms

Energy Technology Data Exchange (ETDEWEB)

Landini, M. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy); Dipartimento di fisica, Universita di Trento, I-38123 Povo (Trento) (Italy); Roy, S.; Carcagni, L.; Trypogeorgos, D. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); Fattori, M.; Inguscio, M.; Modugno, G. [LENS and Dipartimento di Fisica e Astronomia, Universita di Firenze, I-50019 Sesto Fiorentino (Italy); INFN, Sezione di Firenze, I-50019 Sesto Fiorentino (Italy)

2011-10-15

We investigate the sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of system and an adiabatic ramping of the laser parameters allows us to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25{+-}3 {mu}K and 47{+-}5 {mu}K in high-density samples of the two isotopes {sup 39}K and {sup 41}K, respectively. Our findings should find application to other atomic systems.

Sub-Doppler laser cooling of potassium atoms

International Nuclear Information System (INIS)

Landini, M.; Roy, S.; Carcagni, L.; Trypogeorgos, D.; Fattori, M.; Inguscio, M.; Modugno, G.

2011-01-01

We investigate the sub-Doppler laser cooling of bosonic potassium isotopes, whose small hyperfine splitting has so far prevented cooling below the Doppler temperature. We find instead that the combination of a dark optical molasses scheme that naturally arises in this kind of system and an adiabatic ramping of the laser parameters allows us to reach sub-Doppler temperatures for small laser detunings. We demonstrate temperatures as low as 25±3 μK and 47±5 μK in high-density samples of the two isotopes 39 K and 41 K, respectively. Our findings should find application to other atomic systems.

Study of XUV lasers produced by a CO/sub 2/ laser

International Nuclear Information System (INIS)

Daido, H.; Miura, E.; Kitagawa, Y.; Kato, Y.; Nishihara, K.; Sawai, K.; Nakai, S.S.; Yamanaka, C.

1988-01-01

The authors present recent progress at ILE, Osaka University in plasma recombination-pumped XUV lasers produced by a CO/sub 2/ laser. One way to produce large-population inversion with this scheme is rapid cooling of the gain medium keeping a high electron density, because the three-body recombination probability is proportional to the square of the electron density. The authors used a cylinder-type target made of 30-μm thick parylene (C/sub 8/H/sub 8/) whose diameter and length are 3 and 4 mm. The laser irradiated the 2500-A thick parylene foil attached to the center of the cylinder. The fully ablated plasma expands isotropically, producing an almost uniform plasma on the cylinder wall. Then the almost fully ionized carbon plasma is cooled by heat transport from the hot plasma to the wall. The estimated cooling time is a few nanoseconds assuming classical heat transport

Growth, spectroscopy and laser operation of Ho:KY(WO{sub 4}){sub 2}

Energy Technology Data Exchange (ETDEWEB)

Jambunathan, V. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); HiLASE Centre, Institute of Physics ASCR, Za Radnicí 828, 25241 Dolní Břežany (Czech Republic); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Loiko, P.A. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n. E-43007 Tarragona (Spain); Griebner, U.; Petrov, V. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., D-12489 Berlin (Germany); Yumashev, K.V. [Center for Optical Materials and Technologies, Belarusian National Technical University, 65/17 Nezavisimosti Ave., 220013 Minsk (Belarus); and others

2016-11-15

Monoclinic Ho:KY(WO{sub 4}){sub 2} crystals doped with up to 7.5 at.% Ho are grown by the Top Seeded Solution Growth-Slow Cooling method. The evolution of their unit cell parameters in dependence on the Ho doping and temperature is studied. The polarized low-temperature (6 K) optical absorption of the Ho{sup 3+} ion is investigated in detail to determine the energy of the Stark sub-levels. Room-temperature absorption, stimulated-emission and gain cross-section spectra of Ho:KY(WO{sub 4}){sub 2} crystals are derived for polarizations parallel to the principal optical axes, E||N{sub p}, N{sub m} and N{sub g}. The maximum absorption cross-section for the {sup 5}I{sub 8}→{sup 5}I{sub 7} transition is 1.60×10{sup −20} cm{sup 2} at 1961.0 nm and the maximum stimulated-emission cross-section for the {sup 5}I{sub 7}→{sup 5}I{sub 8} transition is 2.65×10{sup −20} cm{sup 2} at 2056.3 nm (for E||N{sub m}). The radiative lifetime of the upper laser level of the Ho{sup 3+} ion ({sup 5}I{sub 7}) amounts to 4.8 ms. Continuous-wave Ho{sup 3+} laser operation is achieved under in-band pumping by a Tm laser at 1946 nm. In the microchip configuration, the maximum output power reached 205 mW at 2105 nm with a slope efficiency as high as 85%.

Surface enhanced Raman scattering of gold nanoparticles supported on copper foil with graphene as a nanometer gap

International Nuclear Information System (INIS)

Xiang, Quan; Zhu, Xupeng; Chen, Yiqin; Duan, Huigao

2016-01-01

Gaps with single-nanometer dimensions (<10 nm) between metallic nanostructures enable giant local field enhancements for surface enhanced Raman scattering (SERS). Monolayer graphene is an ideal candidate to obtain a sub-nanometer gap between plasmonic nanostructures. In this work, we demonstrate a simple method to achieve a sub-nanometer gap by dewetting a gold film supported on monolayer graphene grown on copper foil. The Cu foil can serve as a low-loss plasmonically active metallic film that supports the imaginary charge oscillations, while the graphene can not only create a stable sub-nanometer gap for massive plasmonic field enhancements but also serve as a chemical enhancer. We obtained higher SERS enhancements in this graphene-gapped configuration compared to those in Au nanoparticles on Cu film or on graphene–SiO 2 –Si. Also, the Raman signals measured maintained their fine features and intensities over a long time period, indicating the stability of this Au–graphene–Cu hybrid configuration as an SERS substrate. (paper)

Coatings synthesised by the pulsed laser ablation of a B{sub 4}C/W{sub 2}B{sub 5} ceramic composite

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar, Fann Dakar (Senegal); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050 Johannesburg (South Africa); Nuru, Z.Y.; Kotsedi, L.; Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Van Zyl, R.R. [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville campus, PO Box 1906, Bellville, 7530 (South Africa)

2015-10-30

A pellet of B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was characterised and subjected to pulsed laser ablation for the deposition of coatings on corning glass substrates. We reports an attempt to produce coatings from B{sub 4}C/W{sub 2}B{sub 5} by pulsed laser deposition (PLD). The thermal, electric and mechanical properties of B{sub 4}C/W{sub 2}B{sub 5} suggest that coatings synthesised from this composite can be used for space applications. The samples were characterised using X-ray Diffraction, Atomic Force Microscopy and Heavy Ion Elastic Recoil Detection Analysis. The characterisation of the samples deposited on soda lime corning glass showed that the laser energy used in this PLD was enough to obtain non amorphous coatings formed by some alteration of the tungsten carbide crystal lattice at room temperature, and that there was no stoichiometry transfer as would be expected from PLD. The coating also showed space applicable features worth investigating. - Highlights: • B{sub 4}C/W{sub 2}B{sub 5} ceramic composite was ablated for deposition on corning glass subtrates. • Non-amorphous coating was obtained at room temperature. • There was no stoichiometry transfer as would be expected from Pulsed Laser Deposition.

Performance of synthetic antiferromagnetic racetrack memory: domain wall versus skyrmion

KAUST Repository

Tomasello, R; Puliafito, V; Martinez, E; Manchon, Aurelien; Ricci, M; Carpentieri, M; Finocchio, G

2017-01-01

A storage scheme based on racetrack memory, where the information can be coded in a domain or a skyrmion, seems to be an alternative to conventional hard disk drive for high density storage. Here, we perform a full micromagnetic study

A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university.

Science.gov (United States)

Choi, Y H; Song, J B; Yang, D G; Kim, Y G; Hahn, S; Lee, H G

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university

Science.gov (United States)

Choi, Y. H.; Song, J. B.; Yang, D. G.; Kim, Y. G.; Hahn, S.; Lee, H. G.

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

Transport in reversibly laser-modified YBa2Cu3O/sub 7-//sub x/ superconducting thin films

International Nuclear Information System (INIS)

Krchnavek, R.R.; Chan, S.; Rogers, C.T.; De Rosa, F.; Kelly, M.K.; Miceli, P.F.; Allen, S.J.

1989-01-01

A focused argon ion laser beam in a controlled ambient is used to modify the transport properties of superconducting YBa 2 Cu 3 O/sub 7-//sub x/ thin films. The laser-modified region shows a sharp transition temperature (T/sub c/≅76 K) that is reduced from the unmodified regions of the film (T/sub c/≅87 K). In situ monitoring of the room-temperature electrical resistance is used to control the laser processing and prevent formation of the semiconducting phase. The original properties of the superconducting film can be recovered by plasma oxidation indicating that the laser-induced phase is oxygen deficient

Synchronization of sub-picosecond electron and laser pulses

International Nuclear Information System (INIS)

Rosenzweig, J.B.; Le Sage, G.P.

1999-01-01

Sub-picosecond laser-electron synchronization is required to take full advantage of the experimental possibilities arising from the marriage of modern high intensity lasers and high brightness electron beams in the same laboratory. Two particular scenarios stand out in this regard, injection of ultra-short electron pulses in short wavelength laser-driven plasma accelerators, and Compton scattering of laser photons from short electron pulses. Both of these applications demand synchronization, which is sub-picosecond, with tens of femtosecond synchronization implied for next generation experiments. The design of a microwave timing modulator system is now being investigated in more detail. (AIP) copyright 1999 American Institute of Physics

Investigation of uv N/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Jin, Y; Li, Y; Yeh, Y; Lu, C; Wang, B; Hsiang, Z

1979-02-01

By applying the theory of nitrogen molecular laser and the electric circuit theory of a Blumlein structure horizontal discharge pulsed laser, a compact N/sub 2/ laser has been developed with improved spark gap switch, transmission line and laser cavity. This laser is particularly suited to serve as a pumping light source for a dye laser. Experimental studies were performed to determine the laser output characteristics as affected by the following parameters: the electric inductance of laser cavity, the shape of the electrode, the electric inductance of spark gap, the transmission line, and the initial point of discharge.

Discharge pumped F/sub 2/ laser at 1580 A

Energy Technology Data Exchange (ETDEWEB)

Pummer, H; Hohla, K; Diegelmann, M; Reilly, J P

1979-01-01

By pumping mixtures of F/sub 2/ and He in a fast uv-preionized discharge laser emission at 1578 A, probably stemming from the /sup 3/PI/sub 2g/ ..-->.. /sup 3/PI/sub 2u/ transition in molecular fluorine have been obtained. Observed energy is 8.5 mJ in pulses of 15 ns half-width. First experimental results on laser performance and scalability are given.

Bimetallic Ag-Pt Sub-nanometer Supported Clusters as Highly Efficient and Robust Oxidation Catalysts

Energy Technology Data Exchange (ETDEWEB)

Negreiros, Fabio R. [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Halder, Avik [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Yin, Chunrong [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Singh, Akansha [Harish-Chandra Research Institute, HBNI, Chhatnag Road Jhunsi Allahabad 211019 India; Barcaro, Giovanni [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Sementa, Luca [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Tyo, Eric C. [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Pellin, Michael J. [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Bartling, Stephan [Institut für Physik, Universität Rostock, Rostock Germany; Meiwes-Broer, Karl-Heinz [Institut für Physik, Universität Rostock, Rostock Germany; Seifert, Sönke [X-ray Science Division, Argonne National Laboratory, Lemont IL USA; Sen, Prasenjit [Harish-Chandra Research Institute, HBNI, Chhatnag Road Jhunsi Allahabad 211019 India; Nigam, Sandeep [Chemistry Division, Bhabha Atomic Research Centre, Trombay Mumbai- 400 085 India; Majumder, Chiranjib [Chemistry Division, Bhabha Atomic Research Centre, Trombay Mumbai- 400 085 India; Fukui, Nobuyuki [East Tokyo Laboratory, Genesis Research Institute, Inc., Ichikawa Chiba 272-0001 Japan; Yasumatsu, Hisato [Cluster Research Laboratory, Toyota Technological Institute: in, East Tokyo Laboratory, Genesis Research Institute, Inc. Ichikawa, Chiba 272-0001 Japan; Vajda, Stefan [Materials Science Division, Argonne National Laboratory, Lemont IL USA; Nanoscience and Technology Division, Argonne National Laboratory, Lemont IL USA; Institute for Molecular Engineering, University of Chicago, Chicago IL USA; Fortunelli, Alessandro [CNR-ICCOM & IPCF, Consiglio Nazionale delle Ricerche, Pisa Italy; Materials and Process Simulation Center, California Institute of Technology, Pasadena CA USA

2017-12-29

A combined experimental and theoretical investigation of Ag-Pt sub-nanometer clusters as heterogeneous catalysts in the CO -> CO2 reaction (COox) is presented. Ag9Pt2 and Ag9Pt3 clusters are size-selected in the gas phase, deposited on an ultrathin amorphous alumina support, and tested as catalysts experimentally under realistic conditions and by first-principles simulations at realistic coverage. Insitu GISAXS/TPRx demonstrates that the clusters do not sinter or deactivate even after prolonged exposure to reactants at high temperature, and present comparable, extremely high COox catalytic efficiency. Such high activity and stability are ascribed to a synergic role of Ag and Pt in ultranano-aggregates, in which Pt anchors the clusters to the support and binds and activates two CO molecules, while Ag binds and activates O-2, and Ag/Pt surface proximity disfavors poisoning by CO or oxidized species.

Imaging and Patterning on Nanometer Scale Using Coherent EUV Light

International Nuclear Information System (INIS)

Wachulak, P.W.; Fiedorowicz, H.; Bartnik, A.; Marconi, M.C.; Menoni, C.S.; Rocca, J.J.

2010-01-01

Extreme ultraviolet (EUV) covers wavelength range from about 5 nm to 50 nm. That is why EUV is especially applicable for imaging and patterning on nanometer scale length. In the paper periodic nanopatterning realized by interference lithography and high resolution holographic nanoimaging performed in a Gabor in-line scheme are presented. In the experiments a compact table top EUV laser was used. Preliminary studies on using a laser plasma EUV source for nanoimaging are presented as well. (author)

Distal hindlimb kinematics of galloping Thoroughbred racehorses on dirt and synthetic racetrack surfaces.

Science.gov (United States)

Symons, J E; Garcia, T C; Stover, S M

2014-03-01

The effect of racetrack surface (dirt or synthetic) on distal hindlimb kinematics of racehorses running at competition speeds is not known. To compare distal hindlimb and hoof kinematics during stance of breezing (unrestrained gallop) racehorses between dirt and synthetic surfaces. Two-dimensional kinematic video analysis of 5 Thoroughbred racehorses galloping at high speeds (12-17 m/s) on a dirt racetrack and a synthetic racetrack. The positions of kinematic markers applied to the left hindlimb were recorded at 500 Hz. Position, velocity and acceleration of joint angles and hoof translation during stance were calculated in the sagittal plane. Peak translational and angular kinematic values were compared between the dirt and synthetic race surfaces using mixed model analyses of covariance. Maximum and heel-strike metatarsophalangeal (fetlock) angles were greater (Pdirt surface than on the synthetic surface. Maximum fetlock angle occurred earlier during stance on the dirt surface (Pdirt surface (Pdirt surface than on a synthetic surface. Synthetic race surfaces may mitigate risk of injury to hindlimb fetlock structures by reducing fetlock hyperextension and associated strains in fetlock support structures. Differences in hoof slide may contribute to different distal hindlimb kinematics between surfaces. © 2013 EVJ Ltd.

Lithium niobate bulk crystallization promoted by CO{sub 2} laser radiation

Energy Technology Data Exchange (ETDEWEB)

Ferreira, N.M., E-mail: nmferreira@ua.pt [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Costa, F.M. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal); Nogueira, R.N. [Instituto de Telecomunicacoes, 3810-193 Aveiro (Portugal); Graca, M.P.F. [i3N - Aveiro, Physics Department, Aveiro University, Campus Universitario de Santiago, 3810-193 Aveiro (Portugal)

2012-09-15

Highlights: Black-Right-Pointing-Pointer Crystallization of LiNbO{sub 3} nanocrystals in a SiO{sub 2} matrix by CO{sub 2} laser irradiation process. Black-Right-Pointing-Pointer Samples heat-treated at 650 Degree-Sign C (4 h) and laser treated (4 W/500 s) show similar morphology. Black-Right-Pointing-Pointer Glass-ceramics produced by laser process requires a very low processing time. - Abstract: The crystallization induced by laser radiation is a very promising technique to promote glass/ceramic transformation, being already used to produce crystalline patterns on glass surfaces. In this work, a SiO{sub 2}-Li{sub 2}O-Nb{sub 2}O{sub 5} glass, prepared by the sol-gel route, was submitted to CO{sub 2} laser radiation and conventional heat-treatments in order to induce the LiNbO{sub 3} crystallization. The structure and morphology of the samples prepared by both routes was analyzed as a function of exposure time, radiation power and heat-treatment temperatures by XRD, Raman spectroscopy and SEM. The results reveal a correlation between the crystallization degree of LiNbO{sub 3} particles and glass matrix with the heat treatment type and experimental parameters. An heat-treatment at 650 Degree-Sign C/4 h was necessary to induce crystallization in heat treatments samples while 4 W/500 s was enough for laser radiation ones, corresponding a reduction time processing of {approx}14 000 s.

Quench tests and FEM analysis of Nb3Al Rutherford cables and small racetrack magnets

International Nuclear Information System (INIS)

Yamada, R.; Kikuchi, A.; Chlachidze, G.; Ambrosio, G.; Andreev, N.; Barzi, E.; Carcagno, R.; Kashikin, V.V.; Kotelnikov, S.; Lamm, M.; Novitski, I.

2008-01-01

In collaboration between NIMS and Fermilab, we have made copper stabilized Nb 3 Al Rutherford cables, using Nb-matrixed and Ta-matrixed strands. First these cables were investigated at high current in low self field using a flux pump. Using these Rutherford cables, we built and tested small racetrack magnets. The magnet made with the Nb-matrixed strand showed the flux jump instability in low field. The small racetrack magnet wound with the Ta-matrixed Nb 3 Al Rutherford cable was very stable at 4.5 K operation without any instability, as well as at 2.2 K operation. With the successful operation of the small racetrack magnet up to its short sample data, the feasibility of the Nb 3 Al strand and its Rutherford cable for their application to high field magnets is established. The characteristics of Nb 3 Al Rutherford cable is compared with that of the Nb 3 Sn Rutherford cable and the advantages of Nb 3 Al Rutherford cable are discussed

Performance of synthetic antiferromagnetic racetrack memory: domain wall versus skyrmion

International Nuclear Information System (INIS)

Tomasello, R; Puliafito, V; Martinez, E; Manchon, A; Ricci, M; Carpentieri, M; Finocchio, G

2017-01-01

A storage scheme based on racetrack memory, where the information can be coded in a domain or a skyrmion, seems to be an alternative to conventional hard disk drive for high density storage. Here, we perform a full micromagnetic study of the performance of synthetic antiferromagnetic (SAF) racetrack memory in terms of velocity and sensitivity to defects by using experimental parameters. We find that, to stabilize a SAF skyrmion, the Dzyaloshinskii–Moriya interaction in the top and the bottom ferromagnet should have an opposite sign. The velocity of SAF skyrmions and SAF Néel domain walls are of the same order and can reach values larger than 1200 m s −1 if a spin–orbit torque from the spin-Hall effect with opposite sign is applied to both ferromagnets. The presence of disordered anisotropy in the form of randomly distributed grains introduces a threshold current for both SAF skyrmions and SAF domain walls motions. (paper)

A FODO racetrack ring for nuSTORM: design and optimization

Energy Technology Data Exchange (ETDEWEB)

Liu, A.; Bross, A.; Neuffer, D.

2017-07-01

The goal of nuSTORM is to provide well-defined neutrino beams for precise measurements of neutrino cross-sections and oscillations. The nuSTORM decay ring is a compact racetrack storage ring with a circumference of ~ 480 m that incorporates large aperture (60 cm diameter) magnets. There are many challenges in the design. In order to incorporate the Orbit Combination section (OCS), used for injecting the pion beam into the ring, a dispersion suppressor is needed adjacent to the OCS . Concurrently, in order to maximize the number of useful muon decays, strong bending dipoles are needed in the arcs to minimize the arc length. These dipoles create strong chromatic effects, which need to be corrected by nonlinear sextupole elements in the ring. In this paper, a FODO racetrack ring design and its optimization using sextupolar fields via both a Genetic Algorithm (GA) and a Simulated Annealing (SA) algorithm will be discussed.

Performance of synthetic antiferromagnetic racetrack memory: domain wall versus skyrmion

KAUST Repository

Tomasello, R

2017-06-20

A storage scheme based on racetrack memory, where the information can be coded in a domain or a skyrmion, seems to be an alternative to conventional hard disk drive for high density storage. Here, we perform a full micromagnetic study of the performance of synthetic antiferromagnetic (SAF) racetrack memory in terms of velocity and sensitivity to defects by using experimental parameters. We find that, to stabilize a SAF skyrmion, the Dzyaloshinskii–Moriya interaction in the top and the bottom ferromagnet should have an opposite sign. The velocity of SAF skyrmions and SAF Néel domain walls are of the same order and can reach values larger than 1200 m s−1 if a spin–orbit torque from the spin-Hall effect with opposite sign is applied to both ferromagnets. The presence of disordered anisotropy in the form of randomly distributed grains introduces a threshold current for both SAF skyrmions and SAF domain walls motions.

Focusing magnets for HIF based on racetracks

Energy Technology Data Exchange (ETDEWEB)

Martovetsky, N N; Manahan, R R

2000-09-11

Heavy Ion Fusion (HIF) is considered a promising path to a practical fusion reactor. A driver for a HIF reactor will require a large number of quadrupole arrays to focus heavy ion beams. A conceptual design, and trade off studies of the quadrupole array based on racetracks are presented. A comparison with a conventional shell magnet is given and advantages and disadvantages are discussed. A more detailed design of a single quadrupole for the High Current experiment (HCX) is presented and discussed.

Diffraction efficiency enhancement of femtosecond laser-engraved diffraction gratings due to CO{sub 2} laser polishing

Energy Technology Data Exchange (ETDEWEB)

Choi, Hun-Kook [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Chosun University, Gwangju (Korea, Republic of); Jung, Deok; Sohn, Ik-Bu; Noh, Young-Chul; Lee, Yong-Tak [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kim, Jin-Tae [Chosun University, Gwangju (Korea, Republic of); Ahsan, Shamim [Khulna University, Khulna (Bangladesh)

2014-11-15

This research demonstrates laser-assisted fabrication of high-efficiency diffraction gratings in fused-silica glass samples. Initially, femtosecond laser pulses are used to engrave diffraction gratings on the glass surfaces. Then, these micro-patterned glass samples undergo CO{sub 2} laser polishing process. unpolished diffraction gratings encoded in the glass samples show an overall diffraction efficiency of 18.1%. diffraction gratings imprinted on the glass samples and then polished four times by using a CO{sub 2} laser beam attain a diffraction efficiency of 32.7%. We also investigate the diffraction patterns of the diffraction gratings encoded on fused-silica glass surfaces. The proposed CO{sub 2} laser polishing technique shows great potential in patterning high-efficiency diffraction gratings on the surfaces of various transparent materials.

Racetrack microtron rf system

International Nuclear Information System (INIS)

Tallerico, P.J.; Keffeler, D.R.

1985-01-01

The rf system for the National Bureau of Standards (NBS)/Los Alamos cw racetrack microtron is described. The low-power portion consists of five 75-W amplifers that drive two input ports in each of two chopper deflection cavities and one port in the prebuncher cavity. A single 500-kW klystron drives four separate 2380-MHz cavity sections: the two main accelerator sections, a capture section, and a preaccelerator section. The phases and amplitudes in all cavities are controlled by electronic or electromechanical controls. The 1-MW klystron power supply and crowbar system were purchased as a unit; several modifications are described that improve power-supply performance. The entire rf system has been tested and shipped to the NBS, and the chopper-buncher system has been operated with beam at the NBS. 5 refs., 2 figs

Micro/nanostructures formation by femtosecond laser surface processing on amorphous and polycrystalline Ni{sub 60}Nb{sub 40}

Energy Technology Data Exchange (ETDEWEB)

Peng, Edwin, E-mail: edwin.peng@huskers.unl.edu [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Tsubaki, Alfred; Zuhlke, Craig A. [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Wang, Meiyu [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Bell, Ryan [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Lucis, Michael J. [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Anderson, Troy P.; Alexander, Dennis R. [Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States); Gogos, George; Shield, Jeffrey E. [Department of Mechanical and Materials Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

2017-02-28

Highlights: • Femtosecond laser processing of glass-forming Ni{sub 60}Nb{sub 40} produce surface structures. • Cross sectioning, imaging, & TEM sample preparation with dual-beam SEM. • Low laser fluence surface structures’ form by ablation. • High laserfluence surface structures form by ablation and fluid flow. - Abstract: Femtosecond laser surface processing is a technology that can be used to functionalize many surfaces, imparting specialized properties such as increased broadband optical absorption or superhydrophilicity/superhydrophobicity. In this study, two unique classes of surface structures, below surface growth (BSG) and above surface growth (ASG) mounds, were formed by femtosecond laser surface processing on amorphous and polycrystalline Ni{sub 60}Nb{sub 40} with two different grain sizes. Cross sectional imaging of these mounds revealed thermal evidence of the unique formation processes for each class of surface structure. BSG mounds formed on all three substrates using the same laser parameters had similar surface morphology. The microstructures in the mounds were unaltered compared with the substrate before laser processing, suggesting their formation was dominated by preferential valley ablation. ASG mounds had similar morphology when formed on the polycrystalline Ni{sub 60}Nb{sub 40} substrates with 100 nm and 2 μm grain size. However, the ASG mounds had significantly wider diameter and higher peak-to-valley heights when the substrate was amorphous Ni{sub 60}Nb{sub 40}. Hydrodynamic melting was primarily responsible for ASG mound formation. On amorphous Ni{sub 60}Nb{sub 40} substrates, the ASG mounds are most likely larger due to lower thermal diffusivity. There was clear difference in growth mechanism of femtosecond laser processed BSG and ASG mounds, and grain size does not appear to be a factor.

High-quality laser cutting of stainless steel in inert gas atmosphere by ytterbium fibre and CO{sub 2} lasers

Energy Technology Data Exchange (ETDEWEB)

Golyshev, A A; Malikov, A G; Orishich, A M; Shulyat' ev, V B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2014-03-28

Processes of cutting stainless steel by ytterbium fibre and CO{sub 2} lasers have been experimentally compared. The cut surface roughnesses for 3- and 5-mm-thick stainless steel sheets are determined. The absorption coefficient of laser radiation during cutting is measured. It is established that the power absorbed by metal during cutting by the CO{sub 2} laser exceeds that for the ytterbium laser (provided that the cutting speed remains the same). The fact that the maximum cutting speed of the CO{sub 2} laser is lower than that of the ytterbium fibre laser is explained. (laser technologies)

RF cavity for the Novosibirsk race-track microtron-recuperator

International Nuclear Information System (INIS)

Gavrilov, N.; Kuptsov, I.; Kurkin, G.; Mironenko, L.; Petrov, V.; Sedlyarov, I.; Veshcherevich, V.

1994-01-01

Geometry, engineering design and characteristics of a 181 MHz RF cavity are described. The cavity has copper clad stainless steel walls and has a Q of 42,000 and a shunt impedance of 8.5 MOhm. The cavities of that type are parts of an RF system of a CW race-track microtron-recuperator (RTMR). 10 refs.; 16 figs.; 1 tab

Dependence of Parameters of Laser-Produced Au Plasmas on the Incident Laser Energy of Sub-Nanosecond and Picosecond Laser Pulses

International Nuclear Information System (INIS)

Woryna, E.; Badziak, J.; Makowski, J.; Parys, P.; Vankov, A.B.; Wolowski, J.; Krasa, J.; Laska, L.; Rohlena, K.

2001-01-01

The parameters of Au plasma as functions of laser energy for ps pulses are presented and compared with the ones for sub-ns pulses at nearly the same densities of laser energy. The experiments were performed at the IPPLM with the use of CPA (chirped pulse amplification) Nd:glass laser system. Thick Au foil targets were irradiated by normally incident focused laser beams with maximum intensities of 8x10 16 and 2x10 14 W/cm 2 for ps and sub-ns laser pulses, respectively. The characteristics of ion streams were investigated with the use of ion diagnostics methods based on the time-of flight technique. In these experiments the laser energies were changed in the range from 90 to 700 mJ and the measurements were performed at a given focus position FP = 0 and along the target normal for both the laser pulses. The charge carried by the ions, the maximum ion velocities of fast and thermal ion groups, the maximum ion current density as well as the area of photopeak in dependence on the incident laser energy for sub-ns and ps pulses were investigated and discussed. (author)

Vacuum laser acceleration using a radially polarized CO sub 2 laser beam

CERN Document Server

Liu, Y; He, P

1999-01-01

Utilizing the high-power, radially polarized CO sub 2 laser and high-quality electron beam at the Brookhaven Accelerator Test Facility, a vacuum laser acceleration scheme is proposed. In this scheme, optics configuration is simple, a small focused beam spot size can be easily maintained, and optical damage becomes less important. At least 0.5 GeV/m acceleration gradient is achievable by 1 TW laser power.

Phase constituents and microstructure of laser cladding Al{sub 2}O{sub 3}/Ti{sub 3}Al reinforced ceramic layer on titanium alloy

Energy Technology Data Exchange (ETDEWEB)

Li Jianing [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Chen Chuanzhong, E-mail: czchen@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Lin Zhaoqing [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (Ministry of Education), Department of Materials Science, Shandong University, Jing Shi Road 17923, Jinan 250061, Shandong (China); Squartini, Tiziano [INFM - Department of Physics, Siena University, Siena 53100 (Italy)

2011-04-07

Research highlights: > In this study, Fe{sub 3}Al has been chosen as cladding powder due to its excellent properties of wear resistance and high strength, etc. > Laser cladding of Fe{sub 3}Al + TiB{sub 2}/Al{sub 2}O{sub 3} pre-placed alloy powder on Ti-6Al-4V alloy substrate can form the Ti{sub 3}Al/Fe{sub 3}Al + TiB{sub 2}/Al{sub 2}O{sub 3} ceramic layer, which can increase wear resistance of substrate. > In cladding process, Al{sub 2}O{sub 3} can react with TiB{sub 2} leading to formation of Ti{sub 3}Al and B. > This principle can be used to improve the Fe{sub 3}Al + TiB{sub 2} laser-cladded coating. - Abstract: Laser cladding of the Fe{sub 3}Al + TiB{sub 2}/Al{sub 2}O{sub 3} pre-placed alloy powder on Ti-6Al-4V alloy can form the Ti{sub 3}Al/Fe{sub 3}Al + TiB{sub 2}/Al{sub 2}O{sub 3} ceramic layer, which can greatly increase wear resistance of titanium alloy. In this study, the Ti{sub 3}Al/Fe{sub 3}Al + TiB{sub 2}/Al{sub 2}O{sub 3} ceramic layer has been researched by means of electron probe, X-ray diffraction, scanning electron microscope and micro-analyzer. In cladding process, Al{sub 2}O{sub 3} can react with TiB{sub 2} leading to formation of amount of Ti{sub 3}Al and B. This principle can be used to improve the Fe{sub 3}Al + TiB{sub 2} laser cladded coating, it was found that with addition of Al{sub 2}O{sub 3}, the microstructure performance and micro-hardness of the coating was obviously improved due to the action of the Al-Ti-B system and hard phases.

A dye center laser pumped by emission from copper vapor and dye lasers

Energy Technology Data Exchange (ETDEWEB)

Loktyushin, A A; Chernyshev, A I; Soldatov, A N; Sukhanov, V B; Troitskiy, V O

1983-01-01

LiF:F2+ lasing is reported for the case of pumping by total emission with frequencies of 570.6 and 578.2 nanometers or by a single yellow copper vapor laser line and emission from an oxazene-17 dye laser excited by emission from a Cu laser. Lasing with a mean power level of 23 milliwatts with a maximum at 911 nanometers is obtained. The maximum efficiency was 3.4 percent with pumping of the dye centers by emission from the yellow Cu laser line. The lasing characteristics of the laser for all the types of pumping used are given.

Electron acceleration by CO/sub 2/ laser

International Nuclear Information System (INIS)

Fujita, H.; Kitagawa, Y.; Daido, H.

1986-01-01

Experiments on electron acceleration have been performed by LEKKO VIII CO/sub 2/ laser system. The laser light was focused by an off-axis parabolic mirror with the F-number of 1.5 and irradiated to thin foil and pipe targets in order to obtain uniform underdense plasmas. Energy spectrum of electrons was measured by an electron spectrometer in the range of 0.3-1.1 MeV. In the single frequency case, electrons up to 1 MeV were observed in the direction of the laser axis for the laser intensity above 1.6 x 10/sup 14/ W/cm/sup 2/ which was equal to the estimated threshold for forward Raman scattering. Amount of high energy electrons depended on the interaction length and the background hot electron temperature. More electrons could resonate with the plasma wave for the higher hot electron temperature. This was confirmed by particle simulation. In most experiments, the plasma density was estimated of about 0.1 n/sub c/. When the plasma density was reduced to 0.01 n/sub c/ using pre-pulse, high energy electrons were not observed because of the low background hot electron temperature and the higher instability threshold. In the two frequency case, energetic electron beam injection is planned for efficient coupling with fast plasma wave. Pipe target seems to be hopeful because 1) the laser light is confined by the plasma fiber and 2) the phase velocity of the plasma wave is controlled by the transverse mode

Indium-modified Yb:KLu(WO{sub 4}){sub 2} crystal: Growth, spectroscopy and laser operation

Energy Technology Data Exchange (ETDEWEB)

Serres, J.M. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain); Mateos, X., E-mail: xavier.mateos@urv.cat [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain); Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., Berlin D-12489 (Germany); Loiko, P. [ITMO University, 49 Kronverkskiy pr., St. Petersburg 197101 (Russian Federation); Griebner, U.; Petrov, V. [Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, 2A Max-Born-Str., Berlin D-12489 (Germany); Yumashev, K. [Center for Optical Materials and Technologies (COMT), Belarusian National Technical University, 65/17 Nezavisimosti Ave., Minsk 220013 (Belarus); Aguiló, M.; Díaz, F. [Física i Cristallografia de Materials i Nanomaterials (FiCMA-FiCNA), Universitat Rovira i Virgili (URV), Campus Sescelades, c/ Marcellí Domingo, s/n., Tarragona E-43007 (Spain)

2017-03-15

We report on the growth, spectroscopic and laser characterization of a novel monoclinic laser crystal, Yb,In:KLu(WO{sub 4}){sub 2} (Yb,In:KLuW). The absorption, stimulated-emission and gain cross-section spectra of 3.5 at% Yb, 5.5 at% In-doped KLuW are determined at room temperature with polarized light and compared with those for Yb,In:KYW, as well as singly Yb-doped KLuW and KYW crystals. It is found that the introduction of In results in a decrease of the transition cross-sections and in a spectral broadening of the absorption and emission bands. Such a broadening is more pronounced for light polarization E ||N{sub p}. For Yb,In:KLuW, the maximum σ{sub abs} is 9.9×10{sup –20} cm{sup 2} at 980.9 nm for E ||N{sub m} and the corresponding bandwidth of the absorption peak is 3.7 nm. The radiative lifetime for Yb{sup 3+} ions is 237±5 µs. The stimulated-emission cross-sections are σ{sub SE}(m)=2.4×10{sup –20} cm{sup 2} at 1022.4 nm and σ{sub SE}(p)=1.3×10{sup –20} cm{sup 2} at 1039.1 nm corresponding to an emission bandwidth of >30 nm and >35 nm, respectively. The diode-pumped N{sub g}-cut Yb,In:KLuW microchip laser generated 4.11 W at 1042–1048 nm with a slope efficiency of 78%. The Yb,In:KLuW crystal is very promising for the generation of sub-100 fs pulses in mode-locked lasers due to its broadband emission characteristics.

Development of a large aperture Nb3Sn racetrack quadrupole magnet

International Nuclear Information System (INIS)

Ferracin, Paolo; Bartlett, Scott E.; Caspi, Shlomo; Dietderich, Daniel R.; Gourlay, Steven A.; Hannaford, Charles R.; Hafalia, AurelioR.; Lietzke, Alan F.; Mattafirri, Sara; McInturff, Alfred D.; Nyman, Mark; Sabbi, Gianluca

2005-01-01

The U.S. LHC Accelerator Research Program (LARP), a collaboration between BNL, FNAL, LBNL, and SLAC, has among its major objectives the development of advanced magnet technology for an LHC luminosity upgrade. The LBNL Superconducting Magnet Group supports this program with a broad effort involving design studies, Nb 3 Sn conductor development, mechanical models, and basic prototypes. This paper describes the development of a large aperture Nb 3 Sn racetrack quadrupole magnet using four racetrack coils from the LBNL Subscale Magnet (SM) Program. The magnet provides a gradient of 95 T/m in a 110 mm bore, with a peak field in the conductor of 11.2 T. The coils are prestressed by a mechanical structure based on a pre-tensioned aluminum shell, and axially supported with aluminum rods. The mechanical behavior has been monitored with strain gauges and the magnetic field has been measured. Results of the test are reported and analyzed

[Electronic and structural properties of individual nanometer-size supported metallic clusters]. Final performance report

Energy Technology Data Exchange (ETDEWEB)

Reifenberger, R.

1993-09-01

This report summarizes the work performed under contract DOE-FCO2-84ER45162. During the past ten years, our study of electron emission from laser-illuminated field emission tips has taken on a broader scope by addressing problems of direct interest to those concerned with the unique physical and chemical properties of nanometer-size clusters. The work performed has demonstrated that much needed data can be obtained on individual nanometer-size clusters supported on a wide-variety of different substrates. The work was performed in collaboration with R.P. Andres in the School of Chemical Engineering at Purdue University. The Multiple Expansion Cluster Source developed by Andres and his students was essential for producing the nanometer-size clusters studied. The following report features a discussion of these results. This report provides a motivation for studying the properties of nanometer-size clusters and summarizes the results obtained.

Laser nanostructured Co nanocylinders-Al{sub 2}O{sub 3} cermets for enhanced & flexible solar selective absorbers applications

Energy Technology Data Exchange (ETDEWEB)

Karoro, A., E-mail: angela@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Nuru, Z.Y.; Kotsedi, L.; Bouziane, Kh. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa); Mothudi, B.M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Physics Dept., University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk ridge, PO Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure road, Somerset West 7129, PO Box 722, Western Cape (South Africa)

2015-08-30

Highlights: • Co-Al{sub 2}O{sub 3} was synthesized by electrodeposition & femtosecond laser structuring. • The ultrafast laser structuring significantly increases the solar absorption. • Co-Al{sub 2}O{sub 3} exhibited 0.98 solar absorptance and 0.03 thermal emittance. - Abstract: We report on the structural and optical properties of laser surface structured Co nanocylinders-Al{sub 2}O{sub 3} cermets on flexible Aluminium substrate for enhanced solar selective absorbers applications. This new family of solar selective absorbers coating consisting of Co nanocylinders embedded into nanoporous alumina template which were produced by standard electrodeposition and thereafter submitted to femtosecond laser surface structuring. While their structural and chemical properties were investigated by X-ray diffraction, scanning electron microscopy, energy dispersive spectrometry and atomic force microscopy, their optical characteristics were investigated by specular & diffuse reflectance. The optimized samples exhibit an elevated optical absorptance α(λ) above 98% and an emittance ε(λ) ∼0.03 in the spectral range of 200–1100 nm. This set of values was suggested to be related to several surface and volume phenomena such as light trapping, plasmon surface effect as well as angular dependence of light reflection induced by the ultrafast laser multi-scale structuring.

NBS-LASL racetrack microtron

International Nuclear Information System (INIS)

Penner, S.; Debenham, P.H.; Green, D.C.

1980-01-01

The NBS-LASL racetrack microtron (RTM) is a joint project of the National Bureau of Standards (NBS) and the Los Alamos Scientific Laboratory (LASL). This is a new accelerator research project whose goal is to determine the feasibility of building a high-energy, high-current, cw electron accelerator using beam recirculation and room-temperature rf acceleration structures. The NBS-LASL RTM is being designed and built to develop the required technology for a large national 1 to 2 GeV cw accelerator for nuclear physics research and to prove experimentally that high currents can be accelerated successfully in an RTM. Some of the parameters of the NBS-LASL RTM are 185 MeV final energy, 550 μA maximum current, 15 passes, 12 MeV one-pass energy gain, and 2380 MHz frequency. One 450 kW cw klystron will supply rf power to both the 5 MeV injector and the 12 MeV linac in the RTM

Particularities of interaction of CO sub 2 -laser radiation with oxide materials

CERN Document Server

Salikhov, T P

2002-01-01

The results of experimental investigation of vapor phase influence on the interaction parameters of the infrared laser radiation with oxide materials (Al sub 2 O sub 3 , ZrO sub 2 , CeO sub 2) have been presented. A phenomenon of laser radiation by the samples investigated under laser heating has been experimentally discovered for the first time. This phenomenon connected with forming of the stable vapor shell above the irradiated samples was expressed as a sharp drop in temperature on the heating curve and called as an absorption flash. (author)

Studies on laser material processing with nanosecond and sub-nanosecond and picosecond and sub-picosecond pulses

Science.gov (United States)

Zhang, Jie; Tao, Sha; Wang, Brian; Zhao, Jay

2016-03-01

In this paper, laser ablation of widely used metal (Al, Cu. stainless-steel), semiconductor (Si), transparent material (glass, sapphire), ceramic (Al2O3, AlN) and polymer (PI, PMMA) in industry were systematically studied with pulse width from nanosecond (5-100ns), picosecond (6-10ps) to sub-picosecond (0.8-0.95ps). A critical damage zone (CDZ) of up to 100um with ns laser, efficiency were also investigated. This is to explore how to provide industry users the best laser solution for device micro-fabrication with best price. Our studies of cutting and drilling with ns, ps, and sub-ps lasers indicate that it is feasible to achieve user accepted quality and speed with cost-effective and reliable laser by optimizing processing conditions.

Crystallization of 21.25Gd{sub 2}O{sub 3}-63.75MoO{sub 3}-15B{sub 2}O{sub 3} glass induced by femtosecond laser at the repetition rate of 250 kHz

Energy Technology Data Exchange (ETDEWEB)

Zhong, M.J.; Han, Y.M. [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China); Liu, L.P. [Hunan Biological and Electromechanical Polytechnic, Changsha 410126 (China); Zhou, P.; Du, Y.Y.; Guo, Q.T. [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China); Ma, H.L., E-mail: mahl@staff.shu.edu.cn [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China); Dai, Y. [Department of Physics, Shanghai University, 99 Shangda Road, Shanghai 200444 (China)

2010-12-01

We report the formation of {beta}'-Gd{sub 2}(MoO{sub 4}){sub 3} (GMO) crystal on the surface of the 21.25Gd{sub 2}O{sub 3}-63.75MoO{sub 3}-15B{sub 2}O{sub 3} glass, induced by 250 kHz, 800 nm femtosecond laser irradiation. The morphology of the modified region in the glass was clearly examined by scanning electron microscopy (SEM). By micro-Raman spectra, the laser-induced crystals were confirmed to be GMO phases and it is found that these crystals have a strong dependence on the number and power of the femtosecond laser pulses. When the irradiation laser power was 900 mW, not only the Raman peaks of GMO crystals but also some new peaks at 214 cm{sup -1}, 240 cm{sup -1}, 466 cm{sup -1}, 664 cm{sup -1} and 994 cm{sup -1}which belong to the MoO{sub 3} crystals were observed. The possible mechanisms are proposed to explain these phenomena.

Spatially selective Er/Yb-doped CaF{sub 2} crystal formation by CO{sub 2} laser exposure

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo, E-mail: kslim@chungbuk.ac.kr

2014-10-30

Highlights: • Oxyfluoride glass–ceramics containing CaF{sub 2} nanocrystals doped with Er{sup 3+} and Yb{sup 3+} ions were formed on the glass surface by CO{sub 2} laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF{sub 2} nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO{sub 2} laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF{sub 2} and miner Ca{sub 2}SiO{sub 4} nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment.

Spatially selective Er/Yb-doped CaF{sub 2} crystal formation by CO{sub 2} laser exposure

Energy Technology Data Exchange (ETDEWEB)

Kim, Dong-Seon; Lee, Jin-Ho; Lim, Ki-Soo, E-mail: kslim@chungbuk.ac.kr

2015-04-15

Highlights: • Oxyfluoride glass–ceramics containing CaF{sub 2} nanocrystals doped with Er{sup 3+} and Yb{sup 3+} ions were formed on the glass surface by CO{sub 2} laser and a heat gun exposure. • Most of Er and Yb ions were distributed inside CaF{sub 2} nanocrystals and fluorine loss was observed in the EDS element maps. • IR-to-VIS upconversion emission efficiency of laser annealed glass ceramics was much increased and compared with that of the furnace-annealed glass ceramics. • Distributed volume of the glass ceramics were estimated by a confocal fluorescence microscope imaging. - Abstract: We report the glass–ceramic precipitation on the oxyfluoride glass surface by spatially selective annealing with a CO{sub 2} laser and a heat gun exposure. X-ray diffraction analysis showed the formation of major CaF{sub 2} and miner Ca{sub 2}SiO{sub 4} nanoparticles. We observed ∼100 nm nanoparticle aggregation by tunneling electron microscopy and element distribution in glass and crystal phases. Spatial distribution of glass ceramics near the glass surface was probed by confocal fluorescence microscope by using much enhanced emission from the Er ions in the laser-treated area. Strong emissions at 365 nm excitation and visible up-conversion emissions at 980 nm excitation also indicated well incorporation of Er and Yb ions into a crystalline environment.

Nd:YAG laser irradiation effects on electrical properties of polycrystalline Li{sub 0.5}Fe{sub 2.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Mane, Maheshkumar L., E-mail: mane.maheshkumar@hotmail.com [Department of physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India); Dhage, V.N.; Shirsath, Sagar E. [Department of physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India); Sundar, R.; Ranganathan, K.; Oak, S.M. [Solid State Laser Division, Raja Ramanna Centre for Advanced Technology, Indore (M.P.) (India); Jadhav, K.M. [Department of physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431 004 (India)

2012-01-15

Highlights: > Standard double sintering ceramic method. > Infrared and electrical properties of spinel ferrite. > Laser irradiation study. > Conduction mechanism. > Temperature dependence dielectric properties. - Abstract: The polycrystalline spinel structured Li{sub 0.5}Fe{sub 2.5}O{sub 4} ferrite have been prepared by conventional double sintering ceramic method. The samples were palletized and irradiated by Nd:YAG laser with different laser fluencies and characterized by infrared spectroscopy and DC electrical resistivity in order to obtain phase, crystal structure and conduction mechanism in pristine and irradiated samples. The infrared spectroscopy is employed to study the local symmetry and conduction mechanism in crystalline solids before and after irradiation. The DC electrical resistivity measured by two-probe technique from room temperature to beyond Curie temperature with steps of 10 K increases after laser irradiation. Variation of dielectric properties like dielectric constant and dielectric loss tangent is also measured as a function of temperature. A significant reduction in the values of dielectric constant and dielectric loss tangent has been observed with the increase of laser dose.

Effects of ZrB{sub 2} on substructure and wear properties of laser melted in situ ZrB{sub 2p}/6061Al composites

Energy Technology Data Exchange (ETDEWEB)

Zeng, Yida [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Chao, Yuhjin [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); Department of Mechanical Engineering, University of South Carolina, Columbia, SC 29208 (United States); Luo, Zhen, E-mail: lz@tju.edu.cn [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Cai, Yangchuan [School of Material Science and Engineering, Tianjin University, Tianjin 300072 (China); State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yongxian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

2016-03-01

Graphical abstract: - Highlights: • Laser beam partly disperses ZrB{sub 2} particle clusters and showing dispersed particles state after matrix solidification. • Laser melting process narrower cellular spacing in composites than AA6061 matrix. • Compared with matrix alloy, crystal orientation near melted layer edge of the composites is almost random duo to heterogeneous nucleation in melt and pinning effect of laser dispersed ZrB{sub 2} nanoparticles at solidification front. • Laser melted layer shows better wear properties than matrix and composite without laser melting. - Abstract: Aluminum matrix composites reinforced by in situ ZrB{sub 2} particles were successfully fabricated from an Al-KBF{sub 4}-K{sub 2}ZrF{sub 6} system via a direct melt reaction. A laser surface melting strategy is used to improve the surface strength of the in situ ZrB{sub 2p}/6061Al composite, which includes a series of laser-melted composites with different laser power processed by a 2 kW YAG laser generator. XRD and EDS results demonstrated the existence of ZrB{sub 2} nanoparticles in the composite. After laser melting, the penetration depth of the molten pool increases with increasing power density. OM and SEM analysis indicate that the laser melting process yields narrower cellular spacing of the matrix and partly disperses the ZrB{sub 2} particle clusters. Compared with laser-melted matrix alloys, the crystal orientations near the melted layers edge of the composite are almost random due to heterogeneous nucleation in the melt and the pinning effect of laser-dispersed ZrB{sub 2} nanoparticles at the solidification front. Wear test results show that the laser melted layer performs better at wear resistance than both the substrate and the matrix AA6061 by measuring wear mass loss. Compared with composite samples prepared without laser melting, the wear mass loss of the laser melted composites decreased from 61 to 56 mg under a load of 98 N for 60 min.

Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka [Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

2014-07-07

We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8–16 min. Mixture of metastable oxides like InAsO{sub 4,} As{sub 2}O{sub 3} are formed upon oxidation, which are reflected as sharp Raman peaks at ∼240–254 and 180–200 cm{sup −1}. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

Differential optical shadow sensor for sub-nanometer displacement measurement and its application to drag-free satellites.

Science.gov (United States)

Zoellner, Andreas; Tan, Si; Saraf, Shailendhar; Alfauwaz, Abdul; DeBra, Dan; Buchman, Sasha; Lipa, John A

2017-10-16

We present a method for 3D sub-nanometer displacement measurement using a set of differential optical shadow sensors. It is based on using pairs of collimated beams on opposite sides of an object that are partially blocked by it. Applied to a sphere, our 3-axis sensor module consists of 8 parallel beam-detector sets for redundancy. The sphere blocks half of each beam's power in the nominal centered position, and any displacement can be measured by the differential optical power changes amongst the pairs of detectors. We have experimentally demonstrated a displacement sensitivity of 0.87nm/Hz at 1 Hz and 0.39nm/Hz at 10 Hz. We describe the application of the module to the inertial sensor of a drag-free satellite, which can potentially be used for navigation, geodesy and fundamental science experiments as well as ground based applications.

Complex study of transport AC loss in various 2G HTS racetrack coils

Energy Technology Data Exchange (ETDEWEB)

Chen, Yiran, E-mail: yc315@cam.ac.uk [University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom); Zhang, Min; Chudy, Michal; Matsuda, Koichi; Coombs, Tim [University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

2013-04-15

Highlights: ► Comparing transport AC losses of two types of 2G HTS racetrack coils. ► The magnetic substrate in the MAG RABITS coil is the main difference. ► Experimental data agree well with simulation results. ► The transport AC loss in the MAG RABITS coil is 36% higher than that in the IBAD coil. ► It is better to keep all the substrate non-magnetic. -- Abstract: HTS racetrack coils are becoming important elements of an emerging number of superconducting devices such as generators or motors. In these devices the issue of AC loss is crucial, as performance and cooling power are derived from this quantity. This paper presents a comparative study of transport AC loss in two different types of 2G HTS racetrack coils. In this study, both experimental measurements and computer simulation approaches were employed. All the experiments were performed using classical AC electrical method. The finite-element computer model was used to estimate electromagnetic properties and calculate transport AC loss. The main difference between the characterized coils is covered inside tape architectures. While one coil uses tape based on RABITS magnetic substrate, the second coil uses a non-magnetic tape. Ferromagnetic loss caused by a magnetic substrate is an important issue involved in the total AC loss. As a result, the coil with the magnetic substrate surprised with high AC loss and rather low performance.

The growth of nanostructured Cu{sub 2}ZnSnS{sub 4} films by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Che Sulaiman, Nurul Suhada; Nee, Chen Hon [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Ling [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Lee, Yen Sian [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia); Tou, Teck Yong [Faculty of Engineering, Multimedia University, 63100 Cyberjaya, Selangor (Malaysia); Yap, Seong Shan, E-mail: seongshan@gmail.com [UM Power Energy Dedicated Advanced Centre (UMPEDAC), University of Malaya, 50603 Kuala Lumpur (Malaysia)

2015-11-01

Highlights: • Nanostructured CZTS films were grown at room temperature by using 355 nm laser. • CZTS films with E{sub g} of 1.9 eV have been obtained at 2 J cm{sup −2} at room temperature. • At high fluence, Cu/Sn rich droplets affected the overall quality of the films. • Improved crystallinity and E{sub g} of 1.5 eV was obtained at substrate temperature as low as 100 °C. - Abstract: In this work, we investigated on the growth of Cu{sub 2}ZnSnS{sub 4} films by using pulsed Nd:YAG laser (355 nm) ablation of a quaternary Cu{sub 2}ZnSnS{sub 4} target. Depositions were performed at laser fluence from 0.5 to 4 J cm{sup −2}. The films were grown at substrate temperature from 27 °C to 300 °C onto glass and silicon substrates. The dependence of the film morphology, composition, and optical properties are studied and discussed with respect to laser fluence and substrate temperature. Composition analysis from energy dispersive X-ray spectral results show that CZTS films with composition near stoichiometric were obtained at an optimized fluence at 2 J cm{sup −2} by 355 nm laser where the absorption coefficient is >10{sup 4} cm{sup −1}, and optical band gap from a Tauc plot was ∼1.9 eV. At high fluence, Cu and Sn rich droplets were detected which affect the overall quality of the films. The presence of the droplets was associated to the high degree of preferential and subsurface melting on the target during high fluence laser ablation. Crystallinity and optical band gap (1.5 eV) were improved when deposition was performed at substrate temperature of 100 °C.

Absorption homogenization at wavy melt films by CO{sub 2}-lasers in contrast to 1 μm-wavelength lasers

Energy Technology Data Exchange (ETDEWEB)

Kaplan, Alexander F.H., E-mail: alexander.kaplan@ltu.se

2015-02-15

Highlights: • The absorption distribution of 1 μm wavelength lasers compared to 10 μm CO{sub 2}-lasers across a wavy molten steel surface is calculated, at grazing angle of incidence. • For a wide range of surface waviness parameters the CO{sub 2}-laser shows a much more homogenizing absorption behaviour than 1 μm-lasers. • Although the interaction is very complex and non-linear, it is fundamental and very distinct between CO{sub 2}-lasers and 1 μm-lasers, due to their very different Fresnel-absorption characteristics. • The strong local absorption peaks for 1 μm-lasers can cause very strong local boiling and amplification of surface waves, in good correlation to empirical experimental trends. • Such differences can in turn have strong consequences during laser materials processing like laser keyhole welding, laser drilling or laser remote fusion cutting. - Abstract: For wavy metal melts, across a wide range of their topology parameters, lasers with about 1 μm wavelength experience the highest Fresnel absorption around the shoulders of the waves. Calculations show that this induces a strong peak of the absorbed power density of the laser beam. The high temperature gradients have the potential to cause very local boiling and growth of the valleys. In contrast, for a certain parameter category the small Brewster angle for the CO{sub 2}-laser partially homogenizes the temperatures by elevated absorption at domains of grazing incidence. This has the potential to cause opposite consequences on the process, like wave smoothing.

Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

Energy Technology Data Exchange (ETDEWEB)

Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi; Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.jp

2015-01-15

Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths

Effects of electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser scalpel on the healing of intestinal incision

Energy Technology Data Exchange (ETDEWEB)

Puolakkainen, P.; Brackett, K.; Sankar, M.Y.; Joffe, S.; Schroeder, T.

1987-01-01

Leakage after intestinal resection is a serious complication with a high mortality rate. A recent study claims that cutting the intestine with the CO/sub 2/ laser improves the healing of intestinal anastomoses. The present study was undertaken to analyze the effects of electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser on the healing of intestinal incisions. Fifteen piglets were used and the cutting and reanastomosing were performed by using all cutting methods in each animal in randomized order. Resection sites were 50 cm, 100 cm, and 150 cm distal to the ligament of Treitz. On the seventh day the bursting pressures were measured for each anastomosis. They were 172 +/- 17 mmHg for normal bowel segment and 133 +/- 12, 135 +/- 40, and 139 +/- 17 mmHg for electrocautery, CO/sub 2/ laser, and Nd:YAG laser, respectively. There were no mortality, no anastomotic leaks, and no statistically significant differences in the bursting pressures, in histology, or in the healing of anastomotic sites, indicating that electrocautery, CO/sub 2/ laser, and contact Nd:YAG laser scalpel can safely be used in the surgery of small intestine.

Experimental characterization of dielectric-loaded plasmonic waveguide-racetrack resonators at near-infrared wavelengths

DEFF Research Database (Denmark)

Garcia, Cesar; Coello, Victor; Han, Zhanghua

2012-01-01

Dielectric-loaded plasmonic waveguide-racetrack resonators (WRTRs) were designed and fabricated for operating at near-infrared wavelengths (750–850 nm) and characterized using leakage-radiation microscopy. The transmission spectra of the WRTRs are found experimentally and compared to the calculat...

Method for measuring energy-input inhomogeneities in electroionization CO/sub 2/-lasers

Energy Technology Data Exchange (ETDEWEB)

Borovkov, V V; Kornilov, V G; Sukhanov, L V; Chelpanov, V I

1987-08-01

A Michelson interferometer at a wavelength of 0.63 micron was used to measure optical inhomogeneities due to variations of the polarizability of the molecular components in CO/sub 2/-laser mixtures under vibrational excitation in a nonself-sustained electric discharge. It is suggested that the observed effect can be used for the noninertial and noncontact diagnostics of energy-input distribution over the cross section of the active medium of an electroionization CO/sub 2/-laser. Results are presented for N/sub 2/-He, CO/sub 2/-He, CO/sub 2/-N/sub 2/-He, and CO/sub 2/-He mixtures. 10 references.

Racetrack lattices for the TRIUMF KAON factory

International Nuclear Information System (INIS)

Servranckx, R.V.; Craddock, M.K.

1989-05-01

Separated-function racetrack lattices have been developed for the KAON Factory accelerators that have more flexibility than the old circular lattices. The arcs of the large rings have a regular FODO structure with a superimposed six-fold symmetric modulation of the betafunction in order to raise γ t to infinity. In the small rings, γ t is kept high enough by choosing a sufficiently large phase advance in the arcs. Straight sections with zero dispersion are provided for rf cavities and fast injection and extraction, and with controlled dispersion for H - injection and slow extraction. The ion-optical properties of the lattices and the results from tracking studies are discussed

Ultrafast laser and swift heavy ion irradiation: Response of Gd{sub 2}O{sub 3} and ZrO{sub 2} to intense electronic excitation

Energy Technology Data Exchange (ETDEWEB)

Rittman, Dylan R. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Department of Geological Sciences, Stanford University, Stanford, California 94305 (United States); Tracy, Cameron L.; Cusick, Alex B.; Abere, Michael J.; Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Ewing, Rodney C. [Department of Geological Sciences, Stanford University, Stanford, California 94305 (United States)

2015-04-27

In order to investigate the response of materials to extreme conditions, there are several approaches to depositing extremely high concentrations of energy into very small volumes of material, including ultrafast laser and swift heavy ion (SHI) irradiation. In this study, crystalline-to-crystalline phase transformations in cubic Gd{sub 2}O{sub 3} and monoclinic ZrO{sub 2} have been investigated using ultrafast laser irradiation. The phases produced by the extreme conditions of irradiation were characterized by grazing incidence x-ray diffraction (GIXRD) and Raman spectroscopy. Gd{sub 2}O{sub 3} exhibited a cubic-to-monoclinic phase transformation, as evidenced by the appearance of the monoclinic (402{sup ¯}), (003), (310), and (112{sup ¯}) peaks in the GIXRD pattern and of four A{sub g} and three B{sub g} Raman modes. ZrO{sub 2} underwent a monoclinic-to-tetragonal phase transformation, as evidenced by the emergence of the tetragonal (101) peak in the GIXRD pattern and of E{sub g} and A{sub 1g} Raman modes. The new phases formed by ultrafast laser irradiation are high temperature polymorphs of the two materials. No evidence of amorphization was seen in the GIXRD data, though Raman spectroscopy indicated point defect accumulation. These results are identical to those produced by irradiation with SHIs, which also deposit energy in materials primarily through electronic excitation. The similarity in damage process and material response between ultrafast laser and SHI irradiation suggests a fundamental relationship between these two techniques.

Sub-band-gap laser micromachining of lithium niobate

DEFF Research Database (Denmark)

Christensen, F. K.; Müllenborn, Matthias

1995-01-01

method is reported which enables us to do laser processing of lithium niobate using sub-band-gap photons. Using high scan speeds, moderate power densities, and sub-band-gap photon energies results in volume removal rates in excess of 106µm3/s. This enables fast micromachining of small piezoelectric...

Laser cutting equipment for dismantling irradiated PFR fuel sub-assemblies

International Nuclear Information System (INIS)

Higginson, P.R.; Campbell, D.A.

1981-01-01

Laser cutting was identified as a possible technique for dismantling irradiated Prototype Fast Reactor (P.F.R.) fuel sub-assemblies and initial trials showed that it could be used to make essentially swarf free cuts in P.F.R. wrapper material provided sufficient laser power was available to allow use of an inert cutting gas. A programme of development work has established a technique for inert gas cutting with the reliable, commercially available Ferranti MF 400 laser and equipment for laser cutting of sub-assemblies has been installed in the Irradiated Fuel Cave at P.F.R. Test cuts carried out with this equipment on un-irradiated wrapper sections have shown it to be easy to operate remotely, optically stable and reliable in operation. (author)

Investigation of small-scale optical inhomogeneities in an electroionization CO/sub 2/-laser

Energy Technology Data Exchange (ETDEWEB)

Borovkov, V V; Kornilov, V G; Lazhintsev, B V; Nor-arevian, V A; Sukhanov, L V

1987-08-01

A technique for the interferometer investigation of optical inhomogeneities in an electroionization CO/sub 2/-laser in the free-oscillation regime is developed which involves active-medium sounding that is coaxial with the laser resonator. Experimental results are presented on small-scale optical inhomogeneities for a pulsed electroionization laser pumped by a nonself-sustained discharge in a CO/sub 2/:N/sub 2/:He = 1:3:6 mixture at a total pressure of 1 atm. 11 references.

Particles on surfaces of laser ablated Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films

Energy Technology Data Exchange (ETDEWEB)

Zheng, X.Y.; Zhu, S. [Tennessee Univ., Knoxville, TN (United States); Lowndes, D.H.; Warmack, R.J. [Oak Ridge National Lab., TN (United States)

1993-09-01

Pulsed laser deposition of Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} films grown at heater temperature of 720 and 800 C on SrTiO{sub 3} and MgO substrates with thickness ranging from a nominal 5 unit cells to 200 nm were studied by STM and SEM. Size and density of particles present in the films were found to depend on film thickness, growth temperature and substrate. STM images indicate a correlation between film growth mode and particle density: the onset of big particles comes after the growth mode changes from layer-like to island growth.

Soldadura laser de sub-conjuntos para estampagem (Tailored blanks)

DEFF Research Database (Denmark)

Olsen, Flemming Ove

1998-01-01

Laser welding has an increasing role in the automotive industry, namely on the sub-assemblies manufacturing. Several sheet-shape parts are laser welded, on a dissimilar combination of thicknesses and materials, and are afterwards formed (stamped) being transformed in a vehicle body component. In ...

Laser sub-Doppler cooling of atoms in an arbitrarily directed magnetic field

International Nuclear Information System (INIS)

Chang, Soo; Kwon, Taeg Yong; Lee, Ho Seong; Minogin, V.G.

2002-01-01

We analyze the influence of an arbitrarily directed uniform magnetic field on the laser sub-Doppler cooling of atoms. The analysis is done for a (3+5)-level atom excited by a σ + -σ - laser field configuration. Our analysis shows that the effects of the magnetic field depend strongly on the direction of the magnetic field. In an arbitrarily directed magnetic field the laser cooling configuration produces both the main resonance existing already at zero magnetic field and additional sub-Doppler resonances caused by two-photon and higher-order multiphoton processes. These sub-Doppler resonances are, however, well separated on the velocity scale if the Zeeman shift exceeds the widths of the resonances. This allows one to use the main sub-Doppler resonance for an effective laser cooling of atoms even in the presence of the magnetic field. The effective temperature of the atomic ensemble at the velocity of the main resonance is found to be almost the same as in the absence of the magnetic field. The defined structure of the multiphoton resonances may be of importance for the sub-Doppler laser cooling of atoms, atomic extraction from magneto-optical traps, and applications related to the control of atomic motion

Topotactic changes on η-Mo{sub 4}O{sub 11} caused by biased atomic force microscope tip and cw-laser

Energy Technology Data Exchange (ETDEWEB)

Borovšak, Miloš, E-mail: milos.borovsak@ijs.si [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Faculty for Mathematics and Physics, Jadranska ulica 19, 1000 Ljubljana (Slovenia); Šutar, Petra; Goreshnik, Evgeny [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); Mihailovic, Dragan [Jožef Stefan Institute, Jamova cesta 39, 1000 Ljubljana (Slovenia); International Postgraduate School Jožef Stefan, Jamova cesta 39, 1000 Ljubljana (Slovenia)

2015-11-01

Highlights: • We report influencing electronic properties of η-Mo{sub 4}O{sub 11}. • With the biased AFM tip we induce the surface potential changes on η-Mo{sub 4}O{sub 11}. • We used cw-laser to induced similar effect on surface potential on η-Mo{sub 4}O{sub 11}. • We do not influence the surface and topography of the samples. • No change in topography of samples indicates the topotactic transformation. - Abstract: We present topotactic changes on Mo{sub 4}O{sub 11} crystals induced by a biased atomic force microscope tip and continuous laser. The transformation does not change the topography of the samples, while the surface potential shows remarkable changes on areas where the biased AFM tip was applied. No structural changes were observed by Raman spectroscopy, but AFM scans revealed changes to surface potential due to laser illumination. The observed phenomenon could be potentially useful for memristive memory devices considering the fact that properties of other molybdenum oxides vary from metallic to insulators.

Cr{sub 2}O{sub 3} thin films grown at room temperature by low pressure laser chemical vapour deposition

Energy Technology Data Exchange (ETDEWEB)

Sousa, P.M. [Universidade de Lisboa, Faculdade de Ciencias, Departamento de Fisica and ICEMS, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal); Silvestre, A.J., E-mail: asilvestre@deq.isel.ipl.p [Instituto Superior de Engenharia de Lisboa and ICEMS, R. Conselheiro Emidio Navarro 1, 1959-007 Lisboa (Portugal); Conde, O. [Universidade de Lisboa, Faculdade de Ciencias, Departamento de Fisica and ICEMS, Campo Grande, Ed. C8, 1749-016 Lisboa (Portugal)

2011-03-31

Chromia (Cr{sub 2}O{sub 3}) has been extensively explored for the purpose of developing widespread industrial applications, owing to the convergence of a variety of mechanical, physical and chemical properties in one single oxide material. Various methods have been used for large area synthesis of Cr{sub 2}O{sub 3} films. However, for selective area growth and growth on thermally sensitive materials, laser-assisted chemical vapour deposition (LCVD) can be applied advantageously. Here we report on the growth of single layers of pure Cr{sub 2}O{sub 3} onto sapphire substrates at room temperature by low pressure photolytic LCVD, using UV laser radiation and Cr(CO){sub 6} as chromium precursor. The feasibility of the LCVD technique to access selective area deposition of chromia thin films is demonstrated. Best results were obtained for a laser fluence of 120 mJ cm{sup -2} and a partial pressure ratio of O{sub 2} to Cr(CO){sub 6} of 1.0. Samples grown with these experimental parameters are polycrystalline and their microstructure is characterised by a high density of particles whose size follows a lognormal distribution. Deposition rates of 0.1 nm s{sup -1} and mean particle sizes of 1.85 {mu}m were measured for these films.

Continuous room-temperature operation of GaAs-Al/sub x/Ga1/sub -//sub x/As double-heterostructure lasers prepared by molecular-beam epitaxy

International Nuclear Information System (INIS)

Cho, A.Y.; Dixon, R.W.; Casey, H.C. Jr.; Hartman, R.L.

1976-01-01

The continuous (cw) operation at temperatures as high as 100 0 C of stripe-geometry GaAs-Al/sub x/Ga/sub 1-x/As double-heterostructure lasers fabricated by molecular-beam epitaxial (MBE) techniques has been achieved. Improved MBE laser performance was the result of the extensive efforts to eliminate hydrocarbon and water vapor from the growth apparatus. For 12-μm-wide stripe-geometry lasers with 380-μm-long cavities, the cw threshold currents varied between 163 and 297 mA at room temperature

Laser ignition of DAAF, DHT and DAATO{sub 3.5}

Energy Technology Data Exchange (ETDEWEB)

Ali, Arif N.; Sandstrom, Mary M.; Oschwald, David M.; Moore, Kevin M.; Son, Steven F. [Los Alamos National Laboratory, Los Alamos, NM 87544 (United States)

2005-10-01

CO{sub 2} laser ignition experimental results are reported for the high-nitrogen materials 3,6-dihydrazino-1,2,4,5-tetrazine (DHT), 3,3'-diamino-4,4'-azoxyfurazan (DAAF), and mixed N-oxides of 3,3'-azo-bis(6-amino-1,2,4,5-tetrazine) (DAATO{sub 3.5}, where the ''3.5'' indicates the average oxide content) at a maximum irradiance level of approximately 140 W/cm{sup 2}. Diagnostics include a photodiode, indium antimonide (InSb) IR detector, high speed (HS) video and a CO{sub 2} photodetector. ''First light'' is measured for DAATO{sub 3.5} and DAAF, however, due to the low visible light emission of the gas phase, thermal runaway, as measured by the InSb, is used as the ignition criterion for DHT. Ignition in the gas phase is captured by the high speed camera. It is observed that an increase in laser irradiance results in an increase in ignition and flame stand-off distance for DAATO{sub 3.5}. The high-nitrogen material laser ignition results are compared to the common nitramine explosive, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). Laser ignition delays for the different high-nitrogen materials are also compared in the context of Differential Scanning Calorimetry (DSC) data. It is determined that DSC onset temperature, while a rough indicator of ignition delay trends, is not the equivalent of a direct measure of ignition temperature. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

Laser induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} chalcogenide nano colloids

Energy Technology Data Exchange (ETDEWEB)

Tintu, R., E-mail: tintu_tillanivas@yahoo.co.in [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India); Nampoori, V.P.N.; Radhakrishnan, P.; Thomas, Sheenu [International School of Photonics, Cochin University of Science and Technology, Cochin 689110 (India); Unnikrishnan, N.V. [School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam-686560 (India)

2013-04-01

We report the observation of two-photon induced photoluminescence from Ge{sub 28}Se{sub 60}Sb{sub 12} nano colloid solutions using frequency doubled Nd:YAG laser. Quadratic emission intensity dependence verifies the two photon absorption for the observed luminescence at an excitation of 532 nm. The optical band gap of the material is found to be tunable depending on the cluster size of the nano colloids. The cluster formation and the dependence of the cluster size with concentration were confirmed by the SEM analysis. Confocal imaging was done to confirm the emission from the clusters in the nano colloid solutions.

Characterization of diamond thin films deposited by a CO{sub 2} laser-assisted combustion-flame method

Energy Technology Data Exchange (ETDEWEB)

McKindra, Travis, E-mail: mckindra@mst.edu [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); O' Keefe, Matthew J. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Xie Zhiqiang; Lu Yongfeng [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

2010-06-15

Diamond thin films were deposited by a CO{sub 2} laser-assisted O{sub 2}/C{sub 2}H{sub 2}/C{sub 2}H{sub 4} combustion-flame process. The effect of the deposition parameters, in particular the laser wavelength and power, on the film surface morphology, microstructure and phases present was the primary focus of the work. The laser power was set at 100, 400 and 800 W while the wavelength was varied and set at 10.591 {mu}m in the untuned condition and set at 10.532 {mu}m to resonantly match the CH{sub 2}-wagging vibrational mode of the C{sub 2}H{sub 4} molecule when in the tuned condition. When the laser was coupled to the combustion flame during deposition the diamond film growth was enhanced as the lateral grain size increased from 1 {mu}m to greater than 5 {mu}m. The greatest increase in grain size occurred when the wavelength was in the tuned condition. Scanning transmission electron microscopy images from focused-ion beam cross-sectioned samples revealed a sub-layer of smaller grains less than 1 {mu}m in size near the substrate surface at the lower laser powers and untuned wavelength. X-ray diffraction results showed a more intense Diamond (111) peak as the laser power increased from 100 to 800 W for the films deposited with the tuned laser wavelength. Micro-Raman spectra showed a diamond peak nearly twice as intense from the films with the tuned laser wavelength.

Sub-monolayer Deposited InGaAs/GaAs Quantum Dot Heterostructures and Lasers

DEFF Research Database (Denmark)

Xu, Zhangcheng

2004-01-01

deposition, the deposition of a short-period InAs/GaAs superlattice on GaAs (100) surface with an InAs effective thickness of less than 1 monolayer (ML), results in the formatioin of nanometer scale (In,Ga)As QDs of a non-SK class.In this thesis, the SML InGaAs/GaAs QDs are formed by 10 cycles of alternate......The fabrication, characterization and exploitation of self-assembled quantum dot (QD) heterostructures have attracted much attention not only in basic research, but also by the promising device applications such as QD lasers. The Stranski-Krastanow (SK) growth and the submonolayer (SML) deposition...... deposition of 0.5 ML InAs and 2.5 MLGaAs. The growth, structure, and optical properties of SML InGaAs/GaAs QD heterostructures are investigated in detail. SML InGaAs/GaAs QD lasers lasing even at room temperature have been successfully realized. The gain properties of SML InGaAs QD lasers are studied...

Enhancement of conductance of GaAs sub-microwires under external stimuli

Science.gov (United States)

Qu, Xianlin; Deng, Qingsong; Zheng, Kun

2018-03-01

Semiconductors with one dimension on the micro-nanometer scale have many unique physical properties that are remarkably different from those of their bulk counterparts. Moreover, changes in the external field will further modulate the properties of the semiconductor micro-nanomaterials. In this study, we used focused ion beam technology to prepare freestanding ⟨111⟩-oriented GaAs sub-microwires from a GaAs substrate. The effects of laser irradiation and bending or buckling deformation induced by compression on the electrical transport properties of an individual GaAs sub-microwire were studied. The experimental results indicate that both laser irradiation and bending deformation can enhance their electrical transport properties, the laser irradiation resulted in a conductance enhancement of ˜30% compared to the result with no irradiation, and in addition, bending deformation changed the conductance by as much as ˜180% when the average strain was approximately 1%. The corresponding mechanisms are also discussed. This study provides beneficial insight into the fabrication of electronic and optoelectronic devices based on GaAs micro/nano-wires.

Morphology and structural studies of WO{sub 3} films deposited on SrTiO{sub 3} by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Kalhori, Hossein, E-mail: h.kalhori@ph.iut.ac.ir [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of); Porter, Stephen B.; Esmaeily, Amir Sajjad; Coey, Michael [School of Physics and CRANN, Trinity College, Dublin 2 (Ireland); Ranjbar, Mehdi; Salamati, Hadi [Department of Physics, Isfahan University of Technology, Isfahan 84156-8311 (Iran, Islamic Republic of)

2016-12-30

Highlights: • Highly oriented WO{sub 3} stoichiometric films were determined using pulsed laser deposition method. • Effective parameters on thin films including temperature, oxygen partial pressure and laser energy fluency was studied. • A phase transition was observed in WO{sub 3} films at 700 °C from monoclinic to tetragonal. - Abstract: WO{sub 3} films have been grown by pulsed laser deposition on SrTiO{sub 3} (001) substrates. The effects of substrate temperature, oxygen partial pressure and energy fluence of the laser beam on the physical properties of the films were studied. Reflection high-energy electron diffraction (RHEED) patterns during and after growth were used to determine the surface structure and morphology. The chemical composition and crystalline phases were obtained by XPS and XRD respectively. AFM results showed that the roughness and skewness of the films depend on the substrate temperature during deposition. Optimal conditions were determined for the growth of the highly oriented films.

Development and test of a Nb3Sn racetrack magnet using the react and wind technology

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Barzi, E.; Bauer, P.; Carcagno, R.; Chichili, D.; Ewald, K.; Feher, S.; Imbasciati, L.; Kashikhin, V. V.; Limon, P.; Novitski, I.; Orris, D.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.; Tompkins, J.; Yadav, S.; Zlobin, A.V.

2002-01-01

Fermilab is involved in the development of a high field accelerator magnet for future hadron colliders using Nb 3 Sn superconductor and the react-and-wind technology. The magnet design is based on single-layer common coils wound simultaneously into a laminated mechanical structure and impregnated with epoxy. In order to develop and optimize the fabrication techniques and to study the conductor performance, a magnet with flat racetrack type coils in a common coil configuration was assembled and tested. The coils were wound in the mechanical structure and in situ impregnated following a procedure that will be used in the single-layer common coil. The magnetic and mechanical design of the racetrack magnet, the fabrication techniques and the test results are presented and discussed in this paper

Analysis on the electron motion in the laser mixture CO/sub 2/-N/sub 2/-He-CO

Energy Technology Data Exchange (ETDEWEB)

Braglia, G L [Parma Univ. (Italy). Ist. di Fisica; Parma Univ. (Italy). Ist. di Matematica); Bruzzese, R [Naples Univ. (Italy). Ist. Elettrotecnico; Caraffini, G L [Parma Univ. (Italy). Ist. di Matematica

1979-06-02

An analysis of the electron motion in the laser mixture CO/sub 2/-N/sub 2/-He-CO (6:34:54:6) is presented. The transport coefficients are given as a function of E/N. Special attention is turned to the operating characteristics of the laser mixture. The results obtained from the Boltzmann equation are tested by the Monte-Carlo technique for E/N=1.5 10/sup -16/ and 5.0 10/sup -16/ (V cm/sup 2/).

High T<sub>c> superconducting current leads laser fabrication

Directory of Open Access Journals (Sweden)

Díez, J. C.

1998-04-01

Full Text Available In this work is described a laser float zone melting method designed in our laboratory to the development of superconductor Bi<sub>2sub>Sr>2sub>CaCu>2sub>O>8sub> current leads. The most relevant results obtained with different grown conditions and the influence of the process parameters in the properties of superconductor leads are presented.

Las barras de alimentación basadas en el superconductor Bi<sub>2sub>Sr>2sub>CaCu>2sub>O>8sub> son de gran interés práctico para la fabricación de criogeneradores capaces de refrigerar bobinas superconductoras a temperaturas inferiores a 77 K e incluso cercanas a 5 K. Las propiedades mecánicas y eléctricas de dichas barras son fundamentales para determinar su grado de fiabilidad, que en última instancia determinar su aplicabilidad a escala comercial. Los parámetros de fabricación utilizando la fusión zonal inducida por láser permiten obtener fibras gruesas de este superconductor capaces de transportar elevadas corrientes a 77 K y a temperaturas inferiores, y con un comportamiento aceptable frente al ciclado térmico y al paso de elevadas intensidades de corriente eléctrica. En este trabajo se describe un sistema de fusión zonal láser diseñado en nuestro laboratorio para el desarrollo de superconductores y se resumen los resultados más significativos obtenidos según las diversas condiciones de crecimiento estudiadas, la influencia de los diversos parámetros de procesado utilizados sobre las propiedades de las fibras superconductoras obtenidas, así como su potencial uso en dispositivos prácticos.

Study of vibrations and stabilization of linear collider final doublets at the sub-nanometer scale

International Nuclear Information System (INIS)

Bolzon, B.

2007-11-01

CLIC is one of the current projects of high energy linear colliders. Vertical beam sizes of 0.7 nm at the time of the collision and fast ground motion of a few nanometers impose an active stabilization of the final doublets at a fifth of nanometer above 4 Hz. The majority of my work concerned vibrations and active stabilization study of cantilever and slim beams in order to be representative of the final doublets of CLIC. In a first part, measured performances of different types of vibration sensors associated to an appropriate instrumentation showed that accurate measurements of ground motion are possible from 0.1 Hz up to 2000 Hz on a quiet site. Also, electrochemical sensors answering a priori the specifications of CLIC can be incorporated in the active stabilization at a fifth of nanometer. In a second part, an experimental and numerical study of beam vibrations enabled to validate the efficiency of the numerical prediction incorporated then in the simulation of the active stabilization. Also, a study of the impact of ground motion and of acoustic noise on beam vibrations showed that an active stabilization is necessary at least up to 1000 Hz. In a third part, results on the active stabilization of a beam at its two first resonances are shown down to amplitudes of a tenth of nanometer above 4 Hz by using in parallel a commercial system performing passive and active stabilization of the clamping. The last part is related to a study of a support for the final doublets of a linear collider prototype in phase of finalization, the ATF2 prototype. This work showed that relative motion between this support and the ground is below imposed tolerances (6 nm above 0.1 Hz) with appropriate boundary conditions. (author)

Direct writing of sub-wavelength ripples on silicon using femtosecond laser at high repetition rate

International Nuclear Information System (INIS)

Xie, Changxin; Li, Xiaohong; Liu, Kaijun; Zhu, Min; Qiu, Rong; Zhou, Qiang

2016-01-01

Graphical abstract: - Highlights: • The NSRs and DSRs are obtained on silicon surface. • With increasing direct writing speed, the NSRs suddenly changes and becomes the DSRs. • We develop a Sipe–Drude interference theory by considering the thermal excitation. - Abstract: The near sub-wavelength and deep sub-wavelength ripples on monocrystalline silicon were formed in air by using linearly polarized and high repetition rate femtosecond laser pulses (f = 76 MHz, λ = 800 nm, τ = 50 fs). The effects of laser pulse energy, direct writing speed and laser polarization on silicon surface morphology are studied. When the laser pulse energy is 2 nJ/pulse and the direct writing speed varies from 10 to 25 mm/s, the near sub-wavelength ripples (NSRs) with orientation perpendicular to the laser polarization are generated. While the direct writing speed reaches 30 mm/s, the direction of the obtained deep sub-wavelength ripples (DSRs) suddenly changes and becomes parallel to the laser polarization, rarely reported so far for femtosecond laser irradiation of silicon. Meanwhile, we extend the Sipe–Drude interference theory by considering the thermal excitation, and numerically calculate the efficacy factor for silicon irradiated by femtosecond laser pulses. The revised Sipe–Drude interference theoretical results show good agreement with the periods and orientations of sub-wavelength ripples.

FEM for modelling 193 nm excimer laser treatment of SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub x} heterostructures on SOI substrates

Energy Technology Data Exchange (ETDEWEB)

Conde, J.C.; Chiussi, S.; Gontad, F.; Gonzalez, P. [Dpto. Fisica Aplicada, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain); Martin, E. [Dpto. de Mecanica, Maquinas, Motores Termicos y Fluidos, E.T.S.I.I. University of Vigo, Campus Universitario, Rua Maxwell s/n, 36310 Vigo (Spain)

2011-03-15

Research on epitaxial crystalline silicon (c-Si) and silicon-germanium (Si{sub 1-x}Ge{sub x}) alloys growth and annealing for microelectronic purposes, such as Micro- or Nano-Electro-Mechanical Systems (MEMS or NEMS) and Silicon-On-Nothing (SON) devices is continuously in progress. Laser assisted annealing techniques using commercial ArF Excimer Laser sources are based on ultra-rapid heating and cooling cycles induced by the 193 nm pulses of 20 ns, which are absorbed in the near surface region of the heterostructures. During and after the absorption of these laser pulses, complex physical processes appear that strongly depend on sample structure and applied laser pulse energy densities. The control of the experimental parameters is therefore a key task for obtaining high quality alloys. The Finite ElementsMethod (FEM) is a powerful tool for the optimization of such treatments, because it provides the spatial and temporal temperature fields that are produced by the laser pulses. In this work, we have used a FEM commercial software, to predict the temperatures gradients induced by ArF excimer laser over a wide energy densities range, 0.1<{phi}<0.4 J/cm{sup 2}, on different SiO{sub 2}/Si/Si{sub (1-x)}Ge{sub (x)} thin films deposited on SOI substrate. These numerical results allow us to predict the threshold energies needed to reach the melting point (MP) of the Si and SiGe alloy without oxidation of the thin films system. Therefore, it is possible to optimize the conditions to achieve high quality epitaxy films. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Progress in KNbO/sub 3/ crystal growth and its use in second harmonic generation with a cw-Ga/sub 1-x/Al/sub x/As laser

International Nuclear Information System (INIS)

Looser, H.; Gunter, P.; Wu, X.; Arend, H.

1987-01-01

KNbO/sub 3/ is especially well suited for second harmonic generation of dye and Ga/sub 1-x/Al/sub x/As lasers with wavelength λ ≅ 860 nm. Using its high nonlinear optical coefficient, d/sub 32/ = 20.3 pm/V, noncritical type l phase matching is possible for fundamental wavelengths of 840-990 nm with crystal temperatures between -40 and 210 0 C. With a pulsed laser diode the authors previously reported 0.35-mW second harmonic peak power from 0.8-W fundamental frequency distributed among eight modes. In this paper, this work is extended to high-power monomode cw laser diodes. Other device parameters such as temperature stability and influence of the crystal homogeneity on the efficiency are discussed

Laser surface treatment of S235JRC carbon steel with Co{sub 2}B nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Simsek, Tuncay [Hacettepe Univ., Ankara (Turkey). Dept. of Physics Engineering; Baris, Mustafa [Eti Maden Works General Management, Ankara (Turkey). Dept. of Technology Development; Akkurt, Adnan [Gazi Univ., Ankara (Turkey). Dept. of Industrial Design Engineering

2017-06-15

In this study, Co{sub 2}B nanocrystals, which were synthesized in a planetary type mill by using the mechanochemical method, were pre-coated on the surface of S235JRC low carbon steel substrates, and then the surfaces were clad using a CO{sub 2} laser. In the experiments, laser scan speed was kept constant and laser power was specified as the variable parameter. The microstructure and phases of the coatings were investigated by using X-ray diffractometry, scanning electron microscopy, and optical microscopy. The mechanical properties of the coatings were characterized using micro-hardness, ball-on-disc wear, and scratch testing. The thickness of the coatings depending on the laser power was measured in the range 35-71 μm. The hardness and the wear resistance of the coatings were approximately 3 times higher compared to the base metal due to FeN{sub 0.0760}, Fe{sub 15.1}C, FeCo, and B{sub 2}C{sub 5}N{sub 2} phases of the coatings. The most durable coatings against wear were obtained at 174 W and 220 W laser powers.

Simulation study of the sub-terawatt laser wakefield acceleration operated in self-modulated regime

Science.gov (United States)

Hsieh, C.-Y.; Lin, M.-W.; Chen, S.-H.

2018-02-01

Laser wakefield acceleration (LWFA) can be accomplished by introducing a sub-terawatt (TW) laser pulse into a thin, high-density gas target. In this way, the self-focusing effect and the self-modulation that happened on the laser pulse produce a greatly enhanced laser peak intensity that can drive a nonlinear plasma wave to accelerate electrons. A particle-in-cell model is developed to study sub-TW LWFA when a 0.6-TW laser pulse interacts with a dense hydrogen plasma. Gas targets having a Gaussian density profile or a flat-top distribution are defined for investigating the properties of sub-TW LWFA when conducting with a gas jet or a gas cell. In addition to using 800-nm laser pulses, simulations are performed with 1030-nm laser pulses, as they represent a viable approach to realize the sub-TW LWFA driven by high-frequency, diode-pumped laser systems. The peak density which allows the laser peak power PL˜2 Pc r of self-focusing critical power is favourable for conducting sub-TW LWFA. Otherwise, an excessively high peak density can induce an undesired filament effect which rapidly disintegrates the laser field envelope and violates the process of plasma wave excitation. The plateau region of a flat-top density distribution allows the self-focusing and the self-modulation of the laser pulse to develop, from which well-established plasma bubbles can be produced to accelerate electrons. The process of electron injection is complicated in such high-density plasma conditions; however, increasing the length of the plateau region represents a straightforward method to realize the injection and acceleration of electrons within the first bubble, such that an improved LWFA performance can be accomplished.

Potential hydroxyl ultraviolet laser. [Ar-H/sub 2/O

Energy Technology Data Exchange (ETDEWEB)

Chen, C H; Payne, M G

1976-09-01

A strong emission band extending from 3060 to 3120 A was observed following proton beam excitation of an Ar--H/sub 2/O mixture. This emission band was assigned to the transition of OH(A/sup 2/Sigma/sup +/)/sub nu=o/ ..-->.. OH(X/sup 2/Pi)/sub nu=o/. At high argon partial pressure (> 200 torr), the precursor of this emission band is believed to be the argon excimer Ar/sup *//sub 2/(1/sub u/). The fluorescence efficiency of Ar--H/sub 2/O is estimated to be a factor of 4 times that of Ar--N/sub 2/. Development of a highly efficient, tunable uv laser by e-beam pumping is promising.

Structural comparison between La{sub 0.60}Y{sub 0.07}Ca{sub 0.33}MnO{sub 3-{delta}} bulk and pulsed laser deposited thin films

Energy Technology Data Exchange (ETDEWEB)

Teodorescu, V.S. E-mail: teoval@alpha1.infim.ro; Nistor, L.C.; Valeanu, M.; Ghica, C.; Sandu, C.; Mihailescu, I.N.; Ristoscu, C.; Deville, J.P.; Werckmann, J

2000-03-01

This work is a comparative study of the structural and magneto-transport properties of La{sub 0.60}Y{sub 0.07}Ca{sub 0.33}MnO{sub 3-{delta}} (LYCMO) as bulk and thin film. The bulk samples were prepared by solid-state reaction between the corresponding metallic oxides mixed in stoichiometric ratios. The thin film was deposited by pulsed laser deposition on an MgO single crystal using an excimer laser. We show that the structure and stoichiometry of the bulk target are perfectly reproduced in the thin film. We measured the magnetoresistive effect on both the LYCMO pellet and the thin film by using the four-probe technique. The maximum of the MR effect is 680% on the polycrystalline thin film in a 2 T magnetic field.

Digitally controlled chirped pulse laser for sub-terahertz-range fiber structure interrogation.

Science.gov (United States)

Chen, Zhen; Hefferman, Gerald; Wei, Tao

2017-03-01

This Letter reports a sweep velocity-locked laser pulse generator controlled using a digital phase-locked loop (DPLL) circuit. This design is used for the interrogation of sub-terahertz-range fiber structures for sensing applications that require real-time data collection with millimeter-level spatial resolution. A distributed feedback laser was employed to generate chirped laser pulses via injection current modulation. A DPLL circuit was developed to lock the optical frequency sweep velocity. A high-quality linearly chirped laser pulse with a frequency excursion of 117.69 GHz at an optical communication band was demonstrated. The system was further adopted to interrogate a continuously distributed sub-terahertz-range fiber structure (sub-THz-fs) for sensing applications. A strain test was conducted in which the sub-THz-fs showed a linear response to longitudinal strain change with predicted sensitivity. Additionally, temperature testing was conducted in which a heat source was used to generate a temperature distribution along the fiber structure to demonstrate its distributed sensing capability. A Gaussian temperature profile was measured using the described system and tracked in real time, as the heat source was moved.

Enhanced electrical properties of pulsed laser-deposited CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films via processing control

Energy Technology Data Exchange (ETDEWEB)

Jo, Yeon Hwa; Mohanty, Bhaskar Chandra; Cho, Yong Soo [Department of Materials Science and Engineering, Yonsei University, Seoul (Korea, Republic of)

2010-12-15

Polycrystalline CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films were prepared on soda-lime glass substrates using pulsed laser deposition (PLD) with various process parameters such as laser energy, repetition rate and substrate temperature. It was confirmed that there existed a limited laser energy, i.e. less than 300 mJ, to get phase pure CIGS thin films at room temperature. Particularly, even at room temperature, distinct crystalline CIGS phase was observed in the films. Crystallinity of the films improved with increasing substrate temperature as evidenced by the decrease of FWHM from 0.65 degto 0.54 deg. Slightly Cu-rich surface with Cu{sub 2-x}Se phase was confirmed to exist by Raman spectra, depending on substrate temperature. Improved electrical properties, i.e., carrier concentration of {proportional_to}10{sup 18} cm{sup -3} and resistivity of 10{sup -1}{omega} cm at higher substrate temperature for the optimal CIGS films are assumed to be induced by the potential contributions from highly crystallized thin films, existence of Cu{sub 2-x}Se phase and diffusion of Na from substrates to films. (author)

Refinement in the structural and magnetic properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} and its application as laser micro-propellant using ablation confinement

Energy Technology Data Exchange (ETDEWEB)

Raza Ahmad, Muhammad, E-mail: mrazaahmad@gmail.com [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan); Jamil, Yasir, E-mail: yasirjamil@yahoo.com [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Tabasuum, Ayesha [Department of Physics, University of Agriculture, Faisalabad, Punjab (Pakistan); Hussain, Tousif [Centre for Advanced Studies in Physics (CASP), GC University, Lahore, Punjab (Pakistan)

2015-06-15

The transition metal-substituted cobalt ferrite nanoparticles Co{sub 0.5}X{sub 0.5}Fe{sub 2}O{sub 4} (with X=Cu, Zn, Mn and Ni) exhibit a wide range of properties that result in their application in low loss magnetic core materials, vertical recording heads, antenna rods, memory elements, ferrofluids, biomedical applications, sensors and laser propulsion. Keeping in view its importance we investigated for the first time the structural and magnetic properties of the Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4} samples that were subsequently subjected to thermal treatments for different time durations. The average crystallite sizes of the synthesized samples were found in the range of 24–46 nm. The values of the saturation magnetization and coercivity varied from 25.7 to 31.2 emu/g and 523.59 to 927.62 O{sub e}, respectively. The XRD patterns showed that increase in thermal treatment time resulted in the refinement of the structure whereas the SEM micrographs depicted a uniform particle size distribution of the synthesized material. We also explored the application of the synthesized material as a micro-thruster. It was found that the confinement of the laser induced plasma of Co{sub 0.5}×{sub 0.5}Fe{sub 2}O{sub 4} led to an increase in the value of coupling coefficient from the range of 5.747×10{sup −5}–7.0644×10{sup −5} N-s/J for unconfined to that of 1.41×10{sup −4}–2.68×10{sup −4}N-s/J for confined plasma corresponding to the Nd:YAG laser fluencies of 4×10{sup 9} J/m{sup 2}–6×10{sup 9} J/m{sup 2}. - Highlights: • Thermal treatment modifies the properties of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}. • Change in magnetic properties with increase in calcination time. • Confinement increases the laser propulsion parameters of Co{sub 0.5}Ni{sub 0.5}Fe{sub 2}O{sub 4}.

Effects of La{sub 2}O{sub 3} on microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on TiAl intermatallic alloy

Energy Technology Data Exchange (ETDEWEB)

Liu Xiubo [Laboratory for Laser Intelligent Manufacturing, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100080 (China) and School of Materials and Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan Western Road, Zhengzhou 450007, Henan Province (China)]. E-mail: liubobo0828@yahoo.com.cn; Yu Rongli [School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083 (China)

2007-02-15

The effects of La{sub 2}O{sub 3} addition on the microstructure and wear properties of laser clad {gamma}/Cr{sub 7}C{sub 3}/TiC composite coatings on {gamma}-TiAl intermetallic alloy substrates with NiCr-Cr{sub 3}C{sub 2} precursor mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy-dispersive spectrometer (EDS) and block-on-ring wear tests. The responding wear mechanisms are discussed in detail. The results are compared with that for composite coating without La{sub 2}O{sub 3}. The comparison indicates that no evident new crystallographic phases are formed except a rapidly solidified microstructure consisting of the primary hard Cr{sub 7}C{sub 3} and TiC carbides and the {gamma}/Cr{sub 7}C{sub 3} eutectics distributed in the tough {gamma} nickel solid solution matrix. Good finishing coatings can be achieved under a proper amount of La{sub 2}O{sub 3}-addition and a suitable laser processing parameters. The additions of rare-earth oxide La{sub 2}O{sub 3} can refine and purify the microstructure of coatings, relatively decrease the volume fraction of primary blocky Cr{sub 7}C{sub 3} to Cr{sub 7}C{sub 3}/{gamma} eutectics, reduce the dilution of clad material from base alloy and increase the microhardness of the coatings. When the addition of La{sub 2}O{sub 3} is approximately 4 wt.%, the laser clad composite coating possesses the highest hardness and toughness. The composite coating with 4 wt.%La{sub 2}O{sub 3} addition can result the best enhancement of wear resistance of about 30%. However, too less or excessive addition amount of La{sub 2}O{sub 3} have no better influence on wear resistance of the composite coating.

NRF Based Nondestructive Inspection System for SNM by Using Laser-Compton-Backscattering Gamma-Rays

Science.gov (United States)

Ohgaki, H.; Omer, M.; Negm, H.; Daito, I.; Zen, H.; Kii, T.; Masuda, K.; Hori, T.; Hajima, R.; Hayakawa, T.; Shizuma, T.; Kando, M.

2015-10-01

A non-destructive inspection system for special nuclear materials (SNMs) hidden in a sea cargo has been developed. The system consists of a fast screening system using neutron generated by inertial electrostatic confinement (IEC) device and an isotope identification system using nuclear resonance fluorescence (NRF) measurements with laser Compton backscattering (LCS) gamma-rays has been developed. The neutron flux of 108 n/sec has been achieved by the IEC in static mode. We have developed a modified neutron reactor noise analysis method to detect fission neutron in a short time. The LCS gamma-rays has been generated by using a small racetrack microtoron accelerator and an intense sub-nano second laser colliding head-on to the electron beam. The gamma-ray flux has been achieved more than 105 photons/s. The NRF gamma-rays will be measured using LaBr3(Ce) scintillation detector array whose performance has been measured by NRF experiment of U-235 in HIGS facility. The whole inspection system has been designed to satisfy a demand from the sea port.

A UV pre-ionized dual-wavelength short-pulse high-power CO{sub 2} laser facility for laser particle acceleration research

Energy Technology Data Exchange (ETDEWEB)

Ebrahim, N A; Mouris, J F; Davis, R W

1994-12-01

In this report we describe the Chalk River dual-wavelength, short-pulse, single-mode, high-power CO{sub 2} laser facility for research in laser particle acceleration and CANDU materials modifications. The facility is designed and built around UV-preionized transversely-excited atmospheric-pressure (TEA) Lumonics CO{sub 2} laser discharge modules. Peak focussed power densities of up to 2 x 10{sup 14} W/cm{sup 2} in 500 ps pulses have been obtained. (author). 10 refs., 9 figs.

Preparation of high laser-induced damage threshold Ta{sub 2}O{sub 5} films

Energy Technology Data Exchange (ETDEWEB)

Xu, Cheng, E-mail: xucheng@cumt.edu.cn [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Yi, Peng; Fan, Heliang; Qi, Jianwei; Yang, Shuai; Qiang, Yinghuai; Liu, Jiongtian [School of Materials Science and Engineering, China University of Mining and Technology, Xuzhou 221116 (China); Li, Dawei [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2014-08-01

High laser-induced damage threshold (LIDT) Ta{sub 2}O{sub 5} films were prepared by the sol–gel method using TaCl{sub 5} as a new precursor. The optical properties, surface morphologies, chemical composition, absorption and LIDT of the films were investigated. The results showed that the transparent and homogenous Ta{sub 2}O{sub 5} films had small surface roughness, low absorption and high LIDT even with large number of layers. The maximum LIDT at 1064 nm and 12 ns of the films was 24.8 J/cm{sup 2}. The ion chromatograph and Fourier transform infrared spectrum were used to reveal the functions of the addition of H{sub 2}O{sub 2} in the sol formation. It was shown that H{sub 2}O{sub 2} had two important functions, which were the decrease of Cl element content and the rapid generation of tantalum oxide. The high LIDT achieved was mainly due to the nearly free of defects in the films.

Co{sub 3}O{sub 4}/TiO{sub 2} films obtained by laser ablation and sol-gel for the reaction of oxygen liberation in alkaline medium; Peliculas de Co{sub 3}O{sub 4}/TiO{sub 2} obtenidas por ablacion laser y sol-gel para la reaccion de desprendimiento de oxigeno en medio alcalino

Energy Technology Data Exchange (ETDEWEB)

Perez A, J.; Fernandez V, S. M.; Escobar A, L.; Jimenez B, J. [Departamento de Quimica, ININ, Carretera Mexico-Toluca s/n, Ocoyoacac, Estado de Mexico (Mexico)

2008-07-01

The laser ablation technique known as Pulsed Laser Deposition (PLD) is used for obtaining thin films of TiO{sub 2}/SnO{sub 2}, which was later modified with Co{sub 3}O{sub 4} by PLD or by sol-gel technique. The films were characterized by X-ray diffraction, ultraviolet Vis and Raman spectroscopies, scanning electron microscopy and energy analysis of the dispersed X-rays produced by Auger decay. The anatase phase with particles of nano metric size was obtained by depositing the titanium dioxide in argon atmosphere. The Co{sub 3}O{sub 4} films obtained by PLD on the TiO{sub 2} showed the same morphology. The electrocatalytic activity of the films that were used as photo anodes for the reaction of oxygen liberation was carried out in the darkness, with environment light and the light emitted by a xenon lamp. The current density was higher for films of Co{sub 3}O{sub 4}/TiO{sub 2}/SnO{sub 2} obtained by PLD that for cobalt dioxide of mixed valence obtained by sol-gel. (Author)

Racetrack resonator as a loss measurement platform for photonic components.

Science.gov (United States)

Jones, Adam M; DeRose, Christopher T; Lentine, Anthony L; Starbuck, Andrew; Pomerene, Andrew T S; Norwood, Robert A

2015-11-02

This work represents the first complete analysis of the use of a racetrack resonator to measure the insertion loss of efficient, compact photonic components. Beginning with an in-depth analysis of potential error sources and a discussion of the calibration procedure, the technique is used to estimate the insertion loss of waveguide width tapers of varying geometry with a resulting 95% confidence interval of 0.007 dB. The work concludes with a performance comparison of the analyzed tapers with results presented for four taper profiles and three taper lengths.

Spectral properties of hydrothermally-grown Nd:LuAG, Yb:LuAG, and Yb:Lu{sub 2}O{sub 3} laser materials

Energy Technology Data Exchange (ETDEWEB)

Brown, David C., E-mail: DBrown@snakecreeklasers.com [Snake Creek Lasers LLC, Friendsville, PA 18818 (United States); McMillen, Colin D.; Moore, Cheryl; Kolis, Joseph W. [Department of Chemistry and Center for Optical Materials Science and Engineering Technologies, Clemson University, Clemson, SC 29634-0973 (United States); Envid, Victoria [Snake Creek Lasers LLC, Friendsville, PA 18818 (United States)

2014-04-15

We have investigated the hydrothermal growth of, and spectrally characterized, the lutetium based laser materials Nd:LuAG, Yb:LuAG, and Yb:Lu{sub 2}O{sub 3}. Absorption cross-section data are presented for Nd:LuAG at 83, 175, and 295 K. Absorption cross-section data was also obtained for Yb:LuAG at 83, 175, and 295 K; the 295 K data was used to generate emission cross-sections using the method of reciprocity. For Yb:Lu{sub 2}O{sub 3}, we present absorption cross-sections at 295 K as well as emission cross-sections derived using reciprocity. -- Highlights: • We present spectral properties for hydrothermally-grown laser crystals. • Absorption cross-section data are presented for Nd:LuAG and Yb:LuAG at 83, 175, and 295 K. • Emission cross-sections are presented for Yb:LuAG at 295 K derived by reciprocity. • We present absorption cross-sections at 295 K as well as emission cross-sections derived using reciprocity for the laser material Yb:Lu{sub 2}O{sub 3}.

NIST--Los Alamos racetrack microtron status

International Nuclear Information System (INIS)

Wilson, M.A.; Ayres, R.L.; Cutler, R.I.; Debenham, P.H.; Lindstrom, E.R.; Mohr, D.L.; Penner, S.; Rose, J.E.; Young, L.M.

1988-01-01

The NIST-Los Alamos Racetrack Microtron (RTM) is designed to deliver a low-emittance electron beam of up to 0.5 mA cw over an energy range of 17 MeV to 185 MeV. Fed by a 5 MeV injector, the RTM contains two 180 degree end magnets that recirculate the beam up to 15 times through a 12 MeV RF linac. The linac, which operates in a standing-wave mode at 2380 MHz, has been tested to nearly full RF power. At present, the injector has undergone beam tests, and the beam transport system is complete through the 12 MeV linac. A temporary beam line has been installed at the exit of one end magnet to measure the beam energy, energy spread, and emittance after one pass through the accelerator. Preliminary results indicate that the accelerated beam energy spread and emittance are within design goals. 4 refs., 7 figs

Opportunities for sub-laser-cycle spectroscopy in condensed phase

International Nuclear Information System (INIS)

Ivanov, Misha; Smirnova, Olga

2013-01-01

Highlights: ► We discuss how sub-cycle attosecond spectroscopy can be extended from gas to condensed phase. ► We show that attosecond streaking measurements can be applied to bound electrons. ► We discuss time-resolving the formation of band structure in laser fields. - Abstract: To a large extent, progress of attosecond spectroscopy in the gas phase has been driven by designing approaches where time-resolution is not limited by the pulse duration. Instead, the time resolution comes from exploiting the sensitivity of electronic response to the oscillations of the electric field in the laser pulse and attosecond control over these oscillations. This paper discusses perspectives and opportunities for transporting the ideas of sub-cycle spectroscopy from gas to condensed phase

Characteristics of laser irradiated Hg sub 0 ,835 Cd sub 0 ,165 Te analysed by resonant Raman spectroscopy

International Nuclear Information System (INIS)

Scepanovic, M.; Jevtic, M.

1998-01-01

The characteristics of Hg sub 0 ,835 Cd sub 0 ,165 Te sample irradiated by a nanosecond Nd: YAG laser pulse are investigated using a resonant Raman spectroscopy. The pulse energy density of 100 mJ/cm sup 2 is close to the energy threshold of material melting under the irradiated conditions. The presented Raman spectra of the unirradiated and irradiated sample parts point out that the laser irradiation induced a little concentration change in the surface sample layers without the essential structural changes (author)

A model based approach to reference-free straightness measurement at the Nanometer Comparator

Science.gov (United States)

Weichert, C.; Stavridis, M.; Walzel, M.; Elster, C.; Wiegmann, A.; Schulz, M.; Köning, R.; Flügge, J.; Tutsch, R.

2009-06-01

The Nanometer Comparator is the PTB reference length measuring machine for high precision calibrations of line scales and encoder systems. Up to now the Nanometer Comparator allows to measure the position of line structures in one dimension only. For high precision characterisations of masks, scales and incremental encoders, the measurement of the straightness of graduations is a requirement from emerging lithography techniques. Therefore the Nanometer Comparator will be equipped with an additional short range measurement system in the Y-direction, realized as a single path plane mirror interferometer and supposed to achieve sub-nm uncertainties. To compensate the topography of the Y-mirror, the Traceable Multi Sensor (TMS) method will be implemented to achieve a reference-free straightness measurement. Virtual experiments are used to estimate the lower accuracy limit and to determine the sensitive parameters. The virtual experiments contain the influence of the positioning devices, interferometer errors as well as non-perfect adjustment and fabrication of the machine geometry. The whole dynamic measurement process of the Nanometer Comparator including its influence on the TMS analysis, e.g. non-equally spaced measurement points, is simulated. We will present the results of these virtual experiments as well as the most relevant error sources for straightness measurement, incorporating the low uncertainties of the existing and planned measurement systems.

Laser Doppler velocimetry based on the optoacoustic effect in a RF-excited CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Lee, Teaghee; Choi, Jong Woon [Department of Information and Communication, Honam University, Seobong-dong 59-1, Gwansan-gu, Gwangju 506-714 (Korea, Republic of); Kim, Yong Pyung [College of Electronics and Information, Kyunghee University, 1 Seocheon-dong, Giheung-gu, Yongin-si, Gyeonggi-do 446-701 (Korea, Republic of)

2012-09-15

We present a compact optoacoustic laser Doppler velocimetry method that utilizes the self-mixing effect in a RF-excited CO{sub 2} laser. A portion of a Doppler-shifted laser beam, produced by irradiating a single wavelength laser beam on a moving object, is mixed with an originally existing laser beam inside a laser cavity. The fine change of pressure in the laser cavity modulated by the Doppler-shifted frequency is detected by a condenser microphone in the laser tube. In our studies, the frequency of the Doppler signal due to the optoacoustic effect was detected as high as 50 kHz. Our measurements also confirmed that the signal varied linearly with the velocity of the external scatterer (the moving object) and the cosine of the angle between the laser beam and the velocity vector of the object.

Optical switching at 1.55um in silicon racetrack resonators using phase change materials

NARCIS (Netherlands)

Rudé, M.; Pello, J.; Simpson, R.E.; Osmond, J.; Roelkens, G.C.; Tol, van der J.J.G.M.; Pruneri, V.

2013-01-01

An optical switch operating at a wavelength of 1.55¿µm and showing a 12 dB modulation depth is introduced. The device is implemented in a silicon racetrack resonator using an overcladding layer of the phase change data storage material Ge2Sb2Te5, which exhibits high contrast in its optical

Direct laser writing of superconducting patterns of Y1Ba2Cu3O/sub 7-//sub δ/

International Nuclear Information System (INIS)

Gupta, A.; Koren, G.

1988-01-01

Direct argon ion laser writing of 40-μm-wide and 3-μm-thick superconducting lines of Y 1 Ba 2 Cu 3 O/sub 7-//sub δ/ on magnesium oxide (MgO) substrate is reported. A 514.5 nm laser beam of 300 mW was focused onto a thin sprayed film of the nitrate precursors (Y:Ba:Cu = 1:2:3) and scanned over it. The laser beam converted oxides along the irradiation path. The film was then ''developed'' by rinsing it in ethanol, which removed the unirradiated areas, but left the irradiated areas intact. This was followed by the standard oven annealing procedure in flowing oxygen. The resistivity of the laser-written lines as a function of temperature showed an onset and completion of the superconducting transition at 82 and 69 K, respectively. The corresponding values of the unpatterned, blanket film were 82 and 77 K, respectively

On the analysis of the activation mechanisms of sub-melt laser anneals

DEFF Research Database (Denmark)

Clarysse, T.; Bogdanowicz, J.; Goosens, J.

2008-01-01

electrically active concentration level as well as the concurrent mobility is dependent on the dopant concentration level. This implies that the activation of B through the laser anneal process in the explored temperature–time space is governed by kinetic processes (i.e. the dissolution of B–I pairs......In order to fabricate carrier profiles with a junction depth (15 nm) and sheet resistance value suited for sub-32 nm Si-CMOS technology, the usage of sub-melt laser anneal is a promising route to explore. As laser annealed junctions seem to outperform standard anneal approaches, a detailed......) and not by the (temperature related) solid solubility....

Energy relaxation in IR laser excited Hg{sub 1-x}Cd{sub x}Te

Energy Technology Data Exchange (ETDEWEB)

Storebo, A K; Brudevoll, T [FFI - Norwegian Defence Research Establishment, PO Box 25, NO-2027 Kjeller, Norway NTNU (Norwegian University of Science and Technology) (Norway); Olsen, O; Norum, O C [Department of Physics and Department of Electronics and Telecommunications NO-7491 Trondheim (Norway); Breivik, M, E-mail: asta-katrine.storebo@ffi.n [Department of Electronics and Telecommunications NO-7491 Trondheim (Norway)

2009-11-15

IR laser excitation of Hg{sub l-x}Cd{sub x}Te by low-fluence femtosecond and high fluence microsecond pulses was explored for the technologically important alloy fractions x {approx} 0.2 and x {approx} 0.28. We have used first principles (LAPW) electronic structure calculations and finite element modelling, supported by Monte Carlo simulation for the description of femtosecond pulse carrier relaxation and the transport parameters. Laser wavelengths considered were 6.4 - 10.6 {mu}m for x {approx} 0.2 and 3.8 - 4.8 {mu}m for x {approx} 0.28, with an incident 1 microsecond pulse fluence of 2 J/cm{sup 2}. Many energy transfer mechanisms are invoked due to the long timescales of the microsecond pulses, and a main challenge is therefore to elucidate how these interplay in situations away from thermal equilibrium. Mechanisms studied include one- and two-photon absorption (OPA and TPA) across the band gap, inter-valence band absorption (IVA) between light- and heavy hole bands, electron-hole recombination/impact ionization, band gap renormalisation, intra-band free carrier absorption (FCA), excess carrier temperatures, non-equilibrium phonon generation, and refractive index changes. In the high fluence case, lattice temperatures evolve considerably during the laser pulse in response to the heated carriers. The chosen photon energies lie just above the band gap at the starting lattice temperature of 77 K, and nonlinear effects therefore dominate as the material heats up and the band gap begins to exceed the photon energy. Because of the low photon energy we must rely on Auger recombination, inter-valence band absorption and free carrier absorption to heat the carrier plasma. Although some Hg{sub l-x}Cd{sub x}Te material parameters are now relatively well known, existing data for many of the processes are inadequate for cases far away from thermal equilibrium. Furthermore, the role of Auger recombination in relation to non-intrinsic recombination has been a matter of debate

Etching of LiNbO/sub 3/ by laser-driven fusion of salts

International Nuclear Information System (INIS)

Ashby, C.I.H.; Brannon, P.J.

1987-01-01

Lithium niobate exhibits low reactivity with most chemical etchants. Consequently, etching a LiNbO/sub 3/ surface to produce optical structures such as ridge waveguides or grooves for fiber coupling normally requires relatively slow processes such as ion milling. The authors have developed a laser-driven chemical etching process for etching highly unreactive ionic solids based on the fusion of salts in the molten phase and show that the etch rate can be more than 100 times faster than ion milling rates. This process involves spatially localized melting of LiNbO/sub 3/ by high-power density laser pulses with photon energies in excess of the band gap of LiNbO/sub 3/. While molten, LiNbO/sub 3/ undergoes reaction with a surface coating of KF to form niobium oxyfluoride anions by fusion of the salts. The resulting solid is highly water soluble. The insolubility of LiNbO/sub 3/ permits subsequent removal of only the irradiated area by rinsing in water. Surface morphology is determined by laser power density. The process exhibits a wavelength dependence

Calculation of the characteristics of a photoionization TEA CO/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Aver' yanov, N E; Baloshin, Yu A

1979-01-01

Energy and time characteristics have been studied for molecular lasers with active mixture pressures up to atmospheric or high levels. According to the model employed, which was developed for lasers with low active mixture pressure, the basic kinetic equations describing the dynamics of populations of carbon dioxide molecules in a high pressure laser are not written for discrete levels, but for energies stored in each type of oscillation: rate constants of the primary processes of excitation and deexcitation of molecules, relaxation time of different channels of relaxation, and the distribution function of electrons will have a different relationship as a function of partial gas pressures. Earlier equations were used to compute characteristics of lasing pulses of TEA CO/sub 2/ lasers operating under conditions of a semi-self-maintained discharge with preionization of the main volume by uv emission. A new model had to be devised to handle high pressure lasers. Helium was found to be the main supplier of photoelectrons, in spite of the highest ionization potential: addition of nitrogen shapes a uv spectrum optimum for photoionization of helium. CO/sub 2/ is the lasing molecule and also absorbs uv emission. Consideration of CO/sub 2/ molecule dissociation makes the theoretical concept more reliable in comparison with experiment.

SF{sub 6} decomposition and layer formation due to excimer laser photoablation of SiO{sub 2} surface at gas-solid system

Energy Technology Data Exchange (ETDEWEB)

Sajad, Batool [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Parvin, Parviz [Physics Department, Amirkabir University, PO Box 15875-4413, Tehran (Iran, Islamic Republic of); Bassam, Mohamad Amin [Excimer Laser Lab, Emam Hussain University, PO Box 16575-4347, Tehrann (Iran, Islamic Republic of)

2004-12-21

In this work, the effect of an excimer laser has been studied for presenting a method for SF{sub 6} decomposition and simultaneous formation of a SiF{sub 2} layer on amorphous SiO{sub 2}. Though the excimer laser did not establish a gas phase photodissociation, we have shown that UV photoablation leads strongly to molecular decomposition in the SF{sub 6}-SiO{sub 2} system. Moreover, the dependence of the decomposition process on the exposure parameters such as the wavelength and intensity as well as the gas pressure and the focal point distance from the gas-solid interface has been investigated.

The calcium and rare earth oxo-borates, Ca{sub 4}ReO(BO{sub 3}){sub 3} (Re = Gd, Y, La): synthesis and investigations of new non-critical phase matching configurations for frequency conversion at specific laser wavelengths; Les oxoborates de calcium et de lanthanide, Ca{sub 4}LnO(BO{sub 3}){sub 3} (Ln = Gd, Y, La): synthese et recherche d'angles d'accord de phase non critique pour la conversion de frequence de longueurs d'onde Laser specifiques

Energy Technology Data Exchange (ETDEWEB)

Reino, E

2002-12-15

Visible and UV lasers are currently investigated for many applications as data storage, medicine, etc. Intracavity frequency doubling appears as a good solution. Thus, the non-linear family Ca{sub 4}REO(BO{sub 3}){sub 3} (RE = rare earth, RECOB) has shown a considerable interest to produce compact visible laser. In addition, it is possible to tune the compositions of RECOB by partial substitutions in order to achieve non-critical phase matching (NCPM). In the present work, various cationic substitutions have been studied in solid solutions as Gd{sub 1-x}Y{sub x}COB, Gd{sub 1-x}La{sub x}COB, Gd{sub 1-x}Sc{sub x}COB (for the first time), Re{sub 1-x}Bi{sub x}COB (REe = Gd or Y) and (Ca{sub 1-x}Sr{sub x}){sub 4}GdO(BO{sub 3}){sub 3} in order to investigate their crystal growth and adjust the NCPM wavelength by composition. The wavelength range is related to neodymium doped laser materials emitting on the 4F3/2-4I9/2 transition, for example Nd:YAP (YAlO{sub 3}) at 930 nm, Nd:YAG (Y{sub 3}Al{sub 5}O{sub 12}) at 946 nm or Nd:ASL (Sr{sub 1-x}Nd{sub y}La{sub x-y}Mg{sub x}Al{sub 11-x}O{sub 19}) at 900 nm. We have also demonstrated that the compositions for NCPM can be determined from the refractive index of both lattices M{sub 1-x}M'{sub x}COB (M, M' RE) with x = 0 or 1, using the Clausius-Mosotti relation. Two new blue laser systems, constituted of a laser crystal and a non-linear crystal optimized for type-I NCPM second harmonic generation, were achieved: a 946 nm Nd:YAG laser with Gd{sub 0.87}Y{sub 0.13}COB and a 900 nm Nd:ASL laser with Gd{sub 0.56}Y{sub 0.44}COB. Moreover, we have performed for the first time a CW laser action at 900 nm with Nd:ASL. (author)

Effects of ionizing radiation on laser-induced damage in SiO/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Soileau, M J; Mansour, N; Canto, E; Griscom, D L

1988-05-01

The effects of radiation damage on bulk laser-induced damage in SiO/sub 2/ were investigated. Samples studied included Spectrasil A, B, and WF (water free). Measurements of laser-induced breakdown were conducted with 532 and 1064 nm laser pulses of approximately 20 ns duration. Reductions of up to 40% in the laser-induced breakdown threshold were observed at 532 nm for samples exposed to 10/sup 8/ rad of ..gamma..-radiation. The decrease in breakdown threshold for irradiated SiO/sub 2/ samples at 532 nm was found to be proportional to the linear absorption of the specimen at 266 nm. These results are in good agreement with a proposed model which suggests that two-photon absorption initiated avalanche process is responsible for laser-induced breakdown for these materials.

Resistive switching behavior in single crystal SrTiO{sub 3} annealed by laser

Energy Technology Data Exchange (ETDEWEB)

Pan, Xinqiang [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Shuai, Yao, E-mail: yshuai@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Wu, Chuangui, E-mail: cgwu@uestc.edu.cn [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Luo, Wenbo [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Sun, Xiangyu [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Yuan, Ye; Zhou, Shengqiang [Helmholtz-Zentrum Dresden Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Ou, Xin [State Key Laboratory of Functional Material for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China); Zhang, Wanli [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China); Collaboration Innovation Center of Electronic Materials and Devices, University of Electronic Science and Technology of China, Chengdu 610054 (China)

2016-12-15

Highlights: • Laser annealing was used to introduce oxygen vacancies into the single crystal SrTiO{sub 3}. • The effect of laser annealing with different fluence on the single crystal SrTiO{sub 3} was systematically studied. • The concentration of oxygen vacancies can be tuned by changing the fluence of laser. • Resistive switching behavior was observed in the sample with relatively high laser fluence after an electro-forming process. - Abstract: Single crystal SrTiO{sub 3} (STO) wafers were annealed by XeCl laser (λ = 308 nm) with different fluences of 0.4 J/cm{sup 2}, 0.6 J/cm{sup 2} and 0.8 J/cm{sup 2}, respectively. Ti/Pt electrodes were sputtered on the surface of STO wafer to form co-planar capacitor-like structures of Pt/Ti/STO/Ti/Pt. Current-Voltage measurements show that the leakage current is enhanced by increasing laser fluence. Resistive switching behavior is only observed in the sample annealed by laser with relatively high fluence after an electro-forming process. The X-ray photoelectron spectroscopy measurements indicate that the amount of oxygen vacancies increases with the increase of laser fluence. This work indicates resistive switching appears when enough oxygen vacancies are generated by the laser, which form conductive filaments under an external electric field.

Universal liquid-phase laser fabrication of various nano-metals encapsulated by ultrathin carbon shells for deep-UV plasmonics.

Science.gov (United States)

Yu, Miao; Yang, Chao; Li, Xiao-Ming; Lei, Tian-Yu; Sun, Hao-Xuan; Dai, Li-Ping; Gu, Yu; Ning, Xue; Zhou, Ting; Wang, Chao; Zeng, Hai-Bo; Xiong, Jie

2017-06-29

The exploration of localized surface plasmon resonance (LSPR) beyond the usual visible waveband, for example within the ultraviolet (UV) or deep-ultraviolet (D-UV) regions, is of great significance due to its unique applications in secret communications and optics. However, it is still challenging to universally synthesize the corresponding metal nanostructures due to their high activity. Herein, we report a universal, eco-friendly, facile and rapid synthesis of various nano-metals encapsulated by ultrathin carbon shells, significantly with a remarkable deep-UV LSPR characteristic, via a liquid-phase laser fabrication method. Firstly, a new generation of the laser ablation in liquid (LAL) method has been developed with an emphasis on the elaborate selection of solvents to generate ultrathin carbon shells, and hence to stabilize the formed metal nanocrystals. As a result, a series of metal@carbon nanoparticles (NPs), including Cr@C, Ti@C, Fe@C, V@C, Al@C, Sn@C, Mn@C and Pd@C, can be fabricated by this modified LAL method. Interestingly, these NPs exhibit LSPR peaks in the range of 200-330 nm, which are very rare for localized surface plasmon resonance. Consequently, the UV plasmonic effects of these metal@carbon NPs were demonstrated both by the observed enhancement in UV photoluminescence (PL) from the carbon nanoshells and by the improvement of the photo-responsivity of UV GaN photodetectors. This work could provide a universal method for carbon shelled metal NPs and expand plasmonics into the D-UV waveband.

Phase transformations in the rapidly solidified Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy

Energy Technology Data Exchange (ETDEWEB)

Chen, N. [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Yao Kefu [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: kfyao@tsinghua.edu.cn; Louzguine-Luzgin, D.V. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan); Qiu Shengbao [Division of Engineering Materials, Department of Mechanical Engineering, Tsinghua University, Beijing 100084 (China); Ranganathan, S. [Department of Metallurgy, Indian Institute of Science, Bangalore 560 012 (India); Inoue, A. [Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-Ku, Sendai 980-8577 (Japan)

2007-10-15

We report that an approximant phase was initially obtained in amorphous Ti{sub 40}Zr{sub 20}Hf{sub 20}Pd{sub 20} alloy. In the initial stage of the devitrification process, the approximant phase transforms into an icosahedral (I) phase with a high thermal stability while the cF96 Zr{sub 2}Ni-type (space group Fd3-bar m with a=1.25nm and 96 atoms cell{sup -1}) particles precipitate from the amorphous matrix. Eventually the I phase grows to several hundred nanometers when annealed at about 1000K and then transforms into the Zr{sub 2}Ni-type phase with an endothermic reaction.

Sensitive SERS detection at the single-particle level based on nanometer-separated mushroom-shaped plasmonic dimers

Science.gov (United States)

Xiang, Quan; Li, Zhiqin; Zheng, Mengjie; Liu, Qing; Chen, Yiqin; Yang, Lan; Jiang, Tian; Duan, Huigao

2018-03-01

Elevated metallic nanostructures with nanogaps (film deposition. By controlling the initial size of nanogaps in resist structures and the following deposited film thickness, metallic nanogaps could be tuned at the sub-10 nm scale with single-digit nanometer precision. Both experimental and simulated results revealed that gold dimer on mushroom-shaped pillars have the capability to achieve higher SERS enhancement factor comparing to those plasmonic dimers on cylindrical pillars or on a common SiO2/Si substrate, implying that the nanometer-gapped elevated dimer is an ideal platform to achieve the highest possible field enhancement for various plasmonic applications.

Osteoblast interaction with laser cladded HA and SiO{sub 2}-HA coatings on Ti-6Al-4V

Energy Technology Data Exchange (ETDEWEB)

Yang Yuling [Department of Physics, Northeastern University, Shenyang 110004 (China); Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Serpersu, Kaan [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); He Wei, E-mail: whe5@utk.edu [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Department of Mechanical, Aerospace and Biomedical Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Paital, Sameer R. [Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996 (United States); Dahotre, Narendra B. [Department of Materials Science and Engineering, University of North Texas, Denton, TX 76207 (United States)

2011-12-01

In order to improve the bioactivity and biocompatibility of titanium endosseous implants, the morphology and composition of the surfaces were modified. Polished Ti-6Al-4V substrates were coated by a laser cladding process with different precursors: 100 wt.% HA and 25 wt.% SiO{sub 2}-HA. X-ray diffraction of the laser processed samples showed the presence of CaTiO{sub 3}, Ca{sub 3}(PO{sub 4}){sub 2}, and Ca{sub 2}SiO{sub 4} phases within the coatings. From in vitro studies, it was observed that compared to the unmodified substrate all laser cladded samples presented improved cellular interactions and bioactivity. The samples processed with 25 wt.% SiO{sub 2}-HA precursor showed a significantly higher HA precipitation after immersion in simulated body fluid than 100 wt.% HA precursor and titanium substrates. The in vitro biocompatibility of the laser cladded coatings and titanium substrate was investigated by culturing of mouse MC3T3-E1 pre-osteoblast cell line and analyzing the cell viability, cell proliferation, and cell morphology. A significantly higher cell attachment and proliferation rate were observed for both laser cladded 100 wt.% HA and 25 wt.% SiO{sub 2}-HA samples. Compared to 100 wt.% HA sample, 25 wt.% SiO{sub 2}-HA samples presented a slightly improved cellular interaction due to the addition of SiO{sub 2}. The staining of the actin filaments showed that the laser cladded samples induced a normal cytoskeleton and well-developed focal adhesion contacts. Scanning electron microscopic image of the cell cultured samples revealed better cell attachment and spreading for 25 wt.% SiO{sub 2}-HA and 100 wt.% HA coatings than titanium substrate. These results suggest that the laser cladding process improves the bioactivity and biocompatibility of titanium. The observed biological improvements are mainly due to the coating induced changes in surface chemistry and surface morphology. Highlights: {yields} Laser cladding of Ti alloys with bioceramics creates new

Growth and characterization of polycrystalline Ge{sub 1-x}C{sub x} by reactive pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Hernandez, M.P., E-mail: mayrap@fisica.uh.cu [Instituto de Ciencia y Tecnologia de Materiales, Zapata y G, P.O. Box 10400, Universidad de La Habana (Cuba); Farias, M.H.; Castillon, F.F.; Diaz, Jesus A.; Avalos, M. [Centro de Nanociencias y Nanotecnologia, Universidad Nacional Autonoma de Mexico, Km 107 Carretera Tijuana-Ensenada, C.P. 22800 Ensenada, Baja California (Mexico); Ulloa, L. [Universidad de Guadalajara, (CUCEI) Blvd. Marcelino Garcia Barragan 1421, C.P. 44430 Guadalajara, Jalisco (Mexico); Gallegos, J.A.; Yee-Madeiros, H. [Escuela Superior de Fisica y Matematicas-IPN, UP' ALM' , Colonia Lindavista 07738 (Mexico)

2011-03-15

Polycrystalline thin films of Ge-C were grown on Si (1 1 1) substrates by means of reactive pulsed laser deposition with methane pressure of 100 mTorr. Effect substrate temperature, T{sub s}, on C incorporation to substitutional sites (x) in Ge{sub 1-x}C{sub x} was investigated systematically by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyzes. The substrate temperatures were ranging from 250 to 400 deg. C. The substitutional C composition x in the films by XRD were estimated using the Vegard's linear law. The maximum value of x calculated by XRD was 0.032 for T{sub s} of 350 deg. C. The position of the C 1s peak at 283.4 eV in the XPS spectrum confirmed the germanium-carbon alloys. XRD measurements indicated that x increased with T{sub s} from 250 deg. C to 350 deg. C. At T{sub s} = 400 deg. C, the estimation of x was lowered. However, the C content calculated by XPS analyzes increased with T{sub s} being more these values than substitutional C composition x. XPS and XRD analyzes demonstrate that the remaining C atoms are incorporated to interstitial sites. The use of the T{sub s} plays important roles in the incorporation of substitutional C and in restraining C-cluster formation in the reactive pulsed laser deposition growth of Ge-C/Si.

Study on the Heating Behavior of Fe{sub 3}O{sub 4}-Embedded Thermoplastic Polyurethane Adhesive Film via Induction heating

Energy Technology Data Exchange (ETDEWEB)

Bae, Duck Hwan; Shon, Min Young [Pukyong National University, Busan (Korea, Republic of); Oh, Sang Taek; Kim, Gu Ni [Korea Institute of Footwear and Leather Technology, Busan (Korea, Republic of)

2016-08-15

The heating behavior of thermoplastic polyurethane adhesive (TPU) embedded by nanometer or micrometer Fe{sub 3}O{sub 4} particle is examined by induction heating. The effects of the size and the amount of Fe{sub 3}O{sub 4} particle, TPU film thickness, and input power of the induction heater were examined on heating behaviors of TPU. The quantity of heat generated in the TPU films increased with the amount of Fe{sub 3}O{sub 4} particles, film thickness, or input power. On the other hand, the quantity of heat generation of TPU is decreased with increasing Fe{sub 3}O{sub 4} size. We confirmed that the mechanism of hysteresis led to heat loss in the nanometer and micrometer-sized Fe{sub 3}O{sub 4} particles, and it was the key controller of the quantity of heat generated in the Fe{sub 3}O{sub 4} particle-embedded TPU films by induction heating.

Cable testing for Fermilab's high field magnets using small racetrack coils

International Nuclear Information System (INIS)

Feher, S.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bordini, B.; Bossert, R.; Carcagno, R.; Kashikhin, V.I.; Kashikhin, V.V.; Lamm, M.J.; Novitski, I.; Orris, D.; Pischalnikov, Y.; Sylvester, C.; Tartaglia, M.; Yamada, R.; Zlobin, A.V.

2004-01-01

As part of the High Field Magnet program at Fermilab simple magnets have been designed utilizing small racetrack coils based on a sound mechanical structure and bladder technique developed by LBNL. Two of these magnets have been built in order to test Nb 3 Sn cables used in cos-theta dipole models. The powder-in-tube strand based cable exhibited excellent performance. It reached its critical current limit within 14 quenches. Modified jelly roll strand based cable performance was limited by magnetic instabilities at low fields as previously tested dipole models which used similar cable

CO{sub 2} laser-aided waste incineration

Energy Technology Data Exchange (ETDEWEB)

Costes, J R; Guiberteau, P [CEA Centre d` Etudes de la Vallee du Rhone, 30 - Marcoule (France). Dept. d` Exploitation du Retraitement et de Demantelement; Caminat, P; Bournot, P

1994-12-31

Lasers are widely employed in laboratories and in certain industrial applications, notably for welding, cutting and surface treatments. This paper describes a new application, incineration, which appears warranted when the following features are required: high-temperature incineration (> 1500 deg C) with close-tolerance temperature control in an oxidizing medium while ensuring containment of toxic waste. These criteria correspond to the application presented here. Following a brief theoretical introduction concerning the laser/surface interaction, the paper describes the incineration of graphite waste contaminated with alpha-emitting radionuclides. Process feasibility has been demonstrated on a nonradioactive prototype capable of incinerating 10 kg{sup -h-1} using a 7 kW CO{sub 2} laser. An industrial facility with the same capacity, designed to operate within the constraints of an alpha-tight glove box environment, is now at the project stage. Other types of applications with similar requirements may be considered. (authors). 3 refs., 7 figs.

Development of control and data processing system for CO{sub 2} laser interferometer

Energy Technology Data Exchange (ETDEWEB)

Chiba, Shinichi; Kawano, Yasunori; Tsuchiya, Katsuhiko; Inoue, Akira [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

2001-11-01

CO{sub 2} laser interferometer diagnostic has been operating to measure the central electron density in JT-60U plasmas. We have developed a control and data processing system for the CO{sub 2} laser interferometer with flexible functions of data acquisition, data processing and data transfer in accordance with the sequence of JT-60U discharges. This system is mainly composed of two UNIX workstations and CAMAC clusters, in which the high reliability was obtained by sharing the data process functions to the each workstations. Consequently, the control and data processing system becomes to be able to provide electron density data immediately after a JT-60U discharge, routinely. The realtime feedback control of electron density in JT-60U also becomes to be available by using a reference density signal from the CO{sub 2} laser interferometer. (author)

Simultaneous high crystallinity and sub-bandgap optical absorptance in hyperdoped black silicon using nanosecond laser annealing

Energy Technology Data Exchange (ETDEWEB)

Franta, Benjamin, E-mail: bafranta@gmail.com; Pastor, David; Gandhi, Hemi H.; Aziz, Michael J.; Mazur, Eric [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Rekemeyer, Paul H.; Gradečak, Silvija [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

2015-12-14

Hyperdoped black silicon fabricated with femtosecond laser irradiation has attracted interest for applications in infrared photodetectors and intermediate band photovoltaics due to its sub-bandgap optical absorptance and light-trapping surface. However, hyperdoped black silicon typically has an amorphous and polyphasic polycrystalline surface that can interfere with carrier transport, electrical rectification, and intermediate band formation. Past studies have used thermal annealing to obtain high crystallinity in hyperdoped black silicon, but thermal annealing causes a deactivation of the sub-bandgap optical absorptance. In this study, nanosecond laser annealing is used to obtain high crystallinity and remove pressure-induced phases in hyperdoped black silicon while maintaining high sub-bandgap optical absorptance and a light-trapping surface morphology. Furthermore, it is shown that nanosecond laser annealing reactivates the sub-bandgap optical absorptance of hyperdoped black silicon after deactivation by thermal annealing. Thermal annealing and nanosecond laser annealing can be combined in sequence to fabricate hyperdoped black silicon that simultaneously shows high crystallinity, high above-bandgap and sub-bandgap absorptance, and a rectifying electrical homojunction. Such nanosecond laser annealing could potentially be applied to non-equilibrium material systems beyond hyperdoped black silicon.

Influence of an O{sub 2} background gas on the composition and kinetic energies of species in laser induced La{sub 0.4}Ca{sub 0.6}MnO{sub 3} plasmas

Energy Technology Data Exchange (ETDEWEB)

Chen, Jikun; Stender, Dieter; Bator, Matthias; Schneider, Christof W. [Paul Scherrer Institute, General Energy Research Department, CH-5232 Villigen PSI (Switzerland); Lippert, Thomas, E-mail: Thomas.lippert@psi.ch [Paul Scherrer Institute, General Energy Research Department, CH-5232 Villigen PSI (Switzerland); Wokaun, Alexander [Paul Scherrer Institute, General Energy Research Department, CH-5232 Villigen PSI (Switzerland)

2013-08-01

Oxygen is one of the most commonly used background gases for pulsed laser deposition of oxide thin films. In this work the properties of a 308 nm laser-induced La{sub 0.4}Ca{sub 0.6}MnO{sub 3} plasma were analyzed using a quadrupole mass spectrometer combined with an energy analyzer, to investigate the interaction between the various plasma species and the background gas. The composition and kinetic energies of the plasma species were compared in vacuum and an O{sub 2} background gas at different pressures. It has been observed that the O{sub 2} background gas decreases the kinetic energy of the positively charged atomic plasma species. In addition, the interaction with the O{sub 2} background gas causes the generation of positive diatomic oxide species of LaO{sup +}, CaO{sup +} and MnO{sup +}. The amount of negatively charged diatomic or tri-atomic oxide species decreases in the O{sub 2} background compared to vacuum, while the amount of O{sub 2}{sup −} increases strongly.

Assessing the concept of structure sensitivity or insensitivity for sub-nanometer catalyst materials

Science.gov (United States)

Crampton, Andrew S.; Rötzer, Marian D.; Ridge, Claron J.; Yoon, Bokwon; Schweinberger, Florian F.; Landman, Uzi; Heiz, Ueli

2016-10-01

The nature of the nano-catalyzed hydrogenation of ethylene, yielding benchmark information pertaining to the concept of structure sensitivity/insensitivity and its applicability at the bottom of the catalyst particle size-range, is explored with experiments on size-selected Ptn (n = 7-40) clusters soft-landed on MgO, in conjunction with first-principles simulations. As in the case of larger particles both the direct ethylene hydrogenation channel and the parallel hydrogenation-dehydrogenation ethylidyne-producing route must be considered, with the fundamental uncovering that at the reaction exhibits characteristics consistent with structure sensitivity, in contrast to the structure insensitivity found for larger particles. In this size-regime, the chemical properties can be modulated and tuned by a single atom, reflected by the onset of low temperature hydrogenation at T > 150 K catalyzed by Ptn (n ≥ 10) clusters, with maximum room temperature reactivity observed for Pt13 using a pulsed molecular beam technique. Structure insensitive behavior, inherent for specific cluster sizes at ambient temperatures, can be induced in the more active sizes, e.g. Pt13, by a temperature increase, up to 400 K, which opens dehydrogenation channels leading to ethylidyne formation. This reaction channel was, however found to be attenuated on Pt20, as catalyst activity remained elevated after the 400 K step. Pt30 displayed behavior which can be understood from extrapolating bulk properties to this size range; in particular the calculated d-band center. In the non-scalable sub-nanometer size regime, however, precise control of particle size may be used for atom-by-atom tuning and manipulation of catalyzed hydrogenation activity and selectivity.

Assembly and Tests of SQ02, a Nb3Sn Racetrack Quadrupole Magnet for LARP

International Nuclear Information System (INIS)

Ferracin, Paolo; Ambrosio, G.; Barzi, E.; Caspi, S.; Dietderich, D.R.; Feher, S.; Gourlay, S.A.; Hafalia, A.R.; Hannaford, C.R.; Lizarazo, J.; Lietzke, A.F.; McInturff, A.D.; Sabbi, G.L.; Zlobin, A.V.

2007-01-01

The US LHC Accelerator Research Program (LARP) consists of four US laboratories (BNL, FNAL, LBNL, and SLAC) collaborating with CERN to achieve a successful commissioning of the LHC and to develop the next generation of Interaction Region magnets. In 2004, a large aperture Nb 3 Sn racetrack quadrupole magnet (SQ01) has been fabricated and tested at LBNL. The magnet utilized four subscale racetrack coils and was instrumented with strain gauges on the support structure and directly over the coil's turns. SQ01 exhibited training quenches in two of the four coils and reached a peak field in the conductor of 10.4 T at a current of 10.6 kA. After the test, the magnet was disassembled, inspected with pressure indicating films, and reassembled with minor modifications. A second test (SQ01b) was performed at FNAL and included training studies, strain gauge measurements and magnetic measurements. Magnet inspection, test results, and magnetic measurements are reported and discussed, and a comparison between strain gauge measurements and 3D finite element computations is presented

Effects of Nd:YAG laser irradiation on structural and magnetic properties of Li{sub 0.5}Fe{sub 2.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Mane, Maheshkumar L. [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431004 (India); Sundar, R.; Ranganathan, K.; Oak, S.M. [Solid State Laser Division, Raja Raman Research Center for Advanced Technology, Indore (M.P.) (India); Jadhav, K.M., E-mail: drkmjadhav@yahoo.co [Department of Physics, Dr. Babasaheb Ambedkar Marathwada University, Aurangabad (M.S.) 431004 (India)

2011-02-15

In the present paper we report our results on the effect of Nd:YAG laser irradiation on the structural and magnetic properties of Li{sub 0.5}Fe{sub 2.5}O{sub 4} spinel ferrite prepared by solid-state reaction technique. X-ray diffraction analysis was carried out to confirm the formation of the single phase cubic spinel structure. The lattice constant calculated from X-ray diffraction data (XRD) goes on increasing with non irradiated phase to exceeding higher doses of irradiation. The distribution of the substituted ions over the different lattice sites is determined from XRD and infrared spectra. The damage structure and morphological investigations were carried out by using scanning electron microscopy and transmission electron microscopy techniques. It has been observed from our data on magnetic properties that laser irradiation severely affects the magnetization. From the magnetization measurements it has been observed that the saturation magnetization decreases with increase in the laser dose rate. The observed reduction in the saturation magnetization after irradiation is understood on the basis of the partial formation of paramagnetic centers and rearrangement of cations in the lattice.

Growth parameter enhancement for MoS{sub 2} thin films synthesized by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Serna, Martha I.; Higgins, Marissa; Quevedo-Lopez, Manuel A. [Materials Science and Engineering Department, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States); Moreno, Salvador [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Choi, Hyunjoo [Department of Advanced Materials Engineering, Kookmin University, Jeongneung-dong Seongbuk-gu, Seoul 136-702 (Korea, Republic of); Minary-Jolandan, Majid [Department of Mechanical Engineering, The University of Texas at Dallas, Richardson, TX 75080 (United States); Alan MacDiarmid Nanotech Institute, The University of Texas at Dallas, 800 W Campbell Road RL 10, Richardson TX 75080 (United States)

2016-12-15

Two-dimensional materials such as graphene and MoS{sub 2} have been the main focus of intense research efforts over the past few years. The most common method of exfoliating these materials, although efficient for lab-scale experiments, is not acceptable for large area and practical applications. Here, we report the deposition of MoS{sub 2} layered films on amorphous (SiO{sub 2}) and crystalline substrates (sapphire) using a pulsed laser deposition (PLD) method. Increased substrate temperature (∝700 C) and laser energy density (>530 mJ /cm{sup 2}) promotes crystalline MoS{sub 2} films < 20 nm, as demonstrated by fast Fourier transform (FFT) and transmission electron microscopy (TEM). The method reported here opens the possibility for large area layered MoS{sub 2} films by using a laser ablation processes. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Microfabrication of biomaterials by the sub-ps laser-induced forward transfer process

International Nuclear Information System (INIS)

Karaiskou, A.; Zergioti, I.; Fotakis, C.; Kapsetaki, M.; Kafetzopoulos, D.

2003-01-01

The precise fabrication of micro-dimensioned patterns of biomaterials by the laser microprinting technique using a sub-ps UV laser is described. An ultrashort UV laser has been used to transfer the biomaterial, with low angular divergence, and deposit it onto the substrate with minimum spread and high spatial resolution. The laser-transferred features of 100 μmx100 μm size have been studied by means of scanning electron microscopy and scanning laser confocal fluorescence microscopy. The analysis of DNA and protein microarrays provides an excellent tool to expand our knowledge of genome functions

Site-selective laser spectroscopy of Sm{sup 3+} ions in Y{sub 4}Al{sub 2}O{sub 9}

Energy Technology Data Exchange (ETDEWEB)

Kaczkan, M., E-mail: m.kaczkan@elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland); Boruc, Z. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland); Turczyński, S.; Pawlak, D. [Institute of Electronic Materials Technology, Wolczynska 133, Warsaw 01-919 (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, Warsaw 00-662 (Poland)

2016-02-15

Sm{sup 3+} doped Y{sub 4}Al{sub 2}O{sub 9} (YAM) crystals were prepared by the micro-pulling down method. Optical-absorption and laser-selective-excitation techniques along with luminescence decays have been used to reveal that Sm{sup 3+} ions in YAM normally occupy four sites, which were characterized and discussed. The comprehensive sets of Stark energy levels of the four Sm{sup 3+} centers in YAM were established. The intensity ratio of forced electric dipole ({sup 4}G{sub 5/2} → {sup 6}H{sub 9/2}) and magnetic dipole ({sup 4}G{sub 5/2} → {sup 6}H{sub 5/2}) transitions has been used to estimate the degree of asymmetry of Sm{sup 3+} sites. The lifetime of Sm{sup 3+} ions and the cross-relaxation rates were experimentally determined as a function of concentration for two distinct crystallographic Sm{sup 3+} centers. The dependencies of the nearest surroundings on the relaxation of the {sup 4}G{sub 5/2} excited state was discussed.

Development of laser material processing and laser metrology techniques. Development of the power supply of high power CO{sub 2} laser for material processing

Energy Technology Data Exchange (ETDEWEB)

Lee, Heon Ju; Lee, Yong Hak; Jang, Do Hyun; Kim, Su Hun [Cheju National University, Cheju (Korea, Republic of)

1994-08-01

The 2 Kw solid state RF power supply has been designed and fabricated The power supply was composed of oscillator, driver amplifier and power amplifier. Each part of the power supply was developed and tested. The impedance matching circuit to apply this RF power supply for laser discharge excitation was fabricated also. The RF discharge experiment for the excitation of CO{sub 2} laser was performed. The radiofrequency power supply which has the output power of 2 Kw has been developed. The subsystems of the power supply have been fabricated and their performances were reliable. The RF discharge experiment to generate the laser plasma has been performed and input power density of 6 W/cm{sub 3} has been achieved. (author). 5 refs., 28 figs., 8 tabs.

Sliding stones of Racetrack Playa, Death Valley, USA: The roles of rock thermal conductivity and fluctuating water levels

Czech Academy of Sciences Publication Activity Database

Kletetschka, Günther; Hooke, R. L.; Ryan, A.; Fercana, G.; McKinney, E.; Schwebler, K. P.

2013-01-01

Roč. 195, 1 August (2013), s. 110-117 ISSN 0169-555X Institutional support: RVO:67985831 Keywords : Endorheic * Finite element modeling * hydrogeology * Racetrack playa * sliding stones Subject RIV: DB - Geology ; Mineralogy Impact factor: 2.577, year: 2013

Selective cell culture on UV transparent polymer by F{sub 2} laser surface modification

Energy Technology Data Exchange (ETDEWEB)

Hanada, Yasutaka, E-mail: y-hanada@riken.jp [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Sugioka, Koji [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Kawano, Hiroyuki [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Tsuchimoto, Takayoshi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyamoto, Iwao [Department of Applied Electronics, Faculty of Industrial Science and Technology Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510 (Japan); Miyawaki, Atsushi [RIKEN-Brain Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Midorikawa, Katsumi [RIKEN-Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

2009-09-30

A microchip made of UV transparent polymer (CYTOP) that can perform selective cell culture has been fabricated by F{sub 2} laser surface modification. The refractive index of CYTOP is almost the same as that of culture medium, which is essential for three-dimensional (3D) observation of cells. The F{sub 2} laser modification of CYTOP achieves hydrophilicity only on the laser irradiated area with little deterioration of the optical properties and surface smoothness. After the laser modification, HeLa cells were successfully cultured and strongly adhered only on the modified area of CYTOP. The cells patterned on CYTOP were applied for clear 3D observation using an optical microscope in phase contrast mode.

Nanometer scale materials - characterization and fabrication

International Nuclear Information System (INIS)

Murday, J.S.; Colton, R.J.; Rath, B.B.

1993-01-01

Materials and solid state scientists have made excellent progress in understanding material behavior in length scales from microns to meters. Below a micron, the lack of analytical prowess has been a deterrent. At the atomic scale, chemistry and atomic/molecular physics have also contributed significant understanding of matter. The maturity of these three communities, materials, solid state physics, atomic/molecular physics/chemistry, coupled with the development of analytical capability for nanometer-sized structures, promises to broaden our grasp of materials behavior into the last realm of unexplored size scales-nanometer. The motivation for this effort is driven both by the expectation of novel properties as well as by the potential solution to long standing technological issues. Critical scale lengths for many material properties fall in the nanometer range, examples include superconductor coherence lengths, electron inelastic mean free paths, electron wavelengths in solids, critical lengths for dislocation generation. Structures of nanometer size will undoubtedly show behavior unexpected from experience at the larger and smaller scales. Many technological problems such as adhesion, friction, corrosion, elasticity and fracture are believed to depend critically on nanometer scale phenomena. The millennia-old efforts to improve materials behavior have undoubtedly been slowed by our inability to 'observe' in this size range. (orig.)

Experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers under conditions of minimal roughness

Energy Technology Data Exchange (ETDEWEB)

Golyshev, A A; Malikov, A G; Orishich, A M; Shulyatyev, V B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2014-10-31

The results of an experimental study of laser-oxygen cutting of low-carbon steel using fibre and CO{sub 2} lasers are generalised. The dependence of roughness of the cut surface on the cutting parameters is investigated, and the conditions under which the surface roughness is minimal are formulated. It is shown that for both types of lasers these conditions can be expressed in the same way in terms of the dimensionless variables – the Péclet number Pe and the output power Q of laser radiation per unit thickness of the cut sheet – and take the form of the similarity laws: Pe = const, Q = const. The optimal values of Pe and Q are found. We have derived empirical expressions that relate the laser power and cutting speed with the thickness of the cut sheet under the condition of minimal roughness in the case of cutting by means of radiation from fibre and CO{sub 2} lasers. (laser technologies)

Laser machining micro-structures on diamond surface with a sub-nanosecond pulsed laser

Science.gov (United States)

Wu, Mingtao; Guo, Bing; Zhao, Qingliang

2018-02-01

Micro-structure surface on diamond material is widely used in a series of industrial and scientific applications, such as micro-electromechanical systems (MEMS), nanoelectromechanical systems (NEMS), microelectronics, textured or micro-structured diamond machining tools. The efficient machining of micro-structure on diamond surface is urgently demanded in engineering. In this paper, laser machining square micro-structure on diamond surface was studied with a sub-nanosecond pulsed laser. The influences of laser machining parameters, including the laser power, scanning speed, defocusing quantity and scanning pitch, were researched in view of the ablation depth, material removal rate and machined surface topography. Both the ablation depth and material removal rate increased with average laser power. A reduction of the growth rate of the two parameters was induced by the absorption of the laser plasma plume at high laser power. The ablation depth non-linearly decreased with the increasing of the scanning speed while the material removal rate showed an opposite tendency. The increasing of the defocusing quantity induced complex variation of the ablation depth and the material removal rate. The maximum ablation depth and material removal rate were achieved at a defocusing position. The ablation depth and material removal rate oppositely varied about the scanning pitch. A high overlap ratio was meaningful for achieving a smooth micro-structure surface topography. Laser machining with a large defocusing quantity, high laser power and small scanning pitch was helpful for acquiring the desired micro-structure which had a large depth and smooth micro-structure surface topography.

Control and manipulation of antiferromagnetic skyrmions in racetrack

Science.gov (United States)

Xia, Haiyan; Jin, Chendong; Song, Chengkun; Wang, Jinshuai; Wang, Jianbo; Liu, Qingfang

2017-12-01

Controllable manipulations of magnetic skyrmions are essential for next-generation spintronic devices. Here, the duplication and merging of skyrmions, as well as logical AND and OR functions, are designed in antiferromagnetic (AFM) materials with a cusp or smooth Y-junction structures. The operational time are in the dozens of picoseconds, enabling ultrafast information processing. A key factor for the successful operation is the relatively complex Y-junction structures, where domain walls propagate through in a controlled manner, without significant risks of pinning, vanishing or unwanted depinning of existing domain walls, as well as the nucleation of new domain walls. The motions of a multi-bit, namely the motion of an AFM skyrmion-chain in racetrack, are also investigated. Those micromagnetic simulations may contribute to future AFM skyrmion-based spintronic devices, such as nanotrack memory, logic gates and other information processes.

CO2 laser and plasma microjet process for improving laser optics

Science.gov (United States)

Brusasco, Raymond M.; Penetrante, Bernardino M.; Butler, James A.; Grundler, Walter; Governo, George K.

2003-09-16

A optic is produced for operation at the fundamental Nd:YAG laser wavelength of 1.06 micrometers through the tripled Nd:YAG laser wavelength of 355 nanometers by the method of reducing or eliminating the growth of laser damage sites in the optics by processing the optics to stop damage in the optics from growing to a predetermined critical size. A system is provided of mitigating the growth of laser-induced damage in optics by virtue of very localized removal of glass and absorbing material.

Time-resolved investigations of the fragmentation dynamic of H{sub 2} (D{sub 2}) in and with ultra-short laser pulses; Zeitaufgeloeste Untersuchungen zur Fragmentationsdynamik von H{sub 2} (D{sub 2}) in ultra-kurzen Laserpulsen

Energy Technology Data Exchange (ETDEWEB)

Ergler, T.

2006-07-19

In course of this work pump-probe experiments aimed to study ultrafast nuclear motion in H{sub 2} (D{sub 2}) fragmentation by intense 6-25 fs laser pulses have been carried out. In order to perform time-resolved measurements, a Mach-Zehnder interferometer providing two identical synchronized laser pulses with the time-delay variable from 0 to 3000 fs with 300 as accuracy and long-term stability has been built. The laser pulses at the intensities of up to 10{sup 15} W/cm{sup 2} were focused onto a H{sub 2} (D{sub 2}) molecular beam leading to the ionization or dissociation of the molecules, and the momenta of all charged reactions fragments were measured with a reaction microscope. With 6-7 fs pulses it was possible to probe the time evolution of the bound H{sup +}{sub 2} (D{sup +}{sub 2}) nuclear wave packet created by the first (pump) laser pulse, fragmenting the molecule with the second (probe) pulse. A fast delocalization, or ''collapse'', and subsequent ''revival'' of the vibrational wave packet have been observed. In addition, the signatures of the ground state vibrational excitation in neutral D{sub 2} molecule have been found, and the dominance of a new, purely quantum mechanical wave packet preparation mechanism (the so-called ''Lochfrass'') has been proved. In the experiments with 25 fs pulses the theoretically predicted enhancement of the ionization probability for the dissociating H{sup +}{sub 2} molecular ion at large internuclear distances has been detected for the first time. (orig.)

Growth and annealing effect of SrTiO{sub 3} thin films grown by pulsed laser deposition using fourth harmonic Nd:YAG pulsed laser

Energy Technology Data Exchange (ETDEWEB)

Takamura, Koji; Fujiwara, Takumi; Yokota, Akinobu; Nakamura, Motonori; Yoshimoto, Ken' ichi [National Institute of Technology, Asahikawa College, 2-2-1-6 Shunkodai, Asahikawa 071-8142 (Japan)

2017-06-15

SrTiO{sub 3} homoepitaxial films were grown by pulsed laser deposition (PLD) using a fourth harmonic Nd:YAG pulsed laser. The substrate temperature was kept constant at 600, 700, or 800 C. The laser energy was set at 9-25 mJ on the polycrystal SrTiO{sub 3} target. Post-procedure annealing was performed in the air for 24 h. The X-ray diffraction measurement results showed that the lattice constant of the film was only 0.010 Aa larger than that of the substrate and was not dependent on the annealing temperature. We demonstrated the possibility of growing near-stoichiometric SrTiO{sub 3} film by PLD using an Nd:YAG laser. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Determination of ultra-short laser induced damage threshold of KH{sub 2}PO{sub 4} crystal: Numerical calculation and experimental verification

Energy Technology Data Exchange (ETDEWEB)

Cheng, Jian [Center for Precision Engineering, School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210 (United States); Chen, Mingjun, E-mail: chenmj@hit.edu.cn, E-mail: chowdhury.24@osu.edu; Wang, Jinghe; Xiao, Yong [Center for Precision Engineering, School of Mechatronics Engineering, Harbin Institute of Technology, Harbin 150001 (China); Kafka, Kyle; Austin, Drake; Chowdhury, Enam, E-mail: chenmj@hit.edu.cn, E-mail: chowdhury.24@osu.edu [Department of Physics, The Ohio State University, 191 W. Woodruff Ave, Columbus, OH 43210 (United States)

2016-03-15

Rapid growth and ultra-precision machining of large-size KDP (KH{sub 2}PO{sub 4}) crystals with high laser damage resistance are tough challenges in the development of large laser systems. It is of high interest and practical significance to have theoretical models for scientists and manufacturers to determine the laser-induced damage threshold (LIDT) of actually prepared KDP optics. Here, we numerically and experimentally investigate the laser-induced damage on KDP crystals in ultra-short pulse laser regime. On basis of the rate equation for free electron generation, a model dedicated to predicting the LIDT is developed by considering the synergistic effect of photoionization, impact ionization and decay of electrons. Laser damage tests are performed to measure the single-pulse LIDT with several testing protocols. The testing results combined with previously reported experimental data agree well with those calculated by the model. By taking the light intensification into consideration, the model is successfully applied to quantitatively evaluate the effect of surface flaws inevitably introduced in the preparation processes on the laser damage resistance of KDP crystals. This work can not only contribute to further understanding of the laser damage mechanisms of optical materials, but also provide available models for evaluating the laser damage resistance of exquisitely prepared optical components used in high power laser systems.

Side-pumped Nd:YVO{sub 4} cw laser with grazing-incidence small angle configuration; Laser de Nd:YVO{sub 4} bombeado transversalmente em configuracao com angulo rasante interno

Energy Technology Data Exchange (ETDEWEB)

Camargo, Fabiola de Almeida

2006-07-01

Within the existing variety of laser cavity geometries and gain materials there is one combination that is particularly interesting because of its reduced complexity and high efficiency: the edge-pumped slab-laser using grazing-incidence geometry and a gain media with a very high pump absorption cross-section. In this work we studied a diode side-pumped Nd:YVO{sub 4} cw laser. We describe a single and a multiple bounce laser configurations. We demonstrate 22 W of multimode output power for 35 watts of pump power with a single pass through the gain media. A high optical-to-optical conversion efficiency of 63% and a slope efficiency of 74% with a very compact and simple Nd:YVO{sub 4} cavity that uses joint stability zones was achieved. The beam quality was M{sup 2} = 26 x 11 in the horizontal and vertical direction, respectively. With a double pass configuration we achieved 17 watts with a better beam quality of M{sup 2} = 3,4 x 3,7, in the horizontal and vertical direction, respectively. (author)

Micromachining of Al<sub>2sub>O>3sub>-TiC ceramics by excimer laser

Directory of Open Access Journals (Sweden)

Oliveira, V.

1998-04-01

Full Text Available Micromachining of Al<sub>2sub>O>3sub>-TiC ceramic using a KrF excimer laser was studied in the fluence range 2 to 8 J/cm² . The ablation rate decreases and the roughness increases with the first pulses but after about 200 pulses the process reaches a stationary stage where both roughness and ablation rate become constant. Observation of the processed areas by scanning electron microscopy showed that a globular topography is formed during the first stage and that the surface topography remains unchanged with further pulses. This globular topography is responsible for the variation of roughness and ablation rate observed during the first stage. EDS analysis showed that the globular features present an external region with higher titanium content and a core formed of unaffected material.

Se estudia el micromecanizado de cerámicas Al<sub>2sub>O>3sub>-TiC mediante un láser de excímero de KrF con un rango de fluencia de 2 a 8 J/cm² . La velocidad de ablación disminuye y la rugosidad aumenta con los primeros pulsos. Sin embargo, después de 200 pulsos, el proceso alcanza el régimen estacionario, donde tanto la rugosidad como la velocidad de ablación permanecen constantes. La observación mediante SEM de determinadas áreas mostraban una topografía globular formada durante la primera etapa, mientras que con los siguientes pulsos permanece in cambios. Esta topografía globular es responsable de la variación de rugosidad y de la velocidad de ablación observada durante las primeras etapas del proceso. Los análisis de EDS sobre las zonas globulares mostraron la existencia de una región externa rica en titanio y un núcleo formado por el material sin afectar.

The solidification behaviour of the UO{sub 2}–ThO{sub 2} system in a laser heating study

Energy Technology Data Exchange (ETDEWEB)

Böhler, R. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Delft University of Technology, Faculty of Applied Sciences, Department of Radiation Science and Technology, Mekelweg 15, 2629 JB Delft (Netherlands); Quaini, A. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); Capriotti, L. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Çakır, P. [Ege Univerity, Institute of Nuclear Sciences, 35100 Bornova Izmir (Turkey); European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Beneš, O.; Boboridis, K.; Guiot, A. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Luzzi, L. [Politecnico di Milano, Department of Energy, Enrico Fermi Center for Nuclear Studies (CeSNEF), via La Masa 34, 20156 Milano (Italy); Konings, R.J.M. [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany); Manara, D., E-mail: dario.manara@ec.europa.eu [European Commission, Joint Research Centre, Institute for Transuranium Elements (ITU), P.O. Box 2340, 76125 Karlsruhe (Germany)

2014-12-15

Highlights: • Melting of the full UO{sub 2}–ThO{sub 2} system was studied by laser heating. • A minimum melting point was found around 5 mol% ThO{sub 2} and T = 3098 K. • Ideal solution behaviour near melting was observed for compositions richer in ThO{sub 2}. • These compounds were also studied by Raman spectroscopy before and after melting. - Abstract: The high-temperature phase diagram of the UO{sub 2}–ThO{sub 2} system has been experimentally revisited in the present study for the first time since 1970, using a laser heating approach combined with fast pyrometry in a thermal arrest method. The melting/solidification temperature, which is of fundamental information for a reactor design was studied here. It was found that low addition of ThO{sub 2} to UO{sub 2} would result in a slight decrease of the solidification temperature. A minimum was found at 3098 K around a composition of 5 mol% ThO{sub 2}. The solid/liquid transition temperature was then observed to increase again with increasing ThO{sub 2} fraction. The literature value of pure ThO{sub 2} (around 3630 K) was well reproduced here. Important experimental difficulties, stemming from the high temperatures reached during the measurements, as well as a complete investigation with electron microscopy, Raman spectroscopy and powder X-ray diffraction, are extensively discussed. These results show the importance of the high-temperature oxygen chemistry in this actinide oxide compound.

Surface oxidation of porous ZrB{sub 2}-SiC ceramic composites by continuous-wave ytterbium fibre laser

Energy Technology Data Exchange (ETDEWEB)

Mahmod, Dayang Salyani Abang, E-mail: dygsalyani@gmail.com [Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia); Glandut, Nicolas [SPCTS, UMR 7315, CNRS, University of Limoges, European Ceramic Center, 12 Rue Atlantis, 87068 Limoges (France); Khan, Amir Azam [Department of Mechanical and Manufacturing Engineering, Faculty of Engineering, Universiti Malaysia Sarawak, 94300 Kota Samarahan, Sarawak (Malaysia); Labbe, Jean-Claude [SPCTS, UMR 7315, CNRS, University of Limoges, European Ceramic Center, 12 Rue Atlantis, 87068 Limoges (France)

2015-12-01

Highlights: • Surface oxidation of ZrB{sub 2}-SiC ceramic composites by Yb-fibre laser. • Round spiral laser pattern created for the surface oxidation. • Presence of laser-formed oxide scale and unaffected beneath regions. • Crazed but uncracked surface oxide. • A dense glassy SiO{sub 2}-rich layer exhibited enhances oxidation resistance. - Abstract: Surface treatment of ceramic substrates by a laser beam can allow to incorporate interesting properties to these ceramics. In the present work, surface oxidation of ca. 30% porous ZrB{sub 2}-SiC ceramic composites by using an ytterbium fibre laser was conducted. Oxidation of ceramic substrates through this process under ambient conditions has certain advantages compared to the classical oxidation method. A particular spiral laser pattern was created in order to produce an oxidized structure on ZrB{sub 2}-SiC porous substrates. The laser parameters were as follows i.e., laser power of 50, 60 and 70 W, a beam diameter of 1.25 mm, velocity of 2 mm/s, acceleration and deceleration of 1 mm/s{sup 2}. The microstructural and morphological changes in the laser-treated region was examined using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. At laser power of 70 W, the sample exhibits uniform oxidation. It revealed that the very porous bulk beneath remained unaffected and unoxidized because this laser-formed oxide scale protects the substrate from oxidation. The presence of oxidized and unaffected regions indicated a high degree of heat localization. The dense glassy SiO{sub 2}-rich layer prevents the inward oxygen diffusion into the inner bulk hence enhances the oxidation resistance.

Epitaxial growth of Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si substrates by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Paulraj, Joseph; Wang, Rongping; Sellars, Matthew; Luther-Davies, Barry [Australian National University, Laser Physics Centre, Research School of Physics and Engineering, Acton, Canberra, ACT (Australia)

2016-04-15

We investigated the optimal conditions to prepare high-quality Sc{sub 2}O{sub 3} films on Gd{sub 2}O{sub 3}-buffered Si wafers using pulsed laser deposition technique with an aim at developing waveguide devices that can transform the performance of the gradient echo quantum memory based on bulk crystals. Under the optimal conditions, only oxide and Si (2 2 2) peaks appeared in the X-ray diffraction pattern. The Sc{sub 2}O{sub 3} (2 2 2) diffraction peak was located at 2θ=31.5 with a full width at half maxima (FWHM) of 0.16 , and its rocking curve had a FWHM of 0.10 . In-plane epitaxial relationship was confirmed by X-ray pole figure where Sc{sub 2}O{sub 3} (1 1 1) was parallel to Si (1 1 1). High-resolution TEM images indicated clear interfaces and perfect lattice images with sharp electron diffraction dots. All these results confirm that the oxide films on Si were single crystalline with high quality. (orig.)

Topological insulator: Bi{sub 2}Se{sub 3}/polyvinyl alcohol film-assisted multi-wavelength ultrafast erbium-doped fiber laser

Energy Technology Data Exchange (ETDEWEB)

Guo, Bo; Yao, Yong, E-mail: yaoyong@hit.edu.cn; Yang, Yan-Fu; Yuan, Yi-Jun; Wang, Rui-Lai [Department of Electronic and Information Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Wang, Shu-Guang; Ren, Zhong-Hua [Department of Materials Science and Engineering, Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Yan, Bo [College of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450052 (China)

2015-02-14

We experimentally demonstrate a multi-wavelength ultrafast erbium-doped fiber laser incorporating a μm-scale topological insulator: Bi{sub 2}Se{sub 3}/Polyvinyl Alcohol film as both an excellent saturable absorber for mode-locking and a high-nonlinear medium to induce a giant third order optical nonlinear effect for mitigating the mode competition of erbium-doped fiber laser and stabilizing the multi-wavelength oscillation. By properly adjusting the pump power and the polarization state, the single-, dual-, triple-, four-wavelength mode-locking pulse could be stably initiated. For the four-wavelength operation, we obtain its pulse width of ∼22 ps and a fundamental repetition rate of 8.83 MHz. The fiber laser exhibits the maximum output power of 9.7 mW with the pulse energy of 1.1 nJ and peak power of 50 W at the pump power of 155 mW. Our study shows that the simple, stable, low-cost multi-wavelength ultrafast fiber laser could be applied in various potential fields, such as optical communication, biomedical research, and radar system.

NBS/LANL racetrack microtron control system

International Nuclear Information System (INIS)

Ayres, R.L.; Martin, E.R.; Trout, R.E.; Wilson, B.L.; Yoder, N.R.

1985-01-01

The distributed intelligence control system for the NBS/LANL racetrack microtron (RTM) is now nearing completion, with all major subsystems implemented and tested, thus providing some operating experience with most of the control system innovations. These include a triple hierarchy of microprocessor-based control elements, consisting of a primary control station and multiple secondary and tertiary control stations; light-link coupling to a tertiary station which operates at a 100 kV potential; a common database shared by separate microprocessors for handling hardware control and operator interactions; and joy stick control of the entire system. A unique secondary station interpreter program was used to great advantage for testing and checkout of various control and monitoring subsystems. The hardware design of the control system is based on Multibus I crates containing commercial Multibus I boards and a few custom designed boards. The primary-secondary data link is a high speed, bidirectional, full-duplex, 8-bit, ''byte'' parallel link designed for this application. This link permits very fast updating of the monitored data (> 5 per second) and timely response to operator control inputs at the primary station

Electrical transport properties and laser-induced voltage effect in La{sub 0.8}Ca{sub 0.2}MnO{sub 3} epitaxial thin films

Energy Technology Data Exchange (ETDEWEB)

Theingi, Mya [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China); University of Yangon, Department of Chemistry, Yangon (Myanmar); Ma, Ji; Zhang, Hui; Cui, Qi; Yi, Jianhong; Chen, Qingming [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China)

2014-03-15

La{sub 0.8}Ca{sub 0.2}MnO{sub 3} (LCMO) thin films about 200 nm thickness were grown on untilted and tilted (5 , 10 and 15 ) LaAlO{sub 3} (100) single crystal substrates by pulsed laser deposition technique. Electrical properties of the epitaxial thin films were studied by conventional four-probe technique and the anisotropic thermoelectric properties of the films grown on the tilted substrates have been investigated by laser-induced voltage (LIV) measurements. X-ray diffraction analysis and atomic force microscopy results show that the prepared LCMO thin films have a single phase and high crystalline quality. The remarkably large temperature coefficient of resistance (TCR) values (above 11 %/K) are observed in the all films. TCR value reaches 18 %/K on the film grown on 10 tilted substrate. The intensity of LIV signals monotonously increases with the tilting angles, and the largest signal is 148 mV with the fast time response 229 ns for the film grown on 15 tilted substrate. (orig.)

Self-Raman Nd:YVO4 Laser and Electro-Optic Technology for Space-Based Sodium Lidar Instrument

Science.gov (United States)

Krainak, Michael A.; Yu, Anthony W.; Janches, Diego; Jones, Sarah L.; Blagojevic, Branimir; Chen, Jeffrey

2014-01-01

We are developing a laser and electro-optic technology to remotely measure Sodium (Na) by adapting existing lidar technology with space flight heritage. The developed instrumentation will serve as the core for the planning of an Heliophysics mission targeted to study the composition and dynamics of Earth's mesosphere based on a spaceborne lidar that will measure the mesospheric Na layer. We present performance results from our diode-pumped tunable Q-switched self-Raman c-cut Nd:YVO4 laser with intra-cavity frequency doubling that produces multi-watt 589 nm wavelength output. The c-cut Nd:YVO4 laser has a fundamental wavelength that is tunable from 1063-1067 nanometers. A CW (Continuous Wave) External Cavity diode laser is used as a injection seeder to provide single-frequency grating tunable output around 1066 nanometers. The injection-seeded self-Raman shifted Nd:VO4 laser is tuned across the sodium vapor D2 line at 589 nanometers. We will review technologies that provide strong leverage for the sodium lidar laser system with strong heritage from the Ice Cloud and Land Elevation Satellite-2 (ICESat-2) Advanced Topographic Laser Altimeter System (ATLAS). These include a space-qualified frequency-doubled 9 watts-at-532-nanometer wavelength Nd:YVO4 laser, a tandem interference filter temperature-stabilized fused-silica-etalon receiver and high-bandwidth photon-counting detectors.

Repetitively pulsed TEA CO{sub 2} laser and its application for second harmonic generation in ZnGeP{sub 2} crystal

Energy Technology Data Exchange (ETDEWEB)

Koval' chuk, L V; Grezev, A N; Niz' ev, V G; Yakunin, V P [Institute on Laser and Information Technologies, Russian Academy of Sciences, Shatura, Moscow Region (Russian Federation); Mezhevov, V S [Kaluga Laser Innovation and Technology Centre, Obninsk, Kaluga region (Russian Federation); Goryachkin, D A [Russian State Scientific Center for Robotics and Technical Cybernetics, St. Petersburg (Russian Federation); Sergeev, V V; Kalintsev, A G [Open Joint Stock Company S.I.Vavilov State Optical Institute, St. Petersburg (Russian Federation)

2015-10-31

Experimental results are presented on the development of a radiation source emitting at a wavelength of 4.775 μm with a pulse energy up to 50 mJ and an average power up to several watts in short pulse trains. A TEA CO{sub 2} laser and a nonlinear converter based on a ZnGeP{sub 2} crystal, which are specially designed for these experiments, are described. The main limitations of nonlinear conversion and possible ways to overcome these limitations are considered. (lasers)

Moscow University race-track microtron control system: ideas and development

International Nuclear Information System (INIS)

Chepurnov, A.S.; Gribov, I.V.; Morozov, S.Yu.; Shumakov, A.V.; Zinoviev, S.V.

1992-01-01

Moscow University race-track microtron (RTM) control system is a star-shape network of LSI-11 compatible microcomputers. Each of them is connected with RTM systems via CAMAC; optical fiber coupling is also used. Control system software is designed on Pascal-1, supplemented with real time modules and Macro. A unified real time technique and reenterable data acquisition drivers allow to simplify development of control drivers and algorithms. Among the latter three main types are used: DDC methods, those, based on optimization technique and algorithms, applying models of microtron's systems. Man-machine interface is based on concept of the 'world of accelerator'. It supports means to design, within hardware possibilities, various computer images of the RTM. (author)

Qualitative and quantitative analysis of an additive element in metal oxide nanometer film using laser induced breakdown spectroscopy.

Science.gov (United States)

Xiu, Junshan; Liu, Shiming; Sun, Meiling; Dong, Lili

2018-01-20

The photoelectric performance of metal ion-doped TiO 2 film will be improved with the changing of the compositions and concentrations of additive elements. In this work, the TiO 2 films doped with different Sn concentrations were obtained with the hydrothermal method. Qualitative and quantitative analysis of the Sn element in TiO 2 film was achieved with laser induced breakdown spectroscopy (LIBS) with the calibration curves plotted accordingly. The photoelectric characteristics of TiO 2 films doped with different Sn content were observed with UV visible absorption spectra and J-V curves. All results showed that Sn doping could improve the optical absorption to be red-shifted and advance the photoelectric properties of the TiO 2 films. We had obtained that when the concentration of Sn doping in TiO 2 films was 11.89  mmol/L, which was calculated by the LIBS calibration curves, the current density of the film was the largest, which indicated the best photoelectric performance. It indicated that LIBS was a potential and feasible measured method, which was applied to qualitative and quantitative analysis of the additive element in metal oxide nanometer film.

Comments on Racetrack playa: Rocks moved by wind alone

Science.gov (United States)

Sanz-Montero, M. E.; Cabestrero, Ó.; Rodríguez-Aranda, J. P.

2016-03-01

The mechanisms by which rocks move across the beds of playa lakes leaving tracks continue to be debated (Sanz-Montero and Rodríguez-Aranda, 2013; Norris et al., 2014; Sanz-Montero et al., 2015a,b; Baumgardner and Shaffer, 2015; Jones and Hooke, 2015). In this regard, the article by Jones and Hooke (Aeolian Research 19, 2015) is particularly interesting since it provides a description of these mechanisms by R. Jones who, during a storm event in 1972, was probably the first person to witness movement of rocks. The dominant meteorological conditions described by Jones during the period when the tracks were formed are, significantly, rather similar to those previously described by Clements (1952) at Little Bonnie Claire Playa (Nevada, USA). The storm conditions referred to in the article also coincide with the observations, measurements and deductions made by Sanz-Montero and Rodríguez-Aranda (2013) and Sanz-Montero et al. (2015a,b) at Altillo Chica playa lake, Central Spain. Furthermore, we were able to carry out an on-site analysis of the sedimentary structures at Racetrack playa in June 2015, allowing us to verify the similarity of the features present at both sites. Together with the important role played by gusty winds in the formation of the tracks, all the above mentioned studies point to the presence of a thin veneer of water, just a few millimeters deep, in the area of the playa lake where the rock movements occur. However, Jones and Hooke (2015) disregard the force exerted by moving water and analyze the coefficient of friction assuming that the rocks are moved by wind alone. We offer an alternative explanation for the movement of rocks both at Racetrack and Altillo Chica playa lake which considers not only the wind but also the role played by moving water in conjunction with other parameters which modify the erosion thresholds (rocks acting as obstacles) and reduce friction (benthic microorganisms).

CO sub 2 laser-heated diamond-anvil cell methodology revisited

CERN Document Server

Hearne, G; Zhao, J

2002-01-01

A description is given of CO sub 2 laser heating system for attaining high temperatures at pressure in a diamond-anvil cell (DAC). The main purpose of this paper is to demonstrate that a relatively inexpensive set-up, perhaps affordable to many high-pressure laboratories, may be commissioned for laser-heated DAC experiments to achieve comparable extreme P-T conditions to those attained with more sophisticated stations documented in the literature. A novel idea of using the analogue output of a CCD camera to estimate the peak temperature and map the temperature distribution across the hot-spot has been tested. In an additional initial experiment on cubic zirconia (c-ZrO sub 2) we present evidence from a Raman characterization of the sample that temperatures exceeding 4000 K have been obtained at pressure in the DAC.

Sub-wavelength patterning of organic monolayers via nonlinear processing with continuous-wave lasers

Energy Technology Data Exchange (ETDEWEB)

Mathieu, Mareike; Hartmann, Nils, E-mail: nils.hartmann@uni-due.de [Fakultaet fuer Chemie, Universitaet Duisburg-Essen, 45117 Essen (Germany); CeNIDE-Center for Nanointegration Duisburg-Essen, 47048 Duisburg (Germany); NETZ-NanoEnergieTechnikZentrum, 47048 Duisburg (Germany)

2010-12-15

In recent years, nonlinear processing with continuous-wave lasers has been demonstrated to be a facile means of rapid nanopatterning of organic monolayers down to the sub-100 nm range. In this study, we report on laser patterning of thiol-based organic monolayers with sub-wavelength resolution. Au-coated silicon substrates are functionalized with 1-hexadecanethiol. Irradiation with a focused beam of an Ar{sup +} laser operating at {lambda}=514 nm allows one to locally remove the monolayer. Subsequently, the patterns are transferred into the Au film via selective etching in a ferri-/ferrocyanide solution. Despite a 1/e{sup 2} spot diameter of about 2.8 {mu}m, structures with lateral dimensions down to 250 nm are fabricated. The underlying nonlinear dependence of the patterning process on laser intensity is traced back to the interplay between the laser-induced transient local temperature rise and the thermally activated desorption of the thiol molecules. A simple thermokinetic analysis of the data allows us to determine the effective kinetic parameters. These results complement our previous work on photothermal laser patterning of ultrathin organic coatings, such as silane-based organic monolayers, organo/silicon interfaces and supported membranes. A general introduction to nonlinear laser processing of organic monolayers is presented.

Local electrophoresis deposition assisted by laser trapping coupled with a spatial light modulator for three-dimensional microfabrication

Science.gov (United States)

Matsuura, Toshiki; Takai, Takanari; Iwata, Futoshi

2017-10-01

We describe a novel three-dimensional fabrication technique using local electrophoresis deposition assisted by laser trapping coupled with a spatial light modulator (SLM). In a solution containing nanometer-scale colloidal Au particles, multiple laser spots formed on a conductive substrate by the SLM gathered the nanoparticles together, and then the nanoparticles were electrophoretically deposited onto the substrate by an applied electrical field. However, undesirable sub-spots often appeared due to optical interference from the multiple laser spots, which deteriorated the accuracy of the deposition. To avoid the appearance of undesirable sub-spots, we proposed a method using quasi-multiple spots, which we realized by switching the position of a single spot briefly using the SLM. The method allowed us to deposit multiple dots on the substrate without undesirable sub-dot deposition. By moving the substrate downward during deposition, multiple micro-pillar structures could be fabricated. As a fabrication property, the dependence of the pillar diameter on laser intensity was investigated by changing the number of laser spots. The smallest diameter of the four pillars fabricated in this study was 920 nm at the laser intensity of 2.5 mW. To demonstrate the effectiveness of the method, multiple spiral structures were fabricated. Quadruple spirals of 46 µm in height were successfully fabricated with a growth rate of 0.21 µm/s using 2200 frames of the CGH patterns displayed in the SLM at a frame rate of 10 fps.

Effect of annealing on structural and optical properties of Cu{sub 2}ZnSnS{sub 4} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Surgina, G.D., E-mail: silvereye@bk.ru [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation); Nevolin, V.N. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); P.N. Lebedev Physical Institute of the Russian Academy of Sciences, Moscow 119991 (Russian Federation); Sipaylo, I.P.; Teterin, P.E. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Medvedeva, S.S. [Immanuel Kant Baltic Federal University, Kaliningrad 236041 (Russian Federation); Lebedinsky, Yu.Yu.; Zenkevich, A.V. [National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409 (Russian Federation); Moscow Institute of Physics and Technology, Dolgoprudny, Moscow region 141700 (Russian Federation)

2015-11-02

In this work, we compare the effect of different types of thermal annealing on the morphological, structural and optical properties of Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films grown by reactive Pulsed Laser Deposition in H{sub 2}S flow. Rutherford backscattering spectrometry, atomic force microscopy, X-ray diffraction, Raman spectroscopy and optical spectrophotometry data reveal dramatic increase of the band gap and the crystallite size without the formation of secondary phases upon annealing in N{sub 2} at the optimized conditions. - Highlights: • Cu{sub 2}ZnSnS{sub 4} (CZTS) thin films were grown at room temperature. • Reactive Pulsed Laser Deposition in H{sub 2}S flow was used as a growth method. • Effect of annealing conditions on CZTS structural and optical properties is revealed. • Both the grain size and the band gap of CZTS film increase following the annealing. • Annealing in N{sub 2} effectively inhibits the formation of Sn{sub x}S secondary phases.

Energetic, spectral, and temporal characteristics of a two-wave CO/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Bertel' , I.M.; Petukhov, V.O.; Prokopov, A.P.; Tochitskii, S.Ya.; Churakov, V.V.

1987-09-01

This work studies the energetic and temporal parameters of a pulsed two-wave TEA CO/sub 2/ laser's radiation and the means for controlling these parameters. Obtaining the two-wave generation regime in CO/sub 2/ lasers uses, as is known, spatial splitting of the radiation, different variants of operating diffraction gratings, and placing a cell with selectively absorbing gas in the resonator. To realize the simultaneous two-wave generation regime in the present work, a double-resonant scheme is used with mutually orthogonal polarizers to spatially separate the radiation.

In vitro mesenchymal stem cell response to a CO{sub 2} laser modified polymeric material

Energy Technology Data Exchange (ETDEWEB)

Waugh, D.G., E-mail: d.waugh@chester.ac.uk [Laser Engineering and Manufacturing Research Centre, Faculty of Science and Engineering, University of Chester, Chester CH1 4BJ (United Kingdom); Hussain, I. [School of Life Sciences, Brayford Pool, University of Lincoln, Lincoln LN6 7TS (United Kingdom); Lawrence, J.; Smith, G.C. [Laser Engineering and Manufacturing Research Centre, Faculty of Science and Engineering, University of Chester, Chester CH1 4BJ (United Kingdom); Cosgrove, D. [School of Life Sciences, Brayford Pool, University of Lincoln, Lincoln LN6 7TS (United Kingdom); Toccaceli, C. [Laser Engineering and Manufacturing Research Centre, Faculty of Science and Engineering, University of Chester, Chester CH1 4BJ (United Kingdom)

2016-10-01

With an ageing world population it is becoming significantly apparent that there is a need to produce implants and platforms to manipulate stem cell growth on a pharmaceutical scale. This is needed to meet the socio-economic demands of many countries worldwide. This paper details one of the first ever studies in to the manipulation of stem cell growth on CO{sub 2} laser surface treated nylon 6,6 highlighting its potential as an inexpensive platform to manipulate stem cell growth on a pharmaceutical scale. Through CO{sub 2} laser surface treatment discrete changes to the surfaces were made. That is, the surface roughness of the nylon 6,6 was increased by up to 4.3 μm, the contact angle was modulated by up to 5° and the surface oxygen content increased by up to 1 atom %. Following mesenchymal stem cell growth on the laser treated samples, it was identified that CO{sub 2} laser surface treatment gave rise to an enhanced response with an increase in viable cell count of up to 60,000 cells/ml when compared to the as-received sample. The effect of surface parameters modified by the CO{sub 2} laser surface treatment on the mesenchymal stem cell response is also discussed along with potential trends that could be identified to govern the mesenchymal stem cell response.

Preparation of TiO sub 2 nanoparticles by pulsed laser ablation: Ambient pressure dependence of crystallization

CERN Document Server

Matsubara, M; Yamaki, T; Itoh, H; Abe, H

2003-01-01

Pulsed laser ablation (PLA) with a KrF excimer laser was used to prepare fine particles of titanium dioxide (TiO sub 2). The ablation in an atmosphere of Ar and O sub 2 (5:5) at total pressures of >= 1 Torr led to the formation of TiO sub 2 nanoparticles composed of anatase and rutile structures without any suboxides. The weight fraction of the rutile/anatase crystalline phases was dependent on the pressure of the Ar/O sub 2 gas. The TiO sub 2 nanoparticles had a spherical shape and their size, ranging from 10 and 14 nm, also appeared to be dependent on the ambient pressure. (author)

Growth of centimeter-scale atomically thin MoS{sub 2} films by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Siegel, Gene; Venkata Subbaiah, Y. P.; Prestgard, Megan C.; Tiwari, Ashutosh, E-mail: tiwari@eng.utah.edu [Nanostructured Materials Research Laboratory, Department of Materials Science and Engineering, University of Utah, Salt Lake City, Utah 84112 (United States)

2015-05-01

We are reporting the growth of single layer and few-layer MoS{sub 2} films on single crystal sapphire substrates using a pulsed-laser deposition technique. A pulsed KrF excimer laser (wavelength: 248 nm; pulse width: 25 ns) was used to ablate a polycrystalline MoS{sub 2} target. The material thus ablated was deposited on a single crystal sapphire (0001) substrate kept at 700 °C in an ambient vacuum of 10{sup −6} Torr. Detailed characterization of the films was performed using atomic force microscopy (AFM), Raman spectroscopy, UV-Vis spectroscopy, and photoluminescence (PL) measurements. The ablation of the MoS{sub 2} target by 50 laser pulses (energy density: 1.5 J/cm{sup 2}) was found to result in the formation of a monolayer of MoS{sub 2} as shown by AFM results. In the Raman spectrum, A{sub 1g} and E{sup 1}{sub 2g} peaks were observed at 404.6 cm{sup −1} and 384.5 cm{sup −1} with a spacing of 20.1 cm{sup −1}, confirming the monolayer thickness of the film. The UV-Vis absorption spectrum exhibited two exciton absorption bands at 672 nm (1.85 eV) and 615 nm (2.02 eV), with an energy split of 0.17 eV, which is in excellent agreement with the theoretically predicted value of 0.15 eV. The monolayer MoS{sub 2} exhibited a PL peak at 1.85 eV confirming the direct nature of the band-gap. By varying the number of laser pulses, bi-layer, tri-layer, and few-layer MoS{sub 2} films were prepared. It was found that as the number of monolayers (n) in the MoS{sub 2} films increases, the spacing between the A{sub 1g} and E{sup 1}{sub 2g} Raman peaks (Δf) increases following an empirical relation, Δf=26.45−(15.42)/(1+1.44 n{sup 0.9}) cm{sup −1}.

David Adler Lectureship Award in the Field of Materials Physics: Racetrack Memory - a high-performance, storage class memory using magnetic domain-walls manipulated by current

Science.gov (United States)

Parkin, Stuart

2012-02-01

Racetrack Memory is a novel high-performance, non-volatile storage-class memory in which magnetic domains are used to store information in a ``magnetic racetrack'' [1]. The magnetic racetrack promises a solid state memory with storage capacities and cost rivaling that of magnetic disk drives but with much improved performance and reliability: a ``hard disk on a chip''. The magnetic racetrack is comprised of a magnetic nanowire in which a series of magnetic domain walls are shifted to and fro along the wire using nanosecond-long pulses of spin polarized current [2]. We have demonstrated the underlying physics that makes Racetrack Memory possible [3,4] and all the basic functions - creation, and manipulation of a train of domain walls and their detection. The physics underlying the current induced dynamics of domain walls will also be discussed. In particular, we show that the domain walls respond as if they have mass, leading to significant inertial driven motion of the domain walls over long times after the current pulses are switched off [3]. We also demonstrate that in perpendicularly magnetized nanowires there are two independent current driving mechanisms: one derived from bulk spin-dependent scattering that drives the domain walls in the direction of electron flow, and a second interfacial mechanism that can drive the domain walls either along or against the electron flow, depending on subtle changes in the nanowire structure. Finally, we demonstrate thermally induced spin currents are large enough that they can be used to manipulate domain walls. [4pt] [1] S.S.P. Parkin, US Patent 6,834,005 (2004); S.S.P. Parkin et al., Science 320, 190 (2008); S.S.P. Parkin, Scientific American (June 2009). [0pt] [2] M. Hayashi, L. Thomas, R. Moriya, C. Rettner and S.S.P. Parkin, Science 320, 209 (2008). [0pt] [3] L. Thomas, R. Moriya, C. Rettner and S.S.P. Parkin, Science 330, 1810 (2010). [0pt] [4] X. Jiang et al. Nat. Comm. 1:25 (2010) and Nano Lett. 11, 96 (2011).

Generation of MoS{sub 2} quantum dots by laser ablation of MoS{sub 2} particles in suspension and their photocatalytic activity for H{sub 2} generation

Energy Technology Data Exchange (ETDEWEB)

Baldoví, Herme G.; Latorre-Sánchez, Marcos; Esteve-Adell, Iván [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain); Khan, Anish; Asiri, Abdullah M. [King Abdulaziz University, Center of Excellence for Advanced Materials Research (Saudi Arabia); Kosa, Samia A. [King Abdulaziz University, Chemistry Department, Faculty of Science (Saudi Arabia); Garcia, Hermenegildo, E-mail: hgarcia@qim.upv.es [Universitat Politècnica de València, Instituto Universitario de Tecnología Química CSIC-UPV and Departamento de Química (Spain)

2016-08-15

MoS{sub 2} quantum dots (QDs) have been obtained in colloidal suspensions by 532 nm laser ablation (7 ns fwhp/pulse, 50 mJ/pulse) of commercial MoS{sub 2} particles in acetonitrile. High-resolution transmission electron microscopy images show a lateral size distribution from 5 to 20 nm, but a more homogeneous particle size of 20 nm can be obtained by silica gel chromatography purification in acetonitrile. MoS{sub 2} QDs obtained by laser ablation are constituted by 3–6 MoS{sub 2} layers (1.8–4 nm thickness) and exhibit photoluminescence whose λ{sub PL} varies from 430 to 530 nm depending on the excitation wavelength. As predicted by theory, the confinement effect and the larger periphery in MoS{sub 2} QDs increasing the bandgap and having catalytically active edges are reflected in an enhancement of the photocatalytic activity for H{sub 2} generation upon UV–Vis irradiation using CH{sub 3}OH as sacrificial electron donor due to the increase in the reduction potential of conduction band electrons and the electron transfer kinetics.

Repetitively pulsed, double discharge TEA CO/sub 2/ laser

Energy Technology Data Exchange (ETDEWEB)

Hamilton, D C; James, D J; Ramsden, S A

1975-10-01

The design and operation of a repetitively pulsed TEA CO/sub 2/ laser is described. Average powers of up to 400 W at a repetition frequency of 200 pulses/s have been obtained. The system has also been used to provide long pulses (over 20 ..mu..s) and tunable single axial mode pulses.

CsPbBr{sub 3} nanocrystal saturable absorber for mode-locking ytterbium fiber laser

Energy Technology Data Exchange (ETDEWEB)

Zhou, Yan; Li, Yue; Xu, Jianqiu; Tang, Yulong, E-mail: yulong@sjtu.edu.cn [Key Laboratory for Laser Plasmas (MOE), Department of Physics and Astronomy, Collaborative Innovation Center of IFSA, Shanghai Jiao Tong University, Shanghai 200240 (China); Hu, Zhiping; Tang, Xiaosheng [Key Laboratory of Optoelectronic Technology and Systems of the Education Ministry of China, College of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

2016-06-27

Cesium lead halide perovskite nanocrystals (CsPbX{sub 3}, X = Cl, Br, I) have been reported as efficient light-harvesting and light-emitting semiconductor materials, but their nonlinear optical properties have been seldom touched upon. In this paper, we prepare layered CsPbBr{sub 3} nanocrystal films and characterize their physical properties. Broadband linear absorption from ∼0.8 to over 2.2 μm and nonlinear optical absorption at the 1-μm wavelength region are measured. The CsPbBr{sub 3} saturable absorber (SA), manufactured by drop-casting of colloidal CsPbBr{sub 3} liquid solution on a gold mirror, shows modulation depth and saturation intensity of 13.1% and 10.7 MW/cm{sup 2}, respectively. With this SA, mode-locking operation of a polarization-maintained ytterbium fiber laser produces single pulses with duration of ∼216 ps, maximum average output power of 10.5 mW, and the laser spectrum is centered at ∼1076 nm. This work shows that CsPbBr{sub 3} films can be efficient SA candidates for fiber lasers and also have great potential to become broadband linear and nonlinear optical materials for photonics and optoelectronics.

Evolution of the racetrack microtron control system

International Nuclear Information System (INIS)

Martin, E.R.; Schneider, C.M.; Martinez, V.A.; Trout, R.E.; Gritzo, R.E.

1982-01-01

Ultimately, the true measure of a control system lies in how well initial decisions allow for exigencies, as the overall machine evolves and requirements solidify. Recognizing that advances in electronic technology virtually guarantee that any system will be technologically out of date by the time it is operational, the criteria really do not involve the state of the technological advancement, but instead legitimately ask whether the control-system design can adjust to the inevitable machine-design changes, whether the operators can use it to control the machine in a reasonable manner, whether it was built within budget constraints, or, in short, whether it works. On these bases, our initial decisions on the racetrack microtron (RTM) control system have been increasingly vindicated as the system has evolved, and we feel that our experiences have shed some light on just which criteria are of real importance, and which are merely a part of the lore of popular misinformation. Unless the basic requirements are met, technical elegance is no virtue, and when they are met, design simplicity is no vice

Nanocrystalline Sr{sub 2}CeO{sub 4} thin films grown on silicon by laser ablation

Energy Technology Data Exchange (ETDEWEB)

Perea, Nestor [Posgrado en Fisica de Materiales, CICESE-UNAM, Km. 107 Carretera Tijuana-Ensenada, Ensenada, B.C., 22860 (Mexico); Hirata, G.A. [Centro de Ciencias de la Materia Condensada-UNAM, Km. 107 Carretera Tijuana Ensenada, Ensenada, B.C. 22860 (Mexico)]. E-mail: hirata@ccmc.unam.mx

2006-02-21

Blue-white luminescent Sr{sub 2}CeO{sub 4} thin films were deposited by using pulsed laser ablation ({lambda} = 248 nm wavelength) on 500 deg. C silicon (111) substrates under an oxygen pressure of 55 mTorr. High-resolution electron transmission microscopy, electron diffraction and X-ray diffraction analysis revealed that the films were composed of nanocrystalline Sr{sub 2}CeO{sub 4} grains of the order of 20-30 nm with a preferential orientation in the (130) crystallographic direction. The excitation and photoluminescence spectra measured on the films maintained the characteristic emission of bulk Sr{sub 2}CeO{sub 4} however, the emission peak appeared narrower and blue-shifted as compared to the luminescence spectrum of the target. The blue-shift and a preferential crystallographic orientation during the growth formation of the film is related to the nanocrystalline nature of the grains due to the quantum confinement behavior and surface energy minimization in nanostructured systems.

Nanometer Characterization/Manipulation Facility

Data.gov (United States)

Federal Laboratory Consortium — FUNCTION: Characterizes the nanometer scale of biological, chemical, physical, electronic, and mechanical properties of surfaces and thin films using scanning probe...

Effect of Ca doping level on the laser-induced voltages in tilted La{sub 1-x}Ca{sub x}MnO{sub 3} (0.1 ≤ x ≤ 0.7) thin films

Energy Technology Data Exchange (ETDEWEB)

Ma, Ji; Zhang, Hui; Chen, Qingming; Liu, Xiang [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China); Theingi, Mya [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China); University of Yangon, Department of Chemistry, Yangon (Myanmar)

2014-03-15

Tilted La{sub 1-x}Ca{sub x}MnO{sub 3} (0.1 ≤ x ≤ 0.7) thin films have been grown on vicinal cut LaAlO{sub 3} (100) substrate by pulsed laser deposition. The laser-induced voltage effect was studied at room temperature with the KrF excimer laser using as the thermal source. The relationships between Ca doping level and voltage signal, response time and anisotropy Seebeck coefficient were established. The voltage signal and anisotropy Seebeck coefficient increase at first with increasing Ca doping level, reach a maximum at the same Ca content around x = 0.5, and then decrease. The respond time decreases with the Ca concentration increasing, and changes very little after x = 0.5. The figure of merit F{sub m} was also the largest at this doping level, indicating a potential good performance of the photodetector devices. The variation of intrinsic structural and transport anisotropy induced by the change of Ca concentration has been proposed to account for the different LIV effects observed in LCMO thin films. (orig.)

Reactivity of laser-cleaned stones to a SO<sub>2sub> ageing test

Directory of Open Access Journals (Sweden)

Alonso, F.J.

2004-03-01

Full Text Available In order to study the reaction or susceptibility of Nd:YAG laser cleaned stones to polluted atmospheres, several types of stone, both cemented (limestone and crystalline (marble, granite, were exposed to an atmosphere having simulated SO<sub>2sub> pollution. The subsequent effects on the specimens were assessed for variations in surface morphology, weight and colour The main conclusion is that the application of laser irradiation to the selected stone specimens does not significantly influence their reaction to sulphur dioxide

Con el fin de estudiar la reactividad o susceptibilidad frente a un ambiente contaminado de piedras limpiadas con radiación láser Nd:YAG, se ha sometido una serie de materiales rocosos cementados (calizas y cristalinos (mármol, granito a un ensayo de exposición a atmósfera concentrada en dióxido de azufre. Los efectos producidos en las muestras ensayadas se han valorado en función de las variaciones en la morfología superficial, en el peso y en el color. Se concluye que la aplicación de radiación láser a las muestras de piedra seleccionadas no influye, de manera significativa, en la reactividad de éstas frente al dióxido de azufre.

Using the integral equations method to model a 2G racetrack coil with anisotropic critical current dependence

Science.gov (United States)

Martins, F. G. R.; Sass, F.; Barusco, P.; Ferreira, A. C.; de Andrade, R., Jr.

2017-11-01

Second-generation (2G) superconducting wires have already proved their potential in several applications. These materials have a highly nonlinear behavior that turns an optimized engineering project into a challenge. Between several numerical techniques that can be used to perform this task, the integral equations (IE) method stands out for avoiding mesh problems by representing the 2G wire cross-sectional area by a line. While most applications need to be represented in a 3D geometry, the IE is limited to longitudinal or axisymmetric models. This work demonstrates that a complex 3D geometry can be modeled by several coupled simulations using the IE method. In order to prove this statement, the proposed technique was used to simulate a 2G racetrack coil considering the self-field magnitude (B) and incidence angle (θ) on the tape. The J c characteristic was modeled in terms of parallel and normal to the tape plane magnetic field components (J c(B ∥ , B ⊥)) obtained from a V-I(B, θ) characterization of a tape segment. This result was implemented using commercial software with both A-V (vector magnetic potential and scalar voltage potential) and IE coupled simulations solved by finite elements. This solution bypasses the meshing problem due to the tapes slim geometry, considering each turn a single 1D model, all magnetically interacting in two 2D models. The simulations results are in good agreement to what was both expected and observed in the literature. The simulation is compared to the measured V-I characteristic for a single pancake racetrack coil built with same geometry as its simulation models, and a theoretical study demonstrates the possibilities of the proposed tool for analyzing a racetrack coil current density and electric field behavior in each of its turns.

Effect of Mo and nano-Nd{sub 2}O{sub 3} on the microstructure and wear resistance of laser cladding Ni-based alloy coatings

Energy Technology Data Exchange (ETDEWEB)

Ding, Lin; Hu, Shengsun; Shen, Junqi [Tianjin University, Tianjin Key Laboratory of Advanced Joining Technology, School of Materials Science and Engineering, Tianjin (China); Quan, Xiumin [Lu' an Vocation Technology College, School of Automobile and Mechanical and Electrical Engineering, Lu' an (China)

2016-04-15

Three kinds of coatings were successfully prepared on Q235 steel by laser cladding technique through adulterating with Mo and nano-Nd{sub 2}O{sub 3} into Ni-based alloys. The effect of Mo and nano-Nd{sub 2}O{sub 3} on the microstructure and properties of Ni-based coatings was investigated systematically by means of optical microscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive spectroscopy, and microhardness testing and wear testing. The results indicated a certain amount of fine grains and polygonal equiaxed grains synthesized after adding Mo and nano-Nd{sub 2}O{sub 3}. Both the microhardness and wear resistance of Ni-based coatings improved greatly with a moderate additional amount of Mo and nano-Nd{sub 2}O{sub 3}. The largest improvement in microhardness was 31.9 and 14.7 %, and the largest reduction in loss was 45.0 and 30.7 %, respectively, for 5.0 wt% Mo powders and 1.0 wt% nano-Nd{sub 2}O{sub 3}. The effect of Mo on microhardness and wear resistance of laser cladding Ni-based alloy coatings is greater than the effect of nano-Nd{sub 2}O{sub 3}. (orig.)

Interferometrically enhanced sub-terahertz picosecond imaging utilizing a miniature collapsing-field-domain source

Science.gov (United States)

Vainshtein, Sergey N.; Duan, Guoyong; Mikhnev, Valeri A.; Zemlyakov, Valery E.; Egorkin, Vladimir I.; Kalyuzhnyy, Nikolay A.; Maleev, Nikolai A.; Näpänkangas, Juha; Sequeiros, Roberto Blanco; Kostamovaara, Juha T.

2018-05-01

Progress in terahertz spectroscopy and imaging is mostly associated with femtosecond laser-driven systems, while solid-state sources, mainly sub-millimetre integrated circuits, are still in an early development phase. As simple and cost-efficient an emitter as a Gunn oscillator could cause a breakthrough in the field, provided its frequency limitations could be overcome. Proposed here is an application of the recently discovered collapsing field domains effect that permits sub-THz oscillations in sub-micron semiconductor layers thanks to nanometer-scale powerfully ionizing domains arising due to negative differential mobility in extreme fields. This shifts the frequency limit by an order of magnitude relative to the conventional Gunn effect. Our first miniature picosecond pulsed sources cover the 100-200 GHz band and promise milliwatts up to ˜500 GHz. Thanks to the method of interferometrically enhanced time-domain imaging proposed here and the low single-shot jitter of ˜1 ps, our simple imaging system provides sufficient time-domain imaging contrast for fresh-tissue terahertz histology.

Development and fabrication of a Bi-2223 racetrack coil for generator applications

International Nuclear Information System (INIS)

Herd, K.G.; Salasoo, L.; Laskaris, E.T.; Ranze, R.A.; King, C.G.

1996-01-01

The development and fabrication of a layer-wound, epoxy-impregnated Bi-2223 high-temperature superconducting (HTS) racetrack coil which generates 40,000 ampere-turns of magnetomotive force (MMF) at 25 K is described. The coil was wound using Ag-sheathed Bi-2223 tape conductor laminated with copper foils for strength enhancement and insulated using a paper-wrap method. After epoxy impregnation, the coil was tested over a range of 16--25 K in a vacuum dewar using a closed-cycle helium refrigeration system. Descriptions of the tape lamination and insulation processing, the coil winding and impregnation, and the experimental test setup are given

Photothermal effects and toxicity of Fe{sub 3}O{sub 4} nanoparticles via near infrared laser irradiation for cancer therapy

Energy Technology Data Exchange (ETDEWEB)

Dunn, Andrew W. [The Materials Science and Engineering Program, Dept. of Mechanical and Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221 (United States); Ehsan, Sadat M.; Mast, David [Department of Physics, University of Cincinnati, Cincinnati, OH 45221 (United States); Pauletti, Giovanni M. [The James L. Winkle College of Pharmacy, University of Cincinnati, Cincinnati, OH 45267 (United States); Xu, Hong [Nano Biomedical Research Center, School of Biomedical Engineering, Med-X Research Institute, Shanghai Jiao Tong University, Shanghai 200030 (China); Zhang, Jiaming; Ewing, Rodney C. [Department of Geological and Environmental Sciences, Stanford University, Stanford, CA 94305 (United States); Shi, Donglu, E-mail: donglu.shi@uc.edu [The Materials Science and Engineering Program, Dept. of Mechanical and Materials Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH 45221 (United States); Shanghai East Hospital, The Institute for Biomedical Engineering and Nano Science, Tongji University School of Medicine, Shanghai 200120 (China)

2015-01-01

The photothermal effect of magnetite (Fe{sub 3}O{sub 4}) nanoparticles was characterized by photonic absorption in the near-infrared (NIR) region. Upon laser irradiation at 785 nm, the Fe{sub 3}O{sub 4} nanoparticles generate localized hyperthermia in tumorous lesions, which is an effective strategy for cancer therapy; however, uncoated magnetite possesses an innate toxicity which can lead to drawbacks in the clinical setting. To reduce innate toxicity, a poly(acrylic acid) (PAA) coating on the nanoparticles was investigated in order to determine the alterations to stability and the degree of toxicity in an attempt to create a higher utility vector. It was found that the PAA coating significantly reduced the innate toxicity of the uncoated magnetite. Furthermore, the efficacy of PAA-coated magnetite nanoparticles (PAA-Fe{sub 3}O{sub 4}) was investigated for treating MDA-MB-231 (human mammary gland adenocarcinoma) cultures in viable concentration ranges (0.1–0.5 mg/ml). An appropriate PAA-Fe{sub 3}O{sub 4} concentration range was then established for inducing significant cell death by hyperthermic ablation, but not through innate toxicity. - Highlights: • Uncoated magnetite NPs possess high innate toxicity in MDA-MB-231 cultures. • PAA coating significantly reduces innate toxicity and stabilizes magnetite NPs. • Thermal ablation begins at 0.2 mg/ml for PAA-Fe{sub 3}O{sub 4} at 785 nm NIR laser, 38.5 kW/m{sup 2}. • 38.5 kW/m{sup 2} does not significantly affect MDA-MB-231 viability in-vitro.

High pulse energy sub-nanosecond Tm-doped fiber laser

Science.gov (United States)

Cserteg, Andras; Guillemet, Sebastien; Hernandez, Yves; Giannone, Domenico

2012-02-01

We report a core pumped thulium-doped fiber amplifier that generates 1.4 μJ pulses at 1980 nm with a repetition rate of 3.6 MHz preserving the original spectral bandwidth of the oscillator. The amplifier chain is seeded by a passively modelocked fiber laser with 5 mW output power and the pulses are stretched to 800 picoseconds. The amplifier is core pumped by a single mode erbium fiber laser. The slope efficiency is 35%. To the best of our knowledge, this is the first demonstration of sub nanosecond pulses with energies higher than 1 μJ coming out of a thulium-doped fiber amplifier.

Enhanced photocatalytic properties of hierarchical three-dimensional TiO{sub 2} grown on femtosecond laser structured titanium substrate

Energy Technology Data Exchange (ETDEWEB)

Huang, Ting, E-mail: huangting@bjut.edu.cn; Lu, Jinlong; Xiao, Rongshi; Wu, Qiang; Yang, Wuxiong

2017-05-01

Highlights: • The hierarchical 3D-TiO{sub 2} is fabricated on femtosecond laser structured Ti substrate. • The formation mechanism of hierarchical 3D-TiO{sub 2} is proposed. • The structure-induced improvement of photocatalytic activity is reported. - Abstract: Three-dimensional micro-/nanostructured TiO{sub 2} (3D-TiO{sub 2}) fabricated on titanium substrate effectively improves its performance in photocatalysis, dye-sensitized solar cell and lithium-ion battery applications. In this study, the hierarchical 3D-TiO{sub 2} with anatase phase directly grown on femtosecond laser structured titanium substrate is reported. First, the primary columnar arrays were fabricated on the surface of titanium substrate by femtosecond laser structuring. Next, the secondary nano-sheet substructures were grown on the primary columnar arrays by NaOH hydrothermal treatment. Followed by ion-exchange process in HCl and annealing in the air, the hierarchical anatase 3D-TiO{sub 2} was achieved. The hierarchical anatase 3D-TiO{sub 2} exhibited enhanced performances in light harvesting and absorption ability compared to that of nano-sheet TiO{sub 2} grown on flat titanium surface without femtosecond laser structuring. The photocatalytic degradation of methyl orange reveals that photocatalytic efficiency of the hierarchical anatase 3D-TiO{sub 2} was improved by a maximum of 57% compared to that of nano-sheet TiO{sub 2} (55% vs 35%). Meanwhile, the hierarchical anatase 3D-TiO{sub 2} remained mechanically stable and constant in consecutive degradation cycles, which promises significance in practical application.

Molecules in strong laser fields. In depth study of H{sub 2} molecule

Energy Technology Data Exchange (ETDEWEB)

Awasthi, Manohar

2009-10-29

A method for solving the time-dependent Schroedinger equation (TDSE) describing the electronic motion of the molecules exposed to very short intense laser pulses has been developed. The time-dependent electronic wavefunction is expanded in terms of a superposition of field-free eigenstates. The field-free eigenstates are calculated in two ways. In the first approach, which is applicable to two electron systems like H{sub 2}, fully correlated field-free eigenstates are obtained in complete dimensionality using configuration-interaction calculation where the one-electron basis functions are built from B splines. In the second approach, which is even applicable to larger molecules, the field-free eigenstates are calculated within the single-active-electron (SAE) approximation using density functional theory. In general, the method can be divided into two parts, in the first part the field-free eigenstates are calculated and then in the second part a time propagation for the laser pulse parameters is performed. The H{sub 2} molecule is the testing ground for the implementation of both the methods. The reliability of the configuration interaction (CI) based method for the solution of TDSE (CI-TDSE) is tested by comparing results in the low-intensity regime to the prediction of lowest-order perturbation theory. Another test for the CI-TDSE method is in the united atom limit for the H{sub 2} molecule. By selecting a very small value of the internuclear distance close to zero for the H{sub 2} molecule, Helium atom is obtained. Once the functionality and the reliability of the method is established, it is used for obtaining accurate results for molecular hydrogen exposed to intense laser fields. The results for the standard 800 nm Titanium-Sapphire laser and its harmonics at 400 nm and 266 nm are shown. The results for a scan over a wide range of incident photon energies as well as dependence on the internuclear distance are presented. The photoelectron spectra including

Performance of an rf beam monitor on the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Cutler, R.I.

1985-01-01

A prototype rf beam-position, current, and phase monitor has been used on the 100-keV injector beamline of the racetrack microtron (RTM) where performance was measured with the chopped and bunched beam. This monitor works with both a pulsed beam and a cw beam. The pulsed beam consists of beam pulses with a FWHM of 40 ns. The rf beam monitor was tested with beam currents from approx. 50 to 600 μA. The rf beam monitor will be described and its performance will be reported. 6 refs., 5 figs

Topography and local modification of the HoBa2Cu3O/sub 7-//sub x/(001) surface using scanning tunneling microscopy

International Nuclear Information System (INIS)

Heinzelmann, H.; Anselmetti, D.; Wiesendanger, R.; Guentherodt, H.; Kaldis, E.; Wisard, A.

1988-01-01

The topography of the (001) surface of a high T/sub c/ superconducting HoBa 2 Cu 3 O/sub 7-//sub x/ single crystal was investigated in air using scanning tunneling microscopy. We found large, flat terraces separated by growth steps. The heights of these steps correspond to multiples of the c-axis lattice constant of 11.7 A of the perovskite structure. These steps have been verified by atomic force microscopy. On a smaller scale the flat terraces showed some fine structure with a corrugation height of 4 to 5 A and a lateral extent of several nanometers. In addition, we succeeded in creating nanometer-sized structures by increasing the sample bias voltage and tunneling current

Experimental study on concrete cutting by CO{sub 2} laser beam

Energy Technology Data Exchange (ETDEWEB)

Kutsumizu, Akira; Tomura, Hidemasa; Wakizaka, Tatsuya; Hishikawa, Kyoichi; Moriya, Masahiro [Ohbayashi Corp., Tokyo (Japan)

1994-10-01

Methods for dismantling nuclear reactor facilities must meet particularly exacting requirements imposed by heavily reinforced and radioactivated reactor shield walls. Conventional methods do not meet all such requirements, however. Intrigued by excellent characteristics of the laser cutting method relative to nuclear facility demolition, we carried out an experimental study to make a comprehensive evaluation of its characteristics, especially for deep cutting, with success in identifying main factors affecting the cutting depth of a laser and characterizing its cutting behavior. The study results indicate that a 50 kW class CO{sub 2} laser has a potential to provide a practicable cutting speed and depth. (author).

Optimization of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin film by pulsed laser deposition for spin injection

Energy Technology Data Exchange (ETDEWEB)

Jain, Sourabh, E-mail: sourabhjain@ee.iitb.ac.in [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Sharma, Himanshu [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Kumar Shukla, Amit [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Tomy, C.V. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India); Palkar, V.R.; Tulapurkar, Ashwin [Department of Electrical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai-400076 (India)

2014-09-01

We have investigated low temperature magnetic properties of La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) thin films on SrTiO{sub 3} (STO) substrate deposited by pulsed laser deposition (PLD). We observed a large change in the Curie temperature T{sub C} when the LSMO film thickness is reduced from 4 nm (T{sub C}∼280 K) to 2 nm (T{sub C} ∼100 K), which is a result of high strain present at the STO–LSMO interface. The presence of the strain is confirmed by a grazing angle X-ray diffraction (XRD) technique where a particular peak is shifted away from the bulk peak position as we decrease the thickness. In a LSMO/Pb[Zr{sub y}Ti{sub 1−y}]O{sub 3} (PZT)/LSMO magnetic tunnel junction (MTJ), these LSMO thin films can be used for spin injection into the tunnel barrier. Here spin current can be manipulated by changing the strain present at the LSMO–PZT interface by using piezoelectric properties of PZT.

Laser-assisted synthesis of ultra-small anatase TiO{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Amin, M. [Department of Physics, University of Maryland, College Park, MD 20742 (United States); Tomko, J.; Naddeo, J.J.; Jimenez, R.; Bubb, D.M. [Department of Physics, Rutgers University, Camden, NJ 08102 (United States); Steiner, M.; Fitz-Gerald, J. [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); O’Malley, S.M., E-mail: omallese@camden.rutgers.edu [Department of Physics, Rutgers University, Camden, NJ 08102 (United States)

2015-09-01

Highlights: • Transformation of polymorphic TiO{sub 2} NPs to ultra-small particles via laser processing. • Bandgap shift explained by quantum confinement and the Brus model. • High-frequency shockwave ripples related to laser induced stress-wave reflections. • Visible light sensitization observed for LAL prepared polymorphic particles. - Abstract: Titanium dioxide is one of the most important materials today in terms of green technology. In this work, we synthesis ultra-small titanium dioxide nanoparticles (NPs) via a two step process involving infrared laser ablation of a bulk titanium target in DDI water and subsequent irradiation of the colloidal solution with visible light. The as-prepared NPs contain defect states related to oxygen vacancies which lead to visible light sensitization as observed by photodegradation of methylene blue. Irradiation of the colloidal TiO{sub 2} solution, with a 532 nm picosecond laser, lead to fragmentation and ultimate formation of ultra-small (<3 nm) anatase particles. Shadowgraph was utilized to capture shockwave and cavitation bubble propagation during both the ablation and fragmentation processes. High-frequency ripples within the primary shockwave are identified as coming from laser induced stress-wave reflections within the metal target. A blueshift of the bandgap, for the ultra-small NPs, is explained by quantum confinement effects and rationalized using the Brus model.

Silicon isotope separation utilizing infrared multiphoton dissociation of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser light

Energy Technology Data Exchange (ETDEWEB)

Yokoyama, Atsushi; Ohba, Hironori; Hashimoto, Masashi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Ishii, Takeshi; Ohya, Akio [Nuclear Development Corp., Tokai, Ibaraki (Japan); Arai, Shigeyoshi [Hill Research Co. Ltd., Tokyo (Japan)

2002-08-01

Silicon isotope separation has been done by utilizing the Infrared Multiphoton Dissociation (IRMPD) of Si{sub 2}F{sub 6} irradiated with two-color CO{sub 2} laser lights. The two-color excitation method improved the separation efficiency keeping the high enrichment factors. For example, 99.74% of {sup 28}Si was obtained at 49.63% dissociation of Si{sub 2}F{sub 6} after the simultaneous irradiation of 200 pulses with 966.23 cm{sup -1} photons (0.084 J/cm{sup 2}) and 954.55 cm{sup -1} photons (0.658 J/cm{sup 2}), while 2000 pulses were needed to obtain 99.35% of {sup 28}Si at 35.6% dissociation in the case of only one-color irradiation at 954.55 cm{sup -1} (0.97 J/cm{sup 2}). (author)

Design Modifications, Fabrication and Test of HFDB-03 Racetrack Magnet Wound with Pre-Reacted Nb3Sn Rutherford Cable

International Nuclear Information System (INIS)

Ambrosio, G.; Andreev, N.; Barzi, E.; Bhashyam, S.; Carcagno, R.; Feher, S.; Imbasciati, L.; Lamm, M.; Pischalnikov, Y.; Tartaglia, M.; Tompkins, J.; Zlobin, A.V.

2004-01-01

A 10 T racetrack magnet (HFDB-03) wound with pre-reacted Nb3Sn Rutherford cable has been fabricated and tested at Fermilab. This magnet is the third one in a proof-of-principle series for the use of the React-and-Wind technology in common-coil dipole magnets for future accelerators. It consists of two flat racetrack coils (28 turns each) separated by 5 mm. The maximum field on the coil, at the short sample limit of 16530 A, is 10 tesla. The cable has 41 strands with 0.7 mm diameter and the minimum bend radius in the magnet ends is 90 mm. The predecessor of this magnet (HFDB-02) reached 78 % of the short sample limit at 7.7 T. The mechanical design was improved and the fabrication procedure was slightly modified in order to address possible causes of limitation. In this paper we present the mechanical design and analysis of HFDB-03, the modifications to the fabrication procedure and the test results

Microstructure and wear behavior of {gamma}/Al{sub 4}C{sub 3}/TiC/CaF{sub 2} composite coating on {gamma}-TiAl intermetallic alloy prepared by Nd:YAG laser cladding

Energy Technology Data Exchange (ETDEWEB)

Liu Xiubo [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China)], E-mail: liubobo0828@yahoo.com.cn; Shi Shihong [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China); Guo Jian [School of Materials and Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan West Road, Zhengzhou 450007 (China); Fu Geyan; Wang Mingdi [School of Mechanical and Electronic Engineering, 178 Ganjiang East Road, Soochow University, Suzhou 215021 (China)

2009-03-15

As a further step in obtaining high performance elevated temperature self-lubrication anti-wear composite coatings on TiAl alloy, a novel Ni-P electroless plating method was adopted to encapsulate the as-received CaF{sub 2} in the preparation of precursor NiCr-Cr{sub 3}C{sub 2}-CaF{sub 2} mixed powders with an aim to decrease its mass loss and increase its compatibility with the metal matrix during a Nd:YAG laser cladding. The microstructure of the coating was examined using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) and the friction and wear behavior of the composite coatings sliding against the hardened 0.45% C steel ring was evaluated using a block-on-ring wear tester at room temperature. It was found that the coating had a unique microstructure consisting of primary dendrites TiC and block Al{sub 4}C{sub 3} carbides reinforcement as well as fine isolated spherical CaF{sub 2} solid lubrication particles uniformly dispersed in the NiCrAlTi ({gamma}) matrix. The good friction-reducing and anti-wear abilities of the laser clad composite coating was suggested to the Ni-P electroless plating and the attendant reduction of mass loss of CaF{sub 2} and the increasing of it's wettability with the NiCrAlTi ({gamma}) matrix during the laser cladding process.

Silicon nanostructures produced by laser direct etching

DEFF Research Database (Denmark)

Müllenborn, Matthias; Dirac, Paul Andreas Holger; Petersen, Jon Wulff

1995-01-01

A laser direct-write process has been applied to structure silicon on a nanometer scale. In this process, a silicon substrate, placed in a chlorine ambience, is locally heated above its melting point by a continuous-wave laser and translated by high-resolution direct-current motor stages. Only...

Narrow-band tunable terahertz emission from ferrimagnetic Mn{sub 3-x}Ga thin films

Energy Technology Data Exchange (ETDEWEB)

Awari, N. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); University of Groningen, 9747 AG Groningen (Netherlands); Kovalev, S., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Fowley, C., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Green, B.; Yildirim, O.; Lindner, J.; Fassbender, J.; Deac, A. M.; Gensch, M. [Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstr. 400, 01328 Dresden (Germany); Rode, K., E-mail: s.kovalev@hzdr.de, E-mail: c.fowley@hzdr.de, E-mail: rodek@tcd.ie; Lau, Y.-C.; Betto, D.; Thiyagarajah, N.; Coey, J. M. D. [CRANN, AMBER and School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Gallardo, R. A. [Departamento de Física, Universidad Técnica Federico Santa María, Avenida España 1680, 2390123 Valparíso (Chile)

2016-07-18

Narrow-band terahertz emission from coherently excited spin precession in metallic ferrimagnetic Mn{sub 3-x}Ga Heusler alloy nanofilms has been observed. The efficiency of the emission, per nanometer film thickness, is comparable or higher than that of classical laser-driven terahertz sources based on optical rectification. The center frequency of the emission from the films can be tuned precisely via the film composition in the range of 0.20–0.35 THz, making this type of metallic film a candidate for efficient on-chip terahertz emitters. Terahertz emission spectroscopy is furthermore shown to be a sensitive probe of magnetic properties of ultra-thin films.

Nanometer scale thermometry in a living cell

Science.gov (United States)

Kucsko, G.; Maurer, P. C.; Yao, N. Y.; Kubo, M.; Noh, H. J.; Lo, P. K.; Park, H.; Lukin, M. D.

2014-01-01

Sensitive probing of temperature variations on nanometer scales represents an outstanding challenge in many areas of modern science and technology1. In particular, a thermometer capable of sub-degree temperature resolution over a large range of temperatures as well as integration within a living system could provide a powerful new tool for many areas of biological, physical and chemical research; possibilities range from the temperature-induced control of gene expression2–5 and tumor metabolism6 to the cell-selective treatment of disease7,8 and the study of heat dissipation in integrated circuits1. By combining local light-induced heat sources with sensitive nanoscale thermometry, it may also be possible to engineer biological processes at the sub-cellular level2–5. Here, we demonstrate a new approach to nanoscale thermometry that utilizes coherent manipulation of the electronic spin associated with nitrogen-vacancy (NV) color centers in diamond. We show the ability to detect temperature variations down to 1.8 mK (sensitivity of 9mK/Hz) in an ultra-pure bulk diamond sample. Using NV centers in diamond nanocrystals (nanodiamonds, NDs), we directly measure the local thermal environment at length scales down to 200 nm. Finally, by introducing both nanodiamonds and gold nanoparticles into a single human embryonic fibroblast, we demonstrate temperature-gradient control and mapping at the sub-cellular level, enabling unique potential applications in life sciences. PMID:23903748

Experimental comparison of laser energy losses in high-quality laser-oxygen cutting of low-carbon steel using radiation from fibre and CO{sub 2} lasers

Energy Technology Data Exchange (ETDEWEB)

Golyshev, A A; Malikov, A G; Orishich, A M; Shulyat' ev, V B [S.A. Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2015-09-30

We report a comparative experimental study of laseroxygen cutting of low-carbon steel using a fibre laser with a wavelength of 1.07 μm and a CO{sub 2} laser with a wavelength of 10.6 μm at the sheet thickness of 3 – 16 mm. For the two lasers we have measured the dependence of the cutting speed on the radiation power and determined the cutting speed at which the surface roughness is minimal. The coefficient of laser radiation absorption in the laser cutting process is measured for these lasers at different values of the cutting speed and radiation power. It is found that the minimal roughness of the cut surface is reached at the absorbed laser energy per unit volume of the removed material, equal to 11 – 13 J mm{sup -3}; this value is the same for the two lasers and does not depend on the sheet thickness. (laser technologies)

Hierarchical domain structure of lead-free piezoelectric (Na{sub 1/2} Bi{sub 1/2})TiO{sub 3}-(K{sub 1/2} Bi{sub 1/2})TiO{sub 3} single crystals

Energy Technology Data Exchange (ETDEWEB)

Luo, Chengtao, E-mail: lchentao@vt.edu; Wang, Yaojin; Ge, Wenwei; Li, Jiefang; Viehland, Dwight [Materials Science and Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Delaire, Olivier [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Li, Xiaobin; Luo, Haosu [Shanghai Institute of Ceramics, Chinese Academy of Sciences, 215 Chengbei Road, Jiading, Shanghai 201800 (China)

2016-05-07

We report a unique hierarchical domain structure in single crystals of (Na{sub 1/2}Bi{sub 1/2})TiO{sub 3}-xat. %(K{sub 1/2}Bi{sub 1/2})TiO{sub 3} for x = 5 and 8 by transmission electron microscopy (TEM). A high density of polar nano-domains with a lamellar morphology was found, which were self-assembled into a quadrant-like configuration, which then assembled into conventional ferroelectric macro-domains. Studies by high resolution TEM revealed that the polar lamellar regions contained a coexistence of in-phase and anti-phase oxygen octahedral tilt regions of a few nanometers in size. Domain frustration over multiple length scales may play an important role in the stabilization of the hierarchy, and in reducing the piezoelectric response of this Pb-free piezoelectric solid solution.

Angular distribution of species in pulsed laser deposition of La{sub x}Ca{sub 1−x}MnO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Ojeda-G-P, Alejandro [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Schneider, Christof W., E-mail: christof.schneider@psi.ch [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland); Döbeli, Max [Ion Beam Physics, ETH Zurich, CH-8093 Zurich (Switzerland); Lippert, Thomas; Wokaun, Alexander [Paul Scherrer Institut, General Energy Research Department, 5232 Villigen-PSI (Switzerland)

2015-05-01

Highlights: • The angular distribution of species was analyzed for different pressures. • Results show a non-congruent transfer of composition from target to substrate. • Film thickness and composition show different angular distributions. - Abstract: The angular distribution of species from a La{sub 0.4}Ca{sub 0.6}MnO{sub 3} target irradiated with a 248 nm nanosecond pulsed laser was investigated by Rutherford backscattering spectrometry for four different Ar pressures. The film thickness angular distribution was also analyzed using profilometry. Depending on the background gas pressure, the target to substrate distance, and the angular location the film thickness and composition varies considerably. In particular the film composition could vary by up to 17% with respect to the composition of the target material.

Epitaxial thin-film growth of Ruddlesden-Popper-type Ba{sub 3}Zr{sub 2}O{sub 7} from a BaZrO{sub 3} target by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Butt, Shariqa Hassan; Rafique, M.S.; Siraj, K.; Latif, A.; Afzal, Amina [University of Engineering and Technology, Laser and Optronics Centre, Department of Physics, Lahore (Pakistan); Awan, M.S. [Ibn-e-Sina Institute of Science and Technology (ISIT), Islamabad (Pakistan); Bashir, Shazia [Government College University, Centre for Advanced Studies in Physics, Lahore (Pakistan); Iqbal, Nida [Universiti Teknologi Malaysia, Medical Devices and Technology Group (MEDITEG), Faculty of Biosciences and Medical Engineering, Johor Bahru, Johor (Malaysia)

2016-07-15

Ruddlesden-Popper Ba{sub 3}Zr{sub 2}O{sub 7} thin films have been synthesized via pulsed laser deposition (PLD) technique. The optimization of deposition parameters in PLD enables the formation of thin film of metastable Ba{sub 3}Zr{sub 2}O{sub 7} phase from BaZrO{sub 3} target. In order to see the post-annealing effects on the structural and optical properties, the deposited Ba{sub 3}Zr{sub 2}O{sub 7} thin films were annealed at 500, 600 and 800 C. X-ray diffraction (XRD) reveals the formation of Ba{sub 3}Zr{sub 2}O{sub 7} phase with tetragonal structure. The changes in the surface of the deposited films were analysed by FE-SEM and AFM. The thin film post-annealed at 500 C exhibited the best structural, optical and surface properties. Furthermore, the chemical states and chemical composition of the films were determined by X-ray photoelectron spectroscopy (XPS) near the surface. The XPS results show that Ba, Zr and O exist mainly in the form of Ba{sub 3}Zr{sub 2}O{sub 7} Ruddlesden-Popper-type perovskite structure. (orig.)

Thermodynamic analysis of binary Fe{sub 85}B{sub 15} to quinary Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloys for primary crystallizations of α-Fe in nanocrystalline soft magnetic alloys

Energy Technology Data Exchange (ETDEWEB)

Takeuchi, A., E-mail: takeuchi@imr.tohoku.ac.jp; Zhang, Y.; Takenaka, K.; Makino, A. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan)

2015-05-07

Fe-based Fe{sub 85}B{sub 15}, Fe{sub 84}B{sub 15}Cu{sub 1}, Fe{sub 82}Si{sub 2}B{sub 15}Cu{sub 1}, Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, and Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} (NANOMET{sup ®}) alloys were experimental and computational analyzed to clarify the features of NANOMET that exhibits high saturation magnetic flux density (B{sub s}) nearly 1.9 T and low core loss than conventional nanocrystalline soft magnetic alloys. The X-ray diffraction analysis for ribbon specimens produced experimentally by melt spinning from melts revealed that the samples were almost formed into an amorphous single phase. Then, the as-quenched samples were analyzed with differential scanning calorimeter (DSC) experimentally for exothermic enthalpies of the primary and secondary crystallizations (ΔH{sub x1} and ΔH{sub x2}) and their crystallization temperatures (T{sub x1} and T{sub x2}), respectively. The ratio ΔH{sub x1}/ΔH{sub x2} measured by DSC experimentally tended to be extremely high for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy, and this tendency was reproduced by the analysis with commercial software, Thermo-Calc, with database for Fe-based alloys, TCFE7 for Gibbs free energy (G) assessments. The calculations exhibit that a volume fraction (V{sub f}) of α-Fe tends to increase from 0.56 for the Fe{sub 85}B{sub 15} to 0.75 for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy. The computational analysis of the alloys for G of α-Fe and amorphous phases (G{sub α-Fe} and G{sub amor}) shows that a relationship G{sub α-Fe} ∼ G{sub amor} holds for the Fe{sub 85}Si{sub 2}B{sub 12}Cu{sub 1}, whereas G{sub α-Fe} < G{sub amor} for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy at T{sub x1} and that an extremely high V{sub f} = 0.75 was achieved for the Fe{sub 85}Si{sub 2}B{sub 8}P{sub 4}Cu{sub 1} alloy by including 2.8 at. % Si and 4.5 at. % P into α-Fe. These computational results indicate that the Fe{sub 85}Si{sub 2}B{sub

Optical properties change in laser-induced Te/As{sub 2}Se{sub 3} chalcogenide thin films

Energy Technology Data Exchange (ETDEWEB)

Behera, Mukta; Naik, Ramakanta [Utkal University, Department of Physics, Bhubaneswar (India)

2016-10-15

In the present work, we report the change in optical parameters due to the deposition and photo-induced diffusion of Te layer into the chalcogenide As{sub 2}Se{sub 3} film. The photo-diffusion creates a solid solution of As-Se-Te which has potential application in optical devices. The Te/As{sub 2}Se{sub 3} bilayer films prepared by thermal evaporation technique were studied by various experimental techniques. The photo-diffusion of Te into As{sub 2}Se{sub 3} matrix was done by 532-nm laser irradiation. The structure of the As{sub 2}Se{sub 3}, as-prepared and irradiated Te/As{sub 2}Se{sub 3} films was studied by X-ray diffraction which were amorphous in nature. The presence of all the elements was checked by energy-dispersive X-ray analysis, and the optical transmission spectra were recorded by Fourier transform infrared spectrometer. The optical band gap is reduced by the deposition and diffusion of Te into As{sub 2}Se{sub 3} film which is due to the increase in density of defect states in the gap region. The transmission is decreased, whereas the absorption efficiency is increased with the increase in disorderness. The X-ray photoelectron spectroscopy carried out on these films gives information about the bonding change due to the photo-diffusion process. Therefore, this is an important result which will open up new directions for the application of this material in semiconducting devices. (orig.)

A design study of a 100 MeV race-track microtron/pulse-stretcher accelerator system

International Nuclear Information System (INIS)

Alvinsson, R.; Eriksson, M.

1976-04-01

A proposed design of an accelerator system with large duty-factor is described. The system is composed of a race-track microtron and a pulse-stretcher. The maximum particle energy is 100 MeV and the beam current is estimated to be up to 10 μA within +- 100 keV. The intended use is mainly for nuclear physics experiments with high precision, where the combination of large mean current and limited pulse intensity is essential. (Auth.)

La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited by pulsed laser ablation for spintronic applications

Energy Technology Data Exchange (ETDEWEB)

Martino, Maurizio; Cesaria, Maura; Caricato, Anna Paola [Physics Department, University of Salento, Via Arnesano, 73100 Lecce (Italy); Maruccio, Giuseppe [Physics Department, University of Salento, Via Arnesano, 73100 Lecce (Italy); NNL CNR-Istituto di Nanoscienze, Via Arnesano, 73100 Lecce (Italy); Cola, Adriano; Farella, Isabella [Institute for Microelectronics and Microsystems, IMM-CNR, 73100 Lecce (Italy)

2011-08-15

Among spintronic materials, mixed-valence manganite La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) is widely investigated due to its half-metal nature. LSMO thin films were grown by pulsed laser deposition (PLD) onto amorphous silica substrates heated at nearly 600 C. An ArF excimer laser was chosen to induce ablation due to its more energetic photons compared to the other quoted excimer laser sources. Different oxygen pressures were considered in order to study the influence of oxygen on the LSMO optical and electrical properties. In this respect, the visible transparency percentage of the deposited films is found good enough for spin-OLED applications. The absorption coefficient shows an absorption band tunable as a function of the oxygen content. Its energetic location and evolution with the oxygen content demonstrate it originates from radiative transitions between the spin-majority bands separated by the Jahn-Teller distortion. All of this lets relate the deposition oxygen pressure to the Mn{sup 3+} ion content in each film and interpret electrical data. The 200 and 100 nm thick samples exhibit weak metallic transport behavior at room temperature with a resistivity of 4.8 and 6.9 {omega} cm, respectively. Concerning the resistivity response versus temperature, the measured low metal-insulator transition temperature (150 K) is related to the sample structural features as involved by the depositions. Two different transport mechanisms describe the conductivity regime of the deposited samples, namely the small polaron variable range hopping (VRH) and the Arrhenius law. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Using Femtosecond Laser Subcellular Surgery as a Tool to Study Cell Biology

Energy Technology Data Exchange (ETDEWEB)

Shen, N; Colvin, M E; Huser, T

2007-02-27

Research on cellular function and regulation would be greatly advanced by new instrumentation using methods to alter cellular processes with spatial discrimination on the nanometer-scale. We present a novel technique for targeting submicrometer sized organelles or other biologically important regions in living cells using femtosecond laser pulses. By tightly focusing these pulses beneath the cell membrane, we can vaporize cellular material inside the cell through nonlinear optical processes. This technique enables non-invasive manipulation of the physical structure of a cell with sub-micrometer resolution. We propose to study the role mitochondria play in cell proliferation and apoptosis. Our technique provides a unique tool for the study of cell biology.

Experimental study of CO/sub 2/-laser-induced air breakdown over long distances

Energy Technology Data Exchange (ETDEWEB)

Caressa, J.; Autric, M.; Dufresne, D.; Bournot, P.

1979-11-01

Results of an experimental study on air breakdown produced by radiation from a high-power CO/sub 2/ laser are presented. From these measurements, the breakdown threshold over a flux range (1.5 x 10/sup 8/ laser parameters (5sub i/<220 J) was found.

A Mid-IR 14.1 W ZnGeP{sub 2} Optical Parametric Oscillator Pumped by a Tm,Ho:GdVO{sub 4} Laser

Energy Technology Data Exchange (ETDEWEB)

Guo-Li, Zhu; You-Lun, Ju; Tian-Heng, Wang; Yue-Zhu, Wang [National Key Laboratory of Tunable Laser Technology, Harbin Institute of Technology, Harbin 150001 (China)

2009-03-15

We report a high power and high efficiency double resonant ZnGeP{sub 2} (ZGP) optical parametric oscillator (OPO) pumped by a Tm,Ho:GdVO{sub 4} laser. We employ a Tm,Ho:GdVO{sub 4} laser as the pump source operated at 2.049 {mu}m with M{sup 2} = 1.1. The ZGP OPO can generate a total combined output power of 14.1 W at 3.80 {mu}m signal and 4.45 {mu}m idler under pumping power of 28.7 W. The slope efficiency reaches 61.8%, and M{sup 2} = 3.6 for OPO output is obtained. (fundamental areas of phenomenology (including applications))

Films of brookite TiO{sub 2} nanorods/nanoparticles deposited by matrix-assisted pulsed laser evaporation as NO{sub 2} gas-sensing layers

Energy Technology Data Exchange (ETDEWEB)

Caricato, A.P.; Cesaria, M.; Luches, A.; Martino, M. [University of Salento, Department of Physics, Lecce (Italy); Buonsanti, R. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); Catalano, M.; Manera, M.G.; Taurino, A.; Rella, R. [IMM-CNR, Institute for Microelectronics and Microsystems, Lecce (Italy); Cozzoli, P.D. [Istituto di Nanoscienze del CNR, National Nanotechnology Laboratory (NNL), Lecce (Italy); University of Salento, Department of Innovation Engineering, Lecce (Italy)

2011-09-15

Titanium dioxide (TiO{sub 2}) nanorods in the brookite phase, with average dimensions of 3-4 nm x 20-50 nm, were synthesized by a wet-chemical aminolysis route and used as precursors for thin films that were deposited by the matrix-assisted pulsed laser evaporation (MAPLE) technique. A nanorod solution in toluene (0.016 wt% TiO{sub 2}) was frozen at the liquid-nitrogen temperature and irradiated with a KrF excimer laser at a fluence of 350 mJ/cm{sup 2} and repetition rate of 10 Hz. Single-crystal Si wafers, silica slides, carbon-coated Cu grids and alumina interdigitated slabs were used as substrates to allow performing different characterizations. Films fabricated with 6000 laser pulses had an average thickness of {proportional_to}150 nm, and a complete coverage of the selected substrate as achieved. High-resolution scanning and transmission electron microscopy investigations evidenced the formation of quite rough films incorporating individually distinguishable TiO{sub 2} nanorods and crystalline spherical nanoparticles with an average diameter of {proportional_to}13 nm. Spectrophotometric analysis showed high transparency through the UV-Vis spectral range. Promising resistive sensing responses to 1 ppm of NO{sub 2} mixed in dry air were obtained. (orig.)

Application of a 980-nanometer diode laser in neuroendoscopy: a case series.

Science.gov (United States)

Reis, Rodolfo Casimiro; Teixeira, Manoel Jacobsen; Mancini, Marilia Wellichan; Almeida-Lopes, Luciana; de Oliveira, Matheus Fernandes; Pinto, Fernando Campos Gomes

2016-02-01

Ventricular neuroendoscopy represents an important advance in the treatment of hydrocephalus. High-power (surgical) Nd:YAG laser and low-level laser therapy (using 685-nm-wavelength diode laser) have been used in conjunction with neuroendoscopy with favorable results. This study evaluated the use of surgical 980-nm-wavelength diode laser for the neuroendoscopic treatment of ventricular diseases. Nine patients underwent a neuroendoscopic procedure with 980-nm diode laser. Complications and follow-up were recorded. Three in-hospital postoperative complications were recorded (1 intraventricular hemorrhage and 2 meningitis cases). The remaining 6 patients had symptom improvement after endoscopic surgery and were discharged from the hospital within 24-48 hours after surgery. Patients were followed for an average of 14 months: 1 patient developed meningitis and another died suddenly at home. The other patients did well and were asymptomatic until the last follow-up consultation. The 980-nm diode laser is considered an important therapeutic tool for endoscopic neurological surgeries. This study showed its application in different ventricular diseases.

Sub-100 fs high average power directly blue-diode-laser-pumped Ti:sapphire oscillator

Science.gov (United States)

Rohrbacher, Andreas; Markovic, Vesna; Pallmann, Wolfgang; Resan, Bojan

2016-03-01

Ti:sapphire oscillators are a proven technology to generate sub-100 fs (even sub-10 fs) pulses in the near infrared and are widely used in many high impact scientific fields. However, the need for a bulky, expensive and complex pump source, typically a frequency-doubled multi-watt neodymium or optically pumped semiconductor laser, represents the main obstacle to more widespread use. The recent development of blue diodes emitting over 1 W has opened up the possibility of directly diode-laser-pumped Ti:sapphire oscillators. Beside the lower cost and footprint, a direct diode pumping provides better reliability, higher efficiency and better pointing stability to name a few. The challenges that it poses are lower absorption of Ti:sapphire at available diode wavelengths and lower brightness compared to typical green pump lasers. For practical applications such as bio-medicine and nano-structuring, output powers in excess of 100 mW and sub-100 fs pulses are required. In this paper, we demonstrate a high average power directly blue-diode-laser-pumped Ti:sapphire oscillator without active cooling. The SESAM modelocking ensures reliable self-starting and robust operation. We will present two configurations emitting 460 mW in 82 fs pulses and 350 mW in 65 fs pulses, both operating at 92 MHz. The maximum obtained pulse energy reaches 5 nJ. A double-sided pumping scheme with two high power blue diode lasers was used for the output power scaling. The cavity design and the experimental results will be discussed in more details.

Improvement in the electronic quality of pulsed laser deposited CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films via post-deposition elemental sulfur annealing process

Energy Technology Data Exchange (ETDEWEB)

Beres, M., E-mail: matthewcberes@gmail.com [University of California, Department of Mechanical Engineering, 6141 Etcheverry Hall, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Yu, K.M., E-mail: kinmanyu@cityu.edu.hk [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); City University of Hong Kong, Department of Physics and Materials Science, 83 Tat Chee Avenue, Kowloon, Hong Kong Special Administrative Region (Hong Kong); Syzdek, J., E-mail: jego.mejl@gmail.com [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States); Bio-Logic USA, 9050 Executive Park Dr NW, Knoxville, TN 37923 (United States); Mao, S.S., E-mail: ssmao@me.berkeley.edu [University of California, Department of Mechanical Engineering, 6141 Etcheverry Hall, Berkeley, CA 94720 (United States); Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, Berkeley, CA 94720 (United States)

2016-06-01

We synthesized CuIn{sub 0.7}Ga{sub 0.3}Se{sub 2} thin films on soda lime glass substrates using pulsed laser deposition and post-annealing under different conditions. Increasing substrate temperature during deposition and vacuum annealing after deposition both increased grain size but had negligible effect on the electronic properties of the films. As-deposited films demonstrated P-type conductivities with high carrier concentrations and low Hall mobilities, but annealing in elemental sulfur environment significantly improved the electronic properties of the films. We found that the incorporation of even small quantities of sulfur into the films reduced carrier concentrations by over three orders of magnitude and increased Hall mobilities by an order of magnitude. This resulted in films with resistivity ~ 5 Ω·cm suitable for photovoltaic applications. - Highlights: • CIGSe thin films were deposited by pulsed laser deposition. • Laser deposition parameters and annealing parameters were investigated. • As-deposited films demonstrated high hole concentrations and low Hall mobilities. • Elemental sulfur annealing significantly enhanced the electronic quality of films.

Probing defect states in polycrystalline GaN grown on Si(111) by sub-bandgap laser-excited scanning tunneling spectroscopy

Science.gov (United States)

Hsiao, F.-M.; Schnedler, M.; Portz, V.; Huang, Y.-C.; Huang, B.-C.; Shih, M.-C.; Chang, C.-W.; Tu, L.-W.; Eisele, H.; Dunin-Borkowski, R. E.; Ebert, Ph.; Chiu, Y.-P.

2017-01-01

We demonstrate the potential of sub-bandgap laser-excited cross-sectional scanning tunneling microscopy and spectroscopy to investigate the presence of defect states in semiconductors. The characterization method is illustrated on GaN layers grown on Si(111) substrates without intentional buffer layers. According to high-resolution transmission electron microscopy and cathodoluminescence spectroscopy, the GaN layers consist of nanoscale wurtzite and zincblende crystallites with varying crystal orientations and hence contain high defect state densities. In order to discriminate between band-to-band excitation and defect state excitations, we use sub-bandgap laser excitation. We probe a clear increase in the tunnel current at positive sample voltages during sub-bandgap laser illumination for the GaN layer with high defect density, but no effect is found for high quality GaN epitaxial layers. This demonstrates the excitation of free charge carriers at defect states. Thus, sub-bandgap laser-excited scanning tunneling spectroscopy is a powerful complimentary characterization tool for defect states.

Multiphoton ionization of (Xe)/sub n/ and (NO)/sub n/ clusters using a picosecond laser

International Nuclear Information System (INIS)

Smith, D.B.; Miller, J.C.

1989-01-01

In an effort to extend the application of multiphoton ionization (MPI) spectroscopy to the study of weakly bound systems, we have begun a systematic investigation of picosecond MPI in van der Waals molecules and clusters. To our knowledge no previous picosecond MPI studies of weakly bound systems have been reported. We present here results of picosecond MPI of Xe/sub n/(n = 1-20) and (NO)/sub n/(n = 1-4) clusters. Previous MPI studies using nanosecond lasers have not detected the NO cluster series, presumably because of fast dissociation channels. The use of high peak-power allows resonant and non-resonant photon absorption to the ionization limit to compete effectively with fast dissociative processes. 10 refs., 2 figs

Photoacoustic thermal characterization of Al{sub 2}O{sub 3}-Ag ceramic nanocomposites

Energy Technology Data Exchange (ETDEWEB)

George, Sajan D. [Institut fuer Nano- und Mikroprozesstechnik, Leibniz Universitaet Hannover, Callinstrasse 36, D 30167, Hannover (Germany)]|[International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)], E-mail: george@nmp.uni-hannover.de; Anappara, Aji A. [NEST-INFM and Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa (Italy)]|[University College, Thiruvanathapuram 695001 (India)]|[Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Warrier, P.R.S. [University College, Thiruvanathapuram 695001 (India); Warrier, K.G.K. [Ceramic Technology Division, Regional Research Laboratory, CSIR, Thiruvanathapuram 695019 (India); Radhakrishnan, P.; Nampoori, V.P.N.; Vallabhan, C.P.G. [International School of Photonics, Cochin University of Science and Technology, Cochin 682022 (India)

2008-09-15

Laser-induced nondestructive photoacoustic (PA) technique has been employed to determine the thermal diffusivity of nanometal (Ag) dispersed ceramic alumina matrix sintered at different temperatures. The thermal diffusivity values are evaluated by knowing the transition frequency from the amplitude spectrum of PA signal using the one-dimensional heat flow model of Rosencwaig and Gersho. Analysis of the data shows that heat transport and hence the thermal diffusivity value is greatly affected by the influence of incorporation of foreign atom. It is also seen that sintering temperature affects the thermal diffusivity value in a substantial manner. The results are interpreted in terms of variation in porosity and carrier-assisted heat transport mechanism in nanometal dispersed ceramics.

Sub-nanometrically resolved chemical mappings of quantum-cascade laser active regions

International Nuclear Information System (INIS)

Pantzas, Konstantinos; Beaudoin, Grégoire; Patriarche, Gilles; Largeau, Ludovic; Mauguin, Olivia; Sagnes, Isabelle; Pegolotti, Giulia; Vasanelli, Angela; Calvar, Ariane; Amanti, Maria; Sirtori, Carlo

2016-01-01

A procedure that produces sub-nanometrically resolved chemical mappings of MOCVD-grown InGaAs/InAlAs/InP quantum cascade lasers is presented. The chemical mappings reveal that, although the structure is lattice-matched to InP, the InAlAs barriers do not attain the nominal aluminum content—48%—and are, in fact, InGaAlAs quaternaries. This information is used to adjust the aluminum precursor flow and fine-tune the composition of the barriers, resulting in a significant improvement of the fabricated lasers. (paper)

Growth of LiMn{sub 2}O{sub 4} thin films by pulsed-laser deposition and their electrochemical properties in lithium microbatteries

Energy Technology Data Exchange (ETDEWEB)

Julien, C. [Univ. Pierre et Marie Curie, Paris (France). LMDH; Haro-Poniatowski, E. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico); Camacho-Lopez, M.A. [LMDH, UMR 7603, Universite Pierre et Marie Curie, 4 place Jussieu, 75252, Paris (France); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, Mexico (Mexico); Jimenez-Jarquin, J. [Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, Mexico (Mexico)

2000-03-01

Films of LiMn{sub 2}O{sub 4} were grown by pulsed-laser deposition (PLD) onto silicon wafers using sintered targets which consisted in the mixture of LiMn{sub 2}O{sub 4} and Li{sub 2}O powders. The film formation has been studied as a function of the preparation conditions, i.e. composition of the target, substrate temperature, and oxygen partial pressure in the deposition chamber. Composition, morphology and structural properties of PLD films have been investigated using Rutherford backscattering spectroscopy, scanning electron microscopy, X-ray diffraction and Raman scattering spectroscopy. The films deposited from target LiMn{sub 2}O{sub 4}+15% Li{sub 2}O have an excellent crystallinity when deposited onto silicon substrate maintained at 300 C in an oxygen partial pressure of 100 mTorr. It is found that such a film crystallizes in the spinel structure (Fd3m symmetry) as evidenced by X-ray diffraction. Well-textured polycrystalline films exhibit crystallite size of 300 nm. Pulsed-laser deposited LiMn{sub 2}O{sub 4} thin films obtained with a polycrystalline morphology were successfully used as cathode materials in lithium microbatteries. The Li//LiMn{sub 2}O{sub 4} thin film cells have been tested by cyclic voltammetry and galvanostatic charge-discharge techniques in the potential range 3.0-4.2 V. Specific capacity as high as 120 mC/cm{sup 2} {mu}m was measured on polycrystalline films. The chemical diffusion coefficients for the Li{sub x}Mn{sub 2}O{sub 4} thin films appear to be in the range of 10{sup -11}-10{sup -12} cm{sup 2}/s. Electrochemical measurements show a good cycleability of PLD films when cells are charged-discharged at current densities of 5-25 {mu}A/cm{sup 2}. (orig.)

Efficient sub-Doppler transverse laser cooling of an indium atomic beam

Energy Technology Data Exchange (ETDEWEB)

Kim, Jae-Ihn

2009-07-23

Laser cooled atomic gases and atomic beams are widely studied samples in experimental research in atomic and optical physics. For the application of ultra cold gases as model systems for e.g. quantum many particle systems, the atomic species is not very important. Thus this field is dominated by alkaline, earthalkaline elements which are easily accessible with conventional laser sources and have convenient closed cooling transition. On the other hand, laser cooled atoms may also be interesting for technological applications, for instance for the creation of novel materials by atomic nanofabrication (ANF). There it will be important to use technologically relevant materials. As an example, using group III atoms of the periodical table in ANF may open a route to generate fully 3D structured composite materials. The minimal requirement in such an ANF experiment is the collimation of an atomic beam which is accessible by one dimensional laser cooling. In this dissertation, I describe transverse laser cooling of an Indium atomic beam. For efficient laser cooling on a cycling transition, I have built a tunable, continuous-wave coherent ultraviolet source at 326 nm based on frequency tripling. For this purpose, two independent high power Yb-doped fiber amplifiers for the generation of the fundamental radiation at {lambda}{sub {omega}} = 977 nm have been constructed. I have observed sub-Doppler transverse laser cooling of an Indium atomic beam on a cycling transition of In by introducing a polarization gradient in the linear-perpendicular-linear configuration. The transverse velocity spread of a laser-cooled In atomic beam at full width at half maximum was achieved to be 13.5{+-}3.8 cm/s yielding a full divergence of only 0.48 {+-} 0.13 mrad. In addition, nonlinear spectroscopy of a 3-level, {lambda}-type level system driven by a pump and a probe beam has been investigated in order to understand the absorption line shapes used as a frequency reference in a previous two

Transmission of reactive pulsed laser deposited VO{sub 2} films in the THz domain

Energy Technology Data Exchange (ETDEWEB)

Émond, Nicolas; Hendaoui, Ali; Ibrahim, Akram; Al-Naib, Ibraheem; Ozaki, Tsuneyuki; Chaker, Mohamed, E-mail: chaker@emt.inrs.ca

2016-08-30

Highlights: • Synthesis of vanadium dioxide (VO{sub 2}) thin films as a function of oxygen pressure (2–25 mTorr) using Reactive Pulsed Laser Deposition (RPLD). • Characterization of RPLD-grown VO{sub 2} thin films in the THz frequency range. • THz switches and/or sensors require VO{sub 2} films deposited at low oxygen pressure (i.e. low transition temperature, large amplitude contrast of THz transmission, narrow hysteresis width). • THz optical memory applications require VO{sub 2} films deposited at high oxygen pressure (broad hysteresis width). - Abstract: This work reports on the characteristics of the insulator-to-metal transition (IMT) of reactive pulsed laser deposited vanadium dioxide (VO{sub 2}) films in the terahertz (THz) frequency range, namely the transition temperature T{sub IMT}, the amplitude contrast of the THz transmission over the IMT ΔA, the transition sharpness ΔT and the hysteresis width ΔH. XRD analysis shows the sole formation of VO{sub 2} monoclinic structure with an enhancement of (011) preferential orientation when varying the O{sub 2} pressure (P{sub O2}) during the deposition process from 2 to 25 mTorr. THz transmission measurements as a function of temperature reveal that VO{sub 2} films obtained at low P{sub O2} exhibit low T{sub IMT}, large ΔA, and narrow ΔH. Increasing P{sub O2} results in VO{sub 2} films with higher T{sub IMT}, smaller ΔA, broader ΔH and asymmetric hysteresis loop. The good control of the VO{sub 2} IMT features in the THz domain could be further exploited for the development of advanced smart devices, such as ultrafast switches, modulators, memories and sensors.

Persistent challenges and frontiers in laser-based chemical analysis - signed, sealed, and delivered?

International Nuclear Information System (INIS)

Latkoczy, C.; Guenther, D.; Kaegi, R.

2009-01-01

Full text: The last years have been dedicated to push the spatial resolution capabilities of laser - based analytical methods towards the nanometer range. Progress, not just in the detection part using enhanced spectrometers but also in the laser sampling process itself using lasers with shorter pulse durations, paved the way to reach such limits. Nevertheless, the understanding of fundamental processes at such dimensions has gained more importance in order to explain and to control the various phenomena involved in the ablation and excitation processes. We will talk about current expectations, challenges and limitations, and present selected instrumental approaches to e.g. determine nanometer-sized colloid particles in aqueous systems. (author)

Diode-pumped passively mode-locked sub-picosecond Yb:LuAG ceramic laser

International Nuclear Information System (INIS)

Zhu Jiang-Feng; Liu Kai; Wang Jun-Li; Yang Yu; Wang Hui-Bo; Gao Zi-Ye; Jiang Li; Xie Teng-Fei; Chao-Yu Li; Pan Yu-Bai; Wei Zhi-Yi

2017-01-01

In this paper the laser activities of a diode-pumped Yb:LuAG ceramic which was prepared by the solid-state reactive sintering method were reported. The maximum output power was 1.86 W in the continuous wave (CW) laser operation, corresponding to a slope efficiency of 53.6%. The CW laser could be tuned from 1030 to 1096 nm by inserting a prism in the cavity. With the assist of a semiconductor saturable absorber mirror (SESAM), passive mode-locking was realized, delivering sub-picosecond pulses with 933 fs duration and an average power of 532 mW at a repetition rate of 90.35 MHz. (paper)

Microstructure and corrosion resistance of TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders

Energy Technology Data Exchange (ETDEWEB)

Diao, Yunhua, E-mail: 990722012@qq.com; Zhang, Kemin, E-mail: zhangkm@sues.edu.cn

2015-10-15

Highlights: • A TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. • A maximum hardness of 1100 HV was achieved in the laser clad TiC/TiB{sub 2} composite layer. • Corrosion resistance of the TC2 alloy in NaCl (3.5 wt%) aqueous solution can be improved after laser cladding. - Abstract: In the present work, a TiC/TiB{sub 2} composite coating was produced onto a TC2 Ti alloy by laser cladding with Ti/TiC/TiB{sub 2} powders. The surface microstructure, phase components and compositions were characterized with methods of optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffractometry (XRD), and energy dispersive spectrometry (EDS). The cladding layer is consisted of Ti, TiC and TiB{sub 2}. And the surface microhardness was measured. After laser cladding, a maximum hardness of 1100 HV is achieved in the laser cladding surface layer, which is more three times higher than that of the TC2 substrate (∼300 HV). Due to the formation of TiC and TiB{sub 2} intermetallic compounds in the alloyed region and grain refinement, the microhardness of coating is higher than TC2 Ti alloy. In this paper, the corrosion property of matrix material and treated samples were both measured in NaCl (3.5 wt%) aqueous solution. From the result we can see that the laser cladding specimens’ corrosion property is clearly becoming better than that of the substrate.

LD-pumped Nd:YVO sub 4 frequency-doubled by CPM LBO laser at 671 nm

CERN Document Server

Zheng Quan; Qian Long Sheng; Zhao Ling

2001-01-01

A design of LD-pumped high efficient Nd:YVO sub 4 /LBO red laser is reported. Using critical phase-matching LBO for the first time, 671 nm red laser is obtained by 1.342 mu m intracavity frequency doubling. With 800 mW incident pump laser, 52 mW and 97 mW TEM00 mode red laser output are obtained by II-typed and I-typed LBO. The optical-to-optical conversions are up to 6.5% and 12.1% respectively

Yttrium-enriched YBa{sub 2}Cu{sub 3}O{sub x} thin films for coated conductors fabricated by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Khoryushin, Alexey V., E-mail: khoryushin@ya.ru [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Mozhaev, Peter B.; Mozhaeva, Julia E.; Andersen, Niels H. [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark); Grivel, Jean-Claude [Department of Energy Conversion and Storage, Technical University of Denmark, DK-4000 Roskilde (Denmark); Hansen, Jørn Bindslev; Jacobsen, Claus S. [Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby (Denmark)

2013-02-14

Highlights: ► YBCO films were fabricated by PLD from targets of various elemental compositions. ► The Y-enriched films contain yttria nanoparticles which provide efficient pinning. ► The best film has 5.5× higher j{sub c}(5 T,50 K) = 2.6MA/cm{sup 2} comparing with a reference film. ► The Y-enriched films remain c-oriented up to 500 nm. ► Films demonstrate no j{sub c} suppression with thickness and remarkable stability with time. -- Abstract: The effects of excess yttria on the structural and electrical properties of the YBa{sub 2}Cu{sub 3}O{sub x} (YBCO) thin films are studied. The films were deposited on (LaAlO{sub 3}){sub 0.3}–(Sr{sub 2}AlTaO{sub 8}){sub 0.7} substrates by pulsed laser ablation from targets with different elemental composition. An increase of yttrium content of the target leads to formation of porous films with significantly improved current-carrying capabilities. Structural studies of these films reveal presence of yttria nanoparticles embedded into the YBCO matrix. The highest obtained critical current density in an external magnetic field of 5 T was 2.6 MA/cm{sup 2} at 50 K and 9.4 MA/cm{sup 2} at 20 K. The fabricated Y-enriched YBCO films remain c-oriented at least up to 600 nm thickness with no significant suppression of the critical current density.

Improved repetition rate mixed isotope CO{sub 2} TEA laser

Energy Technology Data Exchange (ETDEWEB)

Cohn, D. B., E-mail: dbctechnology@earthlink.net [DBC Technology Corp., 4221 Mesa St, Torrance, California 90505 (United States)

2014-09-15

A compact CO{sub 2} TEA laser has been developed for remote chemical detection that operates at a repetition rate of 250 Hz. It emits 700 mJ/pulse at 10.6 μm in a multimode beam with the {sup 12}C{sup 16}O{sub 2} isotope. With mixed {sup 12}C{sup 16}O{sub 2} plus {sup 13}C{sup 16}O{sub 2} isotopes it emits multiple lines in both isotope manifolds to improve detection of a broad range of chemicals. In particular, output pulse energies are 110 mJ/pulse at 9.77 μm, 250 mJ/pulse at 10 μm, and 550 mJ/pulse at 11.15 μm, useful for detection of the chemical agents Sarin, Tabun, and VX. Related work shows capability for long term sealed operation with a catalyst and an agile tuner at a wavelength shift rate of 200 Hz.

Electron plasma waves in CO/sub 2/ laser plasma interactions

International Nuclear Information System (INIS)

Baldis, H.A.; Villeneuve, D.M.; Walsh, C.J.

1984-01-01

During the past few years, the use of Thomson scattering in CO/sub 2/ laser produced plasmas has permitted the identification and study of electron plasma waves and ion waves, driven by various instabilities in the plasma corona, such as Stimulated Raman Scattering (SRS), two plasmon decay, and Stimulated Brillouin Scattering (SBS). Since these instabilities may coexist in the plasma, the density fluctuations associated with one wave may influence the behaviour of one or more of the other instabilities. The authors discuss the experimental evidence of such effects and, in particular, the consequences of a recent experiment in which the ion waves driven by SBS were observed to adversely affect the production of the electron plasma waves driven by SRS. In that experiment, a strong correlation was observed between the onset of SBS and the disappearance of the electron plasma waves driven by SRS at low densities (n/sub e/ n/sub e/ > 0.05 n/sub c/)

Effect of Al{sub 2}Gd on microstructure and properties of laser clad Mg–Al–Gd coatings

Energy Technology Data Exchange (ETDEWEB)

Chen, Hong; Zhang, Ke; Yao, Chengwu [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Dong, Jie [National Engineering Research Center of Light Alloy Net Forming, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Li, Zhuguo, E-mail: lizg@sjtu.edu.cn [Shanghai Key Lab of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China); Emmelmann, Claus [Institute of Laser and System Technologies, Hamburg University of Technology, Hamburg, 21073 (Germany)

2015-03-01

Highlights: • Mg–Al–Gd coatings with different Gd contents were fabricated by fiber laser cladding. • Chemical compositions and crystal structures of the second phases were characterized. • Dispersion of Al{sub 2}Gd led to further grain refining and elevated mechanical properties. • Al{sub 2}Gd improved high-temperature performances by preventing tiny liquation. - Abstract: In order to investigate the effects of Gd addition on the microstructures and properties of magnesium coatings, the Mg–7.5Al–xGd (x = 0, 2.5, 5.0 and 7.5 wt.%) coatings on cast magnesium alloy were fabricated by laser cladding with wire feeding. The results indicated that the gadolinium (Gd) addition led to the formation of a cubic Al{sub 2}Gd phase as well as suppressed the precipitation of eutectic Mg{sub 17}Al{sub 12} phase. The laser clad coating containing nominally 7.5 wt.% Gd presented the highest microhardness, ultimate tensile strength and yield strength at both room temperature and high temperatures. The enhancement of heat resistant capacities was chiefly attributed to the existence of thermally stable Al{sub 2}Gd particles, which prevented tiny liquation of eutectic phases along the grain boundaries and made great contributions on maintaining high yield ratio during high-temperature deformation.

Sub-monolayer dot vertical-cavity surface-emitting lasers

International Nuclear Information System (INIS)

Blokhin, S.A.; Maleev, N.A.; Kuz'menkov, A.G.

2006-01-01

Vertical-cavity surface-emitting lasers (VCSELs) based on submonolayer InGaAs quantum-dot active region and doped with AlGaAs/GaAs distributed Bragg reflectors were grown by molecular beam epitaxy. 3 μm aperture single-mode VCSELs demonstrate lasing at 980 nm with threshold current of 0.6 mA, maximum output power of 4 mW and external differential efficiency as high as 68%. Ultimately low internal optical losses were measured for these multimode sub-monolayer quantum dot VCSELs [ru

Coherent stacking of picosecond laser pulses in a high-Q optical cavity for accelerator applications

International Nuclear Information System (INIS)

Androsov, V.P.; Karnaukhov, I.M.; Telegin, Yu.N.

2007-01-01

We have performed the harmonic analysis of the steady-state coherent pulse-stacking process in a high-Q Fabry-Perot cavity. The expression for the stacked pulse shape is obtained as a function of both the laser cavity and pulse-stacking cavity parameters. We have also estimated the pulse power gains attainable in the laser-optical system of NESTOR storage ring, which is under development at Kharkov Institute of Physics and Technology. It is shown that high power gains (∼10 4 ) can be, in principle, achieved in a cavity, formed with low-absorption, high reflectivity (R ∼ 0.9999) mirrors, if the laser cavity length will differ exactly by half wavelength from the pulse-stacking cavity length. It implies development of the sophisticated frequency stabilization loop for maintaining the cavity length constant within a sub-nanometer range. At the same time, power gains of ∼10 3 can be obtained with medium reflectivity mirrors (R ∼ 0.999) at considerably lower cost

Role of nano-precipitation on the microstructure and shape memory characteristics of a new Ni{sub 50.3}Ti{sub 34.7}Zr{sub 15} shape memory alloy

Energy Technology Data Exchange (ETDEWEB)

Evirgen, A. [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Karaman, I., E-mail: ikaraman@tamu.edu [Department of Materials Science and Engineering, Texas A& M University, College Station, TX 77843 (United States); Pons, J.; Santamarta, R. [Departament de Fisica, Universitat de les Illes Balears, E07122 Palma de Mallorca (Spain); Noebe, R.D. [Materials and Structures Division, NASA Glenn Research Center, Cleveland, OH 44135 (United States)

2016-02-08

The microstructure and shape memory characteristics of the Ni{sub 50.3}Ti{sub 34.7}Zr{sub 15} shape memory alloy were investigated as a function of aging heat treatments that result in nanometer to submicron size precipitates. Microstructure–property relationships were developed by characterizing samples using transmission electron microscopy, differential scanning calorimetry, and load-biased thermal cycling experiments. The precipitate size was found to strongly influence the martensitic transformation–precipitate interactions and ultimately the shape memory characteristics of the alloy. Aging treatments resulting in relatively fine precipitates, which are not an obstacle to twin boundaries and easily bypassed by martensite variants, exhibited higher transformation strain, lower transformation thermal hysteresis, and better thermal and dimensional stability compared to samples with relatively large precipitates. When precipitate dimensions approached several hundred nanometers in size they acted as obstacles to martensite growth, limiting martensite variant and twin size resulting in reduced functional and structural properties. Aging heat treatments were also shown to result in a wide range of transformation temperatures, increasing them above 100 °C in some cases, and affected the stress dependence of the transformation hysteresis and the stress versus transformation temperature relationships for the Ni{sub 50.3}Ti{sub 34.7}Zr{sub 15} alloy.

High mobility amorphous InGaZnO{sub 4} thin film transistors formed by CO{sub 2} laser spike annealing

Energy Technology Data Exchange (ETDEWEB)

Chung, Chen-Yang; Zhu, Bin; Ast, Dieter G.; Thompson, Michael O. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Greene, Raymond G. [Corning Incorporated, Corning, New York 14831 (United States)

2015-03-23

Amorphous InGaZnO{sub 4} (a-IGZO) thin film transistors (TFTs) hold great potential for large area and flexible electronics with current research focused on improving the mobility and stability. In this work, we report on properties of IGZO TFTs fabricated using laser spike annealing (LSA) with a scanned continuous wave CO{sub 2} laser. For peak annealing temperatures near 430 °C and a 1 ms dwell, TFTs exhibit saturation field-effect mobilities above 70 cm{sup 2}/V-s (V{sub on} ∼ −3 V), a value over 4 times higher than furnace-annealed control samples (∼16 cm{sup 2}/V-s). A model linking oxygen deficient defect structures with limited structural relaxation after the LSA anneal is proposed to explain the observed high mobility. This mobility is also shown to be comparable to the estimated trap-free mobility in oxide semiconductors and suggests that shallow traps can be removed by transient thermal annealing under optimized conditions.

Nanometals - Status and perspective

International Nuclear Information System (INIS)

Faester, S.; Hansen, N.; Huang, X.; Juul Jensen, D.; Ralph, B.

2012-01-01

Nanometals and nanotechnology have over the years been covered in papers, books and conferences - also in many Risoe International Symposia, where the 30th in 2009 dealt solely with nanostructured metals. Since then, rapid progress has been made in synthesis, characterization and modeling, and it is timely to discuss status and perspective also with a view on applications in an international forum such as the Risoe Symposium. Both keynote and contributed papers address important current problems illustrating global research and development in this field. Examples are the development of new synthesis techniques followed by characterization and modeling of microstructures both in 2D and 3D now starting to bridge the micrometer scales. The vital area of mechanical behavior is addressed by the development of new testing techniques and a broad effort to characterize and model mechanical properties of metals strengthened by dislocations and twins. This research has now led to new understanding of both strengthening mechanisms and strengh structure relationships based on experiments in combination with analytical and numerical modeling. The holistic approach to research on nanometals demonstrated by these proceedings can guide both scientists and technologists in their future work also with the aim of introducing into society this new group of advanced materials. Such an effort is important, as science and technology today is significantly affected by politics of governments and international institutions, and therefore a new initiative in the pressent is to include a discussion of research and development in the area of nanometals i USA, China and Japan. (Author)

Nanometals - Status and perspective

Energy Technology Data Exchange (ETDEWEB)

Faester, S.; Hansen, N.; Huang, X.; Juul Jensen, D.; Ralph, B. (eds.)

2012-11-01

Nanometals and nanotechnology have over the years been covered in papers, books and conferences - also in many Risoe International Symposia, where the 30th in 2009 dealt solely with nanostructured metals. Since then, rapid progress has been made in synthesis, characterization and modeling, and it is timely to discuss status and perspective also with a view on applications in an international forum such as the Risoe Symposium. Both keynote and contributed papers address important current problems illustrating global research and development in this field. Examples are the development of new synthesis techniques followed by characterization and modeling of microstructures both in 2D and 3D now starting to bridge the micrometer scales. The vital area of mechanical behavior is addressed by the development of new testing techniques and a broad effort to characterize and model mechanical properties of metals strengthened by dislocations and twins. This research has now led to new understanding of both strengthening mechanisms and strengh structure relationships based on experiments in combination with analytical and numerical modeling. The holistic approach to research on nanometals demonstrated by these proceedings can guide both scientists and technologists in their future work also with the aim of introducing into society this new group of advanced materials. Such an effort is important, as science and technology today is significantly affected by politics of governments and international institutions, and therefore a new initiative in the pressent is to include a discussion of research and development in the area of nanometals i USA, China and Japan. (Author)

Optical properties of (nanometer MCM-41)-(malachite green) composite materials

International Nuclear Information System (INIS)

Li Xiaodong; Zhai Qingzhou; Zou Mingqiang

2010-01-01

Nanosized materials loaded with organic dyes are of interest with respect to novel optical applications. The optical properties of malachite green (MG) in MCM-41 are considerably influenced by the limited nanoporous channels of nanometer MCM-41. Nanometer MCM-41 was synthesized by tetraethyl orthosilicate (TEOS) as the source of silica and cetyltrimethylammonium bromide (CTMAB) as the template. The liquid-phase grafting method has been employed for incorporation of the malachite green molecules into the channels of nanometer MCM-41. A comparative study has been carried out on the adsorption of the malachite green into modified MCM-41 and unmodified MCM-41. The modified MCM-41 was synthesized using a silylation reagent, trimethychlorosilane (TMSCl), which functionalized the surface of nanometer MCM-41 for proper host-guest interaction. The prepared (nanometer MCM-41)-MG samples have been studied by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, low-temperature nitrogen adsorption-desorption technique at 77 K, Raman spectra and luminescence studies. In the prepared (nanometer MCM-41)-MG composite materials, the frameworks of the host molecular sieve were kept intact and the MG located inside the pores of MCM-41. Compared with the MG, it is found that the prepared composite materials perform a considerable luminescence. The excitation and emission spectra of MG in both modified MCM-41 and unmodified MCM-41 were examined to explore the structural effects on the optical properties of MG. The results of luminescence spectra indicated that the MG molecules existed in monomer form within MCM-41. However, the luminescent intensity of MG incorporated in the modified MCM-41 are higher than that of MG encapsulated in unmodified MCM-41, which may be due to the anchored methyl groups on the channels of the nanometer MCM-41 and the strong host-guest interactions. The steric effect from the pore size of the host materials is significant. Raman

Optical bands and energy levels of Nd{sup 3+} ion in the YAl{sub 3}(BO{sub 3}){sub 4} nonlinear laser crystal

Energy Technology Data Exchange (ETDEWEB)

Jaque, D.; Capmany, J.; Garcia Sole, J. [Departamento de Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Luo, Z.D. [Fujian Institute of Research on The Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

1997-11-03

In this paper the polarized optical spectra (absorption and fluorescence) of the Nd{sup 3+} ion in the YAl{sub 3}(BO{sub 3}){sub 4} nonlinear crystal have been systematically investigated at low (10 K) and room temperature. Most energy levels of Nd{sup 3+} in this crystal (103) have been identified and conveniently labelled with their crystal field quantum numbers, {mu}=1/2 and {mu}=3/2. The radiative emitting states have been identified. Analysing the optical absorption spectra with the anisotropic Judd-Ofelt theory, the radiative lifetimes and branching ratios from the metastable state {sup 4}F{sub 3/2} have been calculated. Then, relevant spectroscopic parameters (quantum efficiency and emission cross sections) for laser applications have been estimated. Infrared to visible up-conversion is reported for the first time in this host crystal. (author)

Dispersion effect and auto-reconditioning performance of nanometer ...

Indian Academy of Sciences (India)

This paper reported on dispersion effect and dispersing techniques of nanometer WS2 particles in the green lubricant concocted by us. And it also researched on auto-reconditioning performance of nanometer WS2 particles to the abrasive surfaces of steel ball from four-ball tribology test and piston ring from engine ...

Observation of enhanced infrared absorption in silicon supersaturated with gold by pulsed laser melting of nanometer-thick gold films

Science.gov (United States)

Chow, Philippe K.; Yang, Wenjie; Hudspeth, Quentin; Lim, Shao Qi; Williams, Jim S.; Warrender, Jeffrey M.

2018-04-01

We demonstrate that pulsed laser melting (PLM) of thin 1, 5, and 10 nm-thick vapor-deposited gold layers on silicon enhances its room-temperature sub-band gap infrared absorption, as in the case of ion-implanted and PLM-treated silicon. The former approach offers reduced fabrication complexity and avoids implantation-induced lattice damage compared to ion implantation and pulsed laser melting, while exhibiting comparable optical absorptance. We additionally observed strong broadband absorptance enhancement in PLM samples made using 5- and 10-nm-thick gold layers. Raman spectroscopy and Rutherford backscattering analysis indicate that such an enhancement could be explained by absorption by a metastable, disordered and gold-rich surface layer. The sheet resistance and the diode electrical characteristics further elucidate the role of gold-supersaturation in silicon, revealing the promise for future silicon-based infrared device applications.

Imaging of electric transport mechanisms in a ferromagnetic Ga{sub 0.96}Mn{sub 0.04}As thin film by low-temperature scanning laser microscopy

Energy Technology Data Exchange (ETDEWEB)

Tomaschko, Jochen; Guenon, Stefan; Kleiner, Reinhold; Koelle, Dieter [Physikalisches Institut - Experimentalphysik II, Universitaet Tuebingen (Germany); Goennenwein, Sebastian T.B.; Brandlmaier, Andreas; Althammer, Matthias [Walther-Meissner-Institut, Bayerische Akademie der Wissenschaften, Garching (Germany); Schoch, Wladimir; Limmer, Wolfgang [Institut fuer Halbleiterphysik, Universitaet Ulm (Germany)

2008-07-01

Due to its possible applications in spintronic devices the diluted magnetic semiconductor (DMS) Ga{sub 1-x}Mn{sub x}As has been the subject of intense research. Integral measurements revealed an anisotropic magnetoresistance (AMR) and magnetothermopower (AMTP). Thus, both resistivity and thermopower depend on the orientation of magnetization. By examining a 250 nm thick epitaxially grown Ga{sub 0.96}Mn{sub 0.04}As Hall-bar with scanning laser microscopy these two quantities (more precisely the bolometric signal dR/dT and the Seebeck-coefficient S{sub xx}) could be imaged at temperatures down to 3 K with a spatial resolution of {proportional_to}1 {mu}m. We developed simple models to describe these signals and identified them as electric dipole and monopole plus quadrupole signals, respectively. Efforts to image ferromagnetic domains have been made. Furthermore, we discovered inhomogeneities, not visible with conventional optical microscopy and observed a signal possibly due to the diffusion of electron-hole-pairs created by the laser spot.

Manufacturing of a REBCO racetrack coil using thermoplastic resin aiming at Maglev application

International Nuclear Information System (INIS)

Mizuno, Katsutoshi; Ogata, Masafumi; Hasegawa, Hitoshi

2015-01-01

Highlights: • We propose a novel REBCO coil structure which applies thermoplastic resin. • The thermoplastic resin bonds the coil winding and cooling plates. • The adhesiveness of the resin is strong enough to withstand the thermal stress. • The thermoplastic resin does not cause the degradation because of its high viscosity. • We successfully made a full-scale racetrack REBCO coil with the thermoplastic resin. - Abstract: The REBCO coated conductor is a promising technology for the Maglev application in terms of its high critical temperature. The operating temperature of the on-board magnets can be around 40–50 K with the coated conductor. The REBCO coils are cooled by cryocoolers directly, and hence the thermal design of the REBCO coils significantly changes from that of LTS coils. We have developed a novel REBCO coil structure using thermoplastic resin. The coil is not impregnated and the thermoplastic resin is used to bond the coil winding and the heat transfer members, e.g. copper and aluminum plates. The viscosity of the thermoplastic resin is high enough for the thermoplastic resin not to permeate between the turns in the coil. Therefore, the thermal stress does not occur and the risk of degradation is removed. This paper contains the following three topics. First, the thermal resistance of the thermoplastic resin was measured at cryogenic temperature. Then, a small round REBCO coil was experimentally produced. It has been confirmed that the thermoplastic resin does not cause the degradation and, the adhesion between the coil winding and copper plates withstands the thermal stress. Finally, we successfully produced a full-scale racetrack REBCO coil applying the coil structure with the thermoplastic resin.

Manufacturing of a REBCO racetrack coil using thermoplastic resin aiming at Maglev application

Energy Technology Data Exchange (ETDEWEB)

Mizuno, Katsutoshi, E-mail: mizuno.katsutoshi.14@rtri.or.jp; Ogata, Masafumi; Hasegawa, Hitoshi

2015-11-15

Highlights: • We propose a novel REBCO coil structure which applies thermoplastic resin. • The thermoplastic resin bonds the coil winding and cooling plates. • The adhesiveness of the resin is strong enough to withstand the thermal stress. • The thermoplastic resin does not cause the degradation because of its high viscosity. • We successfully made a full-scale racetrack REBCO coil with the thermoplastic resin. - Abstract: The REBCO coated conductor is a promising technology for the Maglev application in terms of its high critical temperature. The operating temperature of the on-board magnets can be around 40–50 K with the coated conductor. The REBCO coils are cooled by cryocoolers directly, and hence the thermal design of the REBCO coils significantly changes from that of LTS coils. We have developed a novel REBCO coil structure using thermoplastic resin. The coil is not impregnated and the thermoplastic resin is used to bond the coil winding and the heat transfer members, e.g. copper and aluminum plates. The viscosity of the thermoplastic resin is high enough for the thermoplastic resin not to permeate between the turns in the coil. Therefore, the thermal stress does not occur and the risk of degradation is removed. This paper contains the following three topics. First, the thermal resistance of the thermoplastic resin was measured at cryogenic temperature. Then, a small round REBCO coil was experimentally produced. It has been confirmed that the thermoplastic resin does not cause the degradation and, the adhesion between the coil winding and copper plates withstands the thermal stress. Finally, we successfully produced a full-scale racetrack REBCO coil applying the coil structure with the thermoplastic resin.

Experimental observation of chaotic phase synchronization of a periodically pump-modulated multimode microchip Nd:YVO{sub 4} laser

Energy Technology Data Exchange (ETDEWEB)

Lin, Chien-Hui; Kuo, Chie-Tong [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China); Hsu, Tzu-Fang, E-mail: tfhsu@mail.npue.edu.tw [Department of Applied Physics, National Pingtung University of Education, Pingtung 900, Taiwan, ROC (China); Jan, Hengtai; Han, Shiang-Yi [Department of Physics, National Kaohsiung Normal University, No. 62, Shenjhong Rd., Yanchao District, Kaohsiung City 824, Taiwan, ROC (China); Ho, Ming-Chung, E-mail: t1603@nknucc.nknu.edu.tw [Department of Physics, National Kaohsiung Normal University, No. 62, Shenjhong Rd., Yanchao District, Kaohsiung City 824, Taiwan, ROC (China); Jiang, I-Min [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan, ROC (China)

2012-03-12

In this Letter we demonstrate the experimental observation of chaotic phase synchronization (CPS) in a periodically pump-modulated multimode microchip Nd:YVO{sub 4} laser. PS transition is displayed via the stroboscopic technique. We apply the recurrence probability and correlation probability of recurrence to estimate the degree of PS. The degree of PS is studied taking into account the modulation amplitude and modulation frequency. We also propose an experimental compatible numerical simulation to reflect the fact that the Arnold tongues are experimentally and numerically exhibited in the periodically pump-modulated multimode microchip Nd:YVO{sub 4} laser. -- Highlights: ► We show chaotic phase synchronization in a pump-modulated microchip Nd:YVO{sub 4} laser. ► Phase synchronization (PS) transition is displayed via the stroboscopic technique. ► The degree of PS is studied taking into account the modulation parameters. ► The Arnold tongues are experimentally and numerically exhibited in the laser.

Characterization of ultra-fast deposited polycrystalline graphite by a CO{sub 2} laser-assisted combustion-flame method

Energy Technology Data Exchange (ETDEWEB)

McKindra, Travis, E-mail: mckindra@mst.edu [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Patil, Sandeep; O' Keefe, Matthew J. [Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409 (United States); Han Yaoxuan; Ling Hao; Lu Yongfeng [Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, NE 68588 (United States)

2009-02-15

High deposition rate, 750 {mu}m/min, crystalline graphite was deposited on WC substrates by a CO{sub 2} laser-assisted combustion-flame method at laser powers between 300 and 800 W. The structures, which were identified as pillars, were characterized by various methods. The pillars were cylindrical in shape and grew to a size of approximately 3 mm in length and in a few minutes. The laser power did not affect the overall length of the pillar, but caused changes in the physical shape. X-ray and electron diffraction results revealed the pillars to be crystalline graphite regardless of the laser power. Investigation of the pillars by scanning electron microscopy showed two distinct microstructural areas: an inner core of dense material surrounded by an outer shell of lamellar-like material. The core/shell microstructure was unaffected by the level of CO{sub 2} laser power.

LONG-TERM SD-OCT/SLO IMAGING OF NEURORETINA AND RETINAL PIGMENT EPITHELIUM AFTER SUB-THRESHOLD INFRARED LASER TREATMENT OF DRUSEN

Science.gov (United States)

MOJANA, FRANCESCA; BRAR, MANPREET; CHENG, LINGYUN; BARTSCH, DIRK-UWE G.; FREEMAN, WILLIAM R.

2012-01-01

PURPOSE To determine the long-term effect of sub-threshold diode laser treatment for drusen in patients with non-exudative age-related macular degeneration (AMD) with spectral domain optical coherence tomography combined with simultaneous scanning laser ophthalmoscope (SD-OCT/SLO). METHODS 8 eyes of 4 consecutive AMD patients with bilateral drusen previously treated with sub-threshold diode laser were imaged with SD-OCT/SLO. Abnormalities in the outer retina layers reflectivity as seen with SD-OCT/SLO were retrospectively analyzed and compared with color fundus pictures and autofluorescence images (AF) acquired immediately before and after the laser treatment. RESULTS A focal discrete disruptions in the reflectivity of the outer retinal layers was noted in 29% of the laser lesions. The junction in between the inner and outer segment of the photoreceptor was more frequently affected, with associated focal damage of the outer nuclear layer. Defects of the RPE were occasionally detected. These changes did not correspond to threshold burns on color fundus photography, but corresponded to focal areas of increased AF in the majority of the cases. CONCLUSIONS Sub-threshold diode laser treatment causes long-term disruption of the retinal photoreceptor layer as analyzed by SD-OCT/SLO. The concept that sub-threshold laser treatment can achieve a selected RPE effect without damage to rods and cones may be flawed. PMID:21157398

Nanometer size field effect transistors for terahertz detectors

International Nuclear Information System (INIS)

Knap, W; Rumyantsev, S; Coquillat, D; Dyakonova, N; Teppe, F; Vitiello, M S; Tredicucci, A; Blin, S; Shur, M; Nagatsuma, T

2013-01-01

Nanometer size field effect transistors can operate as efficient resonant or broadband terahertz detectors, mixers, phase shifters and frequency multipliers at frequencies far beyond their fundamental cut-off frequency. This work is an overview of some recent results concerning the application of nanometer scale field effect transistors for the detection of terahertz radiation. (paper)

High-power RF controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddl, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kw cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference

Shadowgraphic investigations into the laser-induced forward transfer of different SnO{sub 2} precursor films

Energy Technology Data Exchange (ETDEWEB)

Mattle, Thomas [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Shaw-Stewart, James [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Laboratory for Functional Polymers, Empa Swiss Federal Laboratories for Materials Science and Technology, Überlandstrasse 129, CH-8600 Dübendorf (Switzerland); Hintennach, Andreas [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Daimler AG (Mercedes-Benz Cars), Electrochemical Layers, HPC H152, 70176 Stuttgart (Germany); Schneider, Christof W. [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Lippert, Thomas, E-mail: thomas.lippert@psi.ch [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Wokaun, Alexander [General Energy Research Department, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland)

2013-08-01

Laser-induced forward transfer of different SnO{sub 2} precursor films for sensor applications were investigated using time resolved imaging, from 0 to 2 μs after the onset of the ablation process. Transfers of SnCl{sub 2}(acac){sub 2} and SnO{sub 2} nano-particles, both with and without a triazene polymer dynamic release layer (DRL), were investigated and compared to transfers of aluminum films with a triazene polymer DRL. Shockwave speed and flyer speeds at high laser fluences of Φ = 650 mJ/cm{sup 2} and at the lower fluences, suitable for the transfer of functional and well defined pixels were analyzed. No influence of the use of a triazene polymer DRL on shockwave and flyer speed was observed. Material ejected under transfer condition showed a velocity of around 200 m/s with a weak shockwave.

Gasochromic performance of WO{sub 3}-nanorod thin films fabricated with an ArF excimer laser

Energy Technology Data Exchange (ETDEWEB)

Yaacob, M. H. [RMIT University, Melbourne (Australia); Universiti Putra Malaysia, Selangor (Malaysia); Ou, J. Z.; Wlodarski, W. [RMIT University, Melbourne (Australia); Kim, C. S.; Lee, J. Y. [KAIST, Daejon (Korea, Republic of); Kim, Y. H. [KIST, Seoul (Korea, Republic of); Oh, C. M.; Dhakal, K. P.; Kim, J. Y.; Kang, J. H. [University of Incheon, Incheon (Korea, Republic of)

2012-02-15

Thin films with tungsten trioxide (WO{sub 3}) nanorods were fabricated by using an ArF pulsed laser deposition system. Because the ArF excimer laser operates at a very short wavelength of 193 nm, short enough to expect strong absorption of the photons in the semiconductor oxide targets, and because the clusters incoming to the substrates have high momentum, we could build thin films with good surface morphology. Highly homogeneous arrays of nanorods with sizes mostly in the range of 30 - 40 nm were observed. The absorbance response towards hydrogen (H{sub 2}) gas was investigated for a WO{sub 3} film coated with 25-A-thick palladium (Pd). The Pd/WO{sub 3}-nanorod thin films exhibited excellent gasochromic response when measured in the visible-NIR range (400 - 1000 nm). As low as 0.06% H{sub 2} concentration was clearly sensed. A significant reversible absorbance change and fast recovery (<2 min) were observed when the films were exposed to H{sub 2} at different concentrations.

Experimental study on TiN coated racetrack-type ceramic pipe

Science.gov (United States)

Wang, Jie; Xu, Yan-Hui; Zhang, Bo; Wei, Wei; Fan, Le; Pei, Xiang-Tao; Hong, Yuan-Zhi; Wang, Yong

2015-11-01

TiN film was coated on the internal surface of a racetrack-type ceramic pipe by three different methods: radio-frequency sputtering, DC sputtering and DC magnetron sputtering. The deposition rates of TiN film under different coating methods were compared. The highest deposition rate was 156 nm/h, which was obtained by magnetron sputtering coating. Based on AFM, SEM and XPS test results, the properties of TiN film, such as film roughness and surface morphology, were analyzed. Furthermore, the deposition rates were studied with two different cathode types, Ti wires and Ti plate. According to the SEM test results, the deposition rate of TiN/Ti film was about 800 nm/h with Ti plate cathode by DC magnetron sputtering. Using Ti plate cathode rather than Ti wire cathode can greatly improve the film deposition rate. Supported by National Nature Science Foundation of China (11075157)

Growth of strained, ferroelectric NaNbO{sub 3} thin films by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Sellmann, Jan; Schwarzkopf, Jutta; Duk, Andreas; Kwasniewski, Albert; Schmidbauer, Martin; Fornari, Roberto [IKZ, Berlin (Germany)

2012-07-01

Due to its promising ferro-/piezoelectric properties and high Curie temperature NaNbO{sub 3} has attracted much attention. In contrast to bulk crystals, thin epitaxial films may incorporate and maintain a certain compressive or tensile lattice strain, depending on the used substrate/film combination. This deformation of the crystal lattice is known to strongly influence the ferroelectric properties of perovskites. In the case of NaNbO{sub 3} compressive strain is achieved in films deposited on NdGaO{sub 3} and SrTiO{sub 3} substrates while deposition on DyScO{sub 3} and TbScO{sub 3} leads to tensile in-plane strain. In order to characterize and practically apply the ferroelectric films, it is necessary to embed them in a capacitor structure for which we use pseudomorphically grown SrRuO{sub 3} as bottom electrodes. We report on the deposition of SrRuO{sub 3} and NaNbO{sub 3} single layers on SrTiO{sub 3}, DyScO{sub 3}, TbScO{sub 3} and NbGaO{sub 3} substrates by means of pulsed laser deposition. By adjusting the substrate temperature, the oxygen partial pressure and the laser frequency we have successfully deposited smooth, strained, single phase NaNbO{sub 3} thin films. Investigations of the films by atomic force microscopy and high resolution X-ray diffraction reveal the dependence of the surface morphology and the incorporated lattice strain on the deposition parameters and the lattice mismatch, respectively. All films exhibit piezoelectric properties, as proven by piezoresponse force microscopy.

Sr{sub 2}MgMoO{sub 6−δ} thin films fabricated using pulsed-laser deposition with high concentrations of oxygen vacancies

Energy Technology Data Exchange (ETDEWEB)

Shigematsu, K. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Chikamatsu, A., E-mail: chikamatsu@chem.s.u-tokyo.ac.jp; Fukumura, T. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); JST-CREST, Bunkyo-ku, Tokyo 113-0033 (Japan); Toyoda, S. [Department of Materials Science and Engineering, Kyoto University, Yoshida-honmachi, Kyoto 606-8501 (Japan); Ikenaga, E. [JASRI/SPring-8, Mikazuki-cho, Hyogo 679-5198 (Japan); Hasegawa, T. [Department of Chemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); JST-CREST, Bunkyo-ku, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki, Kanagawa 213-0012 (Japan)

2014-06-30

We fabricated epitaxial thin films of oxygen-vacant Sr{sub 2}MgMoO{sub 6−δ} using pulsed laser deposition. The films showed low resistivity of the order of 10{sup −2} Ω cm at 300 K. X-ray diffraction analyses revealed that Mg and Mo ions in the Sr{sub 2}MgMoO{sub 6−δ} films were considerably disordered, compared to those in bulk Sr{sub 2}MgMoO{sub 6−δ}. The proportion of oxygen vacancies estimated through hard x-ray photoemission measurements was as large as 0.37, and correlated well with the Mg/Mo ordering.

Nanometer-scale temperature measurements of phase change memory and carbon nanomaterials

Science.gov (United States)

Grosse, Kyle Lane

This work investigates nanometer-scale thermometry and thermal transport in new electronic devices to mitigate future electronic energy consumption. Nanometer-scale thermal transport is integral to electronic energy consumption and limits current electronic performance. New electronic devices are required to improve future electronic performance and energy consumption, but heat generation is not well understood in these new technologies. Thermal transport deviates significantly at the nanometer-scale from macroscopic systems as low dimensional materials, grain structure, interfaces, and thermoelectric effects can dominate electronic performance. This work develops and implements an atomic force microscopy (AFM) based nanometer-scale thermometry technique, known as scanning Joule expansion microscopy (SJEM), to measure nanometer-scale heat generation in new graphene and phase change memory (PCM) devices, which have potential to improve performance and energy consumption of future electronics. Nanometer-scale thermometry of chemical vapor deposition (CVD) grown graphene measured the heat generation at graphene wrinkles and grain boundaries (GBs). Graphene is an atomically-thin, two dimensional (2D) carbon material with promising applications in new electronic devices. Comparing measurements and predictions of CVD graphene heating predicted the resistivity, voltage drop, and temperature rise across the one dimensional (1D) GB defects. This work measured the nanometer-scale temperature rise of thin film Ge2Sb2Te5 (GST) based PCM due to Joule, thermoelectric, interface, and grain structure effects. PCM has potential to reduce energy consumption and improve performance of future electronic memory. A new nanometer-scale thermometry technique is developed for independent and direct observation of Joule and thermoelectric effects at the nanometer-scale, and the technique is demonstrated by SJEM measurements of GST devices. Uniform heating and GST properties are observed for

Electrodeposition of Fe{sub 3}O{sub 4} layer from solution of Fe{sub 2}(SO{sub 4}){sub 3} with addition ethylene glycol

Energy Technology Data Exchange (ETDEWEB)

Dahlan, Dahyunir, E-mail: dahyunir@yahoo.com; Asrar, Allan [Department of Physics, Andalas University, Limau Manih Padang 25163, West Sumatera (Indonesia)

2016-03-11

The electrodeposition of Fe{sub 3}O{sub 4} layer from the solution Fe{sub 2}(SO{sub 4}){sub 3} with the addition of ethylene glycol on Indium Tin Oxide (ITO) substrate has been performed. The electrodeposition was carried out using a voltage of 5 volts for 120 seconds, with and without the addition of 2% wt ethylene glycol. Significant effects of temperature on the resulting the samples is observed when they are heated at 400 °C. Structural characterization using X-ray diffraction (XRD) shows that all samples produce a layer of Fe{sub 3}O{sub 4} with particle size less than 50 nanometers. The addition of ethylene glycol and the heating of the sample causes a shrinkage in particle size. The scanning electron microscopy (SEM) characterization shows that Fe{sub 3}O{sub 4} layer resulting from the process of electrodeposition of Fe{sub 2}(SO{sub 4}){sub 3} without ethylene glycol, independent of whether the sample is heated or not, is uneven and buildup. Layer produced by the addition of ethylene glycol without heating produces spherical particles. On contrary, when the layer is heated the spherical particles transform to irregularly-shaped particles with smaller size.

Influence of standing-wave electric field pattern on the laser damage resistance of HfO sub 2 thin films

CERN Document Server

Protopapa, M L; De Tomasi, F; Di Giulio, M; Perrone, M R; Scaglione, S

2002-01-01

The standing-wave electric field pattern that forms inside an optical coating as a consequence of laser irradiation is one of the factors influencing the coating laser-induced damage threshold. The influence of the standing-wave electric field profile on the damage resistance to ultraviolet radiation of hafnium dioxide (HfO sub 2) thin films was investigated in this work. To this end, HfO sub 2 thin films of different thicknesses deposited by the electron beam evaporation technique at the same deposition conditions were analyzed. Laser damage thresholds of the samples were measured at 308 nm (XeCl laser) by the photoacoustic beam deflection technique and microscopic inspections. The dependence of the laser damage threshold on the standing-wave electric field pattern was analyzed.

Stoichiometry control of SrVO{sub 3} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Scheiderer, Philipp; Schmitt, Matthias; Sing, Michael; Claessen, Ralph [Universitaet Wuerzburg, Physikalisches Institut and Roentgen Center for Complex Material Systems (RCCM), 97074 Wuerzburg (Germany)

2016-07-01

Oxide heterostructures exhibit fascinating properties, e.g., the coexistence of superconductivity and ferromagnetism at the interface of LaAlO{sub 3}/SrTiO{sub 3}, but the extraordinary electronic properties of transition metal oxides caused by electron correlation yet wait to be fully harnessed. One suitable candidate for future device applications is the correlated metal SrVO{sub 3}, which can be prepared by pulsed laser deposition (PLD) on commonly used substrates such as SrTiO{sub 3}. Sample fabrication by PLD offers a wide variety of possibilities to manipulate the structural and electronic properties of the grown films in a controlled way. Here we report on the manipulation of the cation and oxygen stoichiometry of SrVO{sub 3} thin films by tuning the laser flux density of the PLD-ablation process and the oxygen background pressure during growth, respectively. In situ photoemission, x-ray diffraction, and temperature dependent resistivity measurements enable us to monitor the structural and electronic changes: Cation off-stoichiometry causes a strong increase of the out-of-plane lattice constant as well as a lower residual resistivity ratio, while excess oxygen is found to induce a shift to higher vanadium valences. After exposure to air a similar shift is detected, indicating an overoxidation of the SrVO{sub 3} film.

Study of the laser-induced damage of reflective components in the sub-picosecond regime

International Nuclear Information System (INIS)

Sozet, Martin

2016-01-01

In this thesis, laser-induced damage phenomenon of reflective components is investigated in the sub-picosecond regime. These components, made of stacks of dielectric materials, are widely used in powerful laser facilities such as PETAL laser. PETAL laser has been built at the CEA-CESTA in France to deliver multi-kJ/500 fs pulses at 1053 nm and reach a power higher than 6 PW. For this kind of laser systems, reflective components are commonly used instead of optics operating in transmission to limit the accumulation of non-linear phase along the beam propagation due to the high intensities. Optical components irradiated by the highest power densities are the pulse compression gratings, transport mirrors and the focusing parabola, located at the end of the laser chain. Nowadays, laser-induced damage is the main factor that limits the overall performances of powerful laser systems. This manuscript presents three study axes to better understand and control damage phenomenon. The first one concerns the conception of reflective optics for the peta-watt applications. The design of new structures has been investigated to reach high diffraction efficiencies in the case of pulse compression gratings and a high reflectivity in the case of mirrors, while reducing the Electric-field enhancement which is one of the causes of the laser-induced damage. The second axis deals with the development of a precise damage metrology with new testing tools which brings new perspectives and a new viewpoint for the assessment of the laser resistance of optical components. Finally, the third axis concerns the study the damage growth after several irradiations in the sub-picosecond regime. The evolution of the damage area during growth sequences is observed and compared to numerical simulations. It enables to improve the understanding in the growth phenomenon. In the end, these studies will allow to develop predictive models of the laser-induced damage and new tools for the conception of

Interaction of ultra soft magnetic materials with the high-T{sub c} superconductor YBCO

Energy Technology Data Exchange (ETDEWEB)

Stahl, Claudia; Treiber, Sebastian; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Walker, Patrick [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Albrecht, Joachim [Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

2013-07-01

We have grown bilayers of optimally doped YBa{sub 2}Cu{sub 3}O{sub 7-δ} (YBCO) and ferromagnetic CoFeB on single-crystalline substrates by pulsed laser deposition and sputtering. These heterostructures are typically composed of about 100 nm YBCO and several 10 nm of CoFeB. Regarding the superconductor, the properties of the YBCO film change as a consequence of the vicinity of the ferromagnet. In detail we investigated the critical current density as a function of temperature, applied field and time as well as the transition temperature by SQUID magnetization measurements and quantitative magneto-optical measurements. The amorphous material CoFeB exhibits an in plane anisotropy and a very low coercivity. From magneto-optical images we find that the flux line lattice of the superconductor is mapped into the magnet and still visible as significant magnetic out-of-plane contrast at room temperature. We discuss this phenomenon as a new route to high-resolution mapping of the flux line distribution on a nanometer scale.

Analysis of process parameters in the laser deposition of YBa{sub 2}Cu{sub 3}O{sub 7} superconducting films by using SVR

Energy Technology Data Exchange (ETDEWEB)

Cai, C.Z., E-mail: caiczh@gmail.com [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Xiao, T.T. [Department of Applied Physics, Chongqing University, Chongqing 401331 (China); Science and Technology on Plasma Physics Laboratory, Research Center of Laser Fusion, CAEP, P.O. Box 919-988, Mianyang 621900 (China); Tang, J.L.; Huang, S.J. [Department of Applied Physics, Chongqing University, Chongqing 401331 (China)

2013-10-15

Highlights: • Proposed new ideas and strategies to improve energy storage density for SMES system. • One is to increase the effective current density in the superconducting coils. • Another is to optimize the configuration of the SMES coil. • A new conceive of energy compression is also proposed. -- Abstract: There are several process parameters in the growth of YBa{sub 2}Cu{sub 3}O{sub 7} superconducting films by using pulsed laser deposition (PLD). The relationship between the response and process parameters is highly nonlinear and quite complicated. It is very valuable to quantitatively estimate the response under different deposition parameters. In this study, according to an experimental data set on the superconducting transition temperature (T{sub c}) and relative resistance ratio (r{sub R}) of 17 samples of YBa{sub 2}Cu{sub 3}O{sub 7} films deposited under various parameters, the support vector regression (SVR) combined with particle swarm optimization (PSO), was proposed to predict the T{sub c} and r{sub R} for YBa{sub 2}Cu{sub 3}O{sub 7} films. The prediction performance of SVR was compared with that of multiple regression analysis (MRA) models. The results strongly support that the generalization ability of SVR model consistently surpasses that of MRA via leave-one-out cross validation (LOOCV). The mean absolute percentage errors for T{sub c} and r{sub R} are 0.37% and 1.51% respectively via LOOCV test of SVR. Sensitivity analysis discovered the most sensitive parameters affecting the T{sub c} and r{sub R}. This study suggests that the established SVR model can be used to accurately foresee the T{sub c} and r{sub R}. And it can be used to optimizing the deposition parameters in the development of YBa{sub 2}Cu{sub 3}O{sub 7} films via PLD.

Laser-induced removal of a dye C.I. Acid Red 87 using n-type WO{sub 3} semiconductor catalyst

Energy Technology Data Exchange (ETDEWEB)

Qamar, M. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Gondal, M.A., E-mail: magondal@kfupm.edu.sa [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Laser Research Laboratory, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Hayat, K. [Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Yamani, Z.H. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Laser Research Laboratory, Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia); Al-Hooshani, K. [Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, KFUPM Box 741, Dhahran 31261 (Saudi Arabia); Chemistry Department, King Fahd University of Petroleum and Minerals, Dhahran 31261 (Saudi Arabia)

2009-10-30

Water contamination by organic substances such as dyes is of great concern worldwide due to their utilization in many industrial processes and environmental concerns. To cater the needs for waste water treatment polluted with organic dyes, laser-induced photocatalytic process was investigated for removal of a dye derivative namely Acid Red 87 using n-type WO{sub 3} semiconductor catalyst. The degradation was investigated in aqueous suspensions of tungsten oxide under different experimental conditions using laser instead of conventional UV lamp as an irradiation source. The degradation process was monitored by measuring the change in dye concentration as a function of laser irradiation time by employing UV spectroscopic analysis. The degradation of dye was studied by varying different parameters such as laser energy, reaction pH, substrate concentration, catalyst concentration, and in the presence of electron acceptors such as hydrogen peroxide (H{sub 2}O{sub 2}), and potassium bromate (KBrO{sub 3}). The degradation rates were found to be strongly dependent on all the above-mentioned parameters. Our experimental results revealed that the dye degradation process was very fast (within few minutes) under laser irradiation as compared to conventional setups using broad spectral lamps (hours or days) and this laser-induced photocatalytic degradation method could be an effective means to eliminate the pollutants present in liquid phase. The experience gained through this study could be beneficial for treatment of waste water contaminated with organic dyes and other organic pollutants.

Preparation of planar CH{sub 3}NH{sub 3}PbI{sub 3} thin films with controlled size using 1-ethyl-2-pyrrolidone as solvent

Energy Technology Data Exchange (ETDEWEB)

Hao, Qiuyan; Chu, Yixia [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Zheng, Xuerong [Key Laboratory of Advanced Ceramics and Machining Technology of Ministry of Education, School of Materials Science and Engineering, Tianjin University, Tianjin 300072 (China); Liu, Zhenya; Liang, Liming [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Qi, Jiakun [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Zhang, Xin [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Gang [School of Chemical Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Hui, E-mail: liuhuihebut@163.com [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Chen, Hongjian [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China); Liu, Caichi, E-mail: ccliu@hebut.edu.cn [Engineering Laboratory of Functional Optoelectronic Crystalline Materials of Hebei Province, School of Materials Science and Engineering, Hebei University of Technology, Tianjin 300132 (China)

2016-06-25

Recently, planar perovskite solar cells based on CH{sub 3}NH{sub 3}PbI{sub 3} have attracted many researcher's interest due to their unique advantages such as simple cell architecture, easy fabrication and potential multijunction construction comparing to the initial mesoporous structure. However, the preparation of planar perovskite films with high quality is still in challenge. In this paper, we developed a vapor-assisted solution process using a novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) instead of the traditional N, N-dimethylformamide (DMF) to construct a high-quality perovskite CH{sub 3}NH{sub 3}PbI{sub 3} thin film with pure phase, high compactness, small surface roughness and controlled size. The phase evolution and growth mechanism of the perovskite films are also discussed. Utilizing the NEP of low volatility and moderate boiling point as solvent, we dried the PbI{sub 2}-NEP precursor films at different temperature under vacuum and then obtained PbI{sub 2} thin films with different crystalline degree from amorphous to highly crystalline. The perovskite films with crystal size ranged from hundreds of nanometers to several micrometers can be prepared by reacting the PbI{sub 2} films of different crystalline degree with CH{sub 3}NH{sub 3}I vapor. Moreover, planar-structured solar cells combining the perovskite film with TiO{sub 2} and spiro-OMeTAD as the electron and holes transporting layer achieves a power conversion efficiency of 10.2%. - Highlights: • A novel and green solvent of 1-Ethyl-2-pyrrolidone (NEP) was used to construct high-quality perovskite CH{sub 3}NH{sub 3}PbI{sub 3} thin film. • The CH{sub 3}NH{sub 3}PbI{sub 3} grain with different sizes ranged from hundreds of nanometers to several micrometers can be obtained. • Planar-structured perovskite CH{sub 3}NH{sub 3}PbI{sub 3} solar cells using NEP as solvent achieves a power conversion efficiency of 10.2%.

Proton-induced nanorod melting in a coating obtained from the pulsed laser ablation of W{sub 2}B{sub 5}/B{sub 4}C

Energy Technology Data Exchange (ETDEWEB)

Tadadjeu Sokeng, I., E-mail: ifriky@tlabs.ac.za [Department of Electrical, Electronics and Computer Engineering, French South African Institute of Technology/Cape Peninsula University of Technology, Bellville Campus, PO Box 1906, Bellville 7530 (South Africa); Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Ngom, B.D. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Laboratoire de Photonique et de Nanofrabrication, Groupes de physique du Solide et Sciences des Matriaux (GPSSM), Facult des sciences et Techniques, Universit Cheikh Anta Diop de Dakar (UCAD), B.P. 25114 Dakar-Fann, Dakar (Senegal); Cummings, F. [Electron Microscopy Unit, University of the Western Cape, Private bag x17, Bellville 7535 (South Africa); Kotsedi, L. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); Msimanga, M. [iThemba LABS Gauten, Private Bag 11, WITS 2050, Johannesburg (South Africa); Maaza, M. [Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, 7129, PO Box 722, Somerset West, Western Cape Province (South Africa); UNESCO-UNISA Africa Chair in Nanosciences/Nanotechnology, College of Graduate Studies, University of South Africa (UNISA), Muckleneuk Ridge, PO Box 392, Pretoria (South Africa); and others

2015-02-01

Highlights: • Coatings from ablated B{sub 4}C/W{sub 2}B{sub 5} were irradiated with 900 keV protons. • Nanorod clusters were observed to melt and disperse. • Uniformly shaped nanorods were observed to grow. • Lateral diffusion of energy and lateral dispersion of matter were observed. - Abstract: Coatings obtained from pulsed laser ablated W{sub 2}B{sub 5}/B{sub 4}C were irradiated with 900keV protons at fluences ranging from about 1×10{sup 15}protons/cm{sup 2} to about 4×10{sup 15}protons/cm{sup 2}. Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) were used to study the resulting structural effects. Clusters of nanorods were observed to disperse and reduce in number with increase in proton fluence. The atomic percentage of constituent elements were observed to vary with proton fluence, both within the nanorods and the film floor. Our results show that the structural effect of proton irradiation on the coating is lateral dispersion of matter.

Ultrafast Self-Assembly of Sub-10 nm Block Copolymer Nanostructures by Solvent-Free High-Temperature Laser Annealing.

Science.gov (United States)

Jiang, Jing; Jacobs, Alan G; Wenning, Brandon; Liedel, Clemens; Thompson, Michael O; Ober, Christopher K

2017-09-20

Laser spike annealing was applied to PS-b-PDMS diblock copolymers to induce short-time (millisecond time scale), high-temperature (300 to 700 °C) microphase segregation and directed self-assembly of sub-10 nm features. Conditions were identified that enabled uniform microphase separation in the time frame of tens of milliseconds. Microphase ordering improved with increased temperature and annealing time, whereas phase separation contrast was lost for very short annealing times at high temperature. PMMA brush underlayers aided ordering under otherwise identical laser annealing conditions. Good long-range order for sub-10 nm cylinder morphology was achieved using graphoepitaxy coupled with a 20 ms dwell laser spike anneal above 440 °C.

Observation of meander pattern in signals from superconducting MgB{sub 2} detector by scanning pulsed laser imaging

Energy Technology Data Exchange (ETDEWEB)

Ishida, Takekazu, E-mail: ishida@center.osakafu-u.ac.jp [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yagi, Ikutaro; Yoshioka, Naohito; Huy, Ho Thanh [Department of Physics and Electronics, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Yotsuya, Tsutomu [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Nanoscience and Nanotechnology Research Center, Osaka Prefecture University, 2-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8570 (Japan); Shimakage, Hisashi [Department of Electrical and Electronic Engineering, College of Engineering, 4-12-1, Nakanarusawa, Hitachi, Ibaraki 316-8511 (Japan); Miki, Shigehito [Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan); Wang, Zhen [Institute for Nanofabrication Research, Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531 (Japan); Kansai Advanced Research Center, National Institute of Information and Communications Technology, 588-2 Iwaoka-cho, Nishi-ku, Kobe, Hyogo 651-2429 (Japan)

2013-01-15

Highlights: ► We fabricate a superconducting MgB{sub 2} meander detector as a solid-state neutron detector. ► MgB{sub 2} detector uses XYZ stage, optical fiber and focused lens to scan as a microscope. ► The 6 μm line-and-space in meandering pattern can be resolved in signals against pulsed laser. -- Abstract: Superconducting MgB{sub 2} meander detector has been imaged by scanning a spot of 1.5-μm focused pulsed laser. The superconducting detector using high-quality {sup 10}B-enriched MgB{sub 2} thin films at higher operating temperatures has been fabricated to utilize a resistance change induced by the nuclear energy of {sup 10}B and neutron. The MgB{sub 2} detector consists of a 200-nm-thick MgB{sub 2} thin-film meander line, a 300-nm-thick SiO protective layer, and 150-nm-thick Nb electrodes with 1-μm MgB{sub 2} wires. The devices were placed in a 4 K refrigerator to control at a certain temperature below T{sub c}. A scanning laser spot can be used by the combination of the XYZ piezo-drive stage and an optical fibre with an aspheric focused lens. The measurement system is fully controlled by LabVIEW based software. We succeeded in observing a line-and-space image of a meandering pattern by analysing response signals.

Thin films of La{sub 0,78}Sr{sub 0,22}MnO{sub 3} by the spin coating method; Filmes finos de La{sub 0,78}Sr{sub 0,22}MnO{sub 3} pelo metodo spin coating

Energy Technology Data Exchange (ETDEWEB)

Macedo, Daniel Araujo de; Cela, Beatriz; Silva, Brena Kelly Oliveira da; Souza, Graziele Lopes de; Paskocimas, Carlos Alberto; Nascimento, Rubens Maribondo do [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Nucleo de Tecnologia. Lab. de Ceramica]. E-mail: damaced@gmail.com

2008-07-01

22% Strontium-doped lanthanum manganite (La{sub 0,78}Sr{sub 0,22}MnO{sub 3} - LSM 22) thin films were prepared using microscope slide cover glass as a substrate. The polymeric resin was obtained by Pechini method and deposited by spin coating technical. The films were made using 1500, 2000 and 2500 rpm speeds and sintered at 500 deg C for 2 hours. X-ray diffraction measures confirmed the presence of LSM 22 at the substrates surface. The morphologic characterization was performed by scanning electronic microscopy in Philips/XL-30 equipment. The deposition method made possible the obtaining of films with good adherence and thickness varying between 322 and 900 nanometers. (author)

Higher pressure periodic CO/sub 2/ laser with non-self-sustaining discharge and UV ionization

Energy Technology Data Exchange (ETDEWEB)

Muratov, E A; Pismennyi, V D; Rakhimov, A T

1979-02-01

Stimulated emission was achieved in a CO/sub 2/ laser operating at 250 torr excited by a periodic non-self-sustaining discharge controlled by a spark source of UV radiation. Use of a UV source operating in periodic pulse regime is shown to permit quasicontinuous operation of the laser with characteristic radiating times up to several hundred microseconds.

Surface modification of the titanium implant using TEA CO{sub 2} laser pulses in controllable gas atmospheres - Comparative study

Energy Technology Data Exchange (ETDEWEB)

Ciganovic, J.; Stasic, J.; Gakovic, B.; Momcilovic, M.; Milovanovic, D. [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia); Bokorov, M. [Faculty of Sciences, Department of Biology and Ecology, University of Novi Sad, Trg Dositeja Obradovica 3, 21000 Novi Sad (Serbia); Trtica, M., E-mail: etrtica@vinca.rs [VINCA Institute of Nuclear Sciences, University of Belgrade, P.O. BOX 522, 11001 Belgrade (Serbia)

2012-01-15

Interaction of a TEA CO{sub 2} laser, operating at 10.6 {mu}m wavelength and pulse duration of 100 ns (FWHM), with a titanium implant in various gas atmospheres was studied. The Ti implant surface modification was typically studied at the moderate laser beam energy density/fluence of 28 J/cm{sup 2} in the surrounding of air, N{sub 2}, O{sub 2} or He. The energy absorbed from the TEA CO{sub 2} laser beam is partially converted to thermal energy, which generates a series of effects, such as melting, vaporization of the molten material, shock waves, etc. The following titanium implant surface changes and phenomena were observed, depending on the gas used: (i) creation of cone-like surface structures in the atmospheres of air, N{sub 2} and O{sub 2}, and dominant micro-holes/pores in He ambient; (ii) hydrodynamic features, most prominent in air; (iii) formation of titanium nitride and titanium oxide layers, and (iv) occurrence of plasma in front of the implant. It can be concluded from this study that the reported laser fluence and gas ambiences can effectively be applied for enhancing the titanium implant roughness and creation of titanium oxides and nitrides on the strictly localized surface area. The appearance of plasma in front of the implants indicates relatively high temperatures created above the surface. This offers a sterilizing effect, facilitating contaminant-free conditions.

DAW structure for the NBS/Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Potter, J.M.

1981-01-01

The results of a testing program on the disk-and-washer (DAW) structure with tee supports are presented. These results have led to the design of a 2.4-m DAW linac for use as the preaccelerator section of the National Bureau of Standards (NBS)/Los Alamos racetrack microtron (RTM). This structure uses two tee supports for each pair of washers, instead of four, and the structure has a larger diameter than earlier test structures. Two properties of this structure, which make it appear to be ideal for the RTM application, are a high shunt impedance and a high cell-to-cell coupling factor. This coupling factor eases construction tolerances and reduces sensitivity to thermal effects from the high rf heating load that will be imposed upon it. The structure is designed to operate at a 100% duty factor with a 1.5-MV/m accelerating gradient at 2380 MHz. This load would detune most accelerating structures. The tuning procedures, the transverse modes, and their effect on the structures design also are presented

Chemically deposited Sb{sub 2}S{sub 3} thin films for optical recording

Energy Technology Data Exchange (ETDEWEB)

Shaji, S; Arato, A; Castillo, G Alan; Palma, M I Mendivil; Roy, T K Das; Krishnan, B [Facultad de IngenierIa Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, San Nicolas de los Garza, Nuevo Leon, C.P- 66450 (Mexico); O' Brien, J J; Liu, J, E-mail: bkrishnan@fime.uanl.m [Center for Nanoscience and Department of Chemistry and Biochemistry, University of Missouri-St. Louis, One Univ. Blvd., St. Louis, MO - 63121 (United States)

2010-02-24

Laser induced changes in the properties of Sb{sub 2}S{sub 3} thin films prepared by chemical bath deposition are described in this paper. Sb{sub 2}S{sub 3} thin films of thickness 550 nm were deposited from a solution containing SbCl{sub 3} and Na{sub 2}S{sub 2}O{sub 3} at 27 {sup 0}C for 5 h. These thin films were irradiated by a 532 nm continuous wave laser beam under different conditions at ambient atmosphere. X-ray diffraction analysis showed amorphous to polycrystalline transformation due to laser exposure of these thin films. Morphology and composition of these films were described. Optical properties of these films before and after laser irradiation were analysed. The optical band gap of the material was decreased due to laser induced crystallization. The results obtained confirm that there is further scope for developing this material as an optical recording media.

Novel two-step laser ablation and ionization mass spectrometry (2S-LAIMS) of actor-spectator ice layers: Probing chemical composition of D{sub 2}O ice beneath a H{sub 2}O ice layer

Energy Technology Data Exchange (ETDEWEB)

Yang, Rui, E-mail: ryang73@ustc.edu; Gudipati, Murthy S., E-mail: gudipati@jpl.nasa.gov [Science Division, Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, California 91109 (United States)

2014-03-14

In this work, we report for the first time successful analysis of organic aromatic analytes imbedded in D{sub 2}O ices by novel infrared (IR) laser ablation of a layered non-absorbing D{sub 2}O ice (spectator) containing the analytes and an ablation-active IR-absorbing H{sub 2}O ice layer (actor) without the analyte. With these studies we have opened up a new method for the in situ analysis of solids containing analytes when covered with an IR laser-absorbing layer that can be resonantly ablated. This soft ejection method takes advantage of the tenability of two-step infrared laser ablation and ultraviolet laser ionization mass spectrometry, previously demonstrated in this lab to study chemical reactions of polycyclic aromatic hydrocarbons (PAHs) in cryogenic ices. The IR laser pulse tuned to resonantly excite only the upper H{sub 2}O ice layer (actor) generates a shockwave upon impact. This shockwave penetrates the lower analyte-containing D{sub 2}O ice layer (spectator, a non-absorbing ice that cannot be ablated directly with the wavelength of the IR laser employed) and is reflected back, ejecting the contents of the D{sub 2}O layer into the vacuum where they are intersected by a UV laser for ionization and detection by a time-of-flight mass spectrometer. Thus, energy is transmitted from the laser-absorbing actor layer into the non-absorbing spectator layer resulting its ablation. We found that isotope cross-contamination between layers was negligible. We also did not see any evidence for thermal or collisional chemistry of PAH molecules with H{sub 2}O molecules in the shockwave. We call this “shockwave mediated surface resonance enhanced subsurface ablation” technique as “two-step laser ablation and ionization mass spectrometry of actor-spectator ice layers.” This method has its roots in the well-established MALDI (matrix assisted laser desorption and ionization) method. Our method offers more flexibility to optimize both the processes—ablation and

Pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 for solid oxide fuel cell application

Energy Technology Data Exchange (ETDEWEB)

Gaur, Anshu, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com; Mohiddon, Md. Ahamad, E-mail: gauranshu20@gmail.com, E-mail: ahamed.vza@gmail.com [National Institute of Technology Andhra Pradesh, Tadepalliguem 534101 (India); Prasad, Muvva D. [UGC Networking Centre, School of Chemistry, University of Hyderabad, Hyderabad 500046, India. Phone:+91-40-23134382, Fax:+91-40-23010227 (India)

2016-05-23

The growth and oxidation study of pulsed laser deposited MnCo{sub 2}O{sub 4} protective layer on SS430 substrate for solid oxide fuel cell application is demonstrated. MnCo{sub 2}O{sub 4} has been achieved in three different ways including, deposition at higher substrate temperature (700°C), and deposition at room temperature on pre-oxidized and untreated SS430 substrate followed by annealing at 700°C for 2 hrs. X-ray diffraction and Raman spectroscopy has been applied to demonstrate the kind of phases developed in each case. These three samples were subjected to heat treatment at 750°C for 5 hr. The extent of undesired Fe{sub 2}O{sub 3} phase formation in the post deposition heat treated samples is discussed based on Raman spectroscopic results.

Sub-nanometer emittance monitor for high brightness synchrotron radiation source

International Nuclear Information System (INIS)

Nakajima, K.

1991-01-01

Method of measuring a very small beam emittance in electron storage rings is presented. The monitor can sense an intrinsic emittance of beam particles by detecting the angular distribution of Compton scatterings of laser photons on beam electrons. It is possible to achieve measurement resolution smaller than 10 -9 m-rad without difficulty. (author)

Morphology and Curie temperature engineering in crystalline La{sub 0.7}Sr{sub 0.3}MnO{sub 3} films on Si by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Nori, Rajashree, E-mail: rajsre@ee.iitb.ac.in; Ganguly, U.; Ravi Chandra Raju, N.; Pinto, R.; Ramgopal Rao, V. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India); Kale, S. N. [Department of Applied Physics, Defence Institute of Advanced Technology (DIAT), Pune 411025 (India); Sutar, D. S. [Central Surface Analytical Facility, Indian Institute of Technology-Bombay (IIT-B), Mumbai 400076 (India)

2014-01-21

Of all the colossal magnetoresistant manganites, La{sub 0.7}Sr{sub 0.3}MnO{sub 3} (LSMO) exhibits magnetic and electronic state transitions above room temperature, and therefore holds immense technological potential in spintronic devices and hybrid heterojunctions. As the first step towards this goal, it needs to be integrated with silicon via a well-defined process that provides morphology and phase control, along with reproducibility. This work demonstrates the development of pulsed laser deposition (PLD) process parameter regimes for dense and columnar morphology LSMO films directly on Si. These regimes are postulated on the foundations of a pressure-distance scaling law and their limits are defined post experimental validation. The laser spot size is seen to play an important role in tandem with the pressure-distance scaling law to provide morphology control during LSMO deposition on lattice-mismatched Si substrate. Additionally, phase stability of the deposited films in these regimes is evaluated through magnetometry measurements and the Curie temperatures obtained are 349 K (for dense morphology) and 355 K (for columnar morphology)—the highest reported for LSMO films on Si so far. X-ray diffraction studies on phase evolution with variation in laser energy density and substrate temperature reveals the emergence of texture. Quantitative limits for all the key PLD process parameters are demonstrated in order enable morphological and structural engineering of LSMO films deposited directly on Si. These results are expected to boost the realization of top-down and bottom-up LSMO device architectures on the Si platform for a variety of applications.

Mathematical Modeling Of The Acceleration Process In Race-track Microtron

CERN Document Server

Gromov, A M; Vasilev, A A

2004-01-01

The precise calculations of beam dynamics are needed to make choice of optimal design parameters of race-track microtron. As a result, the necessary physical require-ments to the accelerator systems become found. For cal-culation of the magnetic field, POISSON LANL code is used. Acceleration of the beam is investigated with the help of the program of MathCad. Nonlinear distribution of the field in magnets of micro-tron with adjustable reverse field was simulated. The equation of motion of a beam in bending magnets of re-circulation system are found and solved by a numerical method. Trajectories of the beam for all orbits in a micro-tron are received. The recursive equation for calculation of the largest area of injected beam phase and power spreads providing steady acceleration process is written. The acceleration of the beam with maximal phase-energy area through all orbits of microtron was simulated. The velocity of accelerated particles on first orbits dif-fers from velocity of light. The minimal energy ...

Enhancement of ferromagnetism in BaFeO{sub 3}-KTa{sub 0.47}Nb{sub 0.53}O{sub 3} multilayers compared to pseudo-cubic BaFeO{sub 3} thin film grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Cianfrone, Joe; Kim, Seonhoo; Kim, Kyeong-Won; Norton, David [Department of Materials Science and Engineering, University of Florida, Gainesville, FL (United States); Ghosh, Siddhartha; Hebard, Arthur F. [Department of Physics, University of Florida, Gainesville, FL (United States)

2017-06-15

Oxide multilayer hetero-structure of BaFeO{sub 3}-KTa{sub 0.47}Nb{sub 0.53}O{sub 3} have been grown using the pulsed laser deposition and the ex situ annealed in a flowing oxygen atmosphere. The multilayer has been characterized using X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. Magnetic properties have been studied via SQUID measurements. Magnetization in the multilayer structure shows significant improvement compared to previous measurements of bare BaFeO{sub 3}. Measuring magnetization as a function of temperature and fitting the resulting M-T curves to Bloch's 3/2 law, yields an estimated Curie temperature (T{sub C}) of around 425 K and a P factor of around 1.5, consistent with magnetization from a three dimensional crystal structure. In spite of using a room temperature ferroelectric KTa{sub 0.47}Nb{sub 0.53}O{sub 3} composition, no evidence of ferroelectricity was observed in multi-layer structure. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Soft-X-Ray Projection Lithography Using a High-Repetition-Rate Laser-Induced X-Ray Source for Sub-100 Nanometer Lithography Processes

NARCIS (Netherlands)

E. Louis,; F. Bijkerk,; Shmaenok, L.; Voorma, H. J.; van der Wiel, M. J.; Schlatmann, R.; Verhoeven, J.; van der Drift, E. W. J. M.; Romijn, J.; Rousseeuw, B. A. C.; Voss, F.; Desor, R.; Nikolaus, B.

1993-01-01

In this paper we present the status of a joint development programme on soft x-ray projection lithography (SXPL) integrating work on high brightness laser plasma sources. fabrication of multilayer x-ray mirrors. and patterning of reflection masks. We are in the process of optimization of a

Fiscal 2000 achievement report on the research and development of nanometer controlled optical disk system; 2000 nendo nanometer seigyo hikari disk system no kenkyu kaihatsu seika hokokusho

Energy Technology Data Exchange (ETDEWEB)

NONE

2001-03-01

Development proceeded of nanometer controlled optical memory technologies as part of systematic research and development aiming at the reinforcement of industrial technology power in the field of data recording. Activities were conducted in the four fields of (1) high density signal processing technology, (2) high performance disk materials technology, (3) disk substrate fabrication technology, and (4) signal detection technology. Discussed in field (1) were multivalue ROM (read only memory) disk signal regeneration, SIL-LBR (solid immersion lens-laser beam recorder), dry etching process using RIE (reactive ion etching), SHG (second harmonic generation) blue laser, and a multivalue ROM disk evaluation system. Studied in field (2) were the evaluation of ROM disk performance dependent on recording materials, development of high density recording materials, and the evaluation of crystallization induction time using a static tester. Studied in the development of high density recording materials was the formation of microscopic recording marks in a phase shift/surface recording type disk comprising a 4-element (Ag-In-Sb-Te) recording layer and an Ag reflection layer. In fiscal 2000, an attempt was made at the 0.07 {mu}m level. (NEDO)

Relativistic electron mirrors from high intensity laser nanofoil interactions

International Nuclear Information System (INIS)

Kiefer, Daniel

2012-01-01

The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ 2 , where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those

Colour and chemical changes of the lime wood surface due to CO{sub 2} laser thermal modification

Energy Technology Data Exchange (ETDEWEB)

Kubovský, Ivan, E-mail: kubovsky@tuzvo.sk; Kačík, František

2014-12-01

Highlights: • Influences of CO{sub 2} laser on lime wood surface were studied. • With growth of the irradiation dose brightness decrease and increase of the total colour difference were observed. • Cellulose degradation and loss of hemicelluloses were observed. • Higher values at the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. • CO{sub 2} laser irradiation can be used as a new colouring method. - Abstract: We studied colour and main wood components changes of lime wood caused by CO{sub 2} laser beam irradiation. The dry surface of lime wood (Tilia vulgaris L.) was irradiated with the CO{sub 2} laser beam (wavelength of 10.6 μm) at different exposures (expressed as the irradiation dose). Colour changes were monitored by the spectrophotometer, chemical changes were observed by the ATR-FTIR spectroscopy and carbohydrates were analysed by the HPLC method. With the growth of the irradiation dose (from 8.1 to 28.7 J cm{sup −2}) lightness (ΔL{sup *}) decrease and increase of the total colour difference (ΔE{sup *}) were observed. Higher values of the input energy lead to accelerating the mutual reaction of the functional groups resulting in the subsequent condensation of lignin. The total decrease in saccharides at the highest irradiation dose reaches 27.39% of the initial amount of saccharides in the reference sample. We have observed degradation and loss of hemicelluloses.

Infrared Spectra and Structures of SiH{sub 2}-(CH{sub 2}){sub 2} and CH{sub 2}=CH-SiH{sub 3} Intermediates Prepared in Reactions of Laser-ablated Silicon Atoms with Ethane

Energy Technology Data Exchange (ETDEWEB)

Cho, Han-Gook [Incheon National University, Incheon (Korea, Republic of); Andrews, Lester [University of Virginia, Charlottesville (United States)

2016-03-15

SiH{sub 2}-(CH{sub 2}){sub 2} and CH{sub 2}=CH-SiH{sub 3} were observed in the matrix IR spectra following reactions of laser-ablated Si atoms with ethane on the basis of correlation with computed frequencies. Evidently photon energy is required for the formation of the cyclic Si compound. These Si complexes are similar to the primary products in the previous studies of group 4 metals, in line with the previous results that s{sup 2}p{sup 2} and s{sup 2}d{sup 2} electronic configurations yield similar products. The relatively long C–C bond in the cyclic Si product reflects the structural strain, and the short C-Si and C-C bonds of CH{sub 3}CH=SiH{sub 2} and CH{sub 2}=CH-SiH{sub 3} show that they are true double bonds in line with the natural bond orders. Reactions of transition-metal atoms with small alkanes and halomethanes have been studied in a series of recent investigations. High oxidation-state products (methylidenes and methylidynes) along with insertion complexes were identified in the matrix spectra. It is interesting whether or not Si, a group 14 metalloid, undergoes similar reactions with larger hydrocarbons to provide higher oxidation-state compounds.

Microstructures induced by excimer laser surface melting of the SiC{sub p}/Al metal matrix composite

Energy Technology Data Exchange (ETDEWEB)

Qian, D.S., E-mail: Daishu.qian@postgrad.manchester.ac.uk; Zhong, X.L.; Yan, Y.Z.; Hashimoto, T.; Liu, Z.

2017-08-01

Highlights: • Microstructural analysis of the excimer laser-melted SiC{sub p}/AA2124;. • Analytical, FEM, and SPH simulation of the laser-material interaction;. • Mechanism of the formation of the laser-induced microstructure. - Abstract: Laser surface melting (LSM) was carried out on the SiC{sub p}/Al metal matrix composite (MMC) using a KrF excimer laser with a fluence of 7 J/cm{sup 2}. The re-solidification microstructure was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy dispersive X-ray detector, and X-ray diffraction (XRD) analysis. It was found that a 2.5 μm thick melted layer was formed in the near-surface region, in which dissolution of the intermetallics and removal of the SiC particles occurred. The thermal and material response upon laser irradiation was simulated using three models, i.e. analytical model, finite element model (FEM) and smoothed-particle hydrodynamics (SPH) model. The effect of SiC particles on the LSM process, the mechanism of the SiC removal and the re-solidification microstructures in the melted layer were discussed. The simulation results were in good agreement with the experimental results and contributed to the generic understanding of the re-solidification microstructures induced by ns-pulsed lasers.

Direct observation and analysis of yolk-shell materials using low-voltage high-resolution scanning electron microscopy: Nanometal-particles encapsulated in metal-oxide, carbon, and polymer

Energy Technology Data Exchange (ETDEWEB)

Asahina, Shunsuke; Suga, Mitsuo; Takahashi, Hideyuki [JEOL Ltd., SM Business Unit, Tokyo (Japan); Young Jeong, Hu [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Galeano, Carolina; Schüth, Ferdi [Department of Heterogeneous Catalysis, Max-Planck-Institut für Kohlenforschung, Mülheim (Germany); Terasaki, Osamu, E-mail: terasaki@mmk.su.se, E-mail: terasaki@kaist.ac.kr [Graduate School of EEWS, WCU/BK21+, KAIST, Daejeon 305-701 (Korea, Republic of); Department of Materials and Environmental Chemistry, Berzelii Centre EXSELENT on Porous Materials, Stockholm University, SE-10691 Stockholm (Sweden)

2014-11-01

Nanometal particles show characteristic features in chemical and physical properties depending on their sizes and shapes. For keeping and further enhancing their features, the particles should be protected from coalescence or degradation. One approach is to encapsulate the nanometal particles inside pores with chemically inert or functional materials, such as carbon, polymer, and metal oxides, which contain mesopores to allow permeation of only chemicals not the nanometal particles. Recently developed low-voltage high-resolution scanning electron microscopy was applied to the study of structural, chemical, and electron state of both nanometal particles and encapsulating materials in yolk-shell materials of Au@C, Ru/Pt@C, Au@TiO{sub 2}, and Pt@Polymer. Progresses in the following categories were shown for the yolk-shell materials: (i) resolution of topographic image contrast by secondary electrons, of atomic-number contrast by back-scattered electrons, and of elemental mapping by X-ray energy dispersive spectroscopy; (ii) sample preparation for observing internal structures; and (iii) X-ray spectroscopy such as soft X-ray emission spectroscopy. Transmission electron microscopy was also used for characterization of Au@C.

Damage Mechanisms In Polymers Upon NIR Femtosecond Pulse Laser Irradiation: Sub-Threshold Processes And Their Implications For Laser Safety Applications

International Nuclear Information System (INIS)

Bonse, Joern; Krueger, Joerg; Solis, Javier; Spielmann, Christian; Lippert, Thomas

2010-01-01

This contribution investigates laser-induced damage of thin film and bulk polymer samples, with the focus on physical processes occurring close to the damage threshold. In-situ real-time reflectivity (RTR) measurements with picosecond (ps) and nanosecond (ns) temporal resolution were performed on thin polymer films on a timescale up to a few microseconds (μs). A model for polymer thin film damage is presented, indicating that irreversible chemical modification processes take place already below the fluence threshold for macroscopic damage. On dye-doped bulk polymer filters (as used for laser goggles), transmission studies using fs-and ps-laser pulses reveal the optical saturation behavior of the material and its relation to the threshold of permanent damage. Implications of the sub-threshold processes for laser safety applications will be discussed for thin film and bulk polymer damage.

Critical element development of standard components for pipe welding/cutting by CO{sub 2} laser

Energy Technology Data Exchange (ETDEWEB)

Oka, Kiyoshi; Kakudate, Satoshi; Nakahira, Masataka [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment] [and others

1994-11-01

In D-T burning reactors such as International Thermonuclear Experimental Reactor(ITER), an internal access is inevitable for welding/cutting of cooling pipes of in-vessel components, because of spatial constraint due to a narrow port opening space. An internal-access pipe welding/cutting equipment is being developed in JAERI. Internal access is to approach through inside a pipe to a welding/cutting position, to use 10kW CO{sub 2} laser beam, and to be applicable to both welding and cutting with using a same processing head. A welding/cutting processing head with 10kW CO{sub 2} laser beam has been fabricated and the basic feasibility has been successfully demonstrated for studies of the internal-access pipe welding/cutting concept using 100-A stainless steel pipe with a thickness of 6.3mm. In this study, the optimum focal point of laser beam, laser power and traveling speed of the head have been investigated together with an adjusting mechanism of a relative distance between the head and the pipe wall. In addition, the radiation resistance of critical elements such as optical lens has been investigated. (author).

Influence of the oxygen pressure on the preferred orientation and optical properties of the pulsed-laser deposited Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} thin films

Energy Technology Data Exchange (ETDEWEB)

Kong, Wenwen [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Gao, Bo [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Jiang, Chunping, E-mail: cpjiang2008@sinano.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China); Key Laboratory of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics of CAS, Suzhou 215123 (China); Chang, Aimin, E-mail: changam@ms.xjb.ac.cn [Key Laboratory of Functional Materials and Devices for Special Environments of CAS, Xinjiang Key Laboratory of Electronic Information Materials and Devices, Xinjiang Technical Institute of Physics & Chemistry of CAS, Urumqi 830011 (China)

2015-11-25

Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4±δ} (MCN) thin films with different oxygen pressures (in the range of 2 × 10{sup −4} to 2 Pa) are prepared on Si(100)/SiO{sub x} substrates by pulsed laser deposition technique. Effects of oxygen pressures on the microstructure and optical properties of the prepared thin films are investigated in detail. The grain sizes of films gradually decrease and the preferential orientation of the MCN films change from (400) to (113) as the oxygen pressure increases. The x-ray photoelectron spectroscopy results show that the composition of these films is proximity to that of the bulk material. In addition, the Mn{sup 3+}/Mn{sup 4+} pairs increase with an increase in the oxygen pressures increase. From spectroscopic ellipsometer spectroscopy, it is found that both the refractive index n and extinction coefficient k of the (400)-oriented films have no obvious peaks, whereas in the (113)-oriented films, peaks are exist. This feature typically originates from a change in the crystal structure as oxygen pressures increase. Furthermore, the Raman active mode (around ca. 650 cm{sup −1}) of (400) films almost disappears, whilst the active mode in (113) films remain. - Highlights: • The Mn{sub 1.56}Co{sub 0.96}Ni{sub 0.48}O{sub 4-δ} (MCN) spinel films are deposited by pulsed laser deposition process at different oxygen pressures. • The preferential orientation of the films changes from (400) plane to (113) as the oxygen pressure increases. • The E{sub g} of the (113) film is twice as large as that of the (400) film. • The Raman active mode (around ca. 650 cm{sup −1}) can be observed in the (113) films while not in the (400) film.

Effects of CO{sub 2} laser irradiation on the wettability and human skin fibroblast cell response of magnesia partially stabilised zirconia

Energy Technology Data Exchange (ETDEWEB)

Hao, L.; Lawrence, J

2003-10-15

Human skin fibroblast cells in vitro responses on the surface of a bioinert zirconia ceramic partially stabilised with magnesia partially stabilised zirconia (MgO-PSZ) bioinert ceramic before and after CO{sub 2} laser treatment were investigated to find the interrelationship between the cell adhesion, wettability and laser parameters. Contact angle, {theta}, measurements of a set of test liquids were a clear indication that surface treatment of the MgO-PSZ with a CO{sub 2} laser brought about a reduction in {theta}, indicating that the wettability of the MgO-PSZ had been enhanced. A relationship was found between the wettability and the microstructure of the MgO-PSZ surface and laser processing parameters. It was subsequently deduced that the factors active in causing the observed modification in the wettability of the MgO-PSZ were the increases in the surface O{sub 2} content and the polar component of the surface energy, {gamma}{sub sv}{sup p}, the latter resulting from surface melting and resolidification. Moreover, the investigation into the human skin fibroblast cell response revealed that the CO{sub 2} laser treatment of the MgO-PSZ had resulted in a surface favourable for cell adhesion, as the extent of cell attachment and adhesion on the MgO-PSZ surface was enhanced depending on laser parameters. Such an improvement in cell adhesion, which could be greatly beneficial to developing enhanced bonding at the tissue and implant interface, was influenced by the surface properties of the modified MgO-PSZ, particular wettability.

Elucidation of C{sub 2} and CN formation mechanisms in laser-induced plasmas through correlation analysis of carbon isotopic ratio

Energy Technology Data Exchange (ETDEWEB)

Dong, Meirong [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Chan, George C.-Y.; Mao, Xianglei; Gonzalez, Jhanis J. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Lu, Jidong [School of Electric Power, South China University of Technology, Guangzhou, Guangdong 510640 (China); Russo, Richard E., E-mail: RERusso@lbl.gov [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

2014-10-01

Laser ablation molecular isotopic spectrometry (LAMIS) was recently reported for rapid isotopic analysis by measuring molecular emission from laser-induced plasmas at atmospheric pressure. With {sup 13}C-labeled benzoic acid as a model sample, this research utilized the LAMIS approach to clarify the formation mechanisms of C{sub 2} and CN molecules during laser ablation of organic materials. Because the isotopic ratios in the molecular bands could deviate from statistical distribution depending on their formation pathways, the dominant mechanism can be identified through a comparison of the experimental observed isotopic patterns in the molecular emission with the theoretical statistical pattern. For C{sub 2} formation, the experimental {sup 12}C{sup 12}C/{sup 13}C{sup 12}C ratios not only support a recombination mechanism through atomic carbon at early delay time but also indicate the presence of other operating mechanisms as the plasma evolves; it is proposed that some of the C{sub 2} molecules are released directly from the aromatic ring of the sample as molecular fragments. In contrast, the temporal profiles in the {sup 12}C/{sup 13}C ratios derived from CN emission exhibited opposite behavior with those derived from C{sub 2} emission, which unambiguously refutes mechanisms that require C{sub 2} as a precursor for CN formation; CN formation likely involves atomic carbon or species with a single carbon atom. - Highlights: • C{sub 2} and CN formation mechanisms during laser ablation of organic material studied • Some C{sub 2} molecules are directly desorbed from the organic compound. • C{sub 2} molecules are not important precursor for CN-radical formation.

Cd-diffused Pb/sub 1-x/Sn/sub x/Te lasers with high output

International Nuclear Information System (INIS)

Lo, W.

1976-01-01

Cd-diffused Pb 1 /sub -//subx/Sn/subx/Te (xapprox.0.13) diode lasers have been fabricated with cw output powers of 1.25 mW (single mode) and 2.4 mW (total) at 10.6 μm. These power levels are attributed to the low-temperature Cd diffusion, a new method of growing low-dislocation-density crystals, and to a contact resistance as low as 3x10 -5 Ω cm 2 . Multimode emission spectra are common for cw operation, but reducing the cavity width encourages single-mode emission, indicating the filamentary nature of modes in these devices

The effects of using flashcards with reading racetrack to teach letter sounds, sight words, and math facts to elementary students with learning disabilities

Directory of Open Access Journals (Sweden)

Rachel Erbey

2011-07-01

Full Text Available The purpose of this study was to measure the effects of reading racetrack and flashcards when teaching phonics, sight words, and addition facts. The participants for the sight word and phonics portion of this study were two seven-year-old boys in the second grade. Both participants were diagnosed with a learning disability. The third participant was diagnosed with attention deficit hyperactivity disorder by his pediatrician and with a learning disability and traumatic brain injury by his school’s multi-disciplinary team.. The dependent measures were corrects and errors when reading from a first grade level sight word list. Math facts were selected based on a 100 add fact test for the third participant. The study demonstrated that racetracks paired with the flashcard intervention improved the students’ number of corrects for each subject-matter area (phonics, sight words, and math facts. However, the results show that some students had more success with it than others. These outcomes clearly warrant further research.

Sub-10-nm suspended nano-web formation by direct laser writing

Science.gov (United States)

Wang, Sihao; Yu, Ye; Liu, Hailong; Lim, Kevin T. P.; Madurai Srinivasan, Bharathi; Zhang, Yong Wei; Yang, Joel K. W.

2018-06-01

A diffraction-limited three-dimensional (3D) direct laser writing (DLW) system based on two-photon polymerization can routinely pattern structures at the 100 nm length scale. Several schemes have been developed to improve the patterning resolution of 3D DLW but often require customized resist formulations or multi-wavelength exposures. Here, we introduce a scheme to produce suspended nano-webs with feature sizes below 10 nm in IP-Dip resist using sub-threshold exposure conditions in a commercial DLW system. The narrowest suspended lines (nano-webs) measured 7 nm in width. Larger ∼20 nm nano-webs were patterned with ∼80% yield at increased laser powers. In addition, closely spaced nano-gaps with a center-to-center distance of 33 nm were produced by patterning vertically displaced suspended lines followed by metal deposition and liftoff. We provide hypotheses and present preliminary results for a mechanism involving the initiation of a percolative path and a strain-induced narrowing in the nano-web formation. Our approach allows selective features to be patterned with dimensions comparable to the sub-10 nm patterning capability of electron-beam lithography (EBL).

Preparation of n-type Bi{sub 2}Te{sub 3} thermoelectric materials by non-contact dispenser printing combined with selective laser melting

Energy Technology Data Exchange (ETDEWEB)

Wu, Keping; Yan, Yonggao; Zhang, Jian; Mao, Yu; Xie, Hongyao; Zhang, Qingjie; Tang, Xinfeng [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan, Hubei (China); Yang, Jihui [Department of Materials Science and Engineering, University of Washington, Seattle, WA (United States); Uher, Ctirad [Department of Physics, University of Michigan, Ann Arbor, MI (United States)

2017-06-15

The manufacturing cost has been a bottle neck for broader applications of thermoelectric (TE) modules. We have developed a rapid, facile, and low cost method that combines non-contact dispenser printing with selective laser melting (SLM) and we demonstrate it on n-type Bi{sub 2}Te{sub 3}-based materials. Using this approach, single phase n-type Bi{sub 2}Te{sub 2.7}Se{sub 0.3} thin layers with the Seebeck coefficient of -152 μV K{sup -1} at 300 K have been prepared. Assembling such thin layers on top of each other, the performance of thus prepared bulk sample is comparable to Bi{sub 2}Te{sub 3}-based materials fabricated by the conventional techniques. Dispenser printing combined with SLM is a promising manufacturing process for TE materials. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Photochemistry of U(BH/sub 4/)/sub 4/ and U(BD/sub 4/)/sub 4/

Energy Technology Data Exchange (ETDEWEB)

Paine, R T; Schonberg, P R; Light, R W [New Mexico Univ., Albuquerque (USA). Dept. of Chemistry; Danen, W C; Freund, S M

1979-01-01

U(BH/sub 4/)/sub 4/ and U(BD/sub 4/)/sub 4/ are observed to undergo complex degradation reactions promoted by broadband UV radiation. The primary products of these reactions appear to be U(BH/sub 4/)/sub 3/, B/sub 2/H/sub 6/, H/sub 2/, U(BD/sub 4/)/sub 3/, B/sub 2/D/sub 6/ and D/sub 2/. Further, U(BD/sub 4/)/sub 4/ undergoes a related decomposition reaction under the influence of CO/sub 2/ laser irradiation at 924.97 cm/sup -1/.

Cytotoxicity of Ultra-pure TiO{sub 2} and ZnO Nanoparticles Generated by Laser Ablation

Energy Technology Data Exchange (ETDEWEB)

Jeong, Minju; Park, Jeong Min; Lee, Eun Jeong; Cho, Yea Seul; Lee, Chunghyun; Kim, Jeong Moo; Hah, Sang Soo [Kyung Hee Univ., Yongin (Korea, Republic of)

2013-11-15

This paper aims to address the cellular toxicity of ultra-pure titanium dioxide (TiO{sub 2}) and zinc oxide (ZnO) nanoparticles (NPs) frequently employed in sunscreens as inorganic physical sun blockers to provide protection against adverse effects of ultraviolet (UV) radiation including UVB (290-320 nm) and UVA (320-400 nm). In consideration that the production and the use of inorganic NPs have aroused many concerns and controversies regarding their safety and toxicity and that microsized TiO{sub 2} and ZnO have been increasingly replaced by TiO{sub 2} and ZnO NPs (< 100 nm), it is very important to directly investigate a main problem related to the intrinsic/inherent toxicity of these NPs and/or their incompatibility with biological objects. In the present study, we took advantage of the laser-assisted method called laser ablation for generation of TiO{sub 2} and ZnO NPs. NPs were prepared through a physical process of irradiating solid targets in liquid phase, enabling verification of the toxicity of ultra-pure NPs with nascent surfaces free from any contamination. Our results show that TiO{sub 2} NPs are essentially non-poisonous and ZnO NPs are more toxic than TiO{sub 2} NPs based on the cell viability assays.

Pb{sub 1–x}Eu{sub x}Te alloys (0 ⩽ x ⩽ 1) as materials for vertical-cavity surface-emitting lasers in the mid-infrared spectral range of 4–5 μm

Energy Technology Data Exchange (ETDEWEB)

Pashkeev, D. A., E-mail: d.pashkeev@gmail.com; Selivanov, Yu. G.; Chizhevskii, E. G.; Zasavitskiy, I. I. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

2016-02-15

The optical properties of epitaxial layers and heterostructures based on Pb{sub 1–x}Eu{sub x}Te alloys (0 ⩽ x ⩽ 1) are analyzed in the context of designing Bragg mirrors and vertical-cavity surface-emitting lasers for the midinfrared spectral range. It is shown that the optimal heteropair for laser microcavities is Pb{sub 1–x}Eu{sub x}Te(x ≈ 0.06)/EuTe. On the basis of this heteropair, highly reflective Bragg mirrors consisting of just three periods and featuring a reflectance of R ⩾ 99.8% at the center of the stop band are grown by molecular-beam epitaxy on BaF{sub 2} (111) substrates. Single-mode optically pumped vertical-cavity surface-emitting lasers for the 4–5 μm spectral range operating at liquid-nitrogen temperatures are demonstrated.

Structural and optical properties of {beta}-FeSi{sub 2}/Si(100) prepared by laser ablation method

Energy Technology Data Exchange (ETDEWEB)

Kakemoto, H; Makita, Y; Obara, A; Tsai, Y; Sakuragi, S; Ando, S; Tsukamoto, T

1997-07-01

{beta}-FeSi{sub 2} is a promising material for the application of various electronic, optoelectronic and energy devices. The authors present here the semiconducting properties of {beta}-FeSi{sub 2} films on Si(100) substrate prepared by laser ablation method. Samples were grown using poly-crystalline bulk {beta}-FeSi{sub 2} prepared by horizontal gradient freeze method. For the monitoring of growth, in-situ observation of ablation plume was made through fluorescence spectroscopy. Reflection of high-energy electron beam diffraction (RHEED) was also made in-situ to see the surface morphology. Characterization of the films by X-ray diffraction presented purely {beta}(220) orientation. Raman scattering measurements at room temperature also indicated that the grown films are semiconducting {beta}-FeSi{sub 2}. Optical absorption spectra at room temperature showed absorption coefficient higher than 10{sup 5} cm{sup {minus}1} above the band-gap ({approximately}1.2 eV). It was revealed that high quality semiconducting {beta}-FeSi{sub 2} films can be fabricated by laser ablation method without post-annealing.

Comparison of Monolithic Optical Frequency Comb Generators Based on Passively Mode-Locked Lasers for Continuous Wave mm-Wave and Sub-THz Generation

DEFF Research Database (Denmark)

Criado, A. R.; de Dios, C.; Acedo, P.

2012-01-01

In this paper, two different Passive Mode-Locked Laser Diodes (PMLLD) structures, a Fabry–Perot cavity and a ring cavity laser are characterized and evaluated as monolithic Optical Frequency Comb Generators (OFCG) for CW sub-THz generation. An extensive characterization of the devices under study...... is carried out based on an automated measurement system that systematically evaluates the dynamic characteristics of the devices, focusing on the figures of merit that define the optimum performance of a pulsed laser source when considered as an OFCG. Sub-THz signals generated with both devices at 60 GHz...... topologies that can be used for the implementation of photonic integrated sub-THz CW generation....

Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

Energy Technology Data Exchange (ETDEWEB)

Bin Mansoor, Saad; Sami Yilbas, Bekir, E-mail: bsyilbas@kfupm.edu.sa

2015-08-15

Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system.

Laser short-pulse heating of an aluminum thin film: Energy transfer in electron and lattice sub-systems

International Nuclear Information System (INIS)

Bin Mansoor, Saad; Sami Yilbas, Bekir

2015-01-01

Laser short-pulse heating of an aluminum thin film is considered and energy transfer in the film is formulated using the Boltzmann equation. Since the heating duration is short and the film thickness is considerably small, thermal separation of electron and lattice sub-systems is incorporated in the analysis. The electron–phonon coupling is used to formulate thermal communication of both sub-systems during the heating period. Equivalent equilibrium temperature is introduced to account for the average energy of all phonons around a local point when they redistribute adiabatically to an equilibrium state. Temperature predictions of the Boltzmann equation are compared with those obtained from the two-equation model. It is found that temperature predictions from the Boltzmann equation differ slightly from the two-equation model results. Temporal variation of equivalent equilibrium temperature does not follow the laser pulse intensity in the electron sub-system. The time occurrence of the peak equivalent equilibrium temperature differs for electron and lattice sub-systems, which is attributed to phonon scattering in the irradiated field in the lattice sub-system. In this case, time shift is observed for occurrence of the peak temperature in the lattice sub-system

Laser interference lithography with highly accurate interferometric alignment

NARCIS (Netherlands)

van Soest, Frank J.; van Wolferen, Hendricus A.G.M.; Hoekstra, Hugo; de Ridder, R.M.; Worhoff, Kerstin; Lambeck, Paul

It is shown experimentally that in laser interference lithography, by using a reference grating, respective grating layers can be positioned with high relative accuracy. A 0.001 degree angular and a few nanometers lateral resolution have been demonstrated.

Sub-micron magnetic patterns and local variations of adhesion force induced in non-ferromagnetic amorphous steel by femtosecond pulsed laser irradiation

Energy Technology Data Exchange (ETDEWEB)

Zhang, Huiyan; Feng, Yuping [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); Nieto, Daniel [Microoptics and GRIN Optics Group, Applied Physics Department, University of Santiago de Compostela, E15782 Santiago de Compostela (Spain); García-Lecina, Eva [Unidad de Superficies Metálicas, IK4-CIDETEC, E20009 Donostia-San Sebastián Gipuzkoa (Spain); Mcdaniel, Clare [National Centre for Laser Applications, School of Physics, National University of Ireland, Galway (Ireland); Díaz-Marcos, Jordi [Unitat de Tècniques Nanomètriques, Centres Científics i Tecnològics, Universitat de Barcelona, E08028 Barcelona (Spain); Flores-Arias, María Teresa [Microoptics and GRIN Optics Group, Applied Physics Department, University of Santiago de Compostela, E15782 Santiago de Compostela (Spain); O’Connor, Gerard M. [National Centre for Laser Applications, School of Physics, National University of Ireland, Galway (Ireland); Baró, Maria Dolors [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); Pellicer, Eva, E-mail: eva.pellicer@uab.cat [Departament de Física, Universitat Autònoma de Barcelona, Bellaterra, E08193 (Spain); and others

2016-05-15

Highlights: • Formation of ripples after femtosecond pulsed laser irradiation (FSPLI) of metallic glass was studied. • Magnetic patterning at the surface of non-ferromagnetic amorphous steel was induced by FSPLI. • The origin of the generated ferromagnetism is the laser-induced devitrification. - Abstract: Periodic ripple and nanoripple patterns are formed at the surface of amorphous steel after femtosecond pulsed laser irradiation (FSPLI). Formation of such ripples is accompanied with the emergence of a surface ferromagnetic behavior which is not initially present in the non-irradiated amorphous steel. The occurrence of ferromagnetic properties is associated with the laser-induced devitrification of the glassy structure to form ferromagnetic (α-Fe and Fe{sub 3}C) and ferrimagnetic [(Fe,Mn){sub 3}O{sub 4} and Fe{sub 2}CrO{sub 4}] phases located in the ripples. The generation of magnetic structures by FSPLI turns out to be one of the fastest ways to induce magnetic patterning without the need of any shadow mask. Furthermore, local variations of the adhesion force, wettability and nanomechanical properties are also observed and compared to those of the as-cast amorphous alloy. These effects are of interest for applications (e.g., biological, magnetic recording, etc.) where both ferromagnetism and tribological/adhesion properties act synergistically to optimize material performance.

CO sub 2 laser cutting of ceramics and metal-ceramic composites. CO sub 2 -Laserschneiden von Keramik und Metall-Keramik-Verbunden

Energy Technology Data Exchange (ETDEWEB)

Wielage, B.; Drozak, J. (Dortmund Univ. (Germany, F.R.). Lehrstuhl fuer Werkstofftechnologie)

1991-01-01

Oxide and non-oxide ceramics as well as active brazed and APS-sprayed metal-ceramic composites are cut by means of a 1500 Watt CO{sub 2} laser. In this context, the experience from ceramics cutting applications is applied to laser cutting of composites. The process parameters, which are adjusted to the property profile and the thickness of the material, permit cutting of ceramics of a maximum thickness of 10 mm with optimal cut edge quality and minimum damage to the material. The parameter sets were also optimized in the case of laser-cut active brazed and plasma-sprayed composites. In terms of roughness, composition and structure of the cut edge, composites can be optimally cut using oxygen as process gas. (orig.).

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

Energy Technology Data Exchange (ETDEWEB)

Bonse, J., E-mail: joern.bonse@bam.de [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Höhm, S. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany); Rosenfeld, A. [Max-Born-Institut für Nichtlineare Optik und Kurzzeitspektroskopie (MBI), Max-Born-Straße 2A, D-12489 Berlin (Germany); Krüger, J. [BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin (Germany)

2016-06-30

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Tribological performance of sub-100-nm femtosecond laser-induced periodic surface structures on titanium

International Nuclear Information System (INIS)

Bonse, J.; Höhm, S.; Koter, R.; Hartelt, M.; Spaltmann, D.; Pentzien, S.; Rosenfeld, A.; Krüger, J.

2016-01-01

Graphical abstract: - Highlights: • Large areas covered with sub-100 nm LIPSS (HSFL) were manufactured by fs-laser irradiation on titanium surfaces. • Tribological performance of HSFL covered areas was qualified in reciprocal sliding tests in two different lubricating oils. • HSFL on titanium do not endure the tribological tests. • For a beneficial tribological performance, the tribological sample deformation must be smaller than the LIPSS modulation depth. - Abstract: Sub-100-nm laser-induced periodic surface structures (LIPSS) were processed on bulk titanium (Ti) surfaces by femtosecond laser pulse irradiation in air (30 fs pulse duration, 790 nm wavelength). The laser peak fluence, the spatial spot overlap, and the number of overscans were optimized in a sample-scanning geometry in order to obtain large surface areas (5 mm × 5 mm) covered homogeneously by the LIPSS. The laser-processed regions were characterized by optical microscopy (OM), white light interference microscopy (WLIM) and scanning electron microscopy (SEM). The friction coefficient of the nanostructured surfaces was tested during 1000 cycles under reciprocal sliding conditions (1 Hz, 1.0 N normal load) against a 10-mm diameter ball of hardened 100Cr6 steel, both in paraffin oil and in engine oil used as lubricants. Subsequently, the corresponding wear tracks were qualified by OM, SEM, and energy dispersive X-ray analyses (EDX). The results of the tribological tests are discussed and compared to that obtained for near wavelength-sized fs-LIPSS, processed under somewhat different irradiation conditions. Some constraints for a beneficial effect of LIPSS on the tribological performance are provided.

Synthesis of Mg(OH)<sub>2sub>, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Energy Technology Data Exchange (ETDEWEB)

Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Howard, Bret. H. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Martello, Donald V. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Soong, Yee [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Chyu, Minking K. [Univ. of Pittsburgh, PA (United States)

2008-11-01

Laser ablation of magnesium in deionized water (DW), solutions of DW and sodium dodecyl sulfate (SDS) with different concentrations, acetone and 2-propanol has been conducted. The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alteration/decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH)<sub>2sub> particles were mainly produced by laser ablation of Mg in either DW or DW-SDS solutions. Ablation in DW yielded particles of fiber-like shapes having a diameter of about 5-10nm and length-as long as 150 nm. Materials produced in DW-SDS solutions were composed of various size and shape particles. Some had rough surfaces with irregular shapes. Small particles were about 20-30 nm and larger particles were about 120 nm. Particles with rodlike, triangular, and plate-like shapes were also observed.

Measurement of the C{sub 2}H{sub 2} destruction kinetics by infrared laser absorption spectroscopy in a pulsed low pressure dc discharge

Energy Technology Data Exchange (ETDEWEB)

Rousseau, A [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Guaitella, O [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Gatilova, L [LPTP, Ecole Polytechnique, CNRS, Route de Saclay, 91 128 Palaiseau Cedex (France); Hannemann, M [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany); Roepcke, J [INP-Greifswald, Friedrich-Ludwig-Jahn-Str. 19, 17489 Greifswald (Germany)

2007-04-07

The kinetics of destruction of C{sub 2}H{sub 2} is investigated in a low pressure pulsed dc discharge in dry air. Tuneable diode laser absorption spectroscopy in the mid-infrared region (1350 cm{sup -1}) has been used to measure the influence of (i) the pulse duration (ii) the pulse repetition rate and (iii) the pulse current on the C{sub 2}H{sub 2} concentration in situ the discharge tube. First, it is shown that in the plasma region under flow conditions the time averaged concentration of C{sub 2}H{sub 2} depends only on the time averaged discharge current. Second, time resolved measurements have been performed in a closed reactor, i.e. under static conditions. A simple kinetic modelling of the pulsed discharge leads to a good agreement with the experimental results and shows that the oxidation rate of C{sub 2}H{sub 2} is mainly controlled by the time averaged concentration of O atoms. Finally, the influence of porous TiO{sub 2} photocatalyst on the C{sub 2}H{sub 2} oxidation rate is reported.

Relativistic electron mirrors from high intensity laser nanofoil interactions

Energy Technology Data Exchange (ETDEWEB)

Kiefer, Daniel

2012-12-21

The reflection of a laser pulse from a mirror moving close to the speed of light could in principle create an X-ray pulse with unprecedented high brightness owing to the increase in photon energy and accompanying temporal compression by a factor of 4γ{sup 2}, where γ is the Lorentz factor of the mirror. While this scheme is theoretically intriguingly simple and was first discussed by A. Einstein more than a century ago, the generation of a relativistic structure which acts as a mirror is demanding in many different aspects. Recently, the interaction of a high intensity laser pulse with a nanometer thin foil has raised great interest as it promises the creation of a dense, attosecond short, relativistic electron bunch capable of forming a mirror structure that scatters counter-propagating light coherently and shifts its frequency to higher photon energies. However, so far, this novel concept has been discussed only in theoretical studies using highly idealized interaction parameters. This thesis investigates the generation of a relativistic electron mirror from a nanometer foil with current state-of-the-art high intensity laser pulses and demonstrates for the first time the reflection from those structures in an experiment. To achieve this result, the electron acceleration from high intensity laser nanometer foil interactions was studied in a series of experiments using three inherently different high power laser systems and free-standing foils as thin as 3nm. A drastic increase in the electron energies was observed when reducing the target thickness from the micrometer to the nanometer scale. Quasi-monoenergetic electron beams were measured for the first time from ultrathin (≤5nm) foils, reaching energies up to ∝35MeV. The acceleration process was studied in simulations well-adapted to the experiments, indicating the transition from plasma to free electron dynamics as the target thickness is reduced to the few nanometer range. The experience gained from those

Structural transformations in MoO{sub x} thin films grown by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Camacho-Lopez, M.A.; Haro-Poniatowski, E. [Departamento de Fisica, Laboratorio de Optica Cuantica, Universidad Autonoma Metropolitana Iztapalapa, Apdo. Postal 55-534, 09340, Mexico D. F. (Mexico); Escobar-Alarcon, L. [Departamento de Fisica, Instituto Nacional de Investigaciones Nucleares, Apdo. Postal 18-1027, 11801, Mexico D. F. (Mexico)

2004-01-01

In this work, laser-induced crystallization in MoO{sub x} thin films (1.8{<=}x{<=}2.1) is reported. This transformation involves a MoO{sub x} oxidation and subsequently a crystallization process from amorphous MoO{sub 3} to crystalline {alpha}MoO{sub 3}. For comparison purposes crystallization is induced thermally, in an oven, as well. The crystallization kinetics is monitored by Raman spectroscopy; a threshold in the energy density necessary to induce the phase transformation is determined in the case of photo-crystallization. This threshold depends on the type of substrate on which the film is deposited. For the thin films deposited on glass substrates, the structural transformation is from amorphous MoO{sub x} to the thermodynamically stable {alpha}MoO{sub 3} crystalline phase. For the thin films deposited on Si(100) the structural transformation is from amorphous MoO{sub x} to a mixture of {alpha}MoO{sub 3} and the thermodynamically unstable {beta}MoO{sub 3} crystalline phases. The structural transformations are also characterized by scanning electron microscopy and light-transmission experiments. (orig.)

Refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films by multiple femtosecond laser pulses

Energy Technology Data Exchange (ETDEWEB)

Lei, Kai; Wang, Yang, E-mail: ywang@siom.ac.cn; Jiang, Minghui; Wu, Yiqun [Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2016-05-07

In this study, the controllable effective refractive index modulation of Sb{sub 70}Te{sub 30} phase-change thin films between amorphous and crystalline states was achieved experimentally by multiple femtosecond laser pulses. The modulation mechanism was analyzed comprehensively by a spectral ellipsometer measurement, surface morphology observation, and two-temperature model calculations. We numerically demonstrate the application of the optically modulated refractive index of the phase-change thin films in a precisely adjustable color display. These results may provide further insights into ultrafast phase-transition mechanics and are useful in the design of programmable photonic and opto-electrical devices based on phase-change memory materials.

Optical response of oxygen deficient La{sub 0.7}Sr{sub 0.3}MnO{sub 3} thin films deposited by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Cesaria, M., E-mail: maura.cesaria@le.infn.it [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); Caricato, A.P.; Leggieri, G.; Martino, M. [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); Maruccio, G. [Department of Mathematics and Physics “Ennio De Giorgi”, University of Salento, Via Arnesano, 73100 Lecce (Italy); National Nanotechnology Laboratory (NNL)-Nanoscience Institute-CNR, Via Arnesano, 73100 Lecce (Italy)

2013-10-31

The optical response of 200 nm thick La{sub 0.7}Sr{sub 0.3}MnO{sub (3−δ)} films, deposited by pulsed laser deposition on amorphous silica substrates heated at nearly 600 °C, under different oxygen pressures (0.1 Pa, 0.5 Pa, 1 Pa, 5 Pa and 10 Pa), is reported. The effects of the oxygen non-stoichiometry are investigated at room temperature dealing with the absorption coefficient and the Tauc's plot method rather than conventional optical conductivity. The absorption curves are evaluated by an algorithm able to realistically describe the behavior of thin films without exploiting numerical extrapolations or simplified theoretical models or ab-initio calculations. Optical features, tunable by the growth oxygen pressure, are discussed based on the known theoretical and experimental scenario. - Highlights: • Overview of the La{sub 0.7}Sr{sub 0.3}MnO{sub 3} basics to highlight basic questions to be assessed. • Optical analysis by the absorption coefficient rather than optical conductivity. • Realistic absorption response that avoids numerical refinements and simulations. • Analysis of the role of oxygen vacancies in tuning the electronic dispersion. • First investigation of direct and indirect transitions by the Tauc's plot.

Polarized spectroscopic properties of Er{sup 3+}:Gd{sub 2}SiO{sub 5} crystal and evaluation of Er{sup 3+}:Yb{sup 3+}:Gd{sub 2}SiO{sub 5} crystal as a 1.55 μm laser medium

Energy Technology Data Exchange (ETDEWEB)

Wang, H. [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); University of Chinese Academy of Sciences, Beijing 100039 (China); Huang, J.H.; Gong, X.H.; Chen, Y.J.; Lin, Y.F.; Luo, Z.D. [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Huang, Y.D., E-mail: huyd@fjirsm.ac.cn [Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China)

2016-10-01

An Er{sup 3+}-doped Gd{sub 2}SiO{sub 5} single crystal with high optical quality has been grown by the Czochralski method. Polarized absorption and fluorescence spectra and fluorescence lifetime of the crystal were measured at room temperature. Intensity parameters, spontaneous emission probabilities, fluorescence branching ratios, and radiative lifetimes were estimated on the basis of the Judd–Ofelt theory. Besides, potentiality of 1.55 μm laser emission in an Er{sup 3+}–Yb{sup 3+} co-doped Gd{sub 2}SiO{sub 5} crystal was evaluated.

Spot size predictions of a focused ion beam based on laser cooling

NARCIS (Netherlands)

Haaf, ten G.; Wouters, S.H.W.; Geer, van der S.B.; Mutsaers, P.H.A.; Luiten, O.J.; Vredenbregt, E.J.D.

2014-01-01

The Atomic Beam Laser Cooled Ion Source (ABLIS) is a new source for focused ion beam instruments, which are used in the semiconductor industry, to image and modify structures on the nanometer length scale. The ABLIS employs laser cooling and compression of an atomic beam of rubidium to increase its

Diode-pumped solid state laser. (Part V). ; Short pulse laser oscillation. Handotai laser reiki kotai laser. 5. ; Tan pulse hasshin

Energy Technology Data Exchange (ETDEWEB)

Kuwabara, M.; Bando, N. (Asahi Glass Co. Ltd., Tokyo (Japan))

1991-12-25

A semiconductor laser (LD) excited solid state laser using an LD as an excited light source is under discussion for its practical applications to measurements, processing, communications, office automation, and medical areas. This paper describes the discussions given on the short pulse transmission using AOQ switching elements in the LD excited solid state laser with a long wave length band (1.3{mu}m), which is expected of its application in the communications and measurements area. Based on a possibility of raising a measurements resolution by making the pluses in the LD excited solid state laser, and experiments were performed using Nd:YLF as a laser host. as a results, it was found that the smaller the effective mode volume V {sub eff},the smaller the pulse width, and that the ratio of number of initial inversion distribution (N{sub i}/N{sub t}), an important parameter to determine pulse widths, can be obtained from the ratio of the LD exciting light to the input power (P{sub in}/P{sub t}). 7 refs., 14 figs., 2 tabs.

High-power rf controls for the NBS-Los Alamos racetrack microtron

International Nuclear Information System (INIS)

Young, L.M.; Biddle, R.S.

1985-01-01

The high-power rf system for the National Bureau of Standards (NBS)-Los Alamos racetrack microtron (RTM) uses waveguide power splitters and waveguide phase shifters to distribute rf power from a single 500-kW cw klystron to four side-coupled accelerating structures. The amplitude and phase of each structure is controlled by a feedback system that uses the waveguide variable power splitters, waveguide phase shifters, and klystron drive as the active control elements. A block diagram of this system is shown, as is a subset of the complete system on which the measurements reported in this paper were performed. The feedback controls on the capture section use low-level rf amplitude and phase controls on the rf drive to the klystron. These controls are very fast with an open loop gain bandwidth of approximately 40 kHz. The feedback loop is identical to the feedback loop used in the chopper/buncher system described in another paper at this conference. 4 refs., 8 figs

Irradiation of amorphous Ta{sub 42}Si{sub 13}N{sub 45} film with a femtosecond laser pulse

Energy Technology Data Exchange (ETDEWEB)

Romano, V. [University of Bern, Institute of Applied Physics, Bern (Switzerland); Bern University of Applied Sciences, Bern (Switzerland); Meier, M. [University of Bern, Institute of Applied Physics, Bern (Switzerland); Theodore, N.D. [Freescale Semiconductor Inc., Tempe, AZ (United States); Marble, D.K. [Tarleton State University, Stephenville, TX (United States); Nicolet, M.A. [California Institute of Technology, Pasadena, CA (United States)

2011-07-15

Films of 260 nm thickness, with atomic composition Ta{sub 42}Si{sub 13}N{sub 45}, on 4'' silicon wafers, have been irradiated in air with single laser pulses of 200 femtoseconds duration and 800 nm wave length. As sputter-deposited, the films are structurally amorphous. A laterally truncated Gaussian beam with a near-uniform fluence of {proportional_to}0.6 J/cm{sup 2} incident normally on such a film ablates 23 nm of the film. Cross-sectional transmission electron micrographs show that the surface of the remaining film is smooth and flat on a long-range scale, but contains densely distributed sharp nanoprotrusions that sometimes surpass the height of the original surface. Dark field micrographs of the remaining material show no nanograins. Neither does glancing angle X-ray diffraction with a beam illuminating many diffraction spots. By all evidence, the remaining film remains amorphous after the pulsed femtosecond irradiation. The same single pulse, but with an enhanced and slightly peaked fluence profile, creates a spot with flat peripheral terraces whose lateral extents shrink with depth, as scanning electron and atomic force micrographs revealed. Comparison of the various figures suggests that the sharp nanoprotrusions result from an ejection of material by brittle fraction and spallation, not from ablation by direct beam-solid interaction. Conditions under which spallation should dominate over ablation are discussed. (orig.)

Fabrication of Micrometer- and Nanometer-Scale Polymer Structures by Visible Light Induced Dielectrophoresis (DEP Force

Directory of Open Access Journals (Sweden)

Wen J. Li

2011-12-01

Full Text Available We report in this paper a novel, inexpensive and flexible method for fabricating micrometer- and nanometer-scale three-dimensional (3D polymer structures using visible light sources instead of ultra-violet (UV light sources or lasers. This method also does not require the conventional micro-photolithographic technique (i.e., photolithographic masks for patterning and fabricating polymer structures such as hydrogels. The major materials and methods required for this novel fabrication technology are: (1 any cross-linked network of photoactive polymers (examples of fabricated poly(ethylene glycol (PEG-diacrylate hydrogel structures are shown in this paper; (2 an Optically-induced Dielectrophoresis (ODEP System which includes an “ODEP chip” (i.e., any chip that changes its surface conductivity when exposed to visible light, an optical microscope, a projector, and a computer; and (3 an animator software hosted on a computer that can generate virtual or dynamic patterns which can be projected onto the “ODEP chip” through the use of a projector and a condenser lens. Essentially, by placing a photosensitive polymer solution inside the microfluidic platform formed by the “ODEP chip” bonded to another substrate, and applying an alternating current (a.c. electrical potential across the polymer solution (typically ~20 Vp-p at 10 kHz, solid polymer micro/nano structures can then be formed on the “ODEP chip” surface when visible-light is projected onto the chip. The 2D lateral geometry (x and y dimensions and the thickness (height of the micro/nano structures are dictated by the image geometry of the visible light projected onto the “ODEP chip” and also the time duration of projection. Typically, after an image projection with intensity ranging from ~0.2 to 0.4 mW/cm2 for 10 s, ~200 nm high structures can be formed. In our current system, the thickness of these polymer structures can be controlled to form from ~200 nanometers to ~3

Time resolved studies of H{sub 2}{sup +} dissociation with phase-stabilized laser pulses

Energy Technology Data Exchange (ETDEWEB)

Fischer, Bettina

2010-06-23

In the course of this thesis, experimental studies on the dissociation of H{sub 2}{sup +}(H{sub 2}{sup +}{yields}p+H) in ultrashort laser pulses with a stabilized carrier-envelope phase (CEP) were carried out. In single-pulse measurements, the ability to control the emission direction of low energetic protons, i.e. the localization of the bound electron at one of the nuclei after dissociation, by the CEP was demonstrated. The coincident detection of the emitted protons and electrons and the measurement of their three-dimensional momentum vectors with a reaction microscope allowed to clarify the localization mechanism. Further control was achieved by a pump-control scheme with two timedelayed CEP-stabilized laser pulses. Here the neutral H{sub 2} molecule was ionized in the first pulse and dissociation was induced by the second pulse. Electron localization was shown to depend on the properties of the bound nuclear wave packet in H{sub 2}{sup +} at the time the control pulse is applied, demonstrating the ability to use the shape and dynamics of the nuclear wave packet as control parameters. Wave packet simulations were performed reproducing qualitatively the experimental results of the single and the two-pulse measurements. For both control schemes, intuitive models are presented, which qualitatively explain the main features of the obtained results. (orig.)

2D surface optical lattice formed by plasmon polaritons with application to nanometer-scale molecular deposition.

Science.gov (United States)

Yin, Yanning; Xu, Supeng; Li, Tao; Yin, Yaling; Xia, Yong; Yin, Jianping

2017-08-10

Surface plasmon polaritons, due to their tight spatial confinement and high local intensity, hold great promises in nanofabrication which is beyond the diffraction limit of conventional lithography. Here, we demonstrate theoretically the 2D surface optical lattices based on the surface plasmon polariton interference field, and the potential application to nanometer-scale molecular deposition. We present the different topologies of lattices generated by simple configurations on the substrate. By explicit theoretical derivations, we explain their formation and characteristics including field distribution, periodicity and phase dependence. We conclude that the topologies can not only possess a high stability, but also be dynamically manipulated via changing the polarization of the excitation laser. Nanometer-scale molecular deposition is simulated with these 2D lattices and discussed for improving the deposition resolution. The periodic lattice point with a width resolution of 33.2 nm can be obtained when the fullerene molecular beam is well-collimated. Our study can offer a superior alternative method to fabricate the spatially complicated 2D nanostructures, with the deposition array pitch serving as a reference standard for accurate and traceable metrology of the SI length standard.

On the analysis of the activation mechanisms of sub-melt laser anneals

International Nuclear Information System (INIS)

Clarysse, T.; Bogdanowicz, J.; Goossens, J.; Moussa, A.; Rosseel, E.; Vandervorst, W.; Petersen, D.H.; Lin, R.; Nielsen, P.F.; Hansen, Ole; Merklin, G.; Bennett, N.S.; Cowern, N.E.B.

2008-01-01

In order to fabricate carrier profiles with a junction depth (∼15 nm) and sheet resistance value suited for sub-32 nm Si-CMOS technology, the usage of sub-melt laser anneal is a promising route to explore. As laser annealed junctions seem to outperform standard anneal approaches, a detailed assessment of the basics of laser induced activation seem appropriate. In this work the electrical activation is studied from a comparison between the dopant profiles as measured by Secondary Ion Mass Spectrometry, and the electrically active fraction as extracted from sheet resistance and mobility measurements. The latter is based on a large variety of techniques. For the sheet resistance we use conventional Four-Point Probe (FPP), Variable Probe Spacing (VPS), contactless junction photo voltage (JPV), Micro Four-Point Probe (M4PP) and an optical technique, namely Model Based Infra-red spectroscopic Reflectrometry (MBIR). For the sheet carrier density and sheet mobility extraction we use conventional Hall (without cloverleaf van der Pauw patterning, to reflect the need for fast turn-round sheet measurements), MBIR, and a recently developed new Hall-like capability using M4PP. By recognizing the interaction between the various parameters as they are not completely independent, it is possible to test the consistency of the various methods and to identify potential short comings. This concept is applied to the activation behavior of low and high implanted Boron doses and indicates that the obtained electrically active concentration level as well as the concurrent mobility is dependent on the dopant concentration level. This implies that the activation of B through the laser anneal process in the explored temperature-time space is governed by kinetic processes (i.e. the dissolution of B-I pairs) and not by the (temperature related) solid solubility

Nonmonotonic behaviour of superconducting critical temperature of Nb/CuNi bilayers with a nanometer range of layer thickness

International Nuclear Information System (INIS)

Morari, R.; Antropov, E.; Socrovisciuc, A.; Prepelitsa, A.; Zdravkov, V.I.; Tagirov, L.R.; Kupriyanov, M.Yu.; Sidorenko, A.S.

2009-01-01

Present work reports the result of the proximity effect investigation for superconducting Nb/CuNi-bilayers with the thickness of the ferromagnetic layer (Cu x Ni 1-x ) being in the sub-nanometer range. It was found a non-monotonic behavior of the critical temperature T c , i.e. its growth with the increasing of the ferromagnetic layer thickness dF, for the series of the samples with constant thickness of Nb layer, (d Nb = const). (authors)

CO{sub 2} laser beam cutting with long-focused optics system

Energy Technology Data Exchange (ETDEWEB)

Okimura, Koji [Mitsubishi Heavy Industries, Ltd., Kobe Shipyard and Machinery Works, Kobe, Hyogo (Japan); Nagura, Yasumi; Ishide, Takashi; Hiramoto, Yoneo

1999-07-01

In cutting the decommissioned nuclear facility, it is required to ensure the safety for dismantling workers, to control the amount of wastes generated by cutting, to reduce the costs, etc. Recently, the laser power has increased remarkably and its application tests are carried out at various fields. In this work, cutting tests were carried out with the CO{sub 2} laser having a long-focused optics system of the meter scale. Then, in the optics system of 5 m focal length, it is possible to cut the steel plates of 30 and 40 mm thickness with the laser power of 20 and 40 kW respectively and 42 mm out diameter steel pipe of 5 mm thickness with that of 20 kW without using assistant gas. This cutting process can be developed such a new dismantling method that may dismantle crowded overhead pipes without a scaffolding, so it is expected to ensure the safety for dismantling workers, to decrease the amount of total radiation exposure and to reduce the costs. (author)

Research on long-range grating interferometry with nanometer resolution

International Nuclear Information System (INIS)

Chu, Xingchun; Zhao, Shanghong; Lü, Haibao

2008-01-01

Grating interferometry that features long range and nanometer resolution is presented. The optical system was established based on a single long metrology grating. The large fringe multiplication was achieved by properly selecting two high-order diffraction beams to form a fringe pattern. The fringe pattern collected by a linear array was first tailored to a few multiples of fringes in order to suppress the effect of the energy leakage on phase-extracting precision when the fast Fourier transform (FFT) algorithm was used to calculate its phase. Thus, the phase-extracting precision of a tailored fringe pattern by FFT was greatly improved. Based on this, a novel subdividing method, which exploited the time-shift property of FFT, was developed to subdivide the fringe with large multiple and high accuracy. Numerical results show that the system resolution reaches 1 nm. The experimental results obtained against a capacitive sensor in the sub-mm range show that the measurement precision of the system is less than 10 nm. (technical design note)

On-chip nanostructuring and impedance trimming of transparent and flexible ITO electrodes by laser induced coherent sub-20 nm cuts

Energy Technology Data Exchange (ETDEWEB)

Afshar, Maziar, E-mail: m.afshar@lmm.uni-saarland.de [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany); Leber, Moritz [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany); Poppendieck, Wigand [Department of Medical Engineering & Neuroprosthetics, Fraunhofer Institute for Biomedical Engineering, St. Ingbert D-66386 (Germany); König, Karsten [Lab for Biophotonics and Laser Technology, Saarland University, Saarbrücken D-66123 (Germany); Seidel, Helmut; Feili, Dara [Lab for Micromechanics, Microfluidics, and Microactuators, Saarland University, Saarbrücken D-66123 (Germany)

2016-01-01

Graphical abstract: - Highlights: • A novel method to make sub-20 nm nanopatterning in ITO thin films by laser writing. • A novel way to functionalize ITO bio-electrodes to yield near-field polarizing feature. • A basic characterization of ITO electrodes was performed by impedance spectroscopy. • Presentation of simulations and possible theoretical approaches to explain the results. - Abstract: In this work, the effect of laser-induced nanostructuring of transparent indium tin oxide (ITO) electrodes on flexible glass is investigated. Multi-electrode arrays (MEA) for electrical and optical characterization of biological cells were fabricated using standard MEMS technologies. Optimal sputter parameters concerning oxygen flow, sputter power and ambient pressure for ITO layers with both good optical and electrical properties were determined. Afterwards, coherent sub-20 nm wide and 150 nm deep nanocuts of many micrometers in length were generated within the ITO electrodes by a sub-15 femtosecond (fs) pulsed laser. The influence of laser processing on the electrical and optical properties of electrodes was investigated. The electrochemical impedance of the manufactured electrodes was measured before and after laser modification using electrochemical impedance spectroscopy. A small reduction in electrode impedance was observed. These nanostructured electrodes show also polarizing effects by the visible spectrum.

Synthesis, structure, and luminescence properties of In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires

Energy Technology Data Exchange (ETDEWEB)

Park, Sunghoon; An, Soyeon; Jin, Changhyun; Lee, Chongmu [Inha University, Incheon (Korea, Republic of)

2012-09-15

In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires were synthesized by using a two-step process: thermal evaporation of a mixture of In and Ge powders and atomic layer deposition of SnO{sub 2}. The core-shell nanowires were characterized using by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy. The In{sub 2}Ge{sub 2}O{sub 7} cores in these core-shell nanowires varied from 50 to 100 nanometers in diameter and up to a few hundreds of micrometers in length, and the SnO{sub 2} shell layer thickness ranged from 5 to 15 nm. Photoluminescence measurements showed that the In{sub 2}Ge{sub 2}O{sub 7} nanowires had a weak broad violet emission band centered at approximately 405 nm. In contrast, the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires had a taller blue-violet emission peak at approximately 440 nm. The optimum shell layer thickness of the In{sub 2}Ge{sub 2}O{sub 7}/SnO{sub 2} core-shell nanowires for the highest PL intensity was found to be 15 nm. Our results also showed that the intensity of the blue-violet emission was increased further by thermal annealing in an Ar atmosphere. The origins of the change on and the enhancement of the luminescence of the In{sub 2}Ge{sub 2}O{sub 7} nanowires by SnO{sub 2} coating and annealing are discussed.

Coherent 3D nanostructure of γ-Al{sub 2}O{sub 3}: Simulation of whole X-ray powder diffraction pattern

Energy Technology Data Exchange (ETDEWEB)

Pakharukova, V.P., E-mail: verapakh@catalysis.ru [Boreskov Institute of Catalysis SB RAS, Pr. Lavrentieva 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova Street 2, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Novosibirsk 630090 (Russian Federation); Yatsenko, D.A. [Boreskov Institute of Catalysis SB RAS, Pr. Lavrentieva 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova Street 2, 630090 Novosibirsk (Russian Federation); Gerasimov, E. Yu.; Shalygin, A.S.; Martyanov, O.N.; Tsybulya, S.V. [Boreskov Institute of Catalysis SB RAS, Pr. Lavrentieva 5, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, Pirogova Street 2, 630090 Novosibirsk (Russian Federation); Research and Educational Center for Energy Efficient Catalysis, Novosibirsk State University, Novosibirsk 630090 (Russian Federation)

2017-02-15

The structure and nanostructure features of nanocrystalline γ-Al{sub 2}O{sub 3} obtained by dehydration of boehmite with anisotropic platelet-shaped particles were investigated. The original models of 3D coherent nanostructure of γ-Al{sub 2}O{sub 3} were constructed. The models of nanostructured γ-Al{sub 2}O{sub 3} particles were first confirmed by a direct simulation of powder X–Ray diffraction (XRD) patterns using the Debye Scattering Equation (DSE) with assistance of high-resolution transmission electron microscopy (HRTEM) study. The average crystal structure of γ-Al{sub 2}O{sub 3} was shown to be tetragonally distorted. The experimental results revealed that thin γ-Al{sub 2}O{sub 3} platelets were heterogeneous on a nanometer scale and nanometer-sized building blocks were separated by partially coherent interfaces. The XRD simulation results showed that a specific packing of the primary crystalline blocks in the nanostructured γ-Al{sub 2}O{sub 3} particles with formation of planar defects on (001), (100), and (101) planes nicely accounted for pronounced diffuse scattering, anisotropic peak broadening and peak shifts in the experimental XRD pattern. The identified planar defects in cation sublattice seem to be described as filling cation non-spinel sites in existing crystallographic models of γ-Al{sub 2}O{sub 3} structure. The overall findings provided an insight into the complex nanostructure, which is intrinsic to the metastable γ-Al{sub 2}O{sub 3} oxide. - Highlights: • Thin plate-like crystallites of γ-Al{sub 2}O{sub 3} were obtained. • Models of 3D coherent nanostructure of γ-Al{sub 2}O{sub 3} were constructed. • Models were verified by simulating XRD patterns using the Debye Scattering Equation. • Specific broadening of XRD peaks was explained in terms of planar defects. • Primary crystalline blocks in γ-Al{sub 2}O{sub 3} are separated by partially coherent interfaces.