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Structural properties of Eu doped GaN and its relation with luminescence properties

MRS Online Proceedings Library (OPL) 2011年第1期831卷 E3.28-E3.28页

作者： Hyungjin Bang Takahiro Maruyama Shigeya Naritsuka Katsuhiro Akimoto 21st Century COE program “Nano Factory” Meijo University 1–501 Shiogamaguchi Tempaku-ku Nagoya 468–8502 Japan Department of materials science and engineering Meijo University 1–501 Shiogamaguchi Tempaku-ku Nagoya 468–8502 Japan Institute of applied physics University of Tsukuba Tennodai 1–1–1 Tsukuba Ibaraki 305–8573 Japan

The Structural properties of Europium (Eu) doped GaN and its relation with optical properties were studied. Concentration quenching of the intensity of the Eu related luminescence observed when Eu concentration exceeds 3 at.%. In situ reflection high-energy electron diffraction (RHEED), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were carried out to study this luminescence quenching and it was discovered that there is close relationship between the luminescence intensity at 622 nm and structural properties. The cause of the concentration quenching is likely related to the polycrystalline growth as well as to the EuN formation.

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Ultrafast Laser Cleaning of Daguerreotypes

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MRS Online Proceedings Library 2011年第1期1319卷 1-5页

作者： Michael J. Abere Ryan D. Murphy Bianca Jackson Gerard Mourou Michel Menu John Mansfield Steven M. Yalisove Materials Science and Engineering University of Michigan Ann Arbor USA Applied Physics Program University of Michigan Ann Arbor USA Center for Solar and Thermal Energy Conversion University of Michigan Ann Arbor USA Institut de Lumière Extrême ENSTA Paris France Centre de recherche et de restauration des musées du France Paris France

An ultrafast laser irradiation method for the removal of corrosion from Daguerreotypes without detrimentally affecting image quality has been developed. Corrosion products such as silver oxide and silver sulfide may be removed by chemical cleaning but these reactions are hard to control and are often damaging to the underlying silver, ruining the image. The Ti:Sapphire 150 fs laser pulses used in this study are focused to a beam diameter of 60 μm and are normally incident to the Daguerreotype. It was found that the corrosion layer has a lower material removal threshold than silver allowing for removal of corrosion with minimal removal of vital information contained in the silver substrate.

关键词： laser ablation corrosion thin film

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SQUARAINE DONORS FOR HIGH EFFICIENCY SMALL MOLECULE SOLAR CELLS

SQUARAINE DONORS FOR HIGH EFFICIENCY SMALL MOLECULE SOLAR CE...

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IEEE Photovoltaic Specialists Conference

作者： Guodan Wei Siyi Wang Xin Xiao C. Kyle Renshaw Lincoln Hall Vyacheslav V. Diev Mark E. Thompson Stephen R. Forrest Department of Materials Science and Engineering University of Michigan Department of Chemistry University of Southern California Department of Electrical Engineering and Computer Science University of Michigan Applied Physics Program University of Michigan

ISBN: (纸本)9781424499663

It has been a challenge to achieve high efficiency organic photovoltaics (OPV) that absorb long wavelength solar radiation without incurring unacceptable reductions in open circuit voltage (V_(oc)) or charge separation efficiency. Based on the parent structure of the 2, 4-bis[4-(N, N-diisobutylamino)-2,6-dihydroxyphenyl] squaraine (SQ), we have increased V_(oc) using a family of highly near-infrared absorbing SQs, achieving values as high as 0.94 V. These SQ donors are: 2, 4-bis[4-(N-Phenyl-1-naphthylamino)-2,6-dihydroxyphenyl] squaraine (1-NPSQ),2,4-bis[4-(N,N-diphenylamino)-2,6 dihydroxyphenyl] squaraine (DPSQ), 2,4-bis[4-(N,N-diphenylamino)-2,6-dihydroxyphenyl] asymmetric squaraine (DPASQ). The spin-cast SQ, 1-NPSQ, DPSQ and DPASQ donors are then coated with the acceptor C_(60) to form bulk heterojunction (BHJ) solar cells that take advantage of their exceptionally high absorption coefficient and nanocrystalline morphology to overcome the short diffusion length characteristic of these materials. Combined with a high short-circuit current density (J_(sc)=10.6 mA/cm~2) and high fill factor (FF=0.64), the optimized 1-NPSQ/C_(60) photovoltaic cells with 1-NPSQ annealed at elevated temperature have a power conversion efficiency of η_p as high as 6.0% (correcting for solar mismatch) at 1 sun (AM 1.5G) simulated solar illumination, which to our knowledge is the highest efficiency reported to date for small molecule OPVs.

关键词： Photovoltaic cells Absorption Annealing Educational institutions Sun USA Councils Heterojunctions

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Optical spectroscopy for quantitative sensing in human pancreatic tissues

Optical spectroscopy for quantitative sensing in human pancr...

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European Conference on Biomedical Optics, ECBO 2011

作者： Wilson, Robert H. Chandra, Malavika Lloyd, William Chen, Leng-Chun Scheiman, James Simeone, Diane McKenna, Barbara Mycek, Mary-Ann Applied Physics Program Univ. of Michigan Ann Arbor MI 48109-1040 United States Department of Biomedical Engineering Univ. of Michigan Ann Arbor MI 48109-2099 United States Department of Internal Medicine Univ. of Michigan Ann Arbor MI 48109-0362 United States Comprehensive Cancer Center Univ. of Michigan Medical School Ann Arbor MI 48109-0944 United States Department of Surgery Univ. of Michigan Ann Arbor MI 48109-5331 United States Department of Pathology Univ. of Michigan Ann Arbor MI 48109-0602 United States

ISBN: (纸本)9780819486837

Pancreatic adenocarcinoma has a five-year survival rate of only 6%, largely because current diagnostic methods cannot reliably detect the disease in its early stages. Reflectance and fluorescence spectroscopies have the potential to provide quantitative, minimally-invasive means of distinguishing pancreatic adenocarcinoma from normal pancreatic tissue and chronic pancreatitis. The first collection of wavelength-resolved reflectance and fluorescence spectra and time-resolved fluorescence decay curves from human pancreatic tissues was acquired with clinically-compatible instrumentation. Mathematical models of reflectance and fluorescence extracted parameters related to tissue morphology and biochemistry that were statistically significant for distinguishing between pancreatic tissue types. These results suggest that optical spectroscopy has the potential to detect pancreatic disease in a clinical setting. © 2011 SPIE-OSA.

关键词： Fluorescence

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Two‐photon Absorption Process in Germano‐silica Glass Fiber Doped with PbSe Quantum‐dots

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AIP Conference Proceedings 2011年第1期1399卷 1005-1006页

作者： Pramod R. Watekar Seongmin Ju Aoxiang Lin Won‐Taek Han aGraduate Program of Photonics and Applied Physics Gwangju 500712 Republic of Korea cPhotonics Research Center School of Electronics Engg. VIT University Chennai 600048 India bDepartment of Information and Communications Gwangju Institue of Science and Technology Gwangju 500712 Republic of Korea dState Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanic Chinese Academy of Sciences Xi'an 710119 People's Republic of China

The PbSe quantum dots‐doped germano‐silica glass fiber was manufactured by using a modified chemical vapor deposition process and the existence of PbSe QDs (∼3.4 nm‐5 nm) was verified by using the TEM and the Raman spectrum measurement. The single photon absorption process related peaks appeared at about 882 nm and 1350 nm and two photon absorption process related peaks were observed at about 1022 nm and 1094 nm.

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On the mechanism of nucleation in pulsed-laser quenched Si films on Si02

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作者： Deng, Y. Hu, Q. Chung, U.J. Chitu, A.M. Limanov, A.B. Im, James S. Program in Materials Science and Engineering Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States

ISBN: (纸本)9781605112220

We have investigated the solid nucleation mechanism in laser-quenched Si films on SiO2. Previously neglected experimental steps, consisting of BHF-etching and irradiation in vacuum, were implemented to reduce potential extrinsic influences. The resulting experimental findings and computational analysis lead us to conclude that solid nucleation consistently takes place heterogeneously at, and only at, the bottom liquid Si-SiO2 interface. © 2010 Materials Research Society.

关键词： Nucleation

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Light-induced dynamics in the Lorentz oscillator model with magnetic forces

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Physical Review A 2010年第1期82卷 013802-013802页

作者： W. M. Fisher S. C. Rand Applied Physics Program University of Michigan Ann Arbor Ann Arbor Michigan 48109 USA

The classical Lorentz oscillator model of bound electron motion ordinarily excludes magnetic forces at nonrelativistic intensities for the simple reason that their magnitude is small. However, perturbative and numerical results show that when the v⃗×B⃗ term is retained, dynamically enhanced terms give rise to large amplitude, magnetically induced charge displacements at zero frequency and at twice the driving frequency in the Cartesian laboratory frame. Numerical simulations of electron motion are in accord with the predictions of perturbative theory for steady-state motion in the classical picture. Direct integration shows that magnetic response which is comparable to electric dipole response can arise in transparent dielectrics at optical frequencies. Parametric instability in the equations of motion is implicated as the source of rapid energy transfer from electric to magnetic motions by reduction of the equations to a complex Mathieu equation.

关键词： Energy transfer

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Work in progress — Merging science inquiry and engineering design: A summer workshop series for middle and high school science teachers

Work in progress — Merging science inquiry and engineering ...

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Frontiers in Education (FIE) Conference

作者： Patricia Carlson Peter Hylton Michael Robinson Renee Rogge Justin Shearer Maarij Syed Deborah Walter The PRISM Program Rose-Hulamn Institute of Technology USA Mechanical Engineering Technology Indiana University Purdue University Indianapolis USA Civil and Environmental Engineering Rose-Hulamn Institute of Technology USA Applied Biology and Biomedical Engineering Rose-Hulamn Institute of Technology USA Chemistry and Biochemistry Rose-Hulamn Institute of Technology USA Physics and Optical Engineering Rose-Hulamn Institute of Technology USA Electrical and Computer Engineering Rose-Hulamn Institute of Technology USA

We report on a two-week professional development workshop for middle and high school science teachers offered as part of a three-year Indiana Department of Education Math-Science Partnership grant awarded to Rose-Hulm... 详细信息

关键词： Conferences Materials Educational institutions Engineering education Standards Adaptation models

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Development of continuous wrapping tantalum barriers for internal-tin Nb3Sn multi-filamentary wires

Development of continuous wrapping tantalum barriers for int...

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International Conference on applied Superconductivity and Electromagnetic Devices, ASEMD

作者： Wu Ming Chen Mustafa Yavuz Xue Kui Fu Shiro Kambe Peter McIntyre Jian Xun Jin Waterloo Institute for Nanotechnology University of Waterloo Waterloo ONT Canada School of Materials Science & Engineering University of New South Wales Sydney NSW Australia Human Sensing Program Graduate School of Science and Engineering Yamagata University Yonezawa Japan Waterloo Institute for Nanotechnology University of Waterloo Cankaya University Ankara ON Turkey Department of Physics Texas A&M University TX USA Center of Applied Superconductivity and Electrical Engineering University of Electronic Science and Technology of China China

A process, continuous wrapping tantalum barrier, has been developed and investigated in order to reduce the manufacturing cost. By avoiding inserting expensive tantalum tube, a long sheet barrier was directly used to wrap a prior restack. In this work, a tantalum barrier with 20 % overlap was wrapped onto sub-elements. Then 18-filament Nb 3 Sn plus 1 copper core restack billet was successfully drawn down and extruded into round wire as thin as a diameter of 0.84 mm. The longitudinal and cross-sectional images revealed most of barriers were continuous and intact. However, further experiments are needed to optimize the process in order to keep the all barriers continuous and intact after manufacturing.

关键词： Niobium-tin Wires Copper Electron tubes Educational institutions Superconducting magnets

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Cutting Reactive Foils Without Igniting Them (A Femtosecond Laser Machining Approach)

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MRS Online Proceedings Library (OPL) 2011年第1期800卷 AA9.8-AA9.8页

作者： Yoosuf N. Picard Hsiao-Hua Liu Stephen J. Speys Joel P. McDonald David P. Adams Timothy P. Weihs Steven M. Yalisove Dept. of Materials Science and Engineering University of Michigan Ann Arbor MI 48109–2176 U.S.A. Center for Ultrafast Optical Science University of Michigan Ann Arbor MI 48109–2099 U.S.A. Dept. of Materials Science and Engineering Johns Hopkins University Baltimore MD 21218–2686 U.S.A. Applied Physics Program University of Michigan Ann Arbor MI 48109–1120 U.S.A. Advanced Manufacturing Processes Lab Sandia National Laboratories Albuquerque NM 87185–0959 U.S.A.

Ni/Al nanostructured multilayer foils were machined with femtosecond pulse-length laser irradiation at various fluences. Scanning electron microscopy, back-scattered electron detection, and atomic force microscopy were used to characterize the resulting laser modified regions. We show that material removal at the micron scale is possible with no ignition of a self-propagation reaction emanating from the irradiated areas, a danger minimized by the fact that the extremely short time duration of the pulse produces negligible heat dissipation into the multilayer system. Nevertheless, initial AFM and BSE results give indication that multilayers may be intermixing and reacting locally in areas smaller than the laser beam diameter, though the exact ignition mechanism is still to be determined.

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