Measurements of the Spectral Light Emission from Decaying High Pressure Helium Plasmas

Energy Technology Data Exchange (ETDEWEB)

Stevefelt, J; Johansson, J

1971-04-15

The rate of electron density decay has been determined in a helium pulsed discharge plasma at pressures ranging from 100 to 600 Torr, primarily during the early afterglow where the electron density is from 1019 to 2 x 1017/m3. Measurements of the electrical conductivity and the absolute intensity of the light emission were made. The effective recombination rate coefficient was found to increase faster than linearly with gas pressure. The total photon emission rate was significantly lower than the effective recombination rate. Below 400 Torr pressure the afterglow was dominated by He-bands, which were related to the recombination of He{sub 2+} and He{sub 3+} ions. At higher pressures the appearance of intense lines originating from the atomic n = 3 and 23 P states is proposed to result from the He{sub 4+} recombination. Absorption measurements of the atomic metastable concentration gave evidence for recombination directly into the 23 S state. The concentration of molecular metastables was surprisingly low. The light emission had a Techi dependence, with 0 < chi < 0.35 for the intense atomic lines and 0.78 < chi < 1.10 for the molecular bands

H{sub 2} dissociation on γ-Al{sub 2}O{sub 3} supported Cu/Pd atoms: A DFT investigation

Energy Technology Data Exchange (ETDEWEB)

Wang, Hongtao [College of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Chen, Lijuan [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Lv, Yongkang, E-mail: lykang@tyut.edu.cn [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Ren, Ruipeng, E-mail: s2003wht@126.com [Key Laboratory of Coal Science and Technology of Shanxi Province and Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China)

2014-01-30

The density functional theory (DFT) was applied to investigate the promotion effects of single Cu and Pd atoms deposition on γ-Al{sub 2}O{sub 3} surface for the adsorption and dissociation of H{sub 2} molecule, which is of importance for many catalysis reactions. Due to its strong Lewis acidity, the tri-coordinated surface Al site was identified to be the most preferable site for both Cu and Pd location. The inner surface electrons rearrangement from O to Al of alumina was found to be a key factor to stabilize the Cu/Pd adsorption configurations, rather than the total electrons transfer between Cu/Pd and the surface. It was found that the supported Cu and Pd atoms are more active for H{sub 2} dissociation than the clean γ-Al{sub 2}O{sub 3} surface. The supported Pd is more active than Cu for H{sub 2} dissociation. In addition, the metal–support interaction of the γ-Al{sub 2}O{sub 3} supported Cu/Pd atoms are more favored than the metal–metal interaction of the metal clusters for the H{sub 2} dissociated adsorption.

Faster than Nyquist signaling algorithms to silicon

CERN Document Server

Dasalukunte, Deepak; Rusek, Fredrik; Anderson, John B

2014-01-01

This book addresses the challenges and design trade-offs arising during the hardware design of Faster-than-Nyquist (FTN) signaling transceivers. The authors describe how to design for coexistence between the FTN system described and Orthogonal frequency-division multiplexing (OFDM) systems, enabling readers to design FTN specific processing blocks as add-ons to the conventional transceiver chain.   • Provides a comprehensive introduction to Faster-than-Nyquist (FTN) signaling transceivers, covering both theory and hardware implementation; • Enables readers to design systems that achieve bandwidth efficiency by making better use of the available spectrum resources; • Describes design techniques to achieve 2x improvement in bandwidth usage with similar performance as that of an OFDM system.  

Fast spatial atomic layer deposition of Al{sub 2}O{sub 3} at low temperature (<100 °C) as a gas permeation barrier for flexible organic light-emitting diode displays

Energy Technology Data Exchange (ETDEWEB)

Choi, Hagyoung; Shin, Seokyoon; Jeon, Hyeongtag, E-mail: hjeon@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Choi, Yeongtae; Kim, Junghun; Kim, Sanghun; Chung, Seog Chul; Oh, Kiyoung [LIG INVENIA Co., Ltd., Seongnam, Gyeonggi 462-807 (Korea, Republic of)

2016-01-15

The authors developed a high throughput (70 Å/min) and scalable space-divided atomic layer deposition (ALD) system for thin film encapsulation (TFE) of flexible organic light-emitting diode (OLED) displays at low temperatures (<100 °C). In this paper, the authors report the excellent moisture barrier properties of Al{sub 2}O{sub 3} films deposited on 2G glass substrates of an industrially relevant size (370 × 470 mm{sup 2}) using the newly developed ALD system. This new ALD system reduced the ALD cycle time to less than 1 s. A growth rate of 0.9 Å/cycle was achieved using trimethylaluminum as an Al source and O{sub 3} as an O reactant. The morphological features and step coverage of the Al{sub 2}O{sub 3} films were investigated using field emission scanning electron microscopy. The chemical composition was analyzed using Auger electron spectroscopy. These deposited Al{sub 2}O{sub 3} films demonstrated a good optical transmittance higher than 95% in the visible region based on the ultraviolet visible spectrometer measurements. Water vapor transmission rate lower than the detection limit of the MOCON test (less than 3.0 × 10{sup −3} g/m{sup 2} day) were obtained for the flexible substrates. Based on these results, Al{sub 2}O{sub 3} deposited using our new high-throughput and scalable spatial ALD is considered a good candidate for preparation of TFE films of flexible OLEDs.

Osmium Atoms and Os2 Molecules Move Faster on Selenium-Doped Compared to Sulfur-Doped Boronic Graphenic Surfaces.

Science.gov (United States)

Barry, Nicolas P E; Pitto-Barry, Anaïs; Tran, Johanna; Spencer, Simon E F; Johansen, Adam M; Sanchez, Ana M; Dove, Andrew P; O'Reilly, Rachel K; Deeth, Robert J; Beanland, Richard; Sadler, Peter J

2015-07-28

We deposited Os atoms on S- and Se-doped boronic graphenic surfaces by electron bombardment of micelles containing 16e complexes [Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-diselenate/dithiolate)] encapsulated in a triblock copolymer. The surfaces were characterized by energy-dispersive X-ray (EDX) analysis and electron energy loss spectroscopy of energy filtered TEM (EFTEM). Os atoms moved ca. 26× faster on the B/Se surface compared to the B/S surface (233 ± 34 pm·s(-1) versus 8.9 ± 1.9 pm·s(-1)). Os atoms formed dimers with an average Os-Os distance of 0.284 ± 0.077 nm on the B/Se surface and 0.243 ± 0.059 nm on B/S, close to that in metallic Os. The Os2 molecules moved 0.83× and 0.65× more slowly than single Os atoms on B/S and B/Se surfaces, respectively, and again markedly faster (ca. 20×) on the B/Se surface (151 ± 45 pm·s(-1) versus 7.4 ± 2.8 pm·s(-1)). Os atom motion did not follow Brownian motion and appears to involve anchoring sites, probably S and Se atoms. The ability to control the atomic motion of metal atoms and molecules on surfaces has potential for exploitation in nanodevices of the future.

Highly efficient visible light TiO{sub 2} photocatalyst prepared by sol-gel method at temperatures lower than 300 {sup o}C

Energy Technology Data Exchange (ETDEWEB)

Wang Desong, E-mail: dswang06@126.com [School of Sciences, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China); Xiao Libin; Luo Qingzhi; Li Xueyan; An Jing [School of Sciences, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China); Duan Yandong [College of Chemical and Pharmaceutical Engineering, Hebei University of Science and Technology, Shijiazhuang, Hebei 050018 (China)

2011-08-15

Graphical abstract: Display Omitted Highlights: {yields} Mesoporous anatase nano-TiO{sub 2} photocatalyst was synthesized by sol-gel method at lower temperature ({<=}300 {sup o}C). {yields} Its visible light photocatalytic activity is greatly higher than that of TiO{sub 2} (P-25) and its photocatalytic stability is excellent. {yields} Carbon self-doping and visible photosensitive organic groups result in the improvement of the visible light photocatalytic activity. -- Abstract: Highly efficient visible light TiO{sub 2} photocatalyst was prepared by the sol-gel method at lower temperature ({<=}300 {sup o}C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The effects of the heat treatment temperature and time of the as-prepared TiO{sub 2} on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength {>=} 400 nm). Results show that the as-prepared TiO{sub 2} nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO{sub 2} is greatly higher than those of the commercial TiO{sub 2} (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO{sub 2}, P3HT/TiO{sub 2}, PANI/TiO{sub 2}, N-TiO{sub 2} and Fe{sup 3+}-TiO{sub 2}) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO{sub 2} can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO{sub 2}. The apparent optical thickness ({tau}{sub app}), local

Atomic radii for atoms with the 6s shell outermost: The effective atomic radius and the van der Waals radius from {sub 55}Cs to {sub 80}Hg

Energy Technology Data Exchange (ETDEWEB)

Tatewaki, Hiroshi, E-mail: htatewak@nsc.nagoya-cu.ac.jp [Graduate School of Natural Sciences, Nagoya City University, Nagoya, Aichi 467-8501 (Japan); Institute of Advanced Studies in Artificial Intelligence, Chukyo University, Toyota, Aichi 470-0393 (Japan); Hatano, Yasuyo [School of Information Science and Technology, Chukyo University, Toyota, Aichi 470-0393 (Japan); Noro, Takeshi [Division of Chemistry, Graduate School of Science, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); Yamamoto, Shigeyoshi [School of International Liberal Studies, Chukyo University, Nagoya, Aichi 466-8666 (Japan)

2015-06-15

We consider, for atoms from {sub 55}Cs to {sub 80}Hg, the effective atomic radius (r{sub ear}), which is defined as the distance from the nucleus at which the magnitude of the electric field is equal to that in He at one half of the equilibrium bond length of He{sub 2}. The values of r{sub ear} are about 50% larger than the mean radius of the outermost occupied orbital of 6s, sub 6s} >. The value of r{sub ear} decreases from {sub 55}Cs to {sub 56}Ba and undergoes increases and decreases with rising nuclear charge from {sub 57}La to {sub 70}Y b. In fact r{sub ear} is understood as comprising two interlaced sequences; one consists of {sub 57}La, {sub 58}Ce, and {sub 64}Gd, which have electronic configuration (4f{sup n−1})(5d{sup 1})(6s{sup 2}), and the remaining atoms have configuration (4f{sup n})(6s{sup 2}). The sphere defined by r{sub ear} contains 85%–90% of the 6s electrons. From {sub 71}Lu to {sub 80}Hg the radius r{sub ear} also involves two sequences, corresponding to the two configurations 5d{sup n+1}6s{sup 1} and 5d{sup n}6s{sup 2}. The radius r{sub ear} according to the present methodology is considerably larger than r{sub vdW} obtained by other investigators, some of who have found values of r{sub vdW} close to sub 6s} >.

Hydrogenation and Deuteration of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} on Cold Grains: A Clue to the Formation Mechanism of C{sub 2}H{sub 6} with Astronomical Interest

Energy Technology Data Exchange (ETDEWEB)

Kobayashi, Hitomi; Kawakita, Hideyo [Koyama Astronomical Observatory, Kyoto Sangyo University Motoyama, Kamigamo, Kita-ku, Kyoto 603-8555 (Japan); Hidaka, Hiroshi; Hama, Tetsuya; Watanabe, Naoki [Institute of Low Temperature Science, Hokkaido University N19-W8, Kita-ku, Sapporo, Hokkaido 060-0819 (Japan); Lamberts, Thanja; Kästner, Johannes, E-mail: h_kobayashi@kyoto-nijikoubou.com [Institute for Theoretical Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

2017-03-10

We quantitatively investigated the hydrogen addition reactions of acetylene (C{sub 2}H{sub 2}) and ethylene (C{sub 2}H{sub 4}) on amorphous solid water (ASW) at 10 and 20 K relevant to the formation of ethane (C{sub 2}H{sub 6}) on interstellar icy grains. We found that the ASW surface enhances the reaction rates for C{sub 2}H{sub 2} and C{sub 2}H{sub 4} by approximately a factor of 2 compared to those on the pure-solid C{sub 2}H{sub 2} and C{sub 2}H{sub 4} at 10 K, probably due to an increase in the sticking coefficient and adsorption energy of the H atoms on ASW. In contrast to the previous proposal that the hydrogenation rate of C{sub 2}H{sub 4} is orders of magnitude larger than that of C{sub 2}H{sub 2}, the present results show that the difference in hydrogenation rates of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} is only within a factor of 3 on both the surfaces of pure solids and ASW. In addition, we found the small kinetic isotope effect for hydrogenation/deuteration of C{sub 2}H{sub 2} and C{sub 2}H{sub 4} at 10 K, despite the requirement of quantum tunneling. At 20 K, the reaction rate of deuteration becomes even larger than that of hydrogenation. These unusual isotope effects might originate from a slightly larger number density of D atoms than H atoms on ASW at 20 K. The hydrogenation of C{sub 2}H{sub 2} is four times faster than CO hydrogenation and can produce C{sub 2}H{sub 6} efficiently through C{sub 2}H{sub 4} even in the environment of a dark molecular cloud.

Investigation of Al{sub 2}O{sub 3} barrier film properties made by atomic layer deposition onto fluorescent tris-(8-hydroxyquinoline) aluminium molecular films

Energy Technology Data Exchange (ETDEWEB)

Maindron, Tony; Aventurier, Bernard [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Ghazouani, Ahlem; Jullien, Tony [LETI/DTSI/SDEP/Laboratoire Dépôt Equipe 2, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Rochat, Névine [LETI/DTSI/Service de Caractérisation des Matériaux et Composants, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France); Simon, Jean-Yves; Viasnoff, Emilie [LETI/DOPT/SCOOP/Laboratoire des Composants pour la Visualisation, CEA-LETI, MINATEC Campus, 17 rue des Martyrs, F-38054 Grenoble Cedex 9 (France)

2013-12-02

Al{sub 2}O{sub 3} films have been deposited at 85 °C by atomic layer deposition onto single 100 nm thick tris-(8-hydroxyquinoline) aluminium (AlQ{sub 3}) films made onto silicon wafers. It has been found that a thick ALD-deposited Al{sub 2}O{sub 3} layer (> 11 nm) greatly prevents the photo-oxidation of AlQ{sub 3} films when exposed to continuous UV irradiation (350 mW/cm{sup 2}). Thin Al{sub 2}O{sub 3} thicknesses (< 11 nm) on the contrary yield lower barrier performances. Defects in the Al{sub 2}O{sub 3} layer have been easily observed as non-fluorescent AlQ{sub 3} singularities, or black spots, under UV light on the system Si/AlQ{sub 3}/Al{sub 2}O{sub 3} stored into laboratory conditions (22 °C/50% Relative Humidity (RH)) for long time scale (∼ 2000 h). Accelerated aging conditions in a climatic chamber (85 °C/85% RH) also allow faster visualization of the same defects (168 h). The black spot density grows upon time and the black spot density occurrence rates have been calculated to be 0.024 h{sup −1}·cm{sup −2} and 0.243 h{sup −1}·cm{sup −2} respectively for the two testing conditions. A detailed investigation of these defects did show that they cannot be ascribed to the presence of a detectable particle. In that sense they are presumably the consequence of the existence of nanometre-scaled defects which cannot be detected onto fresh samples. Interestingly, an additional overcoating of ebeam-deposited SiO{sub 2} onto the Si/AlQ{sub 3}/Al{sub 2}O{sub 3} sample helps to decrease drastically the black spot density occurrence rates down to 0.004 h{sup −1}·cm{sup −2} and 0.04 h{sup −1}·cm{sup −2} respectively for 22 °C/50% RH and 85 °C/85% RH testing conditions. These observations highlight the moisture sensitivity of low temperature ALD-deposited Al{sub 2}O{sub 3} films and confirm the general idea that a single Al{sub 2}O{sub 3} ALD film performs as an ultra-high barrier but needs to be overprotected from water condensation by an

Microstrucural characterization of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} alloys

Energy Technology Data Exchange (ETDEWEB)

Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Lopez, M.; Marin, P. [Instituto de Magnetismo Aplicado, P.O. Box 155, 28230 Madrid (Spain)

2011-06-15

Research highlights: > Two FeSi-base alloys as precursors for small dimension soft magnets. > Small particles rapidly solidified by gas atomisation. > Increase effective magnetic anisotropy constant by alloying segregation. > Magnetic hardenning due to volume decrease. - Abstract: Powder particles of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} and Fe{sub 97}Si{sub 3} soft magnetic alloys have been prepared by gas atomization. The gas atomized powder was microstructurally characterized and the dependence of coercivity with the composition and powder particle size investigated. As-atomized powder particles of both compositions were constituted by a bcc {alpha}-Fe (Si) solid solution. The Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles presented a grain microstructure with dendrite structure, which dendrite arms were enriched in Nb. The coercivity increased as the particle size decreased, with a minimum coercivity, of 5 Oe, measured in the Fe{sub 97}Si{sub 3} alloy in the range of 50-100 {mu}m powder particle size. The coercive fields were quite higher in the Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} than in the Fe{sub 97}Si{sub 3} powder, due to the Nb addition, which produced a phase segregation that leads to a noticeable magnetic hardening.

Quenching of the He/sub μ/ +(2s) atom

International Nuclear Information System (INIS)

Russell, J.E.

1986-01-01

Quenching of the metastable 2s state of the He/sub μ/ + atom in helium gas is discussed. The first part of the discussion, which is devoted entirely to processes occurring after the He/sub μ/ + has become bound to one or more ordinary helium atoms, is based partly on Cohen's calculations of rates of vibrational quenching and partly on estimates obtained in the present paper of rates of Burbidge--de Borde quenching and Ruderman quenching. It is concluded that Burbidge--de Borde quenching or Ruderman quenching, or both, are likely to be more effective than Cohen quenching if the vibrational level of the bound system is low. A recent experiment by von Arb et al. is then analyzed in the light of this conclusion. The analysis is based on the reported absence, or near absence, of Auger electrons accompanying 2s quenching. While it is agreed that the Cohen mechanism occurring in the molecular ion HeHe/sub μ/ + remains the most likely explanation of the experiment, it is concluded that the quenching occurs in comparatively high levels. It is then argued that this conclusion is in accord with some theoretical investigations of three-body association reactions and also with some elementary considerations regarding the relaxation of highly excited diatomic molecules, and it is further concluded that the quenching is most likely to occur in states with very low rotational quantum number and vibrational quantum number 8≤v≤14

Optically polarized atoms understanding light-atom interactions

CERN Document Server

Auzinsh, Marcis; Rochester, Simon M

2010-01-01

This book is addressed at upper-level undergraduate and graduate students involved in research in atomic, molecular, and optical Physics. It will also be useful to researchers practising in this field. It gives an intuitive, yet sufficiently detailed and rigorous introduction to light-atom interactions with a particular emphasis on the symmetry aspects of the interaction, especially those associated with the angular momentum of atoms and light. The book will enable readers to carryout practical calculations on their own, and is richly illustrated with examples drawn from current research topic

A novel visible light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite: Preparation and application in the photo-degradation of pollutants

Energy Technology Data Exchange (ETDEWEB)

Chai, Yuanyuan; Wang, Li; Ren, Jia; Dai, Wei-Lin, E-mail: wldai@fudan.edu.cn

2015-01-01

Graphical abstract: - Highlights: • Highly efficient visible-light-driven Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. • Application in the photo-degradation of RhB. • Synthesis from a facile and simple colloidal method. • 20%-Ag{sub 3}PO{sub 4}/SBA-15 shows 8 times faster degradation rate than Ag{sub 3}PO{sub 4}. • Super stability and recycling ability. - Abstract: A novel visible light-driven environmental-benign Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite photo-catalyst was synthesized for the photo-degradation of pollutants. The exploration on adsorption and photo-catalysis of dye or organic pollution for the nanocomposite was carried out. The adsorption capability for Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite increases by 3 times compared with that of the Ag{sub 3}PO{sub 4} particles. The photo-catalytic activity of nanocomposite is higher than pristine Ag{sub 3}PO{sub 4} nanoparticle for the degradation of RhB or MO under visible light irradiation (λ > 420 nm). The effect of Ag{sub 3}PO{sub 4} loading on the catalytic performance was also studied. The results show that the optimum degradation is achieved over 20% Ag{sub 3}PO{sub 4}/SBA-15. Compared to pure Ag{sub 3}PO{sub 4} nanoparticle, the most efficient catalyst showed 8 times higher photo-catalytic activity for the degradation of RhB. The Ag{sub 3}PO{sub 4}/SBA-15 catalysts were systematically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–Vis diffuse reflectance spectroscopy (DRS), and N{sub 2}-adsorption–desorption isotherms (BET). A possible mechanism scheme regarding photo-degradation enhancement induced by dye enrichments has been proposed on the Ag{sub 3}PO{sub 4}/SBA-15 nanocomposite. Additionally, the SBA-15 support can enhance the efficiency of separation of catalyst from the reaction mixture, implying that the Ag{sub 3}PO{sub 4} loading on the SBA-15 catalyst will not result in the extra environment and health

Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission.

Science.gov (United States)

Wan, Ren-Gang; Zhang, Tong-Yi

2011-12-05

We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution.

Atomic oxygen-MoS sub 2 chemical interactions

Energy Technology Data Exchange (ETDEWEB)

Cross, J.B.; Martin, J.A. (Los Alamos National Lab., NM (USA)); Pope, L.E. (Sandia National Labs., Albuquerque, NM (USA)); Koontz, S.L. (National Aeronautics and Space Administration, Johnson Space Center, Houston, TX (USA))

1990-10-01

The present study shows that an O-atom translation energy of 1.5 eV, SO{sub 2} is generated and outgases from an anhydrous MoS{sub 2} surface with an initial reactivity nearly 50% that of kapton. The reaction of atomic oxygen with MoS{sub 2} has little or no translational energy barrier, i.e. thermally generated atomic oxygen reacts as readily as that having 1.5 eV of translational energy. For MoS{sub 2} films sputter-deposited at 50-70deg C, friction measurements showed a high initial friction coefficient (up to 0.25) for MoS{sub 2} surfaces exposed to atomic oxygen, which dropped to the normal low values after several cycles of operation in air and ultrahigh vacuum. For MoS{sub 2} films deposited at 200deg C, the friction coefficient was not affected by the O-atom exposure. (orig.).

Quantifying the undiscovered geothermal resources of the United States

Science.gov (United States)

Williams, Colin F.; Reed, Marshall J.; DeAngelo, Jacob; Galanis, S. Peter

2009-01-01

In 2008, the U.S. Geological Survey (USGS) released summary results of an assessment of the electric power production potential from the moderate- and high-temperature geothermal resources of the United States (Williams et al., 2008a; USGS Fact Sheet 2008-3082; http://pubs.usgs.gov/fs/2008/3082). In the assessment, the estimated mean power production potential from undiscovered geothermal resources is 30,033 Megawatts-electric (MWe), more than three times the estimated mean potential from identified geothermal systems: 9057 MWe. The presence of significant undiscovered geothermal resources has major implications for future exploration and development activities by both the government and private industry. Previous reports summarize the results of techniques applied by the USGS and others to map the spatial distribution of undiscovered resources. This paper describes the approach applied in developing estimates of the magnitude of the undiscovered geothermal resource, as well as the manner in which that resource is likely to be distributed among geothermal systems of varying volume and temperature. A number of key issues constrain the overall estimate. One is the degree to which characteristics of the undiscovered resources correspond to those observed among identified geothermal systems. Another is the evaluation of exploration history, including both the spatial distribution of geothermal exploration activities relative to the postulated spatial distribution of undiscovered resources and the probability of successful discoveries from the application of standard geothermal exploration techniques. Also significant are the physical, chemical, and geological constraints on the formation and longevity of geothermal systems. Important observations from this study include the following. (1) Some of the largest identified geothermal systems, such as The Geysers vapor-dominated system in northern California and the diverse geothermal manifestations found in Yellowstone

Holographic recording and characterization of photorefractive Bi{sub 2}TeO{sub 5} crystals at 633 nm wavelength light

Energy Technology Data Exchange (ETDEWEB)

Oliveira, Ivan de, E-mail: ivan@ft.unicamp.br [Grupo de Óptica e Modelagem Numérica (GOMNI)-Faculdade de Tecnologia/UNICAMP, Limeira-SP (Brazil); Carvalho, Jesiel F., E-mail: carvalho@if.ufg.br; Fabris, Zanine V. [Instituto de Física/Universidade Federal de Goiás, Goiânia-GO (Brazil); Frejlich, Jaime, E-mail: frejlich@ifi.unicamp.br [Instituto de Física “Gleb Wataghin”/UNICAMP, Campinas-SP (Brazil)

2014-04-28

We report on the holographic recording on photorefractive Bi{sub 2}TeO{sub 5} crystals using λ=633 nm wavelength light. We studied the behavior of this material under the action of this low photonic energy light and found out the presence of a fast and a slow hologram, both of photorefractive nature and exhibiting rather high diffraction efficiencies. The faster and the slower holograms are based on the excitation and diffusion of oppositely charged carriers (likely electrons and holes). Relevant parameters for the photoactive centers responsible for both kind of holograms were characterized using purely holographic techniques. No evidences of non-photosensitive ionic charge carriers being involved in the recording process at room temperature nor self-fixing effects were found.

Magnetic properties of Mg{sub 12}O{sub 12} nanocage doped with transition metal atoms (Mn, Fe, Co and Ni): DFT study

Energy Technology Data Exchange (ETDEWEB)

Javan, Masoud Bezi, E-mail: javan.masood@gmail.com

2015-07-01

Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals (TM=Mn, Fe, Co and Ni) in endohedrally, exohedrally and substitutionally forms were studied using density functional theory with the generalized gradient approximation exchange-correlation functional along 6 different paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The most stable structures were determined with full geometry optimization near the minimum of the binding energy curves of all the examined paths inside and outside of the Mg{sub 12}O{sub 12} nanocage. The results reveal that for all stable structures, the Ni atom has a larger binding energy than the other TM atoms. It is also found that for all complexes additional peaks contributed by TM-3d, 4s and 4p states appear in the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) gap of the host MgO cluster. The mid-gap states are mainly due to the hybridization between TM-3d, 4s and 4p orbitals and the cage π orbitals. The magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved to some extent due to the interaction between the TM and Mg{sub 12}O{sub 12} nanocage, in contrast to the completely quenched magnetic moment of the Fe and Ni atoms in the Mg{sub 11}(TM)O{sub 12} complexes. Furthermore, charge population analysis shows that charge transfer occurs from TM atom to the cage for endohedrally and substitutionally doping. - Highlights: • Binding energy of the Mg{sub 12}O{sub 12} nanocage doped with transition metals was studied. • The most stable structures were determined near the minimum of the binding energy. • The encapsulated Ni atom has a larger binding energy than the other TM atoms. • Magnetic moment of the endohedrally doped TM atoms in the Mg{sub 12}O{sub 12} are preserved.

Atomic and electronic structures of lattice mismatched Cu{sub 2}O/TiO{sub 2} interfaces

Energy Technology Data Exchange (ETDEWEB)

Wang, Shuzhi [Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 66, Berkeley, California 94720 (United States); Kavaipatti, Balasubramaniam; Ramesh, Ramamoorthy [Department of Materials Science and Engineering, University of California at Berkeley, Berkeley, California 94720 (United States); Kim, Sung-Joo; Pan, Xiaoqing [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Ager, Joel W.; Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Materials Sciences Division, Lawrence Berkeley National Laboratory, One Cyclotron Road, Mail Stop 66, Berkeley, California 94720 (United States); Joint Center of Artificial Photosynthesis, Berkeley, California 94720 (United States)

2014-05-26

Heterojunction interfaces between metal oxides are often highly lattice mismatched. The atomic and electronic structures of such interfaces, however, are not well understood. We have synthesized Cu{sub 2}O/TiO{sub 2} heterojunction thin films with 13% lattice mismatch and studied the interface via experimental methods and large-scale density function theory calculations of supercells containing ∼1300 atoms. We find that an interface of epitaxial quality is formed via a coincidence site lattice of 8 Cu{sub 2}O unit cells matching 9 TiO{sub 2} unit cells. Calculations reveal the existence of a dislocation core of the O sublattices at the interface and a random arrangement of one layer of interfacial Cu atoms. The interfacial electronic structure is found to be mostly determined by the interfacial Cu distribution, rather than by the O dislocation core. The conduction band minimum and valence band maximum states are spatially separated, and there is no strongly localized state near the core.

Time Dilation And Changes Of Material Properties Of An Atom (Body) In Speed Of Near Light Speed Based On The ``Substantial Motion'' Theory of Iranian Philosopher, Mulla Sadra

Science.gov (United States)

Gholibeigian, Hassan; Gholibeigian, Kazem

Iranian Philosopher, Sadr-ol-Moteallehin (1571-1640) said in his famous book, Asfar: ''the Universe moves in its entity... and time is its fourth dimension, and time is magnitude of the motion (momentum) of the matter in its entity''. In other words, time for each atom is momentum of its involved fundamental particles, [APS March Meeting 2015, abstract #V1.023]. When an atom (body) moves in speed of near light speed, speed of its involved fundamental particles become slow, and consequently the magnitude of its momentum (time) will decrease. On the other hands, when the spin and orbital angular momentum of an atom changed, it means that its properties, mass, strength of its electromagnetic field and its interaction with momentum changed. As a result, each atom (body) which moves in light speed, lower or faster than that, will get a new identity and vice versa. The special relativity can be the special form of this theory. In this way, black holes will be lighter than their involved masses at rest (a paradox with general relativity). Dark matter/energy may be created at first in B.B (Convection Bang) [AGU Fall Meeting 2015, abstract ID: 58425], in more than light speed, so, if we speed protons to more than light speed (in LHC), we may see dark mater/energy in new space-time. AmirKabir University of Technology.

Barrier properties of plastic films coated with an Al{sub 2}O{sub 3} layer by roll-to-toll atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Hirvikorpi, Terhi, E-mail: Terhi.Hirvikorpi@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Laine, Risto, E-mail: Risto.Laine@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Vähä-Nissi, Mika, E-mail: Mika.Vaha-Nissi@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kilpi, Väinö, E-mail: Vaino.Kilpi@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Salo, Erkki, E-mail: Erkki.Salo@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Li, Wei-Min, E-mail: Wei-Min.Li@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Lindfors, Sven, E-mail: Sven.Lindfors@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland); Vartiainen, Jari, E-mail: Jari.Vartiainen@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kenttä, Eija, E-mail: Eija.Kentta@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Nikkola, Juha, E-mail: Juha.Nikkola@vtt.fi [VTT Technical Research Centre of Finland, P.O. Box 1300, FI-33101 Tampere (Finland); Harlin, Ali, E-mail: Ali.Harlin@vtt.fi [VTT Technical Research Centre of Finland, Biologinkuja 7, Espoo, P.O. Box 1000, FI-02044 VTT (Finland); Kostamo, Juhana, E-mail: Juhana.Kostamo@picosun.com [Picosun Oy, Tietotie 3, FI-02150 Espoo (Finland)

2014-01-01

Thin (30–40 nm) and highly uniform Al{sub 2}O{sub 3} coatings have been deposited at relatively low temperature of 100 °C onto various polymeric materials employing the atomic layer deposition (ALD) technique, both batch and roll-to-roll (R2R) mode. The applications for ALD have long been limited those feasible for batch processing. The work demonstrates that R2R ALD can deposit thin films with properties that are comparable to the film properties fabricated by in batch. This accelerates considerably the commercialization of many products, such as flexible, printed electronics, organic light-emitting diode lighting, third generation thin film photovoltaic devices, high energy density thin film batteries, smart textiles, organic sensors, organic/recyclable packaging materials, and flexible displays, to name a few. - Highlights: • Thin and uniform Al{sub 2}O{sub 3} coatings have been deposited onto polymers materials. • Batch and roll-to-roll (R2R) atomic layer deposition (ALD) have been employed. • Deposition with either process improved the barrier properties. • Sensitivity of coated films to defects affects barrier obtained with R2R ALD.

Gas atomization processing of tin and silicon modified LaNi<sub>5sub> for nickel-metal hydride battery applications

Energy Technology Data Exchange (ETDEWEB)

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

1999-02-12

Numerous researchers have studied the relevant material properties of so-called AB<sub>5sub> alloys for battery applications. These studies involved LaNi<sub>5sub> substituted alloys which were prepared using conventional cast and crush alloying techniques. While valuable to the understanding of metal hydride effects, the previous work nearly ignored the potential for alternative direct powder production methods, like high pressure gas atomization (HPGA). Thus, there is a need to understand the relationship between gas atomization processes, powder particle solidification phases, and hydrogen absorption properties of ultra fine (< 25 μm) atomized powders with high surface area for enhanced battery performance. Concurrently, development of a gas atomization nozzle that is more efficient than all current designs is needed to increase the yield of ultrafine AB<sub>5sub> alloy powder for further processing advantage. Gas atomization processing of the AB<sub>5sub> alloys was demonstrated to be effective in producing ultrafine spherical powders that were resilient to hydrogen cycling for the benefit of improving corrosion resistance in battery application. These ultrafine powders benefited from the rapid solidification process by having refined solute segregation in the microstructure of the gas atomized powders which enabled a rapid anneal treatment of the powders. The author has demonstrated the ability to produce high yields of ultrafine powder efficiently and cost effectively, using the new HPGA-III technology. Thus, the potential benefits of processing AB<sub>5sub> alloys using the new HPGA technology could reduce manufacturing cost of nickel-metal hydride powder. In the near future, the manufacture of AB<sub>5sub> alloy powders could become a continuous and rapid production process. The economic benefit of an improved AB<sub>5sub> production process may thereby encourage the use of nickel-metal hydride rechargeable batteries in electrical vehicle

Single-atom lasing induced atomic self-trapping

International Nuclear Information System (INIS)

Salzburger, T.; Ritsch, H.

2004-01-01

We study atomic center of mass motion and field dynamics of a single-atom laser consisting of a single incoherently pumped free atom moving in an optical high-Q resonator. For sufficient pumping, the system starts lasing whenever the atom is close to a field antinode. If the field mode eigenfrequency is larger than the atomic transition frequency, the generated laser light attracts the atom to the field antinode and cools its motion. Using quantum Monte Carlo wave function simulations, we investigate this coupled atom-field dynamics including photon recoil and cavity decay. In the regime of strong coupling, the generated field shows strong nonclassical features like photon antibunching, and the atom is spatially confined and cooled to sub-Doppler temperatures. (author)

Atomic layer deposition of Al{sub 2}O{sub 3} and Al{sub 2}O{sub 3}/TiO{sub 2} barrier coatings to reduce the water vapour permeability of polyetheretherketone

Energy Technology Data Exchange (ETDEWEB)

Ahmadzada, Tamkin, E-mail: tahm4852@uni.sydney.edu.au [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia); McKenzie, David R.; James, Natalie L.; Yin, Yongbai [School of Physics, University of Sydney, NSW 2006 (Australia); Li, Qing [School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney, NSW 2006 (Australia)

2015-09-30

We demonstrate significantly enhanced barrier properties of polyetheretherketone (PEEK) against water vapour penetration by depositing Al{sub 2}O{sub 3} or Al{sub 2}O{sub 3}/TiO{sub 2} nanofilms grown by atomic layer deposition (ALD). Nanoindentation analysis revealed good adhesion strength of a bilayer Al{sub 2}O{sub 3}/TiO{sub 2} coating to PEEK, while the single layer Al{sub 2}O{sub 3} coating displayed flaking and delamination. We identified three critical design parameters for achieving the optimum barrier properties of ALD Al{sub 2}O{sub 3}/TiO{sub 2} coatings on PEEK. These are a minimum total thickness dependent on the required water vapour transmission rate, the use of an Al{sub 2}O{sub 3}/TiO{sub 2} bilayer coating and the application of the coating to both sides of the PEEK film. Using these design parameters, we achieved a reduction in moisture permeability of PEEK of over two orders of magnitude while maintaining good adhesion strength of the polymer–thin film system. - Highlights: • Atomic layer deposition of Al{sub 2}O{sub 3}/TiO{sub 2} coatings reduced water vapour permeability. • Bilayer coatings reduced the permeability more than single layer coatings. • Bilayer coatings displayed higher adhesion strength than the single layer coatings. • Double-sided coatings performed better than single-sided coatings. • Correlation was found between total thickness and reduced water vapour permeability.

Withholding response to self-face is faster than to other-face.

Science.gov (United States)

Zhu, Min; Hu, Yinying; Tang, Xiaochen; Luo, Junlong; Gao, Xiangping

2015-01-01

Self-face advantage refers to adults' response to self-face is faster than that to other-face. A stop-signal task was used to explore how self-face advantage interacted with response inhibition. The results showed that reaction times of self-face were faster than that of other-face not in the go task but in the stop response trials. The novelty of the finding was that self-face has shorter stop-signal reaction time compared to other-face in the successful inhibition trials. These results indicated the processing mechanism of self-face may be characterized by a strong response tendency and a corresponding strong inhibition control.

Seeing atoms with aberration-corrected sub-Angstroem electron microscopy

Energy Technology Data Exchange (ETDEWEB)

O' Keefe, Michael A. [Materials Science Division, Lawrence Berkeley National Laboratory, National Center for Electron Microscopy, 2R0200, 1 Cyclotron Road, Berkeley, CA 94720-8197 (United States)], E-mail: sub-Angstrom@comcast.net

2008-02-15

High-resolution electron microscopy is able to provide atomic-level characterization of many materials in low-index orientations. To achieve the same level of characterization in more complex orientations requires that instrumental resolution be improved to values corresponding to the sub-Angstroem separations of atom positions projected into these orientations. Sub-Angstroem resolution in the high-resolution transmission electron microscope has been achieved in the last few years by software aberration correction, electron holography, and hardware aberration correction; the so-called 'one-Angstroem barrier' has been left behind. Aberration correction of the objective lens currently allows atomic-resolution imaging at the sub-0.8 A level and is advancing towards resolutions in the deep sub-Angstroem range (near 0.5 A). At current resolution levels, images with sub-Rayleigh resolution require calibration in order to pinpoint atom positions correctly. As resolution levels approach the 'sizes' of atoms, the atoms themselves will produce a limit to resolution, no matter how much the instrumental resolution is improved. By arranging imaging conditions suitably, each atom peak in the image can be narrower, so atoms are imaged smaller and may be resolved at finer separations.

Visible light-responded C, N and S co-doped anatase TiO{sub 2} for photocatalytic reduction of Cr(VI)

Energy Technology Data Exchange (ETDEWEB)

Lei, X.F., E-mail: leixuefei69@163.com [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China); Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive, Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization, Technology and Boron Materials, Shenyang 110819 (China); Xue, X.X.; Yang, H. [Institute of Metallurgical Resource and Environmental Engineering, Northeastern University, Shenyang 110819 (China); Liaoning Key Laboratory of Metallurgical Resource Recycling Science, Shenyang 110819 (China); Liaoning Engineering and Technology Research Center of Boron Resource, Comprehensive, Utilization, Shenyang 110819 (China); Liaoning Provincial Universities Key Laboratory of Boron Resource Ecological, Utilization, Technology and Boron Materials, Shenyang 110819 (China); Chen, C.; Li, X.; Pei, J.X.; Niu, M.C.; Yang, Y.T.; Gao, X.Y. [School of Resources and Materials, Northeastern University at Qinhuangdao, Qinhuangdao 066004 (China)

2015-10-15

The (C, N and S) co-doped TiO{sub 2} (TH-TiO{sub 2}) samples were synthesized by a sol-gel method calcined at 500 °C, employing butyl titanate as the titanium source and thiourea as the dopant. The structures of TH-TiO{sub 2} samples were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), photoluminescence (PL) spectroscopy, Thermo gravimetry and differential thermal analysis (TG-DTA), Scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherms. The photocatalytic activities were checked through the photocatalytic reduction of Cr(VI) as a model compound under visible light irradiation. The results showed that the thiourea content played an important role on the microstructure and photocatalytic activity of the samples. According to XPS results, (C, N and S) atoms were successfully co-doped into the nanostructures of TH-TiO{sub 2} samples. TH-TiO{sub 2} samples with thiourea: Ti molar ratio of 1.5 exhibits higher photocatalytic activity than that of the other samples under visible light irradiation, which can be attributed to the synergic effect of the pure anatase structure, the higher light absorption characteristics in visible regions, separation efficiency of electron–hole pairs, the specific surface area and the optimum (C, N and S) content. - Graphical abstract: (C, N and S) co-doped TiO{sub 2} samples show good photocatalytic activity for Cr (VI) reduction under visible light irradiation. - Highlights: • (C, N and S) co-doping in TH-TiO{sub 2} samples can promote the formation of the pure anatase structure. • (C, N and S) atoms were successfully co-doped into the nanostructures of TH-TiO{sub 2} samples. • The band gap energy of TH-TiO{sub 2} samples reduced after (C, N and S) co-doping. • (C, N and S) co-doped TiO{sub 2} samples were effective for the photocatalytic reduction of Cr(VI) under visible light

Breaking the Myth That Relay Swimming Is Faster Than Individual Swimming.

Science.gov (United States)

Skorski, Sabrina; Etxebarria, Naroa; Thompson, Kevin G

2016-04-01

To investigate if swimming performance is better in a relay race than in the corresponding individual race. The authors analyzed 166 elite male swimmers from 15 nations in the same competition (downloaded from www.swimrankings.net). Of 778 observed races, 144 were Olympic Games performances (2000, 2004, 2012), with the remaining 634 performed in national or international competitions. The races were 100-m (n = 436) and 200-m (n = 342) freestyle events. Relay performance times for the 2nd-4th swimmers were adjusted (+ 0.73 s) to allow for the "flying start." Without any adjustment, mean individual relay performances were significantly faster for the first 50 m and overall time in the 100-m events. Furthermore, the first 100 m of the 200-m relay was significantly faster (P > .001). During relays, swimmers competing in 1st position did not show any difference compared with their corresponding individual performance (P > .16). However, swimmers competing in 2nd-4th relay-team positions demonstrated significantly faster times in the 100-m (P individual events (P team positions were adjusted for the flying start no differences were detected between relay and individual race performance for any event or split time (P > .17). Highly trained swimmers do not swim (or turn) faster in relay events than in their individual races. Relay exchange times account for the difference observed in individual vs relay performance.

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.

Giant light enhancement in atomic clusters

International Nuclear Information System (INIS)

Gadomsky, O. N.; Gadomskaya, I. V.; Altunin, K. K.

2009-01-01

We show that the polarizing effect of the atoms in an atomic cluster can lead to full compensation of the radiative damping of excited atomic states, a change in the sign of the dispersion of the atomic polarizability, and giant light enhancement by the atomic cluster.

Muonic atom-light nucleus interaction

International Nuclear Information System (INIS)

Kuz'michev, V.E.; Peresypkin, V.V.; Efetov, A.V.

1991-01-01

The effective potential of the interaction between light nucleus and two-particle atom at distances greater than its Bohr radius is obtained in the analytic form on the basis of a correct account of three Coulomb particle problem. Features of the interaction between p, t, 4 He, 7 Be nuclei and mesonic atoms μp, μt, μ 4 He and μ 7 Be, that arising from the differences in masses and charges of interacting particles, are studied. The corresponding potentials in the pre-threshold energy range are given. The coefficients of the symptotic formula for the effective are calculated in adiabatic approximation and with regard for the main off-shell corrections. 16 refs.; 4 figs

Taming light with cold atoms

International Nuclear Information System (INIS)

Vestergaard Hau, Lene

2002-01-01

Much of the extraordinary progress of developments in communication (e-mail, and/or internet) has been achieved due to improvements in optical communication. This paper describes a new approach which could improve the speed of communication. The ability to stop light in its tracks by passing it through a cloud of ultracold atoms could lead to new techniques for optical storage. The described slow-light experiments have triggered new physics both on the experimental and theoretical fronts. The cold atom system allows the steepest possible refractive index profiles, and therefore the most dramatic effects, as Doppler effects are eliminated. Furthermore, cold atoms provide maximum flexibility in the choice of beam geometry. This is important for the storage and retrieval of multiple pulses of optical information in an atomic medium, as it would allow individual pulses to be selectively addressed. Slow and stopped light have many potential applications in optical communication and processing, including optical information storage, ultra-sensitive optical switches, and optical delay lines. It could also be used in quantum-information processing, in which quantum-mechanical information is used for computing and communication purposes. On a very different front, slow light provides us with a totally new way of probing the unusual properties of Bose-Einstein condensates

Lasers, light-atom interaction

International Nuclear Information System (INIS)

Cagnac, B.; Faroux, J.P.

2002-01-01

This book has a double purpose: first to explain in a way as simple as possible the interaction processes occurring between atoms and light waves, and secondly to help any scientist that needs further information to improve his knowledge of lasers. The content of this book has been parted into 3 more or less independent sections: 1) effect of an electromagnetic field on a 2-quantum state system, 2) operating mode of lasers in the framework of transition probabilities, and 3) calculation of the emitted wave. Einstein's phenomenological hypothesis has led to probability equations called rate equations, these equations do not give a true representation of the interaction process at the scale of the atom but this representation appears to be true on an average over a large population of atoms. Only quantum mechanics can describe accurately the light-atom interaction but at the cost of a far higher complexity. In the first part of the book quantum mechanics is introduced and applied under 2 simplifying hypothesis: -) the atom system has only 2 non-degenerate states and -) the intensity of the light wave is high enough to involve a large population of photons. Under these hypothesis, Rabi oscillations, Ramsey pattern and the splitting of Autler-Townes levels are explained. The second part is dedicated to the phenomenological model of Einstein that gives good results collectively. In the third part of the book, Maxwell equations are used to compute field spatial distribution that are currently found in experiments involving lasers. (A.C.)

Light forces on an indium atomic beam

International Nuclear Information System (INIS)

Kloeter, B.

2007-01-01

In this thesis it was studied, whether indium is a possible candidate for the nanostructuration respectively atomic lithography. For this known method for the generation and stabilization of the light necessary for the laser cooling had to be fitted to the special properties of indium. The spectroscopy of indium with the 451 nm and the 410 nm light yielded first hints that the formulae for the atom-light interaction for a two-level atom cannot be directly transferred to the indium atom. By means of the obtained parameters of the present experiment predictions for a possible Doppler cooling of the indium atomic beam were calculated. Furthermore the possibility for the direct deposition of indium on a substrate was studied

Single-cell atomic quantum memory for light

International Nuclear Information System (INIS)

Opatrny, Tomas

2006-01-01

Recent experiments demonstrating atomic quantum memory for light [B. Julsgaard et al., Nature 432, 482 (2004)] involve two macroscopic samples of atoms, each with opposite spin polarization. It is shown here that a single atomic cell is enough for the memory function if the atoms are optically pumped with suitable linearly polarized light, and quadratic Zeeman shift and/or ac Stark shift are used to manipulate rotations of the quadratures. This should enhance the performance of our quantum memory devices since less resources are needed and losses of light in crossing different media boundaries are avoided

Comparative study of local atomic structures in Zr{sub 2}Cu{sub x}Ni{sub 1−x} (x = 0, 0.5, 1) metallic glasses

Energy Technology Data Exchange (ETDEWEB)

Huang, Yuxiang [Department of Physics, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Huang, Li, E-mail: huangl@sustc.edu.cn [Department of Physics, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Wang, C. Z.; Ho, K. M. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Department of Physics, Iowa State University, Ames, Iowa 50011 (United States); Kramer, M. J. [Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011 (United States); Materials Science and Engineering, Iowa State University, Ames, Iowa 50011 (United States)

2015-11-21

Extensive analysis has been performed to understand the key structural motifs accounting for the difference in glass forming ability in the Zr-Cu and Zr-Ni binary alloy systems. Here, the reliable atomic structure models of Zr{sub 2}Cu{sub x}Ni{sub 1−x} (x = 0, 0.5, 1) are constructed using the combination of X-ray diffraction experiments, ab initio molecular dynamics simulations and a constrained reverse Monte Carlo method. We observe a systematic variation of the interatomic distance of different atomic pairs with respect to the alloy composition. The ideal icosahedral content in all samples is limited, despite the high content of five-fold symmetry motifs. We also demonstrate that the population of Z-clusters in Zr{sub 2}Cu glass is much higher than that in the Zr{sub 2}Ni and Zr{sub 2}Cu{sub 0.5}Ni{sub 0.5} samples. And Z12 〈0, 0, 12, 0〉 Voronoi polyhedra clusters prefer to form around Cu atoms, while Ni-centered clusters are more like Z11 〈0, 2, 8, 1〉 clusters, which is less energetically stable compared to Z12 clusters. These two different structural properties may account for the higher glass forming ability of Zr{sub 2}Cu alloy than that of Zr{sub 2}Ni alloy.

Assessment of undiscovered conventional oil and gas resources of Thailand

Science.gov (United States)

Schenk, Chris

2011-01-01

The U.S. Geological Survey estimated mean volumes of 1.6 billion barrels of undiscovered conventional oil and 17 trillion cubic feet of undiscovered conventional natural gas in three geologic provinces of Thailand using a geology-based methodology. Most of the undiscovered conventional oil and gas resource is estimated to be in the area known as offshore Thai Basin province.

Biodiversity hotspots house most undiscovered plant species.

Science.gov (United States)

Joppa, Lucas N; Roberts, David L; Myers, Norman; Pimm, Stuart L

2011-08-09

For most organisms, the number of described species considerably underestimates how many exist. This is itself a problem and causes secondary complications given present high rates of species extinction. Known numbers of flowering plants form the basis of biodiversity "hotspots"--places where high levels of endemism and habitat loss coincide to produce high extinction rates. How different would conservation priorities be if the catalog were complete? Approximately 15% more species of flowering plant are likely still undiscovered. They are almost certainly rare, and depending on where they live, suffer high risks of extinction from habitat loss and global climate disruption. By using a model that incorporates taxonomic effort over time, regions predicted to contain large numbers of undiscovered species are already conservation priorities. Our results leave global conservation priorities more or less intact, but suggest considerably higher levels of species imperilment than previously acknowledged.

Light-induced atomic desorption and related phenomena

Energy Technology Data Exchange (ETDEWEB)

Burchianti, A; Bogi, A; Marinelli, C; Mariotti, E; Moi, L [CNISM and Physics Department, University of Siena, 53100 Siena (Italy)], E-mail: burchianti@unisi.it

2009-07-15

We review some recent studies on light-induced atomic desorption (LIAD) from dielectric surfaces. Alkali-metal atoms adsorbed either on organic films or on porous glass are released into the vapor phase under illumination. The measurements were performed in Pyrex resonance cells either coated with siloxane films or containing a porous glass sample. In both cases, the experimental results show that LIAD can be used to produce atomic densities suitable for most atomic physics experiments. Moreover, we find that photoinduced effects, correlated with LIAD, produce reversible formation and evaporation of alkali-metal clusters in porous glass. These processes depend on the light frequency, making the porous glass transmittance controllable by light.

Focusing of atoms with spatially localized light pulses

International Nuclear Information System (INIS)

Helseth, Lars Egil

2002-01-01

We theoretically study the focusing of atoms using strongly localized light pulses. It is shown that when inhomogenously polarized light is focused at high angular apertures, one may obtain useful potentials for atom focusing. Here we analyze the case of pulsed light potentials for red- and blue-detuned focusings of atoms. In particular, we show that the atomic beam aperture must be stopped considerably down in order to reduce the sidelobes of the atomic density, which is similar to the situation often encountered in conventional optics. It is suggested that an annular aperture in front of the atomic beam could be useful for increasing the resolution, at the cost of a lower atomic density

True atomic-scale imaging of a spinel Li{sub 4}Ti{sub 5}O{sub 12}(111) surface in aqueous solution by frequency-modulation atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Kitta, Mitsunori, E-mail: m-kitta@aist.go.jp; Kohyama, Masanori [Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan); Onishi, Hiroshi [Department of Chemistry, Graduate School of Science, Kobe University 1-1 Rokkodai, Nada, Kobe 657-8501 (Japan)

2014-09-15

Spinel-type lithium titanium oxide (LTO; Li{sub 4}Ti{sub 5}O{sub 12}) is a negative electrode material for lithium-ion batteries. Revealing the atomic-scale surface structure of LTO in liquid is highly necessary to investigate its surface properties in practical environments. Here, we reveal an atomic-scale image of the LTO(111) surface in LiCl aqueous solution using frequency-modulation atomic force microscopy. Atomically flat terraces and single steps having heights of multiples of 0.5 nm were observed in the aqueous solution. Hexagonal bright spots separated by 0.6 nm were also observed on the flat terrace part, corresponding to the atomistic contrast observed in the ultrahigh vacuum condition, which suggests that the basic atomic structure of the LTO(111) surface is retained without dramatic reconstruction even in the aqueous solution.

Switching of light with light using cold atoms inside a hollow optical fiber

DEFF Research Database (Denmark)

Bajcsy, Michal; Hofferberth, S.; Peyronel, Thibault

2010-01-01

We demonstrate a fiber-optical switch that operates with a few hundred photons per switching pulse. The light-light interaction is mediated by laser-cooled atoms. The required strong interaction between atoms and light is achieved by simultaneously confining photons and atoms inside the microscopic...... hollow core of a single-mode photonic-crystal fiber....

Phase contrast scanning transmission electron microscopy imaging of light and heavy atoms at the limit of contrast and resolution.

Science.gov (United States)

Yücelen, Emrah; Lazić, Ivan; Bosch, Eric G T

2018-02-08

Using state of the art scanning transmission electron microscopy (STEM) it is nowadays possible to directly image single atomic columns at sub-Å resolution. In standard (high angle) annular dark field STEM ((HA)ADF-STEM), however, light elements are usually invisible when imaged together with heavier elements in one image. Here we demonstrate the capability of the recently introduced Integrated Differential Phase Contrast STEM (iDPC-STEM) technique to image both light and heavy atoms in a thin sample at sub-Å resolution. We use the technique to resolve both the Gallium and Nitrogen dumbbells in a GaN crystal in [[Formula: see text

Fabrication of uniformly dispersed Ag nanoparticles loaded TiO{sub 2} nanotube arrays for enhancing photoelectrochemical and photocatalytic performances under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Yi, Junhui; Zhang, Shengsen; Wang, Hongjuan; Yu, Hao; Peng, Feng, E-mail: cefpeng@scut.edu.cn

2014-12-15

Graphical abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method, which exhibited the enhanced photoelectrochemical and photocatalytic performances under visible-light irradiation due to the more effective separation of photo-generated electron–hole pairs and faster interfacial charge transfer. - Highlights: • Highly dispersed Ag nanoparticles (NPs) are successfully prepared by polyol method. • Ag NPs are uniformly loaded on the surface of the TiO{sub 2} nanotube arrays (NTs). • Ag/TiO{sub 2}-NTs exhibit the enhanced photocatalytic activity under visible-light. • The enhanced photocurrent is explained by electrochemical impedance spectroscopy. - Abstract: Uniformly dispersed Ag nanoparticles (NPs) were successfully loaded on both the outer and inner surface of the TiO{sub 2} nanotube arrays (NTs) through a simple polyol method. The as-prepared Ag/TiO{sub 2}-NTs were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV–vis diffusion reflectance spectroscopy. Photoelectrochemical behaviors were investigated via photocurrent response and electrochemical impedance spectroscopy (EIS). Photocatalytic activity of Ag/TiO{sub 2}-NTs was evaluated by degradation of acid orange II under visible light irradiation. The results showed that photocatalytic efficiency of Ag/TiO{sub 2}-NTs is more than 5 times higher than that of pure TiO{sub 2} NTs. Comparing with the electrochemical deposition method, the photocatalytic activity of Ag/TiO{sub 2}-NTs prepared by polyol method has been obviously increased.

Exchange interactions and the state of iron atoms in Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ}

Energy Technology Data Exchange (ETDEWEB)

Chezhina, N.V., E-mail: chezhina@nc2490.spb.edu [St. Petersburg State University, 7/9 Universitetskaya Nab., 199034 (Russian Federation); Korolev, D.A. [St. Petersburg State University, 7/9 Universitetskaya Nab., 199034 (Russian Federation); Zhuk, N.A. [Syktyvkar State University (Russian Federation); Lutoev, V.P.; Makeev, B.A. [Institute of Geology Komi Scientific Center of Ural branch of Russian Academy of Sciences, Syktyvkar (Russian Federation)

2017-03-15

On the basis of the results of magnetic susceptibility and ESR studies of the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions iron atoms in the solid solutions of cubic modification of bismuth niobate were found to exist as Fe(III) monomers and exchange bound Fe(III)-O-Fe(III) dimers with antiferro- and ferromagnetic type of superexchange. The exchange parameters and the distribution of monomers and dimers in the solid solutions were calculated as a function of paramagnetic atom content. - Graphical abstract: The study of the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions showed that the introduction of iron atoms into the structure of Bi{sub 3}NbO{sub 7} stabilizes the cubic structure of bismuth niobate making the phase transition tetragonal ↔ cubic structure irreversible. In the Bi{sub 3}Nb{sub 1−x}Fe{sub x}O{sub 7−δ} solid solutions we observe the formation of dimers with antiferro- and ferromagnetic exchange. Such clusters are partially retained even at the infinite dilution of the solid solution, which testifies for their rigidity. A sufficiently high parameter of ferromagnetic exchange in a dimer (+53 cm{sup −1}) seems to result from iron atoms being located in the vicinity of oxygen vacancy. - Highlights: • The reversible transition cubic – tetragonal modifications in Bi{sub 3}NbO{sub 7} becomes irreversible. • Only cubic modification of Bi{sub 3}Nb{sub 1-x}Fe{sub x}O{sub 7-δ} is stable due to clusters of Fe atoms. • These clusters are sufficiently strong and retained even at the infinite dilution. • The calculations of magnetic susceptibility give the distribution of the clusters and single atoms.

Synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles and nanowires

Energy Technology Data Exchange (ETDEWEB)

Xie Yi; Heo, Sung Hwan; Kim, Yong Nam; Yoo, Seung Hwa; Cho, Sung Oh, E-mail: socho@kaist.ac.kr [Department of Nuclear and Quantum Engineering, Korea Advanced Institute of Science and Technology (KAIST), 373-1 Guseong, Yuseong, Daejeon 305-701 (Korea, Republic of)

2010-01-08

We present the synthesis and visible-light-induced catalytic activity of Ag{sub 2}S-coupled TiO{sub 2} nanoparticles (NPs) and TiO{sub 2} nanowires (NWs). Through a simple wet chemical process from a mixture of peroxo titanic acid (PTA) solution, thiourea and AgAc, a composite of Ag{sub 2}S NPs and TiO{sub 2} NPs with sizes of less than 7 nm was formed. When the NP composite was further treated with NaOH solution followed by annealing at ambient conditions, a new nanocomposite material comprising Ag{sub 2}S NPs on TiO{sub 2} NWs was created. Due to the coupling with such a low bandgap material as Ag{sub 2}S, the TiO{sub 2} nanocomposites could have a visible-light absorption capability much higher than that of pure TiO{sub 2}. As a result, the synthesized Ag{sub 2}S/TiO{sub 2} nanocomposites exhibited much higher catalytic efficiency for the decomposition of methyl orange than commercial TiO{sub 2} (Degussa P25, Germany) under visible light.

Phase stability and lattice thermal conductivity reduction in CoSb{sub 3} skutterudites, doped with chalcogen atoms

Energy Technology Data Exchange (ETDEWEB)

Battabyal, M., E-mail: manjusha.battabyal@project.arci.res.in; Priyadarshini, B.; Gopalan, R. [International Advanced Research Centre for Powder Metallurgy and New Materials (ARCI), IIT M Research Park, Taramani, Chennai-600113 (India); Pradipkanti, L.; Satapathy, Dillip K. [Department of Physics, Indian Institute of Technology Madras, Chennai-600036 (India)

2016-07-15

We report a significant reduction in the lattice thermal conductivity of the CoSb{sub 3} skuttertudites, doped with chalcogen atoms. Te/Se chalcogen atoms doped CoSb{sub 3} skutterudite samples (Te{sub 0.1}Co{sub 4}Sb{sub 12}, Se{sub 0.1}Co{sub 4}Sb{sub 12}, Te{sub 0.05}Se{sub 0.05}Co{sub 4}Sb{sub 12}) are processed by ball milling and spark plasma sintering. X-ray diffraction data combined with energy dispersive X-ray spectra indicate the doping of Te/Se chalcogen atoms in the skutterudite. The temperature dependent X-ray diffraction confirms the stability of the Te/Se doped CoSb{sub 3} skutterudite phase and absence of any secondary phase in the temperature range starting from 300 K to 773 K. The Raman spectroscopy reveals that different chalcogen dopant atoms cause different resonant optical vibrational modes between the dopant atom and the host CoSb{sub 3} skutterudite lattice. These optical vibrational modes do scatter heat carrying acoustic phonons in a different spectral range. It was found that among the Te/Se chalcogen atoms, Te atoms alter the host CoSb{sub 3} skutterudite lattice vibrations to a larger extent than Se atoms, and can potentially scatter more Sb related acoustic phonons. The Debye model of lattice thermal conductivity confirms that the resonant phonon scattering has important contributions to the reduction of lattice thermal conductivity in CoSb{sub 3} skutterudites doped with Te/Se chalcogen atoms. Lattice thermal conductivity ∼ 0.9 W/mK at 773 K is achieved in Te{sub 0.1}Co{sub 4}Sb{sub 12} skutterudites, which is the lowest value reported so far in CoSb{sub 3} skutterudites, doped with single Te chalcogen atom.

An ENDOR spectrum of H atoms in solid H{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Kumada, Takayuki; Kumagai, J.; Aratono, Yasuyuki; Miyazaki, T. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Kitagawa, N.; Noda, T.

1998-10-01

An ENDOR spectrum of H atoms produced in the {gamma}-rays irradiated solid H{sub 2} was measured at 4.2 K in order to elucidate the structures of the local environment of the H atoms in solid H{sub 2}. We found that the H atoms were not trapped in interstitial sites but in substitutional sites of the solid, and almost all ortho-H{sub 2} molecules at the first nearest sites from the H atoms converted into para-H{sub 2} molecules. This result shows that the ortho-para conversion is induced by electron spins of the H atoms. (author)

Synthesis of porous carbon-doped g-C{sub 3}N{sub 4} nanosheets with enhanced visible-light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Bao, Nan, E-mail: baonan@sdu.edu.cn [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China); Hu, Xinde [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China); Zhang, Qingzhe [Institut National de la Recherche Scientifique (INRS), Centre Énergie Materiaux et Télécommunications, Université du Québec, 1650 Boulevard Lionel-Boulet, Varennes, Québec, J3X 1S2, Canada (Canada); Miao, Xinhan; Jie, Xiuyan; Zhou, Shuai [School of Environmental Science and Engineering, Shandong Key Laboratory of Water Pollution Control and Resource Reuse, Shandong University, Shanda South Road 27, Jinan 250100 (China)

2017-05-01

Highlights: • NSs-APAM photocatalysts were synthesized by a green and handy route. • APAM was used as the intercalator and carbon source in the preparation. • The combination of photo-induced charge carriers was greatly restrained. • Significantly enhanced visible-light photocatalytic activity was witnessed. • The NSs-APAM also showed a good recycling stability. - Abstract: The porous carbon-doped g-C{sub 3}N{sub 4} nanosheets photocatalysts (NSs-APAM) were synthesized using anionic polyacrylamide (APAM) as the intercalator and carbon source via the thermal treatment method. The as-prepared samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption, X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance absorption spectra (UV-DRS) and photoluminescence spectroscopy (PL). The results indicate that the APAM can effectively induce the formation of high-quality nanosheets (NSs) with narrowed bandgap. The specific surface area of NSs-APAM is 118.6 m{sup 2}/g, which is 5-fold larger than bulk g-C{sub 3}N{sub 4}. The carbon doping could narrow the bandgap, from 2.75 eV of g-C{sub 3}N{sub 4} NSs without carbon doping (NSs-Water) to 2.41 eV of NSs-APAM. The two-dimensional NSs structure facilitates the charge separation by shortening the diffusion distance to the surface of photocatalysts. The synergic effects of the carbon doping and unique structural properties contributed to the superior photocatalytic activity of NSs-APAM with 95% degradation rate towards X–3 B after 30 min visible-light irradiation.

Robustness of a bisimulation-type faster-than preorder

Directory of Open Access Journals (Sweden)

Katrin Iltgen

2009-11-01

Full Text Available TACS is an extension of CCS where upper time bounds for delays can be specified. Luettgen and Vogler defined three variants of bismulation-type faster-than relations and showed that they all three lead to the same preorder, demonstrating the robustness of their approach. In the present paper, the operational semantics of TACS is extended; it is shown that two of the variants still give the same preorder as before, underlining robustness. An explanation is given why this result fails for the third variant. It is also shown that another variant, which mixes old and new operational semantics, can lead to smaller relations that prove the same preorder.

Enhanced growth of the red alga Porphyra-Yezoensis Ueda in high CO sub 2 concentrations

Energy Technology Data Exchange (ETDEWEB)

Gao, K.; Aruga, Y.; Asada, K.; Ishihara, T.; Akano, T.; Kiyohara, M. (Kansai Environmental Engineering Centre, Osaka (Japan))

1991-12-01

Leafy thalli of the red alga Porphyra yezoensis Ueda, initiated from conchospores released from free-living conchocelis, were cultured using aeration with high CO{sub 2}. It was found that the higher the CO{sub 2} concentration, the faster the growth of the thalli. Aeration with elevated CO{sub 2} lowered pH in dark, but raised pH remarkably in light with the thalli, because the photosynthetic conversion of HCO{sub 3} {sup -} to OH{sup -} and CO{sub 2} proceeded much faster than the dissociation of hydrated CO{sub 2} releasing H{sup +}. Photosynthesis of the alga was found to be enhanced in the seawater of elevated dissolved inorganic carbon DIC, CO{sub 2} + HCO{sub 3}{sup -} + CO{sub 3}{sup -}. It is concluded that the increased pH in the light resulted in the increase of DIC in the culture media, thus enhancing photosynthesis and growth. The relevance of the results to removal of atmospheric CO{sub 2} by marine algae is discussed.

How to Elect a Leader Faster than a Tournament

OpenAIRE

Alistarh, Dan; Gelashvili, Rati; Vladu, Adrian

2014-01-01

The problem of electing a leader from among $n$ contenders is one of the fundamental questions in distributed computing. In its simplest formulation, the task is as follows: given $n$ processors, all participants must eventually return a win or lose indication, such that a single contender may win. Despite a considerable amount of work on leader election, the following question is still open: can we elect a leader in an asynchronous fault-prone system faster than just running a $\\Theta(\\log n...

Small-polaron model of light atom diffusion

International Nuclear Information System (INIS)

Emin, D.

1977-01-01

A number of researchers have treated the diffusion of light interstitials in metals in strict analogy with the theory for the hopping diffusion of electrons in low-mobility insulators. In other words, these authors view the diffusion of light atoms as simply being an example of small-polaron hopping motion. In this paper the motion of a small polaron is introduced, and the mechanism of its motion is described. The experimental results are then succinctly presented. Next the physical assumptions implicit in the theory are compared with the situation which is believed to characterize the existence and motion of light interstitial atoms in metals. Concomitantly, the modifications of the small-polaron theory required in applying it to light atom diffusion are ennumerated

Confronting the Faster-Than-Light Neutrinos?

Indian Academy of Sciences (India)

How well do we know Special Theory of Relativity, Quantum Mechanics, General ... 1 The principle of relativity: The laws of physics are not affected by the .... If the limiting velocities of the three neutrinos are different, that would lead to neutrino.

Atomic-cascade photons and quantum-mechanical nonlocality

International Nuclear Information System (INIS)

Bell, J.S.

1995-01-01

In recent years there have been several experiments on polarization correlation between photons emitted in atomic cascades. They are supposed to bear on the notion that the consequences of events do not propagate faster than light. This notion is difficult to reconcile with quantum-mechanical predictions for idealized versions of the experiments in question. The present Comment offers a brief introduction to the situation. (author)

Atomic-resolution studies of In{sub 2}O{sub 3}-ZnO compounds on aberration-corrected electron microscopes

Energy Technology Data Exchange (ETDEWEB)

Yu, Wentao

2009-10-23

In this work, the characteristic inversion domain microstructures of In{sub 2}O{sub 3}(ZnO){sub m} (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In{sub 2}O{sub 3}(ZnO){sub 30} were successfully acquired in [1 anti 100] zone axis of ZnO, with projected metal columns of {proportional_to}1.6 A well resolved. From contrast maxima in the TEM images, local lattice distortions at the pyramidal inversion domain boundaries were observed for the first time. Lattice displacements and the strain field in two-dimensions were visualized and measured using the 'DALI' algorithm. Atomically resolved single shot and focal series images of In{sub 2}O{sub 3}(ZnO){sub 30} were achieved in both zone axes of ZnO, [1 anti 100] and [2 anti 1 anti 10], respectively. The electron waves at the exit-plane were successfully reconstructed using the software package 'TrueImage'. Finally, a three dimensional atomic structure model for the pyramidal IDB was proposed, with an In distribution of 10%, 20%, 40%, 20% and 10% of In contents over 5 atom columns along basal planes, respectively. Through a detailed structural study of In{sub 2}O{sub 3}(ZnO){sub m} compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In{sup 3+} atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

Initial oxidation behavior of Ni{sub 3}Al (210) surface induced by supersonic oxygen molecular beam at room temperature

Energy Technology Data Exchange (ETDEWEB)

Xu, Ya, E-mail: XU.Ya@nims.go.jp [Hydrogen Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Sakurai, Junya [Hydrogen Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Teraoka, Yuden; Yoshigoe, Akitaka [Quantum Beam Science Center, Japan Atomic Energy Research Agency, 1-1-1 Kouto, Sayo-cho, Hyogo 679-5148 (Japan); Demura, Masahiko; Hirano, Toshiyuki [Hydrogen Materials Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

2017-01-01

Graphical abstract: - Highlights: • Initial oxidation of Ni{sub 3}Al (210) induced by O{sub 2} beam was investigated. • This was done using real-time synchrotron radiation XPS. • Both the Al and the Ni atoms on the surface were oxidized. • Oxidation of Al progressed much faster than that of Ni. - Abstract: The initial oxidation behavior of a clean Ni{sub 3}Al (210) surface was studied at 300 K using a supersonic O{sub 2} molecular beam (O{sub 2} SSMB) having an O{sub 2} translational energy of 2.3 eV, and real-time photoemission spectroscopy performed with high-brilliance synchrotron radiation. The evolution behaviors of the O 1s, Ni 2p, Al 2p, and Ni 3p spectra were examined during irradiation with the O{sub 2} SSMB. The spectral analysis revealed that both the Al atoms and the Ni atoms on the surface were oxidized; however, the oxidation of Al progressed much faster than that of Ni. The oxidation of Al began to occur and AlO{sub x} was formed at an oxygen coverage of 0.26 monolayer (ML) (1 ML was defined as the atomic density of the Ni{sub 3}Al (210) surface) and saturated at an oxygen coverage of 2.5 ML. In contrast, the oxidation of Ni commenced a little late at an oxygen coverage of 1.6 ML and slowly progressed to saturation, which occurred at an oxygen coverage of 4.89 ML.

R{sub 4}Ir{sub 13}Ge{sub 9} (R=La, Ce, Pr, Nd, Sm) and RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd): Crystal structures with nets of Ir atoms

Energy Technology Data Exchange (ETDEWEB)

Yarema, Maksym [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya Str, 6, UA-79005 Lviv (Ukraine); Swiss Federal Laboratories for Materials Science and Technology (EMPA), Ueberlandstr. 129, CH-8600 Duebendorf (Switzerland); Zaremba, Oksana; Gladyshevskii, Roman [Department of Inorganic Chemistry, Ivan Franko National University of Lviv, Kyryla i Mefodiya Str, 6, UA-79005 Lviv (Ukraine); Hlukhyy, Viktor, E-mail: viktor.hlukhyy@lrz.tu-muenchen.de [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85747 Garching (Germany); Faessler, Thomas F. [Department Chemie, Technische Universitaet Muenchen, Lichtenbergstr. 4, D-85747 Garching (Germany)

2012-12-15

The crystal structures of the new ternary compounds Sm{sub 4}Ir{sub 13}Ge{sub 9} and LaIr{sub 3}Ge{sub 2} were determined and refined on the basis of single-crystal X-ray diffraction data. They belong to the Ho{sub 4}Ir{sub 13}Ge{sub 9} (oP52, Pmmn) and CeCo{sub 3}B{sub 2} (hP5, P6/mmm) structure types, respectively. The formation of isotypic compounds R{sub 4}Ir{sub 13}Ge{sub 9} with R=La, Ce, Pr, Nd, and RIr{sub 3}Ge{sub 2} with R=Ce, Pr, Nd, was established by powder X-ray diffraction. The RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd) compounds exist only in as-cast samples and decompose during annealing at 800 Degree-Sign C with the formation of R{sub 4}Ir{sub 13}Ge{sub 9}. The structure of Sm{sub 4}Ir{sub 13}Ge{sub 9} contains intersecting, slightly puckered nets of Ir atoms (4{sup 4})(4{sup 3}.6){sub 2}(4.6{sup 2}){sub 2} and (4{sup 4}){sub 2}(4{sup 3}.6){sub 4}(4.6{sup 2}){sub 2} that are perpendicular to [0 1 1] as well as to [0 -1 1] and [0 0 1]. The Ir atoms are surrounded by Ge atoms that form tetrahedra or square pyramids (where the layers intersect). The Sm and additional Ir atoms (in trigonal-planar coordination) are situated in channels along [1 0 0] (short translation vector). In the structure of LaIr{sub 3}Ge{sub 2} the Ir atoms form planar Kagome nets (3.6.3.6) perpendicular to [0 0 1]. These nets alternate along the short translation vector with layers of La and Ge atoms. - Graphical abstract: The crystal structures contain the nets of Ir atoms as main structural motif: R{sub 4}Ir{sub 13}Ge{sub 9} contains intersecting slightly puckered nets of Ir atoms, whereas in the structure of RIr{sub 3}Ge{sub 2} the Ir atoms form planar Kagome nets. Highlights: Black-Right-Pointing-Pointer The Ir-rich ternary germanides R{sub 4}Ir{sub 13}Ge{sub 9} (R=La, Ce, Pr, Nd, Sm) and RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd) have been synthesized. Black-Right-Pointing-Pointer The RIr{sub 3}Ge{sub 2} compounds exist only in as-cast samples and decompose during annealing at 800

Insights into thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks and their suppressed reaction with atomically thin AlO{sub x} interlayers

Energy Technology Data Exchange (ETDEWEB)

Ogawa, Shingo, E-mail: Shingo-Ogawa@trc.toray.co.jp [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan); Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Asahara, Ryohei; Minoura, Yuya; Hosoi, Takuji, E-mail: hosoi@mls.eng.osaka-u.ac.jp; Shimura, Takayoshi; Watanabe, Heiji [Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan); Sako, Hideki; Kawasaki, Naohiko; Yamada, Ichiko; Miyamoto, Takashi [Toray Research Center, Inc., 3-3-7 Sonoyama, Otsu, Shiga 520-8567 (Japan)

2015-12-21

The thermal diffusion of germanium and oxygen atoms in HfO{sub 2}/GeO{sub 2}/Ge gate stacks was comprehensively evaluated by x-ray photoelectron spectroscopy and secondary ion mass spectrometry combined with an isotopic labeling technique. It was found that {sup 18}O-tracers composing the GeO{sub 2} underlayers diffuse within the HfO{sub 2} overlayers based on Fick's law with the low activation energy of about 0.5 eV. Although out-diffusion of the germanium atoms through HfO{sub 2} also proceeded at the low temperatures of around 200 °C, the diffusing germanium atoms preferentially segregated on the HfO{sub 2} surfaces, and the reaction was further enhanced at high temperatures with the assistance of GeO desorption. A technique to insert atomically thin AlO{sub x} interlayers between the HfO{sub 2} and GeO{sub 2} layers was proven to effectively suppress both of these independent germanium and oxygen intermixing reactions in the gate stacks.

Layer-by-layer assembled TiO{sub 2} films with high ultraviolet light-shielding property

Energy Technology Data Exchange (ETDEWEB)

Li, Xiaozhou [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Wang, Lin, E-mail: wanglin0317@nwsuaf.edu.cn [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Pei, Yuxin [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Jiang, Jinqiang [State Key Lab of Applied Surface and Colloid Chemistry, College of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an 710062 (China)

2014-11-28

Ultraviolet (UV) B is hazardous to human, plants and animals. With the rapid growth of ozone holes over the earth, the exploration of optical materials that can cut off harmful UV radiation is important. In this work, fusiform TiO{sub 2} nanoparticles were synthesized by a hydrothermal synthesis method. The thin films assembled with TiO{sub 2} nanoparticles and oppositely charged polyelectrolytes were fabricated via a layer-by-layer assembly method. The fabrication of poly(ethylene imine) (PEI)/TiO{sub 2} multilayer films was verified by ultraviolet–visible spectra measurements, scanning electron microscopy and atomic force microscopy. The as-prepared PEI/TiO{sub 2} multilayer films can effectively absorb harmful UVB light and filter off visible light. Most importantly, the PEI/TiO{sub 2} films can be deposited directly on various kinds of hydrophilic substrates such as quartz, glass, silicon and hydrophobic substrates such as polystyrene, polypropylene, polyethylene and polymethyl methacrylate when the hydrophilic substrates were modified to obtain a hydrophilic surface. - Highlights: • PEI/TiO{sub 2} films were fabricated via a layer-by-layer self-assembly method. • The films could effectively absorb harmful UVB light and filter off visible light. • The films could deposit directly on either hydrophilic or hydrophobic substrates.

Facile synthesis of surface N-doped Bi{sub 2}O{sub 2}CO{sub 3}: Origin of visible light photocatalytic activity and in situ DRIFTS studies

Energy Technology Data Exchange (ETDEWEB)

Zhou, Ying, E-mail: yzhou@swpu.edu.cn [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Zhao, Ziyan [State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Wang, Fang; Cao, Kun [The Center of New Energy Materials and Technology, School of Materials Science and Engineering, Southwest Petroleum University, Xindu Rd. 8, Chengdu 610500 (China); Doronkin, Dmitry E. [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany); Dong, Fan [College of Environmental and Biological Engineering, Chonqing Technology and Business University, Chongqing 400067 (China); Grunwaldt, Jan-Dierk, E-mail: grunwaldt@kit.edu [Insititute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), 76131 Karlsruhe (Germany)

2016-04-15

Graphical abstract: Surfactant (CTAB) can induce nitrogen interstitially doping in the Bi{sub 2}O{sub 2}CO{sub 3} surface, leading to the formation of localized states from N−O bond, which probably account for the origin of the visible light activity. Moreover, the photocatalytic NO oxidation processes over Bi{sub 2}O{sub 2}CO{sub 3} were successfully monitored for the first time by in situ DRIFTS. - Highlights: • Interstitially doping N in the Bi{sub 2}O{sub 2}CO{sub 3} surface was achieved at room temperature. • N-doped Bi{sub 2}O{sub 2}CO{sub 3} exhibited significantly enhanced visible light photocatalytic activity compared to the pristine Bi{sub 2}O{sub 2}CO{sub 3}. • The formation of localized states from N−O bond could account for the visible light activity of Bi{sub 2}O{sub 2}CO{sub 3}. • The photocatalytic NO oxidation process was monitored by in situ DRIFTS. - Abstract: Bi{sub 2}O{sub 2}CO{sub 3} nanosheets with exposed {001} facets were prepared by a facile room temperature chemical method. Due to the high oxygen atom density in {001} facets of Bi{sub 2}O{sub 2}CO{sub 3}, the addition of cetyltrimethylammonium bromide (CTAB) does not only influence the growth of crystalline Bi{sub 2}O{sub 2}CO{sub 3}, but also modifies the surface properties of Bi{sub 2}O{sub 2}CO{sub 3} through the interaction between CTAB and Bi{sub 2}O{sub 2}CO{sub 3}. Nitrogen from CTAB as dopant interstitially incorporates in the Bi{sub 2}O{sub 2}CO{sub 3} surface evidenced by both experimental and theoretical investigations. Hence, the formation of localized states from N−O bond improves the visible light absorption and charge separation efficiency, which leads to an enhancement of visible light photocatalytic activity toward to the degradation of Rhodamine B (RhB) and oxidation of NO. In addition, the photocatalytic NO oxidation over Bi{sub 2}O{sub 2}CO{sub 3} nanosheets was successfully monitored for the first time using in situ diffuse reflectance infrared Fourier

Evanescent light-wave atom mirrors, resonators, waveguides, and traps

International Nuclear Information System (INIS)

Dowling, J.P.; Gea-Banacloche, J.

1996-01-01

For many years, it has been known that light can be used to trap and manipulate small dielectric particles and atoms. In particular, the intense coherent light of lasers has been used to cool neutral atoms down to the micro-Kelvin and now even the nano-Kelvin regimes. At such low temperatures, the de Broglie wavelike character of the atoms becomes pronounced, making it necessary to treat the atoms as wave phenomena. To this end, the study of atom optics has recently developed, in which atom optical elements are fabricated in order to manipulate atoms, while utilizing and preserving the coherence and superposition properties inherent in their wavelike propagation. For example, there has been a concerted effort to study theoretically and produce experimentally the atom optic analogs of photonic optical elements, such as atom beam splitters, atom diffraction gratings, atom lenses, atom interferometers, and-last but not least-atom mirrors. It is light-induced atom mirrors, and their application to making atom resonators, waveguides, and traps, that we shall focus on in this chapter. 133 refs., 26 figs., 1 tab

Bottom-up production of meta-atoms for optical magnetism in visible and NIR light

Science.gov (United States)

Barois, Philippe; Ponsinet, Virginie; Baron, Alexandre; Richetti, Philippe

2018-02-01

Many unusual optical properties of metamaterials arise from the magnetic response of engineered structures of sub-wavelength size (meta-atoms) exposed to light. The top-down approach whereby engineered nanostructure of well-defined morphology are engraved on a surface proved to be successful for the generation of strong optical magnetism. It faces however the limitations of high cost and small active area in visible light where nanometre resolution is needed. The bottom-up approach whereby the fabrication metamaterials of large volume or large area results from the combination of nanochemitry and self-assembly techniques may constitute a cost-effective alternative. This approach nevertheless requires the large-scale production of functional building-blocks (meta-atoms) bearing a strong magnetic optical response. We propose in this paper a few tracks that lead to the large scale synthesis of magnetic metamaterials operating in visible or near IR light.

A novel silanized CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane pressure sensitive adhesive

Energy Technology Data Exchange (ETDEWEB)

Fu, Heqing, E-mail: fuhq@scut.edu.cn; Wang, Yin; Chen, Weifeng; Zhou, Wei; Xiao, Jing

2015-10-01

Highlights: • The hydrophobicity, thermal stability, dynamic mechanical properties, as well as adhesive properties of silanized. • CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane (SC/FWPU) were improved with the incorporation of silanized CoFe{sub 2}O{sub 4} into FWPU. • The higher the spreading-penetration parameter is, the faster the contact angle reaches equilibrium, and the faster the SC/FWPU pressure sensitive adhesive penetrates and spreads. - Abstract: A novel silanized CoFe{sub 2}O{sub 4}/fluorinated waterborne polyurethane (SC/FWPU) pressure sensitive adhesive was synthesized and characterized by atomic force microscopy (AFM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA) and contact angle tester. The adhesive properties were measured in a test machine. Experimental results showed that the hydrophobicity, thermal stability, dynamic mechanical properties, as well as adhesive properties of SC/FWPU were improved with the incorporation of SC into FWPU. The dynamic hydrophobicity can be well described by the wetting kinetic model. The spreading-penetration parameter increased with an increase in SC content. The higher the spreading-penetration parameter is, the faster the contact angle reaches equilibrium, and the faster the SC/FWPU pressure sensitive adhesive penetrates and spreads.

Subjective time runs faster under the influence of bright rather than dim light conditions during the forenoon.

Science.gov (United States)

Morita, Takeshi; Fukui, Tomoe; Morofushi, Masayo; Tokura, Hiromi

2007-05-16

The study investigated if 6 h morning bright light exposure, compared with dim light exposure, could influence time sense (range: 5-15 s). Eight women served as participants. The participant entered a bioclimatic chamber at 10:00 h on the day before the test day, where an ambient temperature and relative humidity were controlled at 25 degrees C and 60%RH. She sat quietly in a sofa in 50 lx until 22:00 h, retired at 22:00 h and then slept in total darkness. She rose at 07:00 h the following morning and again sat quietly in a sofa till 13:00 h, either in bright (2500 lx) or dim light (50 lx), the order of light intensities between the two occasions being randomized. The time-estimation test was performed from 13:00 to 13:10 h in 200 lx. The participant estimated the time that had elapsed between two buzzers, ranging over 5-15 s, and inputting the estimate into a computer. The test was carried out separately upon each individual. Results showed that the participants estimated higher durations of the given time intervals after previous exposure to 6 h of bright rather than dim light. The finding is discussed in terms of different load errors (difference between the actual core temperature and its thermoregulatory set-point) following 6-h exposure to bright or dim light in the morning.

Effects of electron correlations application to Ti atoms on physical properties of (LaMnO{sub 3}){sub m}/(SrTiO{sub 3}){sub n} superlattices

Energy Technology Data Exchange (ETDEWEB)

Aezami, A., E-mail: a.aezami@gmail.com; Abolhassani, M.; Elahi, M.

2016-05-15

Magnetic structures and Curie temperatures of the (LaMnO{sub 3}){sub m}/(SrTiO{sub 3}){sub n} superlattices (SLm–n) with m=1, 2, 3 and n=1, 2, 3, 8 were investigated, using density functional theory implemented in Quantum-Espresso open source code. By applying on-site coulomb interaction (Hubbard term U) to Ti atoms for all of these superlattices, using Stoner–Wolfarth model, it was found that the magnetic order of interfacial atoms of these superlattices changed to ferromagnetic by implying U=5 eV on Ti atoms. The inclusion of electron–electron correlation with U=5 eV on the Ti atoms for all of the superlattices made the two dimensional electron gas (2DEG) formed at the interfaces, half-metallic. The obtained values of Curie temperature, calculated within mean field approximation with U=5 eV on the Ti atoms, are in good agreement with the experimental results. - Highlights: • Calculated the magnetic structure and Curie temperature of the (LaMnO{sub 3}){sub m}/(SrTiO{sub 3}){sub n} superlattices with m=1, 2, 3 and n=1, 2, 3, 8 by mean field approximation. • By implying U=5 eV on the Ti atoms, the magnetic order of interfacial atoms of these superlattices has changed to ferromagnetic. • The 2DEG formed at the interface half-metallic have made in these superlattices by the inclusion of electron-electron correlation with U=5 eV on the Ti atoms for all of the superlattices.

Atomic disorder in Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore

Energy Technology Data Exchange (ETDEWEB)

Zhang, F. X. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao, Hebei 066004 (China); Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lang, M. [Department of Nuclear Engineering, University of Tennessee, Knoxville, Tennessee 37996 (United States); Ewing, R. C. [Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States)

2015-05-11

Gd{sub 2}Zr{sub 2}O{sub 7} pyrochlore with different degrees of cation disorder were synthesized by isothermal annealing at various temperatures (1100–1550 °C), and the related changes in the structure were investigated by ambient and high pressure x-ray diffraction (XRD) measurements. Unit cell parameters increase almost linearly with increasing treatment temperature. The degree of cation order in pyrochlore also increases with the increase of temperature, but saturates at ∼60%. The compressibility of the pyrochlore structures decreases when the degree of cation order increases. High pressure XRD measurements also indicate that the phase stability of Gd{sub 2}Zr{sub 2}O{sub 7} is not very sensitive to the degree of atomic disorder in the pyrochlore structure.

Photoluminescence properties of blue light excited Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:Eu{sup 3+} red phosphors

Energy Technology Data Exchange (ETDEWEB)

Fang, Yongzheng; Liu, Fengxin; Hou, Jingshan; Zhang, Yan; Zheng, Xinfeng; Zhang, Na [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Zhao, Guoying, E-mail: zhaogy135@sit.edu.cn [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China); Liao, Meisong [Key Laboratory of Materials for High Powder Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Dai, Guozhang; Long, Mengqiu [School of Physics and Electronics, Central South University, Changsha, Hunan 410083 (China); Liu, Yufeng, E-mail: yfliu@mail.sitp.ac.cn [School of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418 (China)

2016-09-15

A series of red emitting Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:xEu{sup 3+} (0≤x≤0.4) phosphors were synthesized by the conventional solid state reaction, and their photoluminescence properties were investigated in this work. Upon excitation of blue light, the Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:xEu{sup 3+} phosphors exhibit strong red emission at 616 nm, which corresponds to the dominant transition of Eu{sup 3+} ions in Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2} host, originating from the electric dipole transition {sup 5}D{sub 0}–{sup 7}F{sub 2}. Moreover, Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:0.3Eu{sup 3+} phosphor shows more intense photoluminescence than that of other phosphors, where the concentration of Eu{sup 3+} ion is not equal to 0.3. The CIE chromaticity coordinate (0.657, 0.343) of Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:0.3Eu{sup 3+} phosphor is close to National Television Standard Committee standard value (0.670, 0.330) of red phosphors, which indicates Ca{sub 8}La{sub 2}(PO{sub 4}){sub 6}O{sub 2}:0.3Eu{sup 3+} is potential to apply in white light-emitting diodes as an excellent red emitting phosphor.

An efficient visible and UV-light-activated B-N-codoped TiO{sub 2} photocatalytic film for solar depollution prepared via a green method

Energy Technology Data Exchange (ETDEWEB)

Xu Qingchi; Zhang Yan; He Ziming [Nanyang Technological University, School of Chemical and Biomedical Engineering (Singapore); Loo, Say Chye Joachim, E-mail: joachimloo@ntu.edu.sg [Nanyang Technological University, School of Materials Science and Engineering (Singapore); Tan, Timothy Thatt Yang, E-mail: tytan@ntu.edu.sg [Nanyang Technological University, School of Chemical and Biomedical Engineering (Singapore)

2012-08-15

This work reports an efficient visible and UV-light-activated boron and nitrogen codoped TiO{sub 2} porous film prepared via a 'green' and direct coating approach. Such photocatalyst is highly promising for solar depollution application due to its efficient photocatalytic activities in both visible and UV spectrum. The preparation method avoids the use of organic solvents, which are usually more expensive and hazardous compared with water. Using stearic acid as the model organic pollutant, the visible-light photocatalytic activity of optimized porous B-N-codoped TiO{sub 2} film (p-3B-N-TiO{sub 2}) is 3 times higher than that of porous N-doped TiO{sub 2} (p-N-TiO{sub 2}) film, while its UV photocatalytic activity is almost double that of p-N-TiO{sub 2} film and comparable to that of porous TiO{sub 2}. The enhancement in photocatalytic activity is attributed to higher surface area due to the porous structure, improved visible-light absorption attributed to interstitially substituted boron atoms, and coexistence of boron and nitrogen dopants which may reduce Ti{sup 3+} recombination centers.

Assessment of undiscovered conventionally recoverable petroleum resources of the Arabian-Iranian Basin

Science.gov (United States)

Masters, Charles D.; Klemme, H. Douglas; Coury, Anny B.

1982-01-01

The estimates of undiscovered conventionally recoverable petroleum resources in the Arabian-Iranian basin at probability levels of 95 percent, 5 percent, and statistical mean are for oil (in billions of barrels): 72, 337, and 174; and for gas (in trillions of cubic feet): 299, 1792, and 849. The occurrence of petroleum can be accounted for in five definitive geological settings or plays. The assessment of undiscovered resource potential assumes that the new discoveries will expand the occurrence of petroleum in these basic plays; no additional plays with significant petroleum potential were recognized. The five plays listed by geologic age are: (I) Upper Cretaceous and Tertiary, (II) Lower and Middle Cretaceous sandstone, (III) Lower and Middle Cretaceous limestone, (IV) Jurassic, and (V) Permian. The Permian play, located in the south-central Arabian Gulf region and extending northeast-southwest from southern Iran to the Ar Rub' al Khali in Saudi Arabia, accounts for over four-fifths of the mean estimate of undiscovered gas. The remainder of the gas is divided about equally among the other four plays. The Jurassic play, located on the south side of the Arabian Gulf, accounts for slightly less than one-third of the estimated undiscovered oil, which is split equally between Saudi Arabia and Iraq. The Lower and Middle Cretaceous limestone play is located in the southern Gulf region and accounts for about one-fifth of the undiscovered oil, most of which is located in Saudi Arabia and the remainder in the United Arab Emirates. The Lower and Middle Cretaceous sandstone play is centralized in Kuwait at the head of the Arabian Gulf with significant potential extending to the northwest in Iraq; the play accounts for about one-third of the undiscovered oil, the great majority of which is estimated to be in Iraq with the remainder divided between Saudi Arabia and Kuwait. The upper Cretaceous-Tertiary play is located in the Zagros fold belt of Iran and Iraq and accounts for

DOE translation tool: Faster and better than ever

International Nuclear Information System (INIS)

El-Chakieh, T.; Vincent, C.

2006-01-01

CAE's constant push to advance power plant simulation practices involves continued investment in our technologies. This commitment has yielded many advances in our simulation technologies and tools to provide faster maintenance updates, easier process updates and higher fidelity models for power plant simulators. Through this quest, a comprehensive, self-contained and user-friendly DCS translation tool for plant control system emulation was created. The translation tool converts an ABB Advant AC160 and/or AC450 control system, used in both gas turbine-based, fossil and nuclear power plants, into Linux or Windows-based ROSE[reg] simulation schematics. The translation for a full combined-cycle gas turbine (CCGT) plant that comprises more than 5,300 function plans distributed over 15 nodes is processed in less than five hours on a dual 2.8Ghz Xeon Linux platform in comparison to the 12 hours required by CAE's previous translation tool. The translation process, using the plant configuration files, includes the parsing of the control algorithms, the databases, the graphic and the interconnection between nodes. A Linux or Windows API is then used to automatically populate the ROSE[reg] database. Without such a translation, tool or if ?stimulation? of real control system is not feasible or too costly, simulation of the DCS manually takes months of error prone manual coding. The translation can be performed for all the nodes constituting the configuration files of the whole plant DCS, or in order to provide faster maintenance updates and easier process updates, partial builds are possible at 3 levels: a. single schematic updates, b. multi-schematic updates and c. single node updates based on the user inputs into the Graphical User Interface. improvements including: - Process time reduction of over 60%; - All communication connections between nodes are fully automated; - New partial build for one schematic, a group of schematics or a single node; - Availability on PC

Precise atomic-scale investigations of material sputtering process by light gas ions in pre-threshold energy region

CERN Document Server

Suvorov, A L

2002-01-01

Foundation and prospects of the new original technique of the sputtering yield determination of electro-conducting materials and sub-atomic layers on their surface by light gas ions the pre-threshold energy region (from 10 to 500 eV) are considered. The technique allows to identify individual surface vacancies, i.e., to count individual sputtered atoms directly. A short review of the original results obtained by using the developed techniques is given. Data are presented and analyzed concerning energy thresholds of the sputtering onset and energy dependences of sputtering yield in the threshold energy region for beryllium, tungsten, tungsten oxide, alternating tungsten-carbon layers, three carbon materials as well as for sub-atomic carbon layers on surface of certain metals at their bombardment by hydrogen, deuterium and/or helium ions

Synthesis and visible-light-driven photocatalytic activity of p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} nanocubes

Energy Technology Data Exchange (ETDEWEB)

Yang, Songbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Xu, Dongbo [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Biyi; Luo, Bifu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Yan, Xu [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013 (China); Xiao, Lisong, E-mail: xiaolisong123@sina.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China); Shi, Weidong, E-mail: swd1978@ujs.edu.cn [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 212013 (China)

2016-10-15

Highlights: • We firstly report a facile way to prepare the visible-light-driven Ag{sub 2}O/NaTaO{sub 3}p–n heterojunction by chemical precipitation method. • The Ag{sub 2}O/NaTaO{sub 3} heterojunction shows the highest photocatalytic activity than the pure NaTaO{sub 3} and Ag{sub 2}O nanoparticles under visible light. • The enhancement of the heterojunction photocatalytic activity was discussed and the photocatalytic mechanism was tested in our paper. • In summary, we think that the Ag{sub 2}O/NaTaO{sub 3} heterojunction with the strong visible light absorption and efficient photocatalytic activity have been extended application in photocatalysis for organic dyes pollutants degradation and purification of water. - Abstract: The constructing of p–n heterojunction photocatalytic system has received much attention in environmental purification and hydrogen generation from water. In this study, an efficient visible-light-driven p–n heterojunction Ag{sub 2}O/NaTaO{sub 3} was successfully prepared by chemical precipitation method at room temperature. It showed an enhanced photocatalytic activity for the degradation of rhodamine B (RhB) under visible-light irradiation, much higher than those of either individual Ag{sub 2}O or NaTaO{sub 3}. The reactive species scavenger results indicated the superoxide anion radicals (·O{sup 2−}) played key roles in RhB decoloration. From the experimental results and the relative band gap position of these semiconductors, a detailed possible photocatalytic mechanism of the Ag{sub 2}O/NaTaO{sub 3} heterojunction under visible light was proposed. The enhancement of the photocatalytic activity was attributed to the interfacial electronic interaction between NaTaO{sub 3} and Ag{sub 2}O and the high migration efficiency of photogenerated carriers.

Light localization in cold and dense atomic ensemble

International Nuclear Information System (INIS)

Sokolov, Igor

2017-01-01

We report on results of theoretical analysis of possibilities of light strong (Anderson) localization in a cold atomic ensemble. We predict appearance of localization in dense atomic systems in strong magnetic field. We prove that in absence of the field the light localization is impossible. (paper)

Synthesis and structure of Li{sub 4}GeS{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Y [National Inst. of Materials and Chemical Research, Tsukuba (Japan). High Pressure Lab.; Kanatzidis, M G [Michigan State Univ., East Lansing, MI (United States). Dept. of Chemistry

1998-01-01

The compound Li{sub 4}GeS{sub 4} has been prepared as transparent, light yellow moisture-sensitive crystals. Li{sub 4}GeS{sub 4} belongs to the space group Pnma with a = 14.107(6) A, b = 7.770(3) A and c = 6.162(2) A. The crystal structure was solved by direct-methods. The final R and R{sub w}-values are 1.85 and 1.65% for 866 observed reflections. The Li{sub 4}GeS{sub 4} structure has three crystallographically independent lithium sites and one germanium site. The lithium atoms adopt two different coordination types. The Li1 atom is coordinated to five sulfur atoms in a square pyramidal geometry, while the Li2 and Li3 atoms have distorted tetrahedral coordination. The Ge atom is tetrahedrally coordinated by four sulfur atoms and is found as [GeS{sub 4}]{sup 4-} units. The anisotropic three-dimensional crystal structure of Li{sub 4}GeS{sub 4} is described. (orig.) 57 refs.

X-ray diffraction analysis of LiCu{sub 2}O{sub 2} crystals with additives of silver atoms

Energy Technology Data Exchange (ETDEWEB)

Sirotinkin, V. P., E-mail: irotinkin.vladimir@mail.ru; Bush, A. A.; Kamentsev, K. E. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Dau, H. S. [People’s Friendship University of Russia (Russian Federation); Yakovlev, K. A. [Moscow State Technical University of Radio Engineering, Electronics, and Automation (Russian Federation); Tishchenko, E. A. [People’s Friendship University of Russia (Russian Federation)

2015-09-15

Silver-containing LiCu{sub 2}O{sub 2} crystals up to 4 × 8 × 8 mm in size were grown by the crystallization of 80(1-x)CuO · 20{sub x}AgNO{sub 3} · 20Li{sub 2}CO{sub 3} (0 ≤ x ≤ 0.5) mixture melt. According to the X-ray spectral and Rietveld X-ray diffraction data, the maximum amount of silver incorporated in the LiCu{sub 2}O{sub 2} structure is about 4 at % relative to the copper content. It was established that silver atoms occupy statistically crystallographic positions of lithium atoms. The incorporation of silver atoms is accompanied by a noticeable increase in parameter c of the LiCu{sub 2}O{sub 2} rhombic unit cell, a slight increase in parameter a, and a slight decrease in parameter b.

High resolution X-ray spectroscopy in light antiprotonic atoms

CERN Document Server

Borchert, G L; Augsburger, M A; Castelli, C M; Chatellard, D; Egger, J P; El-Khoury, P; Elble, M; Gorke, H; Gotta, D; Hauser, P R; Indelicato, P J; Kirch, K; Lenz, S; Nelms, N; Rashid, K; Schult, O W B; Siems, T; Simons, L M

2000-01-01

At the LEAR facility, CERN, antiprotonic L alpha transitions in light elements have been investigated with a focussing crystal spectrometer. The high resolution of the experiment allowed for the first time to resolve in pH/pH the 2/sup 3/P/sub 0/ state from the close-lying states 2/sup 3/P/sub 2/, 2/sup 1/P/sub 1/, and 2/sup 3/P /sub 1/. In pD the corresponding transitions were found to be more than an order of magnitude broader. To a large extent the results for pH support the meson exchange model. (15 refs).

A practical pathway for the preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} photocatalyst with enhanced visible-light photoactivity

Energy Technology Data Exchange (ETDEWEB)

Cheng, Li; Qiu, Shoufei [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Chen, Juanrong, E-mail: Juanrongchen@ujs.edu.cn [School of Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013 (China); Shao, Jian [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China); Cao, Shunsheng, E-mail: sscaochem@hotmail.com [Institute of Polymer Materials, School of Materials Science and Engineering, Jiangsu University, Zhenjiang 212013 (China)

2017-04-01

Shifting the ultra-violet of titania to visible light driven photocatalysis can be realized by coupling with metallic or non-metallic elements. However, time-consuming multi-step process and significant loss of UV photocatalytic activity of such TiO{sub 2}-based photocatalysts severely hinder their practical applications. In this work, we explore the idea of creating a practical method for the preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} (TiO{sub 2}/Fe{sub 2}O{sub 3}) photocatalyst with controlled visible-light photoactivity. This method only involves the calcination of the mixture (commercial P25 powders and magnetic Fe{sub 3}O{sub 4} nanoparticles) prepared by a mechanical process. The morphology and properties of TiO{sub 2}/Fe{sub 2}O{sub 3} composites were characterized by Transmission electron microscope, X-ray diffraction, UV–vis spectroscopy, and X-ray photoelectron spectroscopy. Results confirm the fusion of TiO{sub 2} and Fe{sub 2}O{sub 3}, which promotes photo-generated electrons/holes migration and separation. Because of the strong synergistic effect, the as-synthesized TiO{sub 2}/Fe{sub 2}O{sub 3} composites manifest an enhanced visible-light photocatalytic activity. Especially, the TiO{sub 2}/Fe{sub 2}O{sub 3} photocatalyst is very easy to be constructed via an one-step protocol that efficiently overcomes the time-consuming multi-step processes used in existed strategies for the preparation of Fe{sub 2}O{sub 3}/TiO{sub 2} photocatalysts, providing a new insight into the practical application of TiO{sub 2}/Fe{sub 2}O{sub 3} visible light photocatalyst. - Highlights: • We introduced a practical preparation of Fe{sub 2}O{sub 3} decorated TiO{sub 2} photocatalyst. • TiO{sub 2}/Fe{sub 2}O{sub 3} was developed using commercial precursors in a high efficient manner. • Visible-light activity of TiO{sub 2}/Fe{sub 2}O{sub 3} could be tuned by changing amount of Fe{sub 3}O{sub 4} precursor. • TiO{sub 2}/Fe{sub 2}O{sub 3} exhibited a higher

Sub-atomic resolution X-ray crystallography and neutron crystallography: promise, challenges and potential.

Science.gov (United States)

Blakeley, Matthew P; Hasnain, Samar S; Antonyuk, Svetlana V

2015-07-01

The International Year of Crystallography saw the number of macromolecular structures deposited in the Protein Data Bank cross the 100000 mark, with more than 90000 of these provided by X-ray crystallography. The number of X-ray structures determined to sub-atomic resolution (i.e. ≤1 Å) has passed 600 and this is likely to continue to grow rapidly with diffraction-limited synchrotron radiation sources such as MAX-IV (Sweden) and Sirius (Brazil) under construction. A dozen X-ray structures have been deposited to ultra-high resolution (i.e. ≤0.7 Å), for which precise electron density can be exploited to obtain charge density and provide information on the bonding character of catalytic or electron transfer sites. Although the development of neutron macromolecular crystallography over the years has been far less pronounced, and its application much less widespread, the availability of new and improved instrumentation, combined with dedicated deuteration facilities, are beginning to transform the field. Of the 83 macromolecular structures deposited with neutron diffraction data, more than half (49/83, 59%) were released since 2010. Sub-mm(3) crystals are now regularly being used for data collection, structures have been determined to atomic resolution for a few small proteins, and much larger unit-cell systems (cell edges >100 Å) are being successfully studied. While some details relating to H-atom positions are tractable with X-ray crystallography at sub-atomic resolution, the mobility of certain H atoms precludes them from being located. In addition, highly polarized H atoms and protons (H(+)) remain invisible with X-rays. Moreover, the majority of X-ray structures are determined from cryo-cooled crystals at 100 K, and, although radiation damage can be strongly controlled, especially since the advent of shutterless fast detectors, and by using limited doses and crystal translation at micro-focus beams, radiation damage can still take place. Neutron

Sub-atomic resolution X-ray crystallography and neutron crystallography: promise, challenges and potential

Directory of Open Access Journals (Sweden)

Matthew P. Blakeley

2015-07-01

Full Text Available The International Year of Crystallography saw the number of macromolecular structures deposited in the Protein Data Bank cross the 100000 mark, with more than 90000 of these provided by X-ray crystallography. The number of X-ray structures determined to sub-atomic resolution (i.e. ≤1 Å has passed 600 and this is likely to continue to grow rapidly with diffraction-limited synchrotron radiation sources such as MAX-IV (Sweden and Sirius (Brazil under construction. A dozen X-ray structures have been deposited to ultra-high resolution (i.e. ≤0.7 Å, for which precise electron density can be exploited to obtain charge density and provide information on the bonding character of catalytic or electron transfer sites. Although the development of neutron macromolecular crystallography over the years has been far less pronounced, and its application much less widespread, the availability of new and improved instrumentation, combined with dedicated deuteration facilities, are beginning to transform the field. Of the 83 macromolecular structures deposited with neutron diffraction data, more than half (49/83, 59% were released since 2010. Sub-mm3 crystals are now regularly being used for data collection, structures have been determined to atomic resolution for a few small proteins, and much larger unit-cell systems (cell edges >100 Å are being successfully studied. While some details relating to H-atom positions are tractable with X-ray crystallography at sub-atomic resolution, the mobility of certain H atoms precludes them from being located. In addition, highly polarized H atoms and protons (H+ remain invisible with X-rays. Moreover, the majority of X-ray structures are determined from cryo-cooled crystals at 100 K, and, although radiation damage can be strongly controlled, especially since the advent of shutterless fast detectors, and by using limited doses and crystal translation at micro-focus beams, radiation damage can still take place

Rational construction of Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with enhanced visible-light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Luo, Jin, E-mail: lj328520504@126.com; Zhou, Xiaosong; Ma, Lin; Xu, Xuyao

2016-12-30

Highlights: • Novel visible-light driven Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites were synthesized. • Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} exhibited enhanced visible-light photocatalytic activity. • The reasons for the enhanced photocatalytic activity were revealed. - Abstract: Novel visible-light driven Z-scheme Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites with different contents of Ag{sub 2}CrO{sub 4} were fabricated by a facile chemical precipitation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL) spectroscopy and photoelectrochemical measurements. Compared with individual g-C{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 4}, the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composites displayed much larger photocatalytic activities for the photocatalytic degradation of methyl orange (MO) solution at room temperature under visible light irradiation (λ > 420 nm). Importantly, the optimum photodegradation rate constant of the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite at a theoretical weight content of 8.0% Ag{sub 2}CrO{sub 4} for the photodegradation of MO was 0.0068 min{sup −1}, which was 5.7 and 4.3 times higher than that of pure g-C{sub 3}N{sub 4} and Ag{sub 2}CrO{sub 4}, respectively. Such enormous enhancement in photocatalytic performance was predominantly ascribed to the efficient separation and transfer of photogenerated electrons and holes at the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} interface imparted through the Z-scheme electron transfer. Furthermore, radical trap experiments depicted that both the holes and superoxide radical anions were thought to dominate oxidative species of the Ag{sub 2}CrO{sub 4}/g-C{sub 3}N{sub 4} composite for MO degradation under visible light irradiation. Ultimately, a tentative Z-scheme photodegradation mechanism

Facile synthesis of CNTs/CaIn{sub 2}S{sub 4} composites with enhanced visible-light photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Xia, Yang; Li, Qin, E-mail: liqin0518@mail.scuec.edu.cn; Wu, Xiaofeng; Lv, Kangle; Tang, Dingguo; Li, Mei, E-mail: limei@mail.scuec.edu.cn

2017-01-01

Highlights: • CNTs/CaIn{sub 2}S{sub 4} (CIS) composites were prepared by a microwave hydrothermal method. • CNTs were embedded tightly in the hierarchical marigold-like CIS microspheres. • Intimate contact between CNTs and CIS made interfacial charge transfer available. • The composite exhibited obviously higher photocatalytic activity than bare CIS. • The composite was applicable in both environment remediation and energy conversion. - Abstract: In response to the continuous concerns to environmental contamination and energy crisis, visible-light-driven photocatalysis has attracted broad attention for its potential applications in environment remediation and energy conversion. In this study, visible-light-responsive CNTs/CaIn{sub 2}S{sub 4} (CIS) composite photocatalyst was designed and synthesized by a facile one-step microwave hydrothermal method. The effects of CNTs content on the crystallinity, structure, light absorption, specific surface area and photocatalytic performance of CIS semiconductor were systematically studied. The results demonstrated that the prepared composite with a suitable amount of CNTs exhibited an apparently enhanced photocatalytic activity than bare CIS for both X-3B dye degradation and H{sub 2} production under visible-light irradiation. The optimal content of CNTs was found to be 1 wt%. The corresponding apparent rate constants of photocatalytic degradation and H{sub 2}-production rate are about two times as that of bare CaIn{sub 2}S{sub 4} semiconductor. Comprehensive analysis demonstrated that such enhancement was mainly attributed to the strong coupling interface between CNTs and CIS, which largely improved the separation efficiency of photogenerated charge carriers in space. However, excessive CNTs resulted in a decreased photocatalytic activity due to the shield of active sites and absorbed photons on the surface of CIS photocatalyst. This work could shed new light on the design and synthesis of carbon material

A facile fabrication of nitrogen-doped electrospun In{sub 2}O{sub 3} nanofibers with improved visible-light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Lu, Na; Shao, Changlu, E-mail: clshao@nenu.edu.cn; Li, Xinghua, E-mail: lixh781@nenu.edu.cn; Miao, Fujun; Wang, Kexin; Liu, Yichun

2017-01-01

Highlights: • N-doped In{sub 2}O{sub 3} nanofibers are facilely fabricated by gaseous ammonia treatment. • Adjusting the annealing temperature leads to different N-doped In{sub 2}O{sub 3} nanofibers. • Nitrogen doping was found to be interstitial mode. • N-In{sub 2}O{sub 3} exhibited effective charge carrier separation and photocatalytic activity. • The photocatalysts can be easily separated from the reaction system. - Abstract: Semiconductor photocatalysis demonstrates to be an effective approach for eliminating most types of environment contaminants and for producing hydrogen. Herein, a facile synthesis route combining electrospinning technique and thermal treatment method under NH{sub 3} atmosphere has been presented as a straightforward protocol for the fabrication of nitrogen-doped In{sub 2}O{sub 3} (N-In{sub 2}O{sub 3}) nanofibers, the nitrogen content of which can be well controlled by adjusting the annealing temperature. Photocatalytic tests show that the N-In{sub 2}O{sub 3} nanofibers demonstrate an improved degradation rate of Rhodamine B (RB) compared with pure In{sub 2}O{sub 3} nanofibers under visible-light irradiation. This can be attributed to the nitrogen atom introducing at interstitial sites as well as the generation of oxygen vacancy on the surface of In{sub 2}O{sub 3} nanofibers, resulting in the enhanced utilization of visible light for the N-In{sub 2}O{sub 3} nanofibers. Furthermore, the obtained N-In{sub 2}O{sub 3} nanofibers with the advantage of ultra-long one-dimensional nanostructures can be recycled several times by facile sedimentation and hence present almost no decrease in photocatalytic activity indicative of a well regeneration capability. Therefore, the as-fabricated nitrogen-doped In{sub 2}O{sub 3} nanofibers as a promising photocatalyst present good photocatalytic degradation of organic pollutant in waste water for practical application.

Efficient solar light harvesting CdS/Co{sub 9}S{sub 8} hollow cubes for Z-scheme photocatalytic water splitting

Energy Technology Data Exchange (ETDEWEB)

Qiu, Bocheng; Zhu, Qiaohong; Du, Mengmeng; Fan, Linggang; Xing, Mingyang; Zhang, Jinlong [Key Lab. for Advanced Materials and Inst. of Fine Chemicals, School of Chemistry and Molecular Engineering, East China Univ. of Science and Technology, Shanghai (China)

2017-03-01

Hollow structures with an efficient light harvesting and tunable interior component offer great advantages for constructing a Z-scheme system. Controlled design of hollow cobalt sulfide (Co{sub 9}S{sub 8}) cubes embedded with cadmium sulfide quantum dots (QDs) is described, using hollow Co(OH){sub 2} as the template and a one-pot hydrothermal strategy. The hollow CdS/Co{sub 9}S{sub 8} cubes utilize multiple reflections of light in the cubic structure to achieve enhanced photocatalytic activity. Importantly, the photoexcited charge carriers can be effectively separated by the construction of a redox-mediator-free Z-scheme system. The hydrogen evolution rate over hollow CdS/Co{sub 9}S{sub 8} is 134 and 9.1 times higher than that of pure hollow Co{sub 9}S{sub 8} and CdS QDs under simulated solar light irradiation, respectively. Moreover, this is the first report describing construction of a hollow Co{sub 9}S{sub 8} based Z-scheme system for photocatalytic water splitting, which gives full play to the advantages of light-harvesting and charges separation. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Fullerene C{sub 70} decorated TiO{sub 2} nanowires for visible-light-responsive photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Cho, Er-Chieh [Department of Clinical Pharmacy, School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110, Taiwan (China); Ciou, Jing-Hao [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Zheng, Jia-Huei; Pan, Job [Department of Clinical Pharmacy, School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei 110, Taiwan (China); Hsiao, Yu-Sheng, E-mail: yshsiao@mail.mcut.edu.tw [Department of Materials Engineering, Ming Chi University of Technology, New Taipei City 24301, Taiwan (China); Lee, Kuen-Chan, E-mail: kclee@kmu.edu.tw [Department of Fragrance and Cosmetic Science, Kaohsiung Medical University, Kaohsiung 80708, Taiwan (China); Huang, Jen-Hsien, E-mail: 295604@cpc.com.tw [Department of Green Material Technology, Green Technology Research Institute, CPC Corporation, Kaohsiung 30010, Taiwan (China)

2015-11-15

Graphical abstract: - Highlights: • TiO{sub 2} nanowire decorated with C{sub 60} and C{sub 70} derivatives has been synthesized. • The fullerenes impede the charge recombination due to its high electron affinity. • The fullerenes expand the utilization of solar light from UV to visible light. • The modified-TiO{sub 2} has great biocompatibility. - Abstract: In this study, we have synthesized C{sub 60} and C{sub 70}-modified TiO{sub 2} nanowire (NW) through interfacial chemical bonding. The results indicate that the fullerenes (C{sub 60} and C{sub 70} derivatives) can act as sinks for photogenerated electrons in TiO{sub 2}, while the fullerene/TiO{sub 2} is illuminated under ultraviolet (UV) light. Therefore, in comparison to the pure TiO{sub 2} NWs, the modified TiO{sub 2} NWs display a higher photocatalytic activity under UV irradiation. Moreover, the fullerenes also can function as a sensitizer to TiO{sub 2} which expand the utilization of solar light from UV to visible light. The results reveal that the C{sub 70}/TiO{sub 2} NWs show a significant photocatalytic activity for degradation of methylene blue (MB) in visible light region. To better understand the mechanism responsible for the effect of fullerenes on the photocatalytic properties of TiO{sub 2}, the electron only devices and photoelectrochemical cells based on fullerenes/TiO{sub 2} are also fabricated and evaluated.

Growth of nicotiana in response to atmospheric CO sub 2 enrichment and various light regimes

Energy Technology Data Exchange (ETDEWEB)

Pope, S.; Thomas, J.F. (North Carolina State Univ., Raleigh (USA))

1989-04-01

Nicotiana tabacum NCTG-22, N. tabacum Petite Havana and N. plumbaginifolia were grown in chambers (24 C, 12-h light) under daytime atmospheric CO{sub 2} levels of 340 ppm (ambient) or 1000 ppm (enriched). All 3 types of tobacco grew faster and had open flowers sooner under CO2 enrichment, but patterns of dry weight distribution varied with type of tobacco. In N. plumbaginifolia significant proportions of dry weight were allocated to stems and branches, while in tabacum types, less was allocated to stems and more to leaves and roots. Increases in dry weight due to CO2 enrichment were accompanied by increases in leaf area and thickness. Plants given a far-red low intensity night break exhibited few differences from controls except having thinner leaves under ambient CO2; but under enriched CO2, had greater total dry weight and thicker leaves containing a higher proportion of spongy mesophyll than controls. A 50% reduction in light intensity led to a comparable reduction in dry weight and leaf area across treatments.

Heavy and light ion irradiation damage effects in δ-phase Sc{sub 4}Hf{sub 3}O{sub 12}

Energy Technology Data Exchange (ETDEWEB)

Wen, J. [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000 (China); Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Li, Y.H., E-mail: liyuhong@lzu.edu.cn [School of Nuclear Science and Technology, Lanzhou University, Lanzhou, Gansu 730000 (China); Tang, M.; Valdez, J.A.; Wang, Y.Q. [Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Patel, M.K.; Sickafus, K.E. [Department of Materials Science & Engineering, The University of Tennessee, Knoxville, TN 37996 (United States)

2015-12-15

Polycrystalline δ-phase Sc{sub 4}Hf{sub 3}O{sub 12} was irradiated with light and heavy ions to study the radiation stability of this compound. In order to explore the ion species spectrum effect, the irradiations were performed with 400 keV Ne{sup 2+} ions to fluences ranging from 1 × 10{sup 14} to 1 × 10{sup 15} ions/cm{sup 2}, 600 keV Kr{sup 3+} ions to fluences ranging from 5 × 10{sup 14} to 5 × 10{sup 15} ions/cm{sup 2}, and 6 MeV Xe{sup 26+} ions to fluences ranging from 2 × 10{sup 13} to 1 × 10{sup 15} ions/cm{sup 2}. Irradiated samples were characterized by various techniques including grazing incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). A complete phase transformation from ordered rhombohedral to disordered fluorite was observed by a fluence of 1 × 10{sup 15} ions/cm{sup 2} with 400 keV Ne{sup 2+} ions, equivalent to a peak ballistic damage dose of ∼0.33 displacements per atom (dpa). Meanwhile, the same transformation was also observed by 600 keV Kr{sup 3+} ions at the same fluence of 1 × 10{sup 15} ions/cm{sup 2}, which however corresponds to a peak ballistic damage dose of ∼2.2 dpa. Only a partial O-D transformation was observed for 6 MeV Xe{sup 26+} ions in the fluence range used. Experimental results indicated that the O-D transformation is observed under both electronic and nuclear stopping dominant irradiation regimes. It was also observed that light ions are more efficient than heavy ions in producing the retained defects that are presumably responsible for the O-D phase transformation. The O-D transformation mechanism is discussed in the context of anion oxygen Frenkel defects and cation antisite defects. We concluded that the irradiation induced O-D transformation is easier to occur in δ-phase compounds with partial order of cations than in that with fully disordered cation structures.

Atomic displacements effects on the electronic properties of Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}

Energy Technology Data Exchange (ETDEWEB)

Camargo M, J. A. [Fundacion Universitaria Internacional del Tropico Americano, Grupo de Investigacion en Ciencias Basicas, Aplicacion e Innovacion, Carrera 19 No. 39-40, Yopal, Yopal (Colombia); Espitia, D.; Baquero, R., E-mail: jcamargo@unitropico.edu.co [Instituto Politecnico Nacional, Centro de Investigacion y de Estudios Avanzados, Departamento de Fisica, Av. IPN 2508, 07360 Mexico D. F. (Mexico)

2015-07-01

The displacements effects of the oxygen atom associated to the Sr-plane (O3) in the electronic properties of Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} (Bi-2223), have been investigated using density functional theory. We determined intervals of the O3 atomic positions for which the band structure calculations show that the Bi-O bands, around the high symmetry point M in the irreducible Brillouin zone, emerge towards higher energies avoiding its contribution at Fermi level, as experimentally has been reported. This procedure does not introduce foreign doping elements into the calculation. Our calculations present a good agreement with the angle-resolved photoemission spectroscopy and nuclear magnetic resonance (NMR) experiments. The two options found differ in character (metallic or nonmetallic) of the Bi-O plane. The are not any experiments, to the best of our knowledge, which determine this character for Bi-2223. (Author)

Atomic Parity Violation Overview and Perspectives

CERN Document Server

CERN. Geneva. Audiovisual Unit

2002-01-01

Optical experiments have demonstrated cases in which mirror symmetry in stable atoms is broken during absorption or emission of light. Such results are in conflict with standard electromagnetic (EM) theory, but can be explained within the unified electroweak theory. Their interpretation is based on exchanges of virtual weak neutral Z_0 bosons between the electrons and the atomic nucleus. These effects were predicted to increase in heavy atoms a little faster than the cube of the atomic number. Moreover, in a highly forbidden transition, like the 6S-7S transition in cesium, the EM interaction is suppressed, leaving the Z_0 exchange a chance to show up. For achieving the determination of the Cs nucleus weak charge, Q_W(Cs), the basic experimental parameter playing in Z_0, exchange the same role as the nuclear charge in the Coulomb interaction, both experimental and theoretical hurdles had to be overcome: first, the excitation and detection of an atomic line with a transition rate about 10^{14} times less than a...

Atomic layer deposition of boron-containing films using B{sub 2}F{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Mane, Anil U., E-mail: amane@anl.gov; Elam, Jeffrey W. [Argonne National Laboratory, Argonne, Illinois 60126 (United States); Goldberg, Alexander; Halls, Mathew D. [Schrödinger, Inc., San Diego, California 92122 (United States); Seidel, Thomas E. [Seitek50, Palm Coast, Florida 32135 (United States); Current, Michael I. [Current Scientific, San Jose, California 95124 (United States); Despres, Joseph; Byl, Oleg; Tang, Ying; Sweeney, Joseph [Entegris, Danbury, Connecticut 06810 (United States)

2016-01-15

Ultrathin and conformal boron-containing atomic layer deposition (ALD) films could be used as a shallow dopant source for advanced transistor structures in microelectronics manufacturing. With this application in mind, diboron tetrafluoride (B{sub 2}F{sub 4}) was explored as an ALD precursor for the deposition of boron containing films. Density functional theory simulations for nucleation on silicon (100) surfaces indicated better reactivity of B{sub 2}F{sub 4} in comparison to BF{sub 3}. Quartz crystal microbalance experiments exhibited growth using either B{sub 2}F{sub 4}-H{sub 2}O for B{sub 2}O{sub 3} ALD, or B{sub 2}F{sub 4}-disilane (Si{sub 2}H{sub 6}) for B ALD, but in both cases, the initial growth per cycle was quite low (≤0.2 Å/cycle) and decreased to near zero growth after 8–30 ALD cycles. However, alternating between B{sub 2}F{sub 4}-H{sub 2}O and trimethyl aluminum (TMA)-H{sub 2}O ALD cycles resulted in sustained growth at ∼0.65 Å/cycle, suggesting that the dense –OH surface termination produced by the TMA-H{sub 2}O combination enhances the uptake of B{sub 2}F{sub 4} precursor. The resultant boron containing films were analyzed for composition by x-ray photoelectron spectroscopy, and capacitance measurements indicated an insulating characteristic. Finally, diffused boron profiles less than 100 Å were obtained after rapid thermal anneal of the boron containing ALD film.

Interfacial reaction of Ni{sub 3}Sn{sub 4} intermetallic compound in Ni/SnAg solder/Ni system under thermomigration

Energy Technology Data Exchange (ETDEWEB)

Yang, Yi-Shan; Yang, Chia-Jung; Ouyang, Fan-Yi, E-mail: fyouyang@ess.nthu.edu.tw

2016-07-25

The growth of Ni{sub 3}Sn{sub 4} intermetallic compound (IMC) between liquid–solid interface in micro-scale Ni/SnAg/Ni system was investigated under a temperature gradient of 160 °C/cm at 260 °C on a hot plate. In contrast to a symmetrical growth of Ni{sub 3}Sn{sub 4} on both interfaces under isothermally annealed at 260 °C, the interfacial Ni{sub 3}Sn{sub 4} IMC exhibited asymmetric growth under a temperature gradient; the growth of Ni{sub 3}Sn{sub 4} at cold interface was faster than that at hot side because of temperature gradient induced mass migration of Ni atoms from the hot end toward the cold end. It was found that two-stage growth behavior of Ni{sub 3}Sn{sub 4} IMC under a temperature gradient. A growth model was established and growth kinetic analysis suggested that the chemical potential gradient controlled the growth of Ni{sub 3}Sn{sub 4} at stage I (0–120 min) whereas the dynamic equilibrium between chemical potential gradient and temperature gradient forces was attained at the hot end at stage II (120–210 min). When dynamic equilibrium was achieved at 260 °C, the critical length-temperature gradient product at the hot end was experimentally estimated to be 489.18 μm × °C/cm and the moving velocity of Ni{sub 3}Sn{sub 4} interface due to Ni consumption was calculated to be 0.134 μm/h. The molar heat of transport (Q*) of Ni atoms in molten SnAg solder was calculated to be +0.76 kJ/mol. - Highlights: • Interfacial reaction in Ni/SnAg solder/Ni system under thermal gradient. • Growth rate of Ni{sub 3}Sn{sub 4} at cold end is faster than that at hot end. • Critical length-temperature gradient product at hot end is 489.2 μm°C/cm at 260 °C. • Velocity of Ni{sub 3}Sn{sub 4} moving interface is 0.134 μm/h during dynamic equilibrium. • Molar heat of transport (Q*) of Ni in molten SnAg was +0.76 kJ/mol.

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

Tunable White-Light Emission in Single-Cation-Templated Three-Layered 2D Perovskites (CH <sub>3sub> CH <sub>2sub> NH <sub>3sub> ) <sub>4sub> Pb <sub>3sub> Br <sub>10–xsub> Cl <sub>x>

Energy Technology Data Exchange (ETDEWEB)

Mao, Lingling; Wu, Yilei; Stoumpos, Constantinos C.; Traore, Boubacar [Institut; Katan, Claudine [Institut; Even, Jacky [Fonctions; Wasielewski, Michael R.; Kanatzidis, Mercouri G.

2017-08-16

Two-dimensional (2D) hybrid halide perovskites come as a family (B)<sub>2sub>(A)>n-1sub>PbnX>3n+1sub> (B and A= cations; X= halide). These perovskites are promising semiconductors for solar cells and optoelectronic applications. Among the fascinating properties of these materials is white-light emission, which has been mostly observed in single-layered 2D lead bromide or chloride systems (n = 1), where the broad emission comes from the transient photoexcited states generated by self-trapped excitons (STEs) from structural distortion. Here we report a multilayered 2D perovskite (n = 3) exhibiting a tunable white-light emission. Ethylammonium (EA+) can stabilize the 2D perovskite structure in EA<sub>4sub>Pb>3sub>Br>10–xsub>Cl_x> (x = 0, 2, 4, 6, 8, 9.5, and 10) with EA⁺ being both the A and B cations in this system. Because of the larger size of EA, these materials show a high distortion level in their inorganic structures, with EA4Pb3Cl10 having a much larger distortion than that of EA<sub>4sub>Pb>3sub>Br>10sub>, which results in broadband white-light emission of EA<sub>4sub>Pb>3sub>Cl>10sub> in contrast to narrow blue emission of EA4Pb3Br10. The average lifetime of the series decreases gradually from the Cl end to the Br end, indicating that the larger distortion also prolongs the lifetime (more STE states). The band gap of EA<sub>4sub>Pb>3sub>Br>10–xsub>Cl_x> ranges from 3.45 eV (x = 10) to 2.75 eV (x = 0), following Vegard’s law. First-principles density functional theory calculations (DFT) show that both EA<sub>4sub>Pb>3sub>Cl>10sub> and EA<sub>4sub>Pb>3sub>Br>10sub> are direct band gap semiconductors. The color rendering index (CRI) of the series improves from 66 (EA<sub>4sub>Pb>3sub>Cl>10sub>) to 83 (EA<sub>4sub>Pb>3sub>Br>0.5sub>Cl>9.5sub>), displaying high tunability and versatility of the

Sub-half-wavelength atom localization via two standing-wave fields

International Nuclear Information System (INIS)

Jin Luling; Sun Hui; Niu Yueping; Gong Shangqing

2008-01-01

We propose a scheme for sub-half-wavelength atom localization in a four-level ladder-type atomic system, which is coupled by two classical standing-wave fields. We find that one of the standing-wave fields can help in enhancing the localization precision, and the other is of crucial importance in increasing the detecting probability and leading sub-half-wavelength localization

Effects of light on NO<sub>3sub> uptake in small forested streams: diurnal and day-to-day variations

Energy Technology Data Exchange (ETDEWEB)

Mulholland, Patrick J [ORNL

2006-08-01

We investigated the effects of autotrophy on short-term variations in nutrient dynamics by measuring diurnal and day-to-day variations in light level, primary productivity, and NO{sub 3}{sup -} uptake during early and late spring in 2 forested streams, the East and West Forks of Walker Branch in eastern Tennessee, USA. We predicted that diurnal and day-to-day variations in NO{sub 3}{sup -} uptake rate would be larger in the West Fork than in the East Fork in early spring because of higher rates of primary productivity resulting from a more stable substratum in the West Fork. We also predicted minimal diurnal variations in both streams in late spring after forest leaf emergence when light levels and primary productivity are uniformly low. Reach-scale rates of gross primary production (GPP) were determined using the diurnal dissolved O{sub 2} change technique, and reach-scale rates of NO{sub 3}{sup -} uptake were determined by tracer {sup 15}N-NO{sub 3}{sup -} additions. In the West Fork, significant diurnal and day-to-day variations in NO{sub 3}{sup -} uptake were related to variations in light level and primary productivity in early spring but not in late spring, consistent with our predictions. In early spring, West Fork NO{sub 3}{sup -} uptake rates were 2 to 3x higher at midday than during predawn hours and 50% higher on 2 clear days than on an overcast day several days earlier. In the East Fork, early spring rates of GPP were 4 to 5x lower than in the West Fork and diurnal and day-to-day variations in NO{sub 3}{sup -} uptake rates were <30%, considerably lower than in the West Fork. However, diurnal variations in NO{sub 3}{sup -} uptake rates were greater in late spring in the East Fork, possibly because of diurnal variation in water temperature. Our results indicate the important role of autotrophs in nutrient uptake in some forested streams, particularly during seasons when forest vegetation is dormant and light levels are relatively high. Our results also

Glomerular barrier behaves as an atomically precise bandpass filter in a sub-nanometre regime

Science.gov (United States)

Du, Bujie; Jiang, Xingya; Das, Anindita; Zhou, Qinhan; Yu, Mengxiao; Jin, Rongchao; Zheng, Jie

2017-11-01

The glomerular filtration barrier is known as a 'size cutoff' slit, which retains nanoparticles or proteins larger than 6-8 nm in the body and rapidly excretes smaller ones through the kidneys. However, in the sub-nanometre size regime, we have found that this barrier behaves as an atomically precise 'bandpass' filter to significantly slow down renal clearance of few-atom gold nanoclusters (AuNCs) with the same surface ligands but different sizes (Au18, Au15 and Au10-11). Compared to Au25 (∼1.0 nm), just few-atom decreases in size result in four- to ninefold reductions in renal clearance efficiency in the early elimination stage, because the smaller AuNCs are more readily trapped by the glomerular glycocalyx than larger ones. This unique in vivo nano-bio interaction in the sub-nanometre regime also slows down the extravasation of sub-nanometre AuNCs from normal blood vessels and enhances their passive targeting to cancerous tissues through an enhanced permeability and retention effect. This discovery highlights the size precision in the body's response to nanoparticles and opens a new pathway to develop nanomedicines for many diseases associated with glycocalyx dysfunction.

Destructive Interference in Coherent Backscattering of Light by an Ensemble of Cold Atoms

International Nuclear Information System (INIS)

Kupriyanov, D.V.; Larionov, N.V.; Sokolov, I.M.; Havey, M.D.

2005-01-01

The coherent backscattering of light by an ensemble of cold atoms located in a magneto-optical trap is investigated theoretically. The dependence of the gain coefficient on the probe frequency is analyzed in a wide spectral range covering the entire hyperfine structure of the excited state. The calculation is performed for 85 Rb atoms. It is found that destructive interference can be observed at certain frequencies, which results in gain coefficients smaller than unity. The angular distribution of scattered light is investigated for corresponding frequencies and the dependence of the shape of the cone of destructive interference on the size of the atomic cloud and its optical thickness is analyzed

TiO{sub 2} modified with Ag nanoparticles synthesized via ultrasonic atomization-UV reduction and the use of kinetic models to determine the acetic acid photocatalytic degradation

Energy Technology Data Exchange (ETDEWEB)

Xu, Yingcao, E-mail: xuyingcao@aliyun.com [State Key Laboratory of Urban Water Resource, Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China); Applied Chemistry Department, School of Science, Northeast Agriculture University, Harbin 150030 (China); You, Hong, E-mail: youhong@hit.edu.cn [State Key Laboratory of Urban Water Resource, Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090 (China)

2014-12-01

Highlights: • The first use of ultrasonic atomization-UV reduction for modifying Ag on TiO{sub 2}. • The first use of kinetics models for the establishment of the photocatalytic degradation of acetic acid using a hyperbolic mathematical model and introducing the concentration factor (α) in the dynamic model. • Photocatalytic experiment design using double-sided TiO{sub 2} and a double-light source. - Abstract: TiO{sub 2} surfaces modified with noble metal nanoparticles have been found to effectively reduce the photogenerated carrier recombination rate and significantly extend the light absorption properties of TiO{sub 2}, thereby greatly increasing its photocatalytic activity. In this paper, highly ordered, double-sided TiO{sub 2} nanotube arrays were prepared using an anodic oxidation method in a home-made reactor using glycerol/water (volume ratio 2:1) and NH{sub 4}F (0.25 mol/L) as the electrolyte, titanium plates (10 cm × 2 cm × 0.5 mm) as the anode and graphite as the cathode at a constant voltage of 25 V. After a 2-h reaction, anatase TiO{sub 2} nanotubes were obtained upon calcination at 450 °C for 4 h. The Ag nanoparticles on the surfaces of the TiO{sub 2} were prepared via ultrasonic atomization-ultraviolet light reduction. First, a silver nitrate solution was sputtered into small droplets under ultrasonication. Then, the Ag{sup +} droplets were reduced to Ag nanoparticles. The surface morphologies, structures and elemental compositions were characterized using SEM, EDS, XRD and XPS. The photocatalytic activities were determined in acetic acid solutions (40–200 mg/L), and a mathematical model for catalytic degradation was established based on a hyperbolic model. The SEM results showed that the diameters of the as-prepared Ag/TiO{sub 2} are approximately 100 nm and that the lengths are approximately 1.8 μm. The XRD crystal structure analysis shows that the anatase phase of the TiO{sub 2} does not change during the Ag modification, and there was

Possibility of faster-than-light particles with real mass

International Nuclear Information System (INIS)

Schommers, W.

1982-01-01

The author derives a new expression for the dependence of mass on velocity without using any space-time conception. This expression is more general than the corresponding law of the special theory of relativity (STR). The deviations from the STR increase with increasing rest mass. Thus one should measure the dependence of mass on velocity for particles (or systems) with a large rest mass. The theory predicts that particles with real mass can travel with hyperlight velocities. The space-time picture discussed here is very close to Mach's conception: it is assumed that the cause for the dynamical behaviour of a particle, which is in uniform translational motion, is due to the action of all the other masses in the universe. Space-time is eliminated as an active cause and, in contrast with the STR, space-time does not form an absolute continuum within the theory discussed here. It turns out that effects based on the transformation formulas (existing between the coordinates and time in a stationary frame and the coordinates and time in a moving frame) are identical to those expected from the Lorentz transformations. (Auth.)

Atomic structure of Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} bulk metallic glass alloy

Energy Technology Data Exchange (ETDEWEB)

Hui, X. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China)], E-mail: huixd01@hotmail.com; Fang, H.Z.; Chen, G.L. [State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Shang, S.L.; Wang, Y. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Qin, J.Y. [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University - Southern Campus, Jinan 250061 (China); Liu, Z.K. [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

2009-01-15

Ab initio molecular dynamics (AIMD) calculations were performed on the atomic configuration of Zr{sub 41.2}Ti{sub 13.8}Cu{sub 12.5}Ni{sub 10}Be{sub 22.5} bulk metallic glass. The local structures were characterized in terms of structure factors (SF), pair correlation functions (PCF), coordinate numbers, bond pairs and Voronoi polyhedra. The glass transition temperature, generalized PCF and SF predicated by AIMD are in good agreement with the experimental data. Icosahedral short-range orders (ISRO) are found to be the most dominant, in view of the presence of the majority of bond pairs with 1551, 1541 and 1431, and Voronoi polyhedra with <0,3,6,1>, <0,2,8,1>, <0,0,12,0> and <0,2,8,4>. Icosahedral medium range orders (IMROs) are formed from icosahedra via the linkage of vertex-, edge-, face- and intercross-shared atoms. The glass structure on the nanometer scale is accumulated by polyhedra through an efficient packing mode. It is suggested that the extraordinary glass-forming ability of this alloy is essentially attributable to the formation of ISRO and IMRO, and the dense packing of atoms.

Restoring locality with faster-than-light velocities

International Nuclear Information System (INIS)

Eberhard, P.H.

1993-01-01

The idea of ''locality'' is a deep rooted concept. It does not have to be abandoned even if ''loophole free'' EPR experiments are performed and confirm the predictions of quantum theory. To satisfy locality, one can imagine that influences at a distance are exerted via mechanisms involving an ether and effects propagating in that ether a velocity V > c. Such model of physical phenomena is not Lorentz invariant but, with V large enough, the model can be made to reproduce the results of all experiments where quantum mechanics and Lorentz invariance have been verified

Recombination of chlorine atoms on plasma-conditioned stainless steel surfaces in the presence of adsorbed Cl{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Stafford, Luc; Poirier, Jean-Sebastien; Margot, Joelle [Departement de Physique, Universite de Montreal, Montreal, Quebec, H3C 3J7 (Canada); Khare, Rohit; Guha, Joydeep; Donnelly, Vincent M, E-mail: luc.stafford@umontreal.c, E-mail: vmdonnelly@uh.ed [Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204 (United States)

2009-03-07

We investigated the interactions of atomic and molecular chlorine with plasma-conditioned stainless steel surfaces through both experiments and modelling. The recombination of Cl during adsorption and desorption of Cl{sub 2} was characterized using a rotating-substrate technique in which portions of the cylindrical substrate surface are periodically exposed to an inductively coupled chlorine plasma and then to an Auger electron spectrometer in separate, differentially pumped chambers. After several hours of exposure to the Cl{sub 2} plasma, the stainless steel substrate became coated with a Si-oxychloride-based layer (Fe : Si : O : Cl {approx} 1 : 13 : 13 : 3) due to chlorine adsorption and the erosion of the silica discharge tube. Desorption of Cl{sub 2} from this surface was monitored through measurements of pressure rises in the Auger chamber as a function of substrate rotation frequency. Significant adsorption and desorption of Cl{sub 2} was observed with the plasma off, similar to that observed previously on plasma-conditioned anodized aluminium surfaces, but with much faster desorption rates that are most likely attributable to the smoother and non-porous stainless steel surface morphology. When the plasma was turned on, a much larger pressure rise was observed due to Langmuir-Hinshelwood recombination of Cl atoms. Recombination coefficients, {gamma}{sub Cl}, ranged from 0.004 to 0.03 and increased with Cl-to-Cl{sub 2} number density ratio. This behaviour was observed previously for anodized aluminium surfaces, and was explained by the blocking of Cl recombination sites by adsorbed Cl{sub 2}. Application of this variable recombination coefficient to the modelling of high-density chlorine plasmas gives a much better agreement with measured Cl{sub 2} percent dissociations compared with predictions obtained with a recombination coefficient that is independent of plasma conditions.

Modification of TiO{sub 2} nanorods by Bi{sub 2}MoO{sub 6} nanoparticles for high performance visible-light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Li Na; Zhu Li [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China); Zhang Weide, E-mail: zhangwd@scut.edu.cn [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China); Yu Yuxiang; Zhang Wenhui; Hou Meifang [School of Chemistry and Chemical Engineering, South China University of Technology, 381 Wushan Road, Guangzhou 510640 (China)

2011-10-13

Highlights: > Bi{sub 2}MoO{sub 6}/TiO{sub 2} heterojunction photocatalysts. > Effective separation of photoexcited electrons and holes. > High visible light photocatalytic activity. - Abstract: In this work, TiO{sub 2} nanorods were prepared by a hydrothermal process and then Bi{sub 2}MoO{sub 6} nanoparticles were deposited onto the TiO{sub 2} nanorods by a solvothermal process. The nanostructured Bi{sub 2}MoO{sub 6}/TiO{sub 2} composites were extensively characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron spectroscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activity of the Bi{sub 2}MoO{sub 6}/TiO{sub 2} composites was evaluated by degradation of methylene blue. The Bi{sub 2}MoO{sub 6}/TiO{sub 2} composites exhibit higher catalytic activity than pure Bi{sub 2}MoO{sub 6} and TiO{sub 2} for degradation of methylene blue under visible light irradiation ({lambda} > 420 nm). Further investigation revealed that the ratio of Bi{sub 2}MoO{sub 6} to TiO{sub 2} in the composites greatly influenced their photocatalytic activity. The experimental results indicated that the composite with Bi{sub 2}MoO{sub 6}:TiO{sub 2} = 1:3 exhibited the highest photocatalytic activity. The enhancement mechanism of the composite catalysts was also discussed.

Construction of stable Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} metal/non-metal nitride hybrids with enhanced visible-light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yinhua, E-mail: yms418@126.com [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 2120013,PR China (China); Liu, Peipei; Chen, YeCheng; Zhou, Zhengzhong; Yang, Haijian [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 2120013,PR China (China); Hong, Yuanzhi; Li, Fan; Ni, Liang [School of Materials Science and Engineering, Jiangsu University, Zhenjiang 2120013,PR China (China); Yan, Yongsheng [School of Chemistry and Chemical Engineering, Jiangsu University, Zhenjiang 2120013,PR China (China); Gregory, Duncan H, E-mail: duncan.gregory@glasgow.ac.uk [School of Chemistry, University of Glasgow, Glasgow G12 8QQ (United Kingdom)

2017-01-01

Highlights: • Novel Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} metal/non-metal nitride hybrids were synthesized. • The hybrid nitrides showed enhanced visible-light photocatalytic performance. • The Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} hybrid nitride exhibited excellent photostability. • The hole is the main photoactive specie for the degradation of RhB. - Abstract: In this paper, a novel Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} metal/non-metal nitride hybrid was successfully synthesized by a facile impregnation method. The photocatalytic activity of Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} hybrid nitrides was evaluated by the degradation of organic dye rhodamine B (RhB) under visible light irradiation, and the result indicated that all Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} samples exhibited distinctly enhanced photocatalytic activities for the degradation of RhB than pure g-C{sub 3}N{sub 4}. The optimal Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} composite sample, with Ta{sub 3}N{sub 5} mass ratio of 2%, demonstrated the highest photocatalytic activity, and its degradation rate constant was 2.71 times as high as that of pure g-C{sub 3}N{sub 4}. The enhanced photocatalytic activity of this Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} metal/metal-free nitride was predominantly attributed to the synergistic effect which increased visible-light absorption and facilitated the efficient separation of photoinduced electrons and holes. The Ta{sub 3}N{sub 5}/g-C{sub 3}N{sub 4} hybrid nitride exhibited excellent photostability and reusability. The possible mechanism for improved photocatalytic performance was proposed. Overall, this work may provide a facile way to synthesize the highly efficient metal/metal-free hybrid nitride photocatalysts with promising applications in environmental purification and energy conversion.

Investigating the Mpemba Effect: When Hot Water Freezes Faster than Cold Water

Science.gov (United States)

Ibekwe, R. T.; Cullerne, J. P.

2016-01-01

Under certain conditions a body of hot liquid may cool faster and freeze before a body of colder liquid, a phenomenon known as the Mpemba Effect. An initial difference in temperature of 3.2 °C enabled warmer water to reach 0 °C in 14% less time than colder water. Convection currents in the liquid generate a temperature gradient that causes more…

Ternary g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/Ag{sub 3}VO{sub 4} nanocomposites: Novel magnetically separable visible-light-driven photocatalysts for efficiently degradation of dye pollutants

Energy Technology Data Exchange (ETDEWEB)

Mousavi, Mitra; Habibi-Yangjeh, Aziz, E-mail: ahabibi@uma.ac.ir

2015-08-01

In this work, novel magnetically separable g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/Ag{sub 3}VO{sub 4} nanocomposites were successfully prepared by anchoring Fe{sub 3}O{sub 4} and Ag{sub 3}VO{sub 4} on surface of the g-C{sub 3}N{sub 4} sheets. The prepared samples were fairly characterized using X-ray diffraction, energy dispersive analysis of X-rays, scanning electron microscopy, transmission electron microscopy, UV–vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, thermogravimetric analysis, and vibrating sample magnetometry techniques. Compared with the g-C{sub 3}N{sub 4} and g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4} samples, the g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/Ag{sub 3}VO{sub 4} nanocomposites displayed higher photocatalytic activity for degradation of rhodamine B under visible-light irradiation. Photocatalytic activity of the nanocomposite with 60% of Ag{sub 3}VO{sub 4} was about 14, 8, and 3-fold higher than those of the g-C{sub 3}N{sub 4}, g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}, and Ag{sub 3}VO{sub 4} samples, respectively. Furthermore, influence of refluxing time, calcination temperature, and scavengers of the reactive species on the degradation activity was investigated in detail and the results were discussed. The enhanced photocatalytic activity of the nanocomposites was attributed to efficiently separation of the charge carriers and their increased visible-light harvesting ability. - Graphical abstract: Display Omitted - Highlights: • g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/Ag{sub 3}VO{sub 4} was prepared as ternary novel visible-light-driven photocatalyst. • Among the prepared samples, g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/Ag{sub 3}VO{sub 4} (60%) has the best activity. • The activity was related to efficiently generation and separation of charge carriers. • The photocatalyst was magnetically separated from the treated solution.

Slow-light solitons in atomic media and doped optical fibers

International Nuclear Information System (INIS)

Korolkova, N.; Sinclair, G.F.; Leonhardt, U.

2005-01-01

Full text: We show how to generate optical solitons in atomic media that can be slowed down or accelerated at will. Such slow-light soliton is a polarization structure propagating with a speed that is proportional to the total intensity of the incident light. Ultimately, this method will allow the storage, retrieval and possibly the manipulation of the quantum information in atomic media. Solitons with controllable speed are constructed generalizing the theory of slow-light propagation to an integrable regime of nonlinear dynamics. For the first time, the inverse scattering method for slow-light solitons is developed. In contrast to the pioneering experimental demonstrations of slow light, we consider strong spin modulations where the non-linear dynamics of light and atoms creates polarization solitons. We also analyze how this scheme can be implemented in optical fibers doped with Lambda-atoms. In quantum-information applications, such slow-light solitons could complement the use of quantum solitons in fibres with the advantage of storing quantum information in media and complement methods for quantum memory with the advantages of non-linear dynamics, in particular the intrinsic stability of solitons. (author)

Optical meta-atom for localization of light with quantized energy.

Science.gov (United States)

Lannebère, Sylvain; Silveirinha, Mário G

2015-10-30

The capacity to confine light into a small region of space is of paramount importance in many areas of modern science. Here we suggest a mechanism to store a quantized 'bit' of light--with a very precise amount of energy--in an open core-shell plasmonic structure ('meta-atom') with a nonlinear optical response. Notwithstanding the trapped light state is embedded in the radiation continuum, its lifetime is not limited by the radiation loss. Interestingly, it is shown that the interplay between the nonlinear response and volume plasmons enables breaking fundamental reciprocity restrictions, and coupling very efficiently an external light source to the meta-atom. The collision of an incident optical pulse with the meta-atom may be used to release the trapped light 'bit'.

Enhanced visible light photocatalytic activity in SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures

Energy Technology Data Exchange (ETDEWEB)

Shen, Hao; Zhao, Xiaoru, E-mail: xrzhao@nwpu.edu.cn; Duan, Libing; Liu, Ruidi; Li, Hui

2017-04-15

Highlights: • Novel SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized. • The core-shell structures exhibited enhanced visible light photocatalytic activity. • The enhanced photocatalytic activity was due to synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}. - Abstract: SnO{sub 2}@g-C{sub 3}N{sub 4} core-shell structures were successfully synthesized by simple calcination of SnO{sub 2} microspheres and urea in a muffle furnace. The investigation of morphologies and microstructures showed that g-C{sub 3}N{sub 4} was wrapped tightly on the surface of SnO{sub 2} microspheres with large intimate interface contact areas between the g-C{sub 3}N{sub 4} shells and SnO{sub 2} cores. The X-ray photoelectron spectroscopy results and photoluminescence spectra demonstrated that the intimate interface contacts could facilitate the transfer and separation of the photogenerated charge carriers at their interface, thus the recombination of the photogenerated electron-hole pairs was impeded. The photocatalytic activity of the synthesized composites was evaluated by the photodegradation of methyl orange under visible light irradiation. It was found that SnO{sub 2}@g-C{sub 3}N{sub 4} exhibited higher photodegradation rate (k = 0.013 min{sup −1}) than that of g-C{sub 3}N{sub 4} (k = 0.008 min{sup −1}) and pure SnO{sub 2}. The enhanced photocatalytic activity could be attributed to the synergic action of SnO{sub 2} and g-C{sub 3}N{sub 4}.

Raman spectra of the solid-solution between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 and RbCa sub 2 Nb sub 3 O sub 1 sub 0

CERN Document Server

Kim, H J; Yun, H S

2001-01-01

A site preference of niobium atom in Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) and RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0), which are the solid-solutions between Rb sub 2 La sub 2 Ti sub 3 O sub 1 sub 0 are RbCa sub 2 Nb sub 3 O sub 1 sub 0 , has been investigated by Raman spectroscopy. The Raman spectra of Rb sub 2 sub - sub x La sub 2 Ti sub 3 sub - sub x Nb sub x O sub 1 sub 0 (0.0<=x<=1.0) gave an evidence that niobium atoms substituted for titanium atoms preferably occupy the highly distorted outer octahedral sites rather than the central ones in triple-octahedral perovskite layers. In contrast, the Raman spectra of RbLa sub 2 sub - sub x Ca sub x Ti sub 2 sub - sub x Nb sub 1 sub + sub x O sub 1 sub 0 (0.0<=x<= 2.0) showed no clear information for the cationic arrangement in perovskite slabs. This difference indicated that a site preference of niobium atoms is observed onl...

Light absorption during alkali atom-noble gas atom interactions at thermal energies: a quantum dynamics treatment.

Science.gov (United States)

Pacheco, Alexander B; Reyes, Andrés; Micha, David A

2006-10-21

The absorption of light during atomic collisions is treated by coupling electronic excitations, treated quantum mechanically, to the motion of the nuclei described within a short de Broglie wavelength approximation, using a density matrix approach. The time-dependent electric dipole of the system provides the intensity of light absorption in a treatment valid for transient phenomena, and the Fourier transform of time-dependent intensities gives absorption spectra that are very sensitive to details of the interaction potentials of excited diatomic states. We consider several sets of atomic expansion functions and atomic pseudopotentials, and introduce new parametrizations to provide light absorption spectra in good agreement with experimentally measured and ab initio calculated spectra. To this end, we describe the electronic excitation of the valence electron of excited alkali atoms in collisions with noble gas atoms with a procedure that combines l-dependent atomic pseudopotentials, including two- and three-body polarization terms, and a treatment of the dynamics based on the eikonal approximation of atomic motions and time-dependent molecular orbitals. We present results for the collision induced absorption spectra in the Li-He system at 720 K, which display both atomic and molecular transition intensities.

Solution-processed PCDTBT capped low-voltage InGaZnO{sub x} thin film phototransistors for visible-light detection

Energy Technology Data Exchange (ETDEWEB)

Wang, Han; Xiao, Yubin; Chen, Zefeng; Xu, Wangying; Long, Mingzhu; Xu, Jian-Bin, E-mail: jbxu@ee.cuhk.edu.hk [Department of Electronic Engineering and Materials Science and Technology Research Center, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong (China)

2015-06-15

The effects of visible-light detection based on solution processed poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′, 3′benzothiadiazole) (PCDTBT) capped InGaZnOx (IGZO) phototransistors with Al{sub 2}O{sub x} serving as gate dielectric are investigated in this paper. The high-k dielectric is used to lower the device operating voltage down to 2 V. Photons emitted from laser sources with the wavelengths (λ) of 532 nm and 635 nm are absorbed through the layer of PCDTBT to generate electron-hole-pairs (EHPs). After the separation of EHPs, electrons are injected into IGZO layer through the p-n junction formed between the IGZO (n-type semiconductor) and the PCDTBT (p-type semiconductor). The photo-generated carriers boost the drain current of the transistors as well as bring about the negative threshold voltage shift. Significant enhanced detection performance is achieved under the laser wavelength of 532 nm. The highest photoresponsivity reaches up to 20 A/W, while the photoresponse rise time comes to 10 ms and the fall time comes to approximate 76 ms, which is much faster than trap assisted IGZO visible light detection. The fabricated phototransistors favor the application of visible-light detectors and/or optical switches.

Nuclear structure of light thallium isotopes as deduced from laser spectroscopy on a fast atom beam

International Nuclear Information System (INIS)

Bounds, J.A.

1985-08-01

After optimizing the system by experiments on /sup 201,203,205/Tl, the neutron-deficient isotopes 189-193 Tl have been studied using the collinear fast atom beam laser spectroscopy system at UNISOR on-line to the Holifield Heavy Ion Research Facility. A sensitive system for the measurements was developed since the light isotopes were available in mass-separated beams of only 7 x 10 4 to 4 x 10 5 atoms per second. By laser excitation of the 535 nm atomic transitions of atoms in the beam, the 6s 2 7s 2 S/sub 1/2/ and 6s 2 6s 2 P/sub 3/2/ hyperfine structures were measured, as were the isotope shifts of the 535 nm transitions. From these, the magnetic dipole moments, spectroscopic quadrupole moments and isotopic changes in mean-square charge radius were deduced. The magnetic dipole moments are consistent with previous data. The /sup 190,192/Tl isotopes show a considerable difference in quadrupole deformations as well as an anomalous isotope shift with respect to 194 Tl. A large isomer shift in 193 Tl is observed implying a larger deformation in the 9/2 - isomer than in the 1/2 + ground state. The /sup 189,191,193/Tl isomers show increasing deformation away from stability. A deformed shell model calculation indicates that this increase in deformation can account for the dropping of the 9/2 - band in these isotopes while an increase in neutron pairing correlations, having opposite and compensating effects on the rotational moment of inertia, maintains the 9/2 - strong-coupled band structure. 105 refs., 27 figs

Effects of pre-sputtered Al interlayer on the atomic layer deposition of Al{sub 2}O{sub 3} films on Mg–10Li–0.5Zn alloy

Energy Technology Data Exchange (ETDEWEB)

Wang, P.C.; Cheng, T.C. [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, H.C., E-mail: hclinntu@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Chen, M.J., E-mail: mjchen@ntu.edu.tw [Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan (China); Lin, K.M. [Department of Materials Science and Engineering, Feng Chia University, Taichung, Taiwan (China); Yeh, M.T. [Amli Materials Technology Co. Ltd., New Taipei, Taiwan (China)

2013-04-01

In this study, a dual-layer of Al/Al{sub 2}O{sub 3} films was deposited on the Mg–10Li–0.5Zn substrate using both techniques of magnetron sputtering and atomic layer deposition (ALD). The pre-sputtered Al interlayer has a crystalline structure and the ALD-Al{sub 2}O{sub 3} film is amorphous. The Al interlayer could effectively obstruct the diffusion out of Li atoms from the Mg–10Li–0.5Zn substrate during the deposition of ALD-Al{sub 2}O{sub 3} film. The Mg–10Li–0.5Zn specimen with a dual-layer of Al/Al{sub 2}O{sub 3} films exhibits a much better corrosion resistance than those specimens with a single layer of sputtered Al or ALD-Al{sub 2}O{sub 3}.

Effect of atomic-arrangement matching on La{sub 2}O{sub 3}/Ge heterostructures for epitaxial high-k-gate-stacks

Energy Technology Data Exchange (ETDEWEB)

Kanashima, T., E-mail: kanashima@ee.es.osaka-u.ac.jp; Zenitaka, M.; Kajihara, Y.; Yamada, S.; Hamaya, K. [Graduate School of Engineering Science, Osaka University, Machkaneyama 1-3, Toyonaka, Osaka 560-8531 (Japan); Nohira, H. [Tokyo City University, 1-28-1 Tamazutumi, Setagaya-ku, Tokyo 158-8557 (Japan)

2015-12-14

We demonstrate a high-quality La{sub 2}O{sub 3} layer on germanium (Ge) as an epitaxial high-k-gate-insulator, where there is an atomic-arrangement matching condition between La{sub 2}O{sub 3}(001) and Ge(111). Structural analyses reveal that (001)-oriented La{sub 2}O{sub 3} layers were grown epitaxially only when we used Ge(111) despite low growth temperatures less than 300 °C. The permittivity (k) of the La{sub 2}O{sub 3} layer is roughly estimated to be ∼19 from capacitance-voltage (C-V) analyses in Au/La{sub 2}O{sub 3}/Ge structures after post-metallization-annealing treatments, although the C-V curve indicates the presence of carrier traps near the interface. By using X-ray photoelectron spectroscopy analyses, we find that only Ge–O–La bonds are formed at the interface, and the thickness of the equivalent interfacial Ge oxide layer is much smaller than that of GeO{sub 2} monolayer. We discuss a model of the interfacial structure between La{sub 2}O{sub 3} and Ge(111) and comment on the C-V characteristics.

Synthesis and characterization of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} and the visible light photocatalytic oxidation of 4-chlorophenol

Energy Technology Data Exchange (ETDEWEB)

Cao Guangxiu [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Department of Chemistry, Shangqiu Normal University, Shangqiu 476000 (China); Li Yaogang [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China); Zhang Qinghong, E-mail: zhangqh@dhu.edu.cn [Engineering Research Center of Advanced Glasses Manufacturing Technology, MOE, Donghua University, Shanghai 201620 (China); Wang Hongzhi, E-mail: wanghz@dhu.edu.cn [State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, Shanghai 201620 (China)

2010-06-15

In this work, we investigated the synergetic effect of La and F on the visible light photocatalytic activity of TiO{sub 2} catalysts. La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} photocatalysts were prepared by a simple sol-gel process using tetrabutyl titanate (TBT), La(NO{sub 3}){sub 3} and NH{sub 4}F as precursors. XPS results revealed that La{sub 2}O{sub 3} accumulated on the surface of TiO{sub 2}, which enhanced the surface area of TiO{sub 2} and inhibited the recombination of electron-hole pairs. It also showed that two kinds of fluorine species were formed and these increased the acid active sites and enhanced the oxidation potential of the photogenerated holes in the valance band. UV-vis diffuse reflection spectra of La{sub 2}O{sub 3}/TiO{sub 2-x}F{sub x} showed that intraband gap states were present and these are probably responsible for its absorption of visible light while the intrinsic absorption band was shifted slightly to a longer wavelength. At molar ratios of La and F to Ti of 1.5:100 and 5:100 and after calcination at 500 deg. C, the degradation rate of 4-chlorophenol (4-CP) over the sample was about 1.2-3.0 times higher than that of the other doped samples and undoped TiO{sub 2}. The total organic carbon (TOC) removal rates of 4-CP showed that 4-CP was mineralized efficiently in the presence of the sample under visible light illumination.

BiOCl{sub x}Br{sub y}I{sub z} (x + y + z = 1) solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances

Energy Technology Data Exchange (ETDEWEB)

Sun, Xiuguo; Zhang, Yangyang; Li, Chunmei; Zhang, Zhifeng; Peng, Zheng; Si, Huayan; Zhang, Jianmin [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Li, Yanting, E-mail: yantingcn@stdu.edu.cn [School of Materials Science and Engineering, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China); Hebei Provincial Key Laboratory of Traffic Engineering materials, Shijiazhuang Tiedao University, Shijiazhuang 050043 (China)

2015-07-25

Highlights: • BiOCl{sub x}Br{sub y}I{sub z} solid solutions were prepared by hydrolysis method. • Band gap of the solid solutions can be controllable by adjusting the molar ratio of halogen ions. • The samples show higher visible light photocatalytic activity than pure BiOX. • Orbital diversification of VB is beneficial to separating the holes and electrons effectively. • The mechanisms are discussed by active species trapping and band theory. - Abstract: A series of BiOCl{sub x}Br{sub y}I{sub z} solid solutions with controllable band gap and highly enhanced visible light photocatalytic performances were synthesized by a simple hydrolysis method. The samples were characterized by X-ray powder diffraction, UV–vis diffuse reflectance spectra, scanning electron microscope, high-resolution transmission electron microscopy and Brunauer–Emmett–Teller analysis. By adjusting the molar ratio of halogen ions, the band gap of BiOCl{sub x}Br{sub y}I{sub z} could be controllable to the suitable value for a photocatalytic reaction. Especially, BiOCl{sub x}Br{sub y}I{sub z} with a 1:1:2 molar ratio of Cl, Br to I showed the highest visible light photocatalytic activity for the degradation of methyl orange than individual BiOX systems. The degradation efficiency could reach over 90% within 60 min. The possible mechanism of photogenerated carrier transfer and higher photocatalytic activity was analyzed by active species trapping and energy band theory.

First observation of the strongly forbidden transition {sup 1}S{sub 0} - {sup 3}P{sub 0} in Strontium, for an atomic clock with trapped atoms; Premiere observation de la transition fortement interdite {sup 1}S{sub 0} - {sup 3}P{sub 0} du strontium, pour une horloge optique a atomes pieges

Energy Technology Data Exchange (ETDEWEB)

Courtillot, I

2003-11-01

This thesis reports the first results towards the realization of an optical clock using trapped strontium atoms. This set up would combine advantages of the different approaches commonly used to develop an atomic frequency standard. The first part describes the cold atoms source which is implemented. A magneto-optical trap operating on the {sup 1}S{sub 0}-{sup 1}P{sub 1} transition at 461 nm is loaded from an atomic beam decelerated by a Zeeman slower. The 461 nm laser is obtained by sum-frequency mixing in a potassium titanyl phosphate (KTP) crystal. The second part is devoted to the different stages developed to achieve the direct excitation of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition in {sup 87}Sr. This line has a theoretical natural width of 10{sup -3} Hz. Before this detection, we obtained an estimate of the resonance frequency by measuring absolute frequencies of several allowed optical transitions. (author)

Enhanced visible light photocatalytic H{sub 2} evolution of metal-free g-C{sub 3}N{sub 4}/SiC heterostructured photocatalysts

Energy Technology Data Exchange (ETDEWEB)

Wang, Biao, E-mail: wangbiao@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); University of the Chinese Academy of Sciences, Beijing 100049 (China); Zhang, Jingtao, E-mail: zhangjtao@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510006 (China); Huang, Feng, E-mail: huangfeng@mail.sysu.edu.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); State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510006 (China)

2017-01-01

Highlights: • Novel g-C{sub 3}N{sub 4}/SiC composite was prepared by synthesizing g-C{sub 3}N{sub 4} on the surface of SiC. • g-C{sub 3}N{sub 4}/SiC composites exhibit much higher H{sub 2} production activity than pure g-C{sub 3}N{sub 4}. • The g-C{sub 3}N{sub 4}/SiC heterojunction mainly accounts for improved photocatalytic activity. - Abstract: g-C{sub 3}N{sub 4} has been attracting much attention for application in visible light photocatalytic water splitting due to its suitable band structure, and high thermal and chemical stability. However, the rapid recombination of photogenerated carriers has inhibited its wide use. For this reason, novel g-C{sub 3}N{sub 4}/SiC composites were prepared via in situ synthesis of g-C{sub 3}N{sub 4} on the surface of SiC, with which g-C{sub 3}N{sub 4} shows tight interaction (chemical bonding). The g-C{sub 3}N{sub 4}/SiC composites exhibit high stability in H{sub 2} production under irradiation with visible light (λ ≥ 420 nm), demonstrating a maximum of 182 μmol g{sup −1} h{sup −1}, being 3.4 times higher than that of pure g-C{sub 3}N{sub 4}. The enhanced photocatalytic H{sub 2} production ability for g-C{sub 3}N{sub 4}/SiC photocatalysts is primarily ascribed to the combined effects of enhanced separation of photogenerated carriers through efficient migration of electron and enlarged surface areas, in addition to the possible contributions of increased hydrophilicity of SiC and polymerization degree of g-C{sub 3}N{sub 4}. This study may provide new insights into the development of g-C{sub 3}N{sub 4}-based composites as stable and efficient photocatalysts for H{sub 2} production from water splitting.

Atomic displacement distributions for light energetic atoms incident on heavy atom targets

International Nuclear Information System (INIS)

Brice, D.K.

1975-01-01

The depth distributions of atomic displacements produced by 4 to 100 keV H, D, and He ions incident on Cr, Mo, and W targets have been calculated using a sharp displacement threshold, E/sub d/ = 35 eV, and a previously described calculational procedure. These displacement depth distributions have been compared with the depth distributions of energy deposited into atomic processes to determine if a proportionality (modified Kinchin--Pease relationship) can be established. Such a relationship does exist for He ions and D ions incident on these metals at energies above 4 keV and 20 keV, respectively. For H ions the two distributions have significantly different shapes at all incident energies considered

Temperature dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1}

Energy Technology Data Exchange (ETDEWEB)

Garcia-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda, Gregorio del Amo, 8, 28040 Madrid (Spain); Hernando, A.; Aragon, A.; Marin, P. [Instituto de Magnetismo Aplicado, IMA, P.O. Box 155, 28230 Madrid (Spain)

2012-09-25

Highlights: Black-Right-Pointing-Pointer An anomalous thermal dependence of the coercive field of gas atomized Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} powder particles under 25 {mu}m powder particle, increasing Hc as temperature increases. Black-Right-Pointing-Pointer It is proposed that Cu rich regions at inter-grain boundaries could act as exchange decoupling regions contributing to the thermal increase of coercivity. Black-Right-Pointing-Pointer This anomalous thermal dependence points out that tailoring microstructure and size, by controlling the cooling rate of more adequate multiphase systems, could be a promising procedure to develop soft or hard magnets, avoiding Rare Earths metals that is nowadays an important target for the engineering of magnetic materials. - Abstract: In this work, the dependence of the coercive field of Fe{sub 73.5}Si{sub 13.5}B{sub 9}Nb{sub 3}Cu{sub 1} gas atomized powder with the temperature for different particle sizes has been studied, observing an anomalous behavior in the under 25 powder particle size fraction. This unusual behavior is related with the microstructure of the powder, and is attributed to the presence of a multiphase magnetic system, with non-magnetic regions decoupling the ferromagnetic domains.

Manipulating Atoms with Light Achievements and Perspectives

CERN Multimedia

CERN. Geneva

2006-01-01

During the last few decades spectacular progress has been achieved in the control of atomic systems by light. It will be shown how it is possible to use the basic conservation laws in atom-photon interactions for polarizing atoms, for trapping them, for cooling them to extremely low temperatures, in the microkelvin, and even in the nanokelvin range. A review will be given of recent advances in this field and of new applications, including atomic clocks with very high relative stability and accuracy, atomic interferometers allowing precise measurement of rotation speeds and gravitational fields, the realization of new states of matter such as Bose-Einstein condensates, matter waves and atom lasers, ultracold molecules. New perspectives opened by these results will be also briefly discussed.

Magnetically separable Cu{sub 2}O/chitosan–Fe{sub 3}O{sub 4} nanocomposites: Preparation, characterization and visible-light photocatalytic performance

Energy Technology Data Exchange (ETDEWEB)

Cao, Chunhua [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, College of Chemical and Environmental Engineering, Jianghan University, Wuhan 430056 (China); Xiao, Ling, E-mail: xiaoling9119@whu.edu.cn [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China); Chen, Chunhua [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, College of Chemical and Environmental Engineering, Jianghan University, Wuhan 430056 (China); Cao, Qihua [School of Resource and Environmental Science, Wuhan University, Wuhan 430072 (China)

2015-04-01

Highlights: • A novel magnetically-separable Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} photocatalyst was in situ prepared. • Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs had rough and porous chitosan surface layer embedded with Fe{sub 3}O{sub 4} NPs. • Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs showed large surface areas and special dimodal pore structure. • Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs showed superparamagnetism and could be easily magnetic separated. • Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs exhibited good visible-light photocatalytic activity and stability. - Abstract: A novel magnetically-separable visible-light-induced photocatalyst, Cu{sub 2}O/chitosan–Fe{sub 3}O{sub 4} nanocomposite (Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NC), was prepared via a facile one-step precipitation–reduction process by using magnetic chitosan chelating copper ions as precursor. The structure and properties of Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs were characterized by XRD, FT-IR, SEM, HRTEM, SAED, EDS, BET, VSM, XPS and UV–vis/DRS. The photocatalytic activity of Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs was evaluated by decolorization of reactive brilliant red X-3B (X-3B) under visible light irradiation. The characterization results indicated that Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs exhibited relatively large specific surface areas and special dimodal pore structure because Cu{sub 2}O was wrapped in chitosan matrix embedded with Fe{sub 3}O{sub 4} nanoparticles. The tight combination of magnetic Fe{sub 3}O{sub 4} and semiconductor Cu{sub 2}O through chitosan made the nanocomposites show good superparamagnetism and photocatalytic activity. It was found that X-3B could be decolorized more efficiently in acidic media than in neutral or alkaline media. The decolorization of X-3B was ascribed to the synergistic effect of photocatalysis and adsorption. Cu{sub 2}O/CS–Fe{sub 3}O{sub 4} NCs could be easily separated from the solution by an external magnet, and the decolorization rates of X-3B

V{sub 18}P{sub 9}C{sub 2}. A complex phosphide carbide

Energy Technology Data Exchange (ETDEWEB)

Boller, Herbert [Linz Univ. (Austria). Inst. fuer Anorganische Chemie; Effenberger, Herta [Wien Univ. (Austria). Inst. fuer Mineralogie und Kristallographie

2016-08-01

V{sub 18}P{sub 9}C{sub 2} crystallizes in the orthorhombic space group Pmma with the lattice parameters a = 17.044(3), b = 3.2219(7), and c = 13.030(2) Aa, Z = 2. The crystal structure is composed of 19 symmetry-independent atoms. The crystal structure is considered as a network formed by the transition metal atoms exhibiting cubic, trigonal prismatic, and octahedral voids centered by V, P, and C atoms, respectively. Vice versa, the V and P atoms form a three-dimensional network. The two CV{sub 6} octahedra are edge- and corner-connected to chains running parallel to [010]. The five unique P atoms are trigonal prismatically coordinated by V atoms with one to three faces capped again by a V atom. The V atoms have mainly cubic environments formed solely by V or by V and P atoms. V{sub 18}P{sub 9}C{sub 2} exhibits some structural relations to other compounds of the ternary system V-P-C as well as to other intermetallic phases. Despite the low carbon content, V{sub 18}P{sub 9}C{sub 2} is considered as a ternary compound rather than an interstitially stabilized (binary) phosphide in view of its special structural features.

Photocatalytic characteristics for the nanocrystalline TiO{sub 2} on the Ag-doped CaAl{sub 2}O{sub 4}:(Eu,Nd) phosphor

Energy Technology Data Exchange (ETDEWEB)

Kim, Jung-Sik, E-mail: jskim@uos.ac.kr; Sung, Hyun-Je; Kim, Bum-Joon

2015-04-15

Highlights: • The photocatalytic reactivity of the TiO{sub 2}-coated on the Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). • The photodecomposition of benzene gas under visible light irradiation. • The TiO{sub 2}-coated on the Ag-doped long-lasting phosphor showed much higher photocatalytic reactivity. • The light emitted from the long-lasting phosphors contributed to the photo generation of TiO{sub 2}. - Abstract: This study investigated the photocatalytic behavior of nanocrystalline TiO{sub 2} deposited on Ag-doped long-lasting phosphor (CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+}). The CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor powders were prepared via conventional sintering using CaCO{sub 3}, Al{sub 2}O{sub 3}, Eu{sub 2}O{sub 3}, and Nd{sub 2}O{sub 3} as raw materials according to the appropriate molar ratios. Silver nanoparticles were loaded on the phosphor by mixing with an aqueous Ag-dispersion solution. Nanocrystalline TiO{sub 2} was deposited on Ag-doped CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} powders via low-pressure chemical vapor deposition (LPCVD). The TiO{sub 2} coated on the phosphor was actively photo-reactive under irradiation with visible light and showed much faster benzene degradation than pure TiO{sub 2}, which is almost non-reactive. The coupling of TiO{sub 2} with phosphor may result in an energy band bending in the junction region, which then induces the TiO{sub 2} crystal at the interface to be photo-reactive under irradiation with visible light. In addition, the intermetallic compound of CaTiO{sub 3} that formed at the interface between TiO{sub 2} and the CaAl{sub 2}O{sub 4}:(Eu{sup 2+},Nd{sup 3+}) phosphor results in the formation of oxygen vacancies and additional electrons that promote the photodecomposition of benzene gas. The addition of Ag nanoparticles enhanced the photocatalytic reactivity of the TiO{sub 2}/CaAl{sub 2}O{sub 4}:Eu{sup 2+},Nd{sup 3+} phosphor. TiO{sub 2} on the Ag

The impact of accelerating faster than exponential population growth on genetic variation.

Science.gov (United States)

Reppell, Mark; Boehnke, Michael; Zöllner, Sebastian

2014-03-01

Current human sequencing projects observe an abundance of extremely rare genetic variation, suggesting recent acceleration of population growth. To better understand the impact of such accelerating growth on the quantity and nature of genetic variation, we present a new class of models capable of incorporating faster than exponential growth in a coalescent framework. Our work shows that such accelerated growth affects only the population size in the recent past and thus large samples are required to detect the models' effects on patterns of variation. When we compare models with fixed initial growth rate, models with accelerating growth achieve very large current population sizes and large samples from these populations contain more variation than samples from populations with constant growth. This increase is driven almost entirely by an increase in singleton variation. Moreover, linkage disequilibrium decays faster in populations with accelerating growth. When we instead condition on current population size, models with accelerating growth result in less overall variation and slower linkage disequilibrium decay compared to models with exponential growth. We also find that pairwise linkage disequilibrium of very rare variants contains information about growth rates in the recent past. Finally, we demonstrate that models of accelerating growth may substantially change estimates of present-day effective population sizes and growth times.

Photon up-converting (Yb,Er){sub 2}O{sub 3} thin films by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Tuomisto, Minnea [Department of Chemistry, University of Turku (Finland); Doctoral Programme in Physical and Chemical Sciences, University of Turku Graduate School (UTUGS), Turku (Finland); Giedraityte, Zivile; Karppinen, Maarit [Department of Chemistry and Materials Science, School of Chemical Engineering, Aalto University (Finland); Lastusaari, Mika [Department of Chemistry, University of Turku (Finland); Turku University Centre for Materials and Surfaces (MatSurf), Turku (Finland)

2017-06-15

We report up-converting (Yb,Er){sub 2}O{sub 3} thin films grown with the atomic layer deposition (ALD) technique. The films are crystalline and show a homogeneous morphology with a roughness less than 1 nm for 40 nm thick films. High-intensity near-infrared (NIR) to green and red two-photon up-conversion emission is obtained with 974 nm excitation through an absorption by Yb{sup 3+}, followed by a Yb{sup 3+}-Er{sup 3+} energy transfer and emission from Er{sup 3+}. The ALD technique promises to be excellent for producing up-converting films for many applications such as near-infrared radiation absorbing layers for solar cells and sensors in point-of-care biomedical diagnostics. Schematic picture of the ALD-grown (Yb,Er){sub 2}O{sub 3} thin film including the up-conversion emission spectra. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Light qubit storage and retrieval using macroscopic atomic ensembles

International Nuclear Information System (INIS)

Sherson, J.; Soerensen, A. S.; Polzik, E. S.; Fiurasek, J.; Moelmer, K.

2006-01-01

We present an experimentally feasible protocol for the complete storage and retrieval of arbitrary light states in an atomic quantum memory using the Faraday interaction between light and matter. Our protocol relies on multiple passages of a single light pulse through the atomic ensemble without the impractical requirement of kilometer-long delay lines between the passages. A time-dependent interaction strength enables the storage and retrieval of states with arbitrary pulse shapes. The fidelity approaches unity exponentially without squeezed or entangled initial states, as illustrated by calculations for a photonic qubit

A facile fabrication of plasmonic g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag ternary heterojunction visible-light photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Dai, Kai, E-mail: daikai940@chnu.edu.cn [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China); Lv, Jiali [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China); Lu, Luhua, E-mail: lhlu@cug.edu.cn [Faculty of Material Science and Chemical Engineering, China University of Geosciences, Wuhan, 430074 (China); Liang, Changhao [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China); Key Laboratory of Materials Physics and Anhui Key Laboratory of Nanomaterials and Nanotechnology, Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031 (China); Geng, Lei; Zhu, Guangping [College of Physics and Electronic Information, Huaibei Normal University, Huaibei, 235000 (China)

2016-07-01

It's important to reduce recombination of electrons and holes and enhance charge transfer through fine controlled interfacial structure. In this work, novel graphitic-C{sub 3}N{sub 4} (g-C{sub 3}N{sub 4})/Ag{sub 2}WO{sub 4}/Ag ternary photocatalyst has been synthesized by deposition of Ag{sub 2}WO{sub 4} onto g-C{sub 3}N{sub 4} template and followed by sun light reduction of Ag{sub 2}WO{sub 4} into Ag{sub 2}WO{sub 4}/Ag. As-prepared g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag presented significantly enhanced photocatalytic performance in degrading methylene blue (MB) under 410 nm LED light irradiation. Metallic Ag{sup 0} is used as plasmonic hot spots to generate high energy charge carriers. Optimal g-C{sub 3}N{sub 4} content has been confirmed to be 40 wt%, corresponding to apparent pseudo-first-order rate constant kapp of 0.0298 min{sup −1}, which is 3.3 times and 37.3 times more than that of pure g-C{sub 3}N{sub 4} and Ag{sub 2}WO{sub 4}, respectively. This novel ternary g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag structure material is an ideal candidate in environmental treatment and purifying applications. - Graphical abstract: A high efficient plasmonic graphitic-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag ternary nanocomposite photocatalyst was synthesized. - Highlights: • g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag ternary nanocomposite photocatalyst was prepared. • g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag showed high photocatalytic activity. • g-C{sub 3}N{sub 4}/Ag{sub 2}WO{sub 4}/Ag showed long reusable life.

Causal events enter awareness faster than non-causal events

Directory of Open Access Journals (Sweden)

Pieter Moors

2017-01-01

Full Text Available Philosophers have long argued that causality cannot be directly observed but requires a conscious inference (Hume, 1967. Albert Michotte however developed numerous visual phenomena in which people seemed to perceive causality akin to primary visual properties like colour or motion (Michotte, 1946. Michotte claimed that the perception of causality did not require a conscious, deliberate inference but, working over 70 years ago, he did not have access to the experimental methods to test this claim. Here we employ Continuous Flash Suppression (CFS—an interocular suppression technique to render stimuli invisible (Tsuchiya & Koch, 2005—to test whether causal events enter awareness faster than non-causal events. We presented observers with ‘causal’ and ‘non-causal’ events, and found consistent evidence that participants become aware of causal events more rapidly than non-causal events. Our results suggest that, whilst causality must be inferred from sensory evidence, this inference might be computed at low levels of perceptual processing, and does not depend on a deliberative conscious evaluation of the stimulus. This work therefore supports Michotte’s contention that, like colour or motion, causality is an immediate property of our perception of the world.

Incorporation of Cu{sub 2}O nanocrystals into TiO{sub 2} photonic crystal for enhanced UV–visible light driven photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Geng, Zhi; Zhang, Yu; Yuan, Xing; Huo, Mingxin; Zhao, Yahui; Lu, Ying, E-mail: luy332@nenu.edu.cn; Qiu, Yue

2015-09-25

Highlights: • The Cu{sub 2}O NCs/TiO{sub 2} PC composite was synthesized and exhibited high photocatalysis. • The improved light harvesting and increased quantum yield was achieved. • The hydroxyl radical was the primary oxidant in Cu{sub 2}O NCs/TiO{sub 2} PC photocatalysis. - Abstract: A 3D UV–visible light responsive photocatalyst was fabricated by infiltrating Cu{sub 2}O nanocrystals (NCs) into TiO{sub 2} photonic crystal (PC). Morphology characterization presented that Cu{sub 2}O NCs with average diameter around 10 nm were dispersed uniformly into TiO{sub 2} PC. The transmittance spectra showed that Cu{sub 2}O NCs/TiO{sub 2} 260, prepared by integrating Cu{sub 2}O NCs with TiO{sub 2} 260 which was fabricated from 260 nm polystyrene spheres, exhibited the highest light harvesting. The photoluminescence spectra confirmed the electron/hole pairs recombination of Cu{sub 2}O NCs/TiO{sub 2} 260 was efficiently inhibited due to the unique heterojunction structure between TiO{sub 2} and Cu{sub 2}O. In the photocatalytic degradation of Rhodamine B and Bisphenol A under UV–visible light (320 nm < λ < 780 nm) irradiation, the kinetic constant using Cu{sub 2}O NCs/TiO{sub 2} 260 was 3.99 and 8.37-fold larger than that using TiO{sub 2} nanoparticle (NP), respectively. The enhanced photocatalysis benefited from the increased light harvesting owing to the excitation of both TiO{sub 2} and Cu{sub 2}O NCs whose optical absorption was intensified by the photonic effect of TiO{sub 2} 260 and the high quantum efficiency due to the Cu{sub 2}O/TiO{sub 2} heterojunction. The hydroxyl radical, generated from the protonation of superoxide radical which was derived from the reduction of oxygen by photogenerated electrons, was the main oxidant responsible for pollutant degradation.

Atom beam sputtered Ag-TiO{sub 2} plasmonic nanocomposite thin films for photocatalytic applications

Energy Technology Data Exchange (ETDEWEB)

Singh, Jaspal; Sahu, Kavita [School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, NewDelhi 110078 (India); Pandey, A. [Solid State Physics Laboratory, Defence Research and Development Organization, Timarpur, Delhi 110054 (India); Kumar, Mohit [Institute of Physics, Sachivalaya Marg, Bhubaneswar, Odisha 751005 (India); Ghosh, Tapas; Satpati, B. [Saha Institute of Nuclear Physics, HBNI, 1/AF, Bidhannagar, Kolkata 700064 (India); Som, T.; Varma, S. [Institute of Physics, Sachivalaya Marg, Bhubaneswar, Odisha 751005 (India); Avasthi, D.K. [Amity Institute of Nanotechnology, Noida 201313, Uttar Pradesh (India); Mohapatra, Satyabrata, E-mail: smiuac@gmail.com [School of Basic and Applied Sciences, Guru Gobind Singh Indraprastha University, Dwarka, NewDelhi 110078 (India)

2017-07-31

The development of nanocomposite coatings with highly enhanced photocatalytic activity is important for photocatalytic purification of water and air. We report on the synthesis of Ag-TiO{sub 2} nanocomposite thin films with highly enhanced photocatalytic activity by atom beam co-sputtering technique. The effects of Ag concentration on the structural, morphological, optical, plasmonic and photocatalytic properties of the nanocomposite thin films were investigated. UV–visible DRS studies revealed the presence of surface plasmon resonance (SPR) peak characteristic of Ag nanoparticles together with the excitonic absorption peak originating from TiO{sub 2} nanoparticles in the nanocomposites. XRD studies showed that the nanocomposite thin films consist of Ag nanoparticles and rutile TiO{sub 2} nanoparticles. The synthesized Ag-TiO{sub 2} nanocomposite thin films with 5 at% Ag were found to exhibit highly enhanced photocatalytic activity for sun light driven photocatalytic degradation of methylene blue in water, indicating their potential application in water purification.

Ternary magnetic g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/AgI nanocomposites: Novel recyclable photocatalysts with enhanced activity in degradation of different pollutants under visible light

Energy Technology Data Exchange (ETDEWEB)

Akhundi, Anise; Habibi-Yangjeh, Aziz, E-mail: ahabibi@uma.ac.ir

2016-05-01

In the present work, we illustrate the preparation of graphitic carbon nitride/magnetite/silver iodide (g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/AgI) nanocomposites, as novel magnetically recyclable visible-light-driven photocatalysts. The nanocomposites were prepared by reflux method at 96 °C with no require to any additives or post preparation treatments. The resultant samples were characterized using XRD, EDX, SEM, TEM, FT-IR, UV–vis DRS, PL, TGA, and VSM techniques. Among the nanocomposites, the sample with 20 percent of AgI displayed superior activity. This nanocomposite exhibited superparamagnetic property with a saturation magnetization of 16.9 emu/g. Photocatalytic activity of the g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/AgI (20%) nanocomposite was about 8.7 and 6.9 fold higher than those of the g-C{sub 3}N{sub 4} and g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4} samples, respectively for degradation of rhodamine B (RhB) under visible-light irradiation. Moreover, we investigated the influence of refluxing time, calcination temperature, and scavengers of the reactive species on the degradation activity. It was demonstrated that the ternary magnetic photocatalyst has considerable activity in degradation of two more dye pollutants. Besides, it was demonstrated that the ternary magnetic nanocomposite has reasonable stability during five recycling experiments. - Highlights: • Novel ternary g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/AgI nanocomposites were prepared using a facile method. • g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}/AgI (20%) has the best activity in degradation of RhB under visible-light. • The activity is 8.7 and 6.9E-fold higher than g-C{sub 3}N{sub 4} and g-C{sub 3}N{sub 4}/Fe{sub 3}O{sub 4}, respectively. • The nanocomposite showed enhance activity in degradation of two more pollutants.

UV light induced insulator-metal transition in ultra-thin ZnO/TiO{sub x} stacked layer grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Saha, D., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Misra, P., E-mail: sahaphys@gmail.com, E-mail: pmisra@rrcat.gov.in; Joshi, M. P.; Kukreja, L. M. [Laser Materials Processing Division, Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

2016-08-28

In the present study, atomic layer deposition has been used to grow a series of Ti incorporated ZnO thin films by vertically stacking different numbers (n = 1–7) of ZnO/TiO{sub x} layers on (0001) sapphire substrates. The effects of defect states mediated chemisorption of O{sub 2} and/OH groups on the electrical properties of these films have been investigated by illuminating the samples under UV light inside a high vacuum optical cryostat. The ultra-thin film having one stacked layer (n = 1) did not show any change in its electrical resistance upon UV light exposure. On the contrary, marginal drop in the electrical resistivity was measured for the samples with n ≥ 3. Most surprisingly, the sample with n = 2 (thickness ∼ 12 nm) showed an insulator to metal transition upon UV light exposure. The temperature dependent electrical resistivity measurement on the as grown film (n = 2) showed insulating behaviour, i.e., diverging resistivity on extrapolation to T→ 0 K. However, upon UV light exposure, it transformed to a metallic state, i.e., finite resistivity at T → 0 K. Such an insulator-metal transition plausibly arises due to the de-trapping of conduction electrons from the surface defect sites which resulted in an upward shift of the Fermi level above the mobility edge. The low-temperature electron transport properties on the insulating film (n = 2) were investigated by a combined study of zero field electrical resistivity ρ(T) and magnetoresistance (MR) measurements. The observed negative MR was found to be in good agreement with the magnetic field induced suppression of quantum interference between forward-going paths of tunnelling electrons. Both ρ(T) and MR measurements provided strong evidence for the Efros-Shklovskii type variable range hopping conduction in the low-temperature (≤40 K) regime. Such studies on electron transport in ultra-thin n-type doped ZnO films are crucial to achieve optimum functionality

Crystal structure and thermoelectric properties of clathrate, Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}: Small cage volume and large disorder of the guest atom

Energy Technology Data Exchange (ETDEWEB)

Roudebush, John H., E-mail: jhr@princeton.edu [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Orellana, Mike [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States); Bux, Sabah [Thermal Energy Conversion Technologies Group, Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109 (United States); Yi Tanghong; Kauzlarich, Susan M. [Department of Chemistry, University of California, One Shields Ave., Davis, CA 95616 (United States)

2012-08-15

Samples with the type-I clathrate composition Ba{sub 8}Ni{sub x}Si{sub 46-x} have been synthesized and their structure and thermoelectric properties characterized. Microprobe analysis indicates the Ni incorporation to be 2.62{<=}x{<=}3.53. The x=3.5 phase crystallizes in the type-I clathrate structure (space group: Pm-3n) with a lattice parameter of 10.2813(3) A. The refined composition was Ba{sub 8}Ni{sub 3.5}Si{sub 42.0}, with small vacancies, 0.4 and 0.5 atoms per formula unit, at the 2a and 6c sites, respectively. The position of the Ba2 atom in the large cage was modeled using a 4-fold split position (24j site), displaced 0.18 A from the cage center (6d site). The volume of the large cage is calculated to be 146 A{sup 3}, smaller than other clathrates with similar cation displacement. The sample shows n-type behavior with a maximum of -50 {mu}V/K at 823 K above which the Seebeck coefficient decreases, suggesting mixed carriers. Lattice thermal conductivity, {kappa}{sub l}, is 55 mW/K above 600 K. - Graphical abstract: Seebeck coefficient and resistivity of the type-I clathrate Ba{sub 8}Ni{sub 3.5}Si{sub 41.0}. Structure show's large displacement of the Ba cation in the large cage (6c site). Highlights: Black-Right-Pointing-Pointer Crystal structure of the Ba{sub 8}Ni{sub 3.5}Si{sub 41.0} reported. Black-Right-Pointing-Pointer Vacancies at the 2a and 6c sites. Black-Right-Pointing-Pointer Large disorder of Ba guest atom, 0.18 A from cage center. Black-Right-Pointing-Pointer Structure is compared to Ba{sub 8}Si{sub 46} and other type-I clathrates. Black-Right-Pointing-Pointer Max Seebeck of -50.7 {mu}V/C at 798.4 K, thermal conductivity {approx}55 mW/K.

Optical properties and visible-light-driven photocatalytic activity of Bi{sub 8}V{sub 2}O{sub 17} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Pu, Yinfu; Liu, Ting; Huang, Yanlin [Soochow University, College of Chemistry, Chemical Engineering and Materials Science (China); Chen, Cuili; Kim, Sun Il; Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Pukyong National University, Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering (Korea, Republic of)

2015-05-15

Bi{sub 8}V{sub 2}O{sub 17} (4Bi{sub 2}O{sub 3}·V{sub 2}O{sub 5}) nanoparticles with the uniform size of about 50 nm were fabricated through the Pechini method. The crystal structure was investigated by X-ray powder diffraction and the structural refinement. The surface of the as-synthesized samples was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy, and X-ray photoelectron spectroscopy. The optical properties, band structure, and the degradation mechanisms were discussed. The experimental results demonstrate that Bi{sub 8}V{sub 2}O{sub 17} nanoparticles have an efficient visible-light absorption with band-gap energy of 1.85 eV and a direct allowed electronic transition. The photocatalytic activity was evaluated by the photodegradation of the methylene blue (MB) under visible-light irradiation (λ > 420 nm) as a function of time. These results indicate that Bi{sub 8}V{sub 2}O{sub 17} could be a potential photocatalyst driven by visible light. The effective photocatalytic activity was discussed on the base of the crystal structure characteristic.

Correlation holography: imaging of atoms when sigma/sub inelastic//sup >>sigma/elastic

International Nuclear Information System (INIS)

Csonka, P.L.

1979-01-01

Atomic-scale resolution of details is possible with this method, even if protons interact with the atoms overwhelmingly inelastically, i.e. when sigma/sub inelastic/ >>sigma/sub elastic/. Observation of small objects is compatible with quantum mechanics even if the disturbance of the object caused by the observation process is arbitrarily small

Quasicubic α-Fe{sub 2}O{sub 3} nanoparticles embedded in TiO{sub 2} thin films grown by atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Tamm, Aile [Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu (Estonia); Seinberg, Liis [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Kozlova, Jekaterina [Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu (Estonia); Link, Joosep [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Pikma, Piret [University of Tartu, Institute of Chemistry, Ravila 14A, 50411 Tartu (Estonia); Stern, Raivo [National Institute of Chemical Physics and Biophysics, Akadeemia tee 23, 12618 Tallinn (Estonia); Kukli, Kaupo [Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu (Estonia); Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014 Helsinki (Finland)

2016-08-01

Monodispersed quasicubic α-Fe{sub 2}O{sub 3} nanoparticles were synthesized from ferric nitrite (Fe(NO{sub 3}){sub 3}), N,N-dimethyl formamide and poly(N-vinyl-2-pyrrolidone). Layers of nanoparticles were attached to HF-etched Si substrates by dip coating and subsequently embedded in thin titanium oxide films grown by atomic layer deposition from TiCl{sub 4} and H{sub 2}O. The deposition of TiO{sub 2} onto Fe{sub 2}O{sub 3} nanoparticles covered the nanoparticles uniformly and anatase phase of TiO{sub 2} was observed in Si/Fe{sub 2}O{sub 3}/TiO{sub 2} nanostructures. In Si/Fe{sub 2}O{sub 3}/TiO{sub 2} nanostructure magnetic domains, observable by magnetic force microscopy, were formed and these nanostructures implied ferromagnetic-like behavior at room temperature with the saturative magnetization and coercivity of 10 kA/m. - Highlights: • Cubic-shaped iron oxide crystallites were supported by thin titanium oxide films. • The process chemistry applied allowed formation of heterogeneous composite. • Atomic layer deposition of titanium oxide on nanocubes was uniform and conformal. • The nanostructures formed can be regarded as magnetically susceptible materials.

The annealing effect on work function variation of WN{sub x}C{sub y} films deposited by remote plasma atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyunjung; Shin, Changhee; Lim, Heewoo; Kim, Manseok [Department of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul (Korea, Republic of); Jang, Woochool; Lee, Kunyoung [Division of Materials Science and Engineering, Hanyang University, Seoul (Korea, Republic of); Yuh, Junhan [Division of Steel Solution, POSCO, Seoul (Korea, Republic of); Jeon, Hyeongtag [Department of Nano-Scale Semiconductor Engineering, Hanyang University, Seoul (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seoul (Korea, Republic of)

2017-07-15

Tungsten-nitrogen-carbide (WN{sub x}C{sub y}) thin films were investigated as the metal gate of complementary metal-oxide-semiconductor (CMOS) devices. WN{sub x}C{sub y} thin films were deposited by employing the remote plasma atomic layer deposition (RPALD) using a bis(tert-butylimido) bis (dimethylamido) tungsten (BTBMW) precursor and hydrogen plasma as a reactant. The growth rate of the WN{sub x}C{sub y} films was about 0.12 nm/cycle. X-ray diffraction (XRD) analysis indicated that the films consisted of a mixture of tungsten carbide and tungsten nitride phases. The atomic force microscope (AFM) analysis further confirmed that the WN{sub x}C{sub y} film surfaces deposited by RPALD were smooth. In addition, the chemical bonding state analysis showed that the WN{sub x}C{sub y} films consisted of WN, WC, and WO phases. To measure the work function of the WN{sub x}C{sub y} film, a MOSCAP (metal oxide semiconductor capacitor) stack was fabricated and the flat band voltage was measured by current-voltage (C-V) measurements. A WN{sub x}C{sub y} work function value of 4.91 eV was suitable for p-MOS and the work function of the WN{sub x}C{sub y} films varied depending on the annealing treatment, and was higher than the work function of the as-deposited WN{sub x}C{sub y} film. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Single Atoms Preparation Using Light-Assisted Collisions

Directory of Open Access Journals (Sweden)

Yin Hsien Fung

2016-01-01

Full Text Available The detailed control achieved over single optically trapped neutral atoms makes them candidates for applications in quantum metrology and quantum information processing. The last few decades have seen different methods developed to optimize the preparation efficiency of single atoms in optical traps. Here we review the near-deterministic preparation of single atoms based on light-assisted collisions and describe how this method can be implemented in different trap regimes. The simplicity and versatility of the method makes it feasible to be employed in future quantum technologies such as a quantum logic device.

Phase-sensitive atomic dynamics in quantum light

Science.gov (United States)

Balybin, S. N.; Zakharov, R. V.; Tikhonova, O. V.

2018-05-01

Interaction between a quantum electromagnetic field and a model Ry atom with possible transitions to the continuum and to the low-lying resonant state is investigated. Strong sensitivity of atomic dynamics to the phase of applied coherent and squeezed vacuum light is found. Methods to extract the quantum field phase performing the measurements on the atomic system are proposed. In the case of the few-photon coherent state high accuracy of the phase determination is demonstrated, which appears to be much higher in comparison to the usually used quantum-optical methods such as homodyne detection.

Manipulation of the magnetic properties in Er{sub 1−x}Co{sub 2} compounds by atomic vacancies

Energy Technology Data Exchange (ETDEWEB)

Zou, Jun-Ding, E-mail: zoujd@zju.edu.cn [School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Yan, Mi, E-mail: mse_yanmi@zju.edu.cn [School of Materials Science and Engineering, State Key Laboratory of Silicon Materials, Key Laboratory of Novel Materials for Information Technology of Zhejiang Province, Zhejiang University, Hangzhou, Zhejiang 310027 (China); Yao, Jin-Lei [Research Center for Solid State Physics and Materials, School of Mathematics and Physics, Suzhou University of Science and Technology, Suzhou 215009 (China)

2015-05-25

Highlights: • The nonstoichiometric Er{sub 1−x}Co{sub 2} compounds are identified. • Er atomic vacancies lead to the volume contracting by 0.37% and enhance T{sub C} by 44%. • The anomalous susceptibility behavior is not exact the same with the Griffiths phase. • The refrigerant capacity of Er{sub 0.97}Co{sub 2} increases from 152 J/kg to 158 J/kg. - Abstract: ErCo{sub 2} compound is a well-known magnetocaloric material which shows giant magnetocaloric effect in the vicinity of first-order phase transition. We demonstrate a new way of fine tuning its crystal structure and magnetic properties. Er atomic vacancies are introduced in order to manipulate the local atomic environment, the phase transition characteristics, and the magnetocaloric effect as well. Er{sub 1−x}Co{sub 2} can be stable over a narrow homogenous range, and maintain the cubic structure. The Bragg peaks shift upward to higher angles, and the unit cell volume contracts with reduction of the Er content. The Curie temperatures in low magnetic field increase from 32 K (ErCo{sub 2}) to 46 K (Er{sub 0.97}Co{sub 2}), and linearly change with the magnetic field in nearly same slope. Er{sub 1−x}Co{sub 2} compounds exhibit anomalous susceptibility behaviors in the paramagnetic state, and deviate from the Curie–Weiss law at around 100 K. The temperature range of anomalous susceptibility behaviors also move upward to higher temperature with reduction of Er content. Er{sub 1−x}Co{sub 2} compounds also show anomalous coercivity behavior in the vicinity of phase transition. Er{sub 1−x}Co{sub 2} compounds exhibit large magnetocaloric effect and good refrigerant capacity in the vicinity of ferrimagnetic–paramagnetic phase transition.

Hydrazine-based synergistic Ti(III)/N doping of surfactant-templated TiO{sub 2} thin films for enhanced visible light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Islam, Syed Z.; Rankin, Stephen E., E-mail: srankin@engr.uky.edu

2016-10-01

This study reports the preparation of titanium (Ti{sup 3+}) and nitrogen co-doped cubic ordered mesoporous TiO{sub 2} thin films using N{sub 2}H{sub 4} treatment. The resulting co-doped TiO{sub 2} (Ti{sup 3+}-N-TiO{sub 2}) thin films show significant enhancements in visible light absorption and photocatalytic activity. Cubic ordered mesoporous TiO{sub 2} thin films were prepared via a sol-gel method with Pluronic F127 as the pore template. After brief calcination, the TiO{sub 2} films were dipped into hydrazine hydrate which acts both as a nitrogen source and as a reducing agent, followed by heating at low temperature (90 °C). The hydrazine treatment period was varied from 5 to 20 h to obtain different degrees of reduction and nitrogen doping. X-ray photoelectron spectroscopy (XPS) analyses and UV–vis absorbance spectra of Ti{sup 3+}-N-TiO{sub 2} films indicate that the incorporated N atoms and Ti{sup 3+} reduce the band gap of TiO{sub 2} and thus enhance the absorption of visible light. The corresponding visible light photocatalytic activity of Ti{sup 3+}-N-TiO{sub 2} films was determined from the photocatalytic degradation of methylene blue under visible light illumination (at 455 nm). The Ti{sup 3+}-N-TiO{sub 2} films prepared with 10 h of treatment show the optimum photocatalytic activity, with a pseudo-first order rate coefficient of 0.12 h{sup −1}, which is 3 times greater than that of undoped TiO{sub 2} films. Calcination temperature and time were varied prior to hydrazine treatment to confirm that a brief calcination at low temperature (10 min at 350 °C) gave the best photochemical activity. In photoelectrochemical water oxidation using a 455 nm LED, the Ti{sup 3+}-N-TiO{sub 2} films prepared with 10 h of N{sub 2}H{sub 4} treatment show about 4 times the photocurrent compared to undoped TiO{sub 2} films. The present study suggests that hydrazine induced doping is a promising approach to enable synergistic incorporation of N and Ti{sup 3+} into the

Enhanced photocatalytic degradation of norfloxacin in aqueous Bi{sub 2}WO{sub 6} dispersions containing nonionic surfactant under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Tang, Lin, E-mail: tanglin@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Wang, Jiajia [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Liu, Yani; Deng, Yaocheng; Zhou, Yaoyu; Tang, Jing; Wang, Jingjing; Guo, Zhi [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2016-04-05

Highlights: • TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi{sub 2}WO{sub 6} dispersions under visible light irradiation (400–750 nm). • Cu{sup 2+} (10 mM) significantly suppressed the photocatalytic degradation of NOF. • FT-IR demonstrated that the NOF adsorbed on Bi{sub 2}WO{sub 6} was completely degraded. • Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis. - Abstract: Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi{sub 2}WO{sub 6} dispersion under visible light irradiation (400–750 nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi{sub 2}WO{sub 6} surface and accelerated NOF photodegradation at the critical micelle concentration (CMC = 0.25 mM). Higher TX100 concentration (>0.25 mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2 h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.

A visible-light-driven photocatalytic activity of vanadate garnet AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Lu, Yuting; Chen, Luyang; Li, Yuze; Huang, Yanlin [Soochow University, College of Chemistry, Chemical Engineering and Materials Science (China); Cheng, Han; Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Pukyong National University, Department of Physics and Interdisciplinary Program of Biomedical, Mechanical and Electrical Engineering (Korea, Republic of)

2015-10-15

A visible-light-driven photocatalyst of nanosized vanadate garnet AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} was prepared by a modified Pechini method. The nanoparticles were characterized with the measurements such as X-ray powder diffraction (XRD) and structural refinements, scanning electron microscope (SEM), and UV–visible (UV–Vis) absorption spectrum. The sample has an efficient absorption in the UV–Vis light region with a narrow band-gap energy of 2.16 eV and an indirect allowed electronic transition. Besides, the photocatalysis of AgCa{sub 2}Ni{sub 2}V{sub 3}O{sub 12} nanoparticles was evaluated by photo-degradation of methylene blue under visible-light irradiation, which shows excellent photocatalytic activity. The effective photocatalytic activity was discussed on the base of the garnet crystal structure such as the activated optical centers of Ni–O octahedron and V–O tetrahedral, highly distorted Ag–O dodecahedra, and long V–V distance in the lattices.

Manipulating mesoscopic multipartite entanglement with atom-light interfaces

International Nuclear Information System (INIS)

Stasinska, J.; Rodo, C.; Paganelli, S.; Birkl, G.; Sanpera, A.

2009-01-01

Entanglement between two macroscopic atomic ensembles induced by measurement on an ancillary light system has proven to be a powerful method for engineering quantum memories and quantum state transfer. Here we investigate the feasibility of such methods for generation, manipulation, and detection of genuine multipartite entanglement (Greenberger-Horne-Zeilinger and clusterlike states) between mesoscopic atomic ensembles without the need of individual addressing of the samples. Our results extend in a nontrivial way the Einstein-Podolsky-Rosen entanglement between two macroscopic gas samples reported experimentally in [B. Julsgaard, A. Kozhekin, and E. Polzik, Nature (London) 413, 400 (2001)]. We find that under realistic conditions, a second orthogonal light pulse interacting with the atomic samples, can modify and even reverse the entangling action of the first one leaving the samples in a separable state.

Precision spectroscopy of the 2S-4P{sub 1/2} transition in atomic hydrogen on a cold thermal beam of optically excited 2S atoms

Energy Technology Data Exchange (ETDEWEB)

Beyer, Axel; Kolachevsky, Nikolai; Alnis, Janis; Yost, Dylan C.; Matveev, Arthur; Parthey, Christian G.; Pohl, Randolf; Udem, Thomas [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Khabarova, Ksenia [FSUE ' VNIIFTRI' , 141570 Moscow (Russian Federation); Haensch, Theodor W. [Max-Planck-Institut fuer Quantenoptik, 85748 Garching (Germany); Ludwig-Maximilians-Universitaet, 80799 Muenchen (Germany)

2013-07-01

The 'proton size puzzle', i.e. the discrepancy between the values for the proton r.m.s. charge radius deduced from precision spectroscopy of atomic hydrogen and electron-proton-scattering on one side and the value deduced from muonic hydrogen spectroscopy on the other side, has been persisting for more than two years now. Although huge efforts have been put into trying to resolve this discrepancy from experimental and theoretical side, no convincing argument could be found so far. In this talk, we report on a unique precision spectroscopy experiment on atomic hydrogen, which is aiming to bring some light to the hydrogen part of the puzzle: In contrast to any previous high resolution experiment probing a transition frequency between the meta-stable 2S state and a higher lying nL state (n=3,4,6,8,12, L=S,P,D), our measurement of the 2S-4P{sub 1/2} transition frequency is the first experiment being performed on a cold thermal beam of hydrogen atoms optically excited to the 2S state. We will discuss how this helps to efficiently suppresses leading systematic effects of previous measurements and present the preliminary results we obtained so far.

Enhanced light harvesting of TiO{sub 2}/La{sub 0.95}Tb{sub 0.05}PO{sub 4} photoanodes for dye-sensitized solar cells

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hongna; He, Benlin, E-mail: blhe@ouc.edu.cn; Tang, Qunwei, E-mail: tangqunwei@ouc.edu.cn

2016-04-15

With an aim of enhancing light harvesting for dye adsorption and therefore photovoltaic performances of dye-sensitized solar cells (DSSCs), we present here an employment of La{sub 0.95}Tb{sub 0.05}PO{sub 4} incorporated TiO{sub 2} nanocrystallites as photoanodes. The preliminary results demonstrate that the dye absorption and therefore electron generation have been markedly enhanced, arising from the conversion of ultraviolet to visible light by La{sub 0.95}Tb{sub 0.05}PO{sub 4}. The crystal structure and light harvesting performances of photoanodes are optimized by adjusting La{sub 0.95}Tb{sub 0.05}PO{sub 4} dosage. The power conversion efficiency is enhanced from 6.52% for pristine TiO{sub 2} based DSSC to 7.27% for the device employing TiO{sub 2}/0.5 wt% La{sub 0.95}Tb{sub 0.05}PO{sub 4}, yielding an efficiency enhancement by 11.35%. This study provides a new strategy for the fabrication of highly efficient DSSCs. - Highlights: • TiO{sub 2}/La{sub 0.95}Tb{sub 0.05}PO{sub 4} nanocrystallites are fabricated by a facile hydrothermal method. • The light intensity and therefore dye excitation have been markedly enhanced. • A conversion efficiency of 7.27% for the DSSC employing TiO{sub 2}/0.5 wt% La{sub 0.95}Tb{sub 0.05}PO{sub 4} is obtained. • The strategy provides new opportunities for efficient DSSCs.

Magnetic and transport properties of Fe{sub {beta}}V{sub 1-{beta}} atom bridge constructed between an STM tip and a solid surface

Energy Technology Data Exchange (ETDEWEB)

Nakanishi, Hiroshi; Kasai, Hideaki E-mail: kasai@dyn.ap.eng.osaka-u.ac.jp; Kishi, Tomoya; Dino, W.A.; Komori, Fumio; Okiji, Ayao

2004-05-01

We have investigated the magnetic and transport properties of an atom bridge made from magnetic materials, which is an atom-scale wire constructed between a scanning tunneling microscopy tip and a solid surface, with the aid of ab initio calculations. In the case of Fe{sub {beta}}V{sub 1-{beta}} alloy atom bridges, we have found that the value of the mean magnetic moment is similar to that of the corresponding alloy bulk, and the quantized conductance contribution from both the majority and minority spin electrons changes as {beta} changes. These properties are different from the case of Fe{sub 1-{alpha}}Ni{sub {alpha}} alloy atom bridge.

Local atomic structure in tetragonal pure ZrO{sub 2} nanopowders

Energy Technology Data Exchange (ETDEWEB)

Acuna, Leandro M.; Lamas, Diego G.; Fuentes, Rodolfo O.; Fabregas, Ismael O. [CITEFA-CONICET, Villa Martelli, Provincia de Buenos Aires (AR). CINSO (Centro de Investigaciones en Solidos); Fantini, Marcia C.A.; Craievich, Aldo F. [Universidade de Sao Paulo (Brazil). Inst. de Fisica; Prado, Rogerio J. [Universidade Federal de Mato Grosso (UFMT), Cuiaba (Brazil). Inst. de Fisica

2010-04-15

The local atomic structures around the Zr atom of pure (undoped) ZrO{sub 2} nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wetchemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO{sub 2} nanopowders can be described by a model consisting of two oxygen subshells (4+4 atoms) with different Zr-O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye-Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to the z direction; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4+2+2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments. (orig.)

Enhanced visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid over ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Qiu, Pengxiang; Yao, Jinhua [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, Engineering Research Center for Chemical Pollution Control, Ministry of Education, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chen, Huan, E-mail: hchen404@njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, Engineering Research Center for Chemical Pollution Control, Ministry of Education, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Jiang, Fang, E-mail: fjiang@njust.edu.cn [Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, Engineering Research Center for Chemical Pollution Control, Ministry of Education, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Xie, Xianchuan [State Key Laboratory of Pollution Control and Resource Reuse, Center for Hydrosciences Research, School of the Environment, Nanjing University, Nanjing 210094 (China)

2016-11-05

Highlights: • A novel flower-on-sheet ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} nanocomposite was synthesized. • ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} showed high visible light catalytic activity for 2,4-D degradation. • The photocatalytic degradation pathway of 2,4-D was investigated. - Abstract: ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} heterojunction photocatalyst was successfully synthesized via a simple hydrothermal method and applied to visible-light photocatalytic decomposition of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous phase. The flower-like ZnIn{sub 2}S{sub 4} particles were dispersed on the surface of g-C{sub 3}N{sub 4} nanosheets in the ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} composite. The composite showed higher separation rate of electron-hole pairs as compared to ZnIn{sub 2}S{sub 4} and g-C{sub 3}N{sub 4}. Consequently, the ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} composite exhibited enhanced visible light photocatalytic decomposition efficiency of 2,4-D, within 20% ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} composite owning the highest photocatalytic efficiency and initial rate. The initial rates of 2,4-D degradation on g-C{sub 3}N{sub 4}, ZnIn{sub 2}S{sub 4}, and 20% ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} were 1.23, 0.57 and 3.69 mmol/(g{sub cat} h), respectively. The h{sup +} and O{sub 2}{sup ·−} were found to be the dominant active species for 2,4-D decomposition. The photocatalytic degradation pathways of 2,4-D by ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} under visible light irradiation were explored. The ZnIn{sub 2}S{sub 4}/g-C{sub 3}N{sub 4} composite displayed high photostability in recycling tests, reflecting its promising potential as an effective visible light photocatalyst for 2,4-D treatment.

Interface sulfur passivation using H{sub 2}S annealing for atomic-layer-deposited Al{sub 2}O{sub 3} films on an ultrathin-body In{sub 0.53}Ga{sub 0.47}As-on-insulator

Energy Technology Data Exchange (ETDEWEB)

Jin, Hyun Soo [Department of Materials Science and Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Cho, Young Jin; Lee, Sang-Moon [High-Performance Device Group, Samsung Advanced Institute of Technology, Samsung Electronics, Yongin 446-712 (Korea, Republic of); Department of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-742 (Korea, Republic of); Kim, Dae Hyun [Department of Materials Science and Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Department of Advanced Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Kim, Dae Woong [Department of Materials Science and Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Lee, Dongsoo [High-Performance Device Group, Samsung Advanced Institute of Technology, Samsung Electronics, Yongin 446-712 (Korea, Republic of); Park, Jong-Bong [Department of Advanced Materials Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of); Won, Jeong Yeon [Analytical Science Group, Computational and Analytical Science Center, Samsung Advanced Institute of Technology, Samsung Electronics, Yongin 446-712 (Korea, Republic of); Lee, Myoung-Jae; Cho, Seong-Ho [High-Performance Device Group, Samsung Advanced Institute of Technology, Samsung Electronics, Yongin 446-712 (Korea, Republic of); Hwang, Cheol Seong, E-mail: cheolsh@snu.ac.kr [Department of Materials Science and Engineering and Inter-university Semiconductor Research Center, Seoul National University, Seoul 151-742 (Korea, Republic of); Park, Tae Joo, E-mail: tjp@hanyang.ac.kr [Department of Materials Science and Engineering, Hanyang University, Ansan 426-791 (Korea, Republic of)

2014-10-01

Highlights: • ALD Al{sub 2}O{sub 3} films were grown on ultrathin-body In{sub 0.53}Ga{sub 0.47}As substrates for III-V compound-semiconductor-based devices. • Interface sulfur passivation was performed with wet processing using (NH{sub 4}){sub 2}S solution, and dry processing using post-deposition annealing under a H{sub 2}S atmosphere. • Electrical properties of the device were better for (NH{sub 4}){sub 2}S wet-treatment than the PDA under a H{sub 2}S atmosphere. • PDA under a H{sub 2}S atmosphere following (NH{sub 4}){sub 2}S wet-treatment resulted in an increased S concentration at the interface, which improved the electrical properties of the devices. - Abstract: Atomic-layer-deposited Al{sub 2}O{sub 3} films were grown on ultrathin-body In{sub 0.53}Ga{sub 0.47}As substrates for III-V compound-semiconductor-based devices. Interface sulfur (S) passivation was performed with wet processing using ammonium sulfide ((NH{sub 4}){sub 2}S) solution, and dry processing using post-deposition annealing (PDA) under a H{sub 2}S atmosphere. The PDA under the H{sub 2}S atmosphere resulted in a lower S concentration at the interface and a thicker interfacial layer than the case with (NH{sub 4}){sub 2}S wet-treatment. The electrical properties of the device, including the interface property estimated through frequency dispersion in capacitance, were better for (NH{sub 4}){sub 2}S wet-treatment than the PDA under a H{sub 2}S atmosphere. They might be improved, however, by optimizing the process conditions of PDA. The PDA under a H{sub 2}S atmosphere following (NH{sub 4}){sub 2}S wet-treatment resulted in an increased S concentration at the interface, which improved the electrical properties of the devices.

Magnetism, microstructure and First Principles calculations of atomized and annealed Ni{sub 3}Al

Energy Technology Data Exchange (ETDEWEB)

García-Escorial, A., E-mail: age@cenim.csic.es [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Crespo, P.; Hernando, A. [Instituto de Magnetismo Aplicado, IMA-UCM, P.O. Box 155, 28230 Madrid (Spain); Lieblich, M. [CENIM-CSIC, Avda. Gregorio del Amo, 8, 28040 Madrid (Spain); Marín, P.; Velasco, V. [Instituto de Magnetismo Aplicado, IMA-UCM, P.O. Box 155, 28230 Madrid (Spain); Ynduráin, F. [Dpto. de Física de la Materia Condensada, UAM, Cantoblanco, 28049 Madrid (Spain)

2014-12-05

Highlights: • The microstructure and order of as-atomized Ni{sub 3}Al powder change with annealing. • The change of the magnetic properties shows the influence of the chemical order. • First Principles calculations show the effect of the density of states to the order. - Abstract: In this work Ni{sub 3}Al powder particles obtained by atomization were characterized magnetically and microstructurally in as-atomized state and after annealing. Upon annealing the X-ray diffraction patterns show a noticeable increase of the signal of the ordered phase γ′-Ni{sub 3}Al, L1{sub 2}, phase and the microstructure evolves from a lamellar and dendrite to a large grain microstructure. The Curie temperature of the as-atomized powder particles is 85 K and decreases after annealing down to 50 K. First Principles calculations were carried out to correlate the experimental observations with local order of Ni and Al atoms and illustrate the importance of the local order in the density of states at the Fermi level, showing how the magnetic moment depends on the Ni and Al atomic position.

Effects of Y dopant on lattice distortion and electrical properties of In{sub 3}SbTe{sub 2} phase-change material

Energy Technology Data Exchange (ETDEWEB)

Choi, Minho; Kwon, Sehyun; Ahn, Jinho [Division of Materials Science and Engineering, Hanyang University, Seoul (Korea, Republic of); Choi, Heechae [Center of Materials Simulation Research, Virtual Lab Inc., Seoul (Korea, Republic of); Center for Computational Science, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Seungchul; Lee, Kwang-Ryeol [Center for Computational Science, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Kim, Yong Tae [Semiconductor Materials and Device Laboratory, Korea Institute of Science and Technology, Seoul (Korea, Republic of)

2017-11-15

Using a computational high-throughput screening method, 29 doping elements have been investigated for improving the thermal and electrical characteristics of In{sub 3}SbTe{sub 2} (IST) phase-change material. Among the 29 dopants, it is found that Y offers largest distortion in the lattice structure of IST with negative doping formation energy while Y substitutes the In site. The atomic lattice images clearly show that the In site is substituted by Y and the distortion angles of the Y-doped IST (Y-IST) are well matched with the calculated results of density functional theory (DFT). Set/reset speed of the Y-IST phase-change memory is faster than IST and Ge{sub 2}Sb{sub 2}Te{sub 5} (GST) devices, which is strongly related with the fast and stable phase transition due to the larger lattice distortion. The power consumption of the Y-IST device is also less than a fourth of that of the GST device. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Total cross section for relativistic positronium interaction with atom

International Nuclear Information System (INIS)

Pak, A.S.; Tarasov, A.V.

1985-01-01

Total cross sections of interaction of positronium relativistic atoms with atoms are calculated. Calculations are conducted within the framework of potential theory in Born approximaton. Contributions in total cross section of coherent (σsub(coh)) and incoherent (σsub(inc)) parts are analyzed. It is shown that for light elements σsub(inc) value is comparable with σsub(coh), and for heavy ones the ratio σsub(inc)/σsub(coh) sufficiently exceeds Zsup(-1) (Z-charge of the atomic nucleus. Numerical calculation results are presented. A conclusion is made on importance of the coherent part account during the calculation of total cross sections

Existence of undiscovered Uranian satellites

International Nuclear Information System (INIS)

Boice, D.C.

1986-04-01

Structure in the Uranian ring system as observed in recent occultations may contain indirect evidence for the existence of undiscovered satellites. Using the Alfven and Arrhenius (1975, 1976) scenario for the formation of planetary systems, the orbital radii of up to nine hypothetical satellites interior to Miranda are computed. These calculations should provide interesting comparisons when the results from the Voyager 2 encounter with Uranus are made public. 15 refs., 1 fig., 1 tab

Field ion microscopy and imaging atom-probe mass spectroscopy of superconducting YBa2Cu3O7/sub -//sub x/

International Nuclear Information System (INIS)

Kellogg, G.L.; Brenner, S.S.

1987-01-01

The structure and composition of the superconducting oxide YBa 2 Cu 3 O/sub 7-//sub x/ have been examined in atomic detail by field ion microscopy and imaging atom-probe mass spectroscopy. The field ion samples were prepared from hot-pressed disks of the oxide powders. Atomic resolution images were obtained with either argon or hydrogen as the imaging gas. Individual layers of atoms were observed which could be field evaporated in a uniform, layer-by-layer manner. Imaging atom-probe analysis of the field ion tips indicated a metal composition which varied noticeably from sample to sample and an oxygen concentration which was consistently much too low

Geology and assessment of undiscovered oil and gas resources of the Zyryanka Basin Province, 2008

Science.gov (United States)

Klett, Timothy; Pitman, Janet K.; Moore, T.E.; Gautier, D.L.

2017-11-22

The U.S. Geological Survey (USGS) recently assessed the potential for undiscovered oil and gas resources of the Zyryanka Basin Province as part of the 2008 USGS Circum-Arctic Resource Appraisal program. The province is in the Russian Federation and is situated on the Omolon superterrane of the Kolyma block. The one assessment unit (AU) that was defined for this study, called the Zyryanka Basin AU, which coincides with the province, was assessed for undiscovered, technically recoverable, conventional resources. The estimated mean volumes of undiscovered resources in the Zyryanka Basin Province are ~72 million barrels of crude oil, 2,282 billion cubic feet of natural gas, and 61 million barrels of natural-gas liquids. About 66 percent of the study area and undiscovered petroleum resources are north of the Arctic Circle.

Digestive ripening facilitated atomic diffusion at nanosize regime: Case of AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Arora, Neha [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Jagirdar, Balaji R., E-mail: jagirdar@ipc.iisc.ernet.in [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012 (India); Klabunde, Kenneth J. [Department of Chemistry, Kansas State University, Manhattan, KS 66506 (United States)

2014-10-15

Highlights: • A digestive ripening facilitated interatomic diffusion process is presented. • Nearly monodisperse AuIn{sub 2} and Ag{sub 3}In intermetallic nanoparticles were synthesized. • Optimization of reaction temperature facilitates interatomic transfer. • Presence of excess ligand plays a crucial role in the digestive ripening process. - Abstract: Monodisperse colloidal gold–indium (AuIn{sub 2}) intermetallic nanoparticles have been synthesized from Au and In colloids using the digestive ripening process. Formation of the intermetallic proceeds via digestive ripening facilitated atomic diffusion of Au and In atoms from the Au and In nanoparticles followed simultaneously by their growth in the solution. Optimization of the reaction temperature was found to be crucial for the formation of AuIn{sub 2} intermetallic from gold and indium nanoparticles. Transmission electron microscopy revealed the presence of nearly monodisperse nanoparticles of Au and AuIn{sub 2} with particle size distribution of 3.7 ± 1.0 nm and 5.0 ± 1.6 nm, respectively. UV–visible spectral studies brought out the absence of SPR band in pure AuIn{sub 2} intermetallic nanoparticles. Optical study and electron microscopy, in combination with powder X-ray diffraction established phase pure AuIn{sub 2} intermetallic nanoparticles unambiguously. The potential of such an unprecedented approach has been further exploited in the synthesis of Ag{sub 3}In intermetallic nanoparticles with the dimension of less than 10 nm.

Visible-light photocatalytic activity of graphene oxide-wrapped Bi{sub 2}WO{sub 6} hierarchical microspheres

Energy Technology Data Exchange (ETDEWEB)

Zhai, Jiali; Yu, Hongwen, E-mail: yuhw@iga.ac.cn; Li, Haiyan; Sun, Lei; Zhang, Kexin; Yang, Hongjun

2015-07-30

Graphical abstract: - Highlights: • GO/Bi{sub 2}WO{sub 6} are readily fabricated by facile bubbling pretreatment and freeze drying. • GO/Bi{sub 2}WO{sub 6} possess excellent photocatalytic activity under visible light irradiation. • The visible light activity of GO/Bi{sub 2}WO{sub 6} is affected by the amount of GO. • The photostablity of GO is due to the photo-generated electrons transfer to Bi{sub 2}WO{sub 6}. - Abstract: A facile approach of fabricating homogeneous graphene oxide (GO)-wrapped Bi{sub 2}WO{sub 6} microspheres (GO/Bi{sub 2}WO{sub 6}) is developed. The transmission electron microscopy (TEM) results show that a heterojunction interface between GO and Bi{sub 2}WO{sub 6}. The UV–vis diffuse reflection spectra (DRS) reveal that the as-prepared GO/Bi{sub 2}WO{sub 6} composites own more intensive absorption in the visible light range compared with pure Bi{sub 2}WO{sub 6}. These characteristic structural and optical properties endow GO/Bi{sub 2}WO{sub 6} composites with enhanced photocatalytic activity. The enhanced photocatalytic activity of the GO/Bi{sub 2}WO{sub 6} is attributed predominantly to the synergetic effect between GO and Bi{sub 2}WO{sub 6}, causing rapid generation and separation of photo-generated charge carriers.

Deflection of slow light by magneto-optically controlled atomic media

International Nuclear Information System (INIS)

Zhou, D. L.; Wang, R. Q.; Zhou, Lan; Yi, S.; Sun, C. P.

2007-01-01

We present a semiclassical theory for light deflection by a coherent Λ-type three-level atomic medium in an inhomogeneous magnetic field or an inhomogeneous control laser. When the atomic energy levels (or the Rabi coupling by the control laser) are position-dependent due to the Zeeman effect caused by the inhomogeneous magnetic field (or due to inhomogeneity of the control field profile), the spatial dependence of the refraction index of the atomic medium will result in an observable deflection of slow signal light when the electromagnetically induced transparency cancels medium absorption. Our theoretical approach based on Fermat's principle in geometrical optics not only provides a consistent explanation for the most recent experiment in a straightforward way, but also predicts the two-photon detuning dependent behaviors and larger deflection angles by three orders of magnitude for the slow signal light deflection by the atomic media in an inhomogeneous off-resonant control laser field

Multiferroic and visible light photocatalytic properties of six-layered perovskite oxide Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20}

Energy Technology Data Exchange (ETDEWEB)

Cheng, Xiangyi; Yang, Hongshun; Ruan, Keqing; Xu, Xiaoliang [University of Science and Technology of China, Key Laboratory of Strongly-Coupled Quantum Matter Physics, Chinese Academy of Sciences and School of Physical Sciences, Hefei (China); Meng, Dechao [University of Science and Technology of China, Hefei National Laboratory for Physical Sciences at Microscale, Hefei (China)

2017-04-15

The layered perovskite-related oxide Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} was prepared by incorporating NdFeO{sub 3} in the host Nd{sub 2}Ti{sub 2}O{sub 7} using floating-zone melting technique. XRD and HRTEM results suggested that the material has a layered structure of n = 6 type. Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} exhibited spin glass-like behavior, and its magnetic behavior was affected by magnetic Nd{sup 3+} ions strongly at low temperature. The ferromagnetic and ferroelectric properties were observed by magnetic and PFM measurements at the room temperature. UV-Vis absorption spectroscopy revealed that the compound is a visible light absorbing photocatalyst with a direct band gap of 2.2 eV. In addition, the photocatalytic behaviors of bulk Nd{sub 6}Ti{sub 4}Fe{sub 2}O{sub 20} were evaluated by photodegradation of rhodamine B under visible light irradiation. (orig.)

Methods for the estimation and economic evaluation of undiscovered uranium endowment and resources

International Nuclear Information System (INIS)

1992-01-01

The present Instruction Manual was prepared as part of a programme of the International Atomic Energy Agency to supply the international uranium community with standard guides for a number of topics related to uranium resource assessment and supply. The quantitative estimation of undiscovered resources and endowments aims at supplying data on potential mineral resources; these data are needed to compare long term projections with one another and to assess the mineral supplies to be obtained from elsewhere. These objectives have relatively recently been supplemented by the concern of land managers and national policy planners to assess the potential of certain lands before the constitution of national parks and other areas reserved from mineral exploration and development. 88 refs, 28 figs, 33 tabs

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.

Influence of atomic ordering on sigma phase precipitation of the Fe{sub 50}Cr{sub 50} alloy

Energy Technology Data Exchange (ETDEWEB)

Vélez, G.Y., E-mail: g.y.velezcastillo@gmail.com [Universidad del Valle, Departamento de Física, A.A. 25360 Cali (Colombia); Instituto de Física, Universidad Autónoma de San Luis Potosí, avenida Manuel Nava 6, zona universitaria, 78290 San Luis Potosí, SLP México (Mexico); Pérez Alcázar, G.A. [Universidad del Valle, Departamento de Física, A.A. 25360 Cali (Colombia)

2015-09-25

Highlights: • σ-FeCr phase can be delayed when α-FeCr phase is ordered. • The formation of σ phase is favored by concentration gradients of α phase. • We determine the iron occupation number of the five sites of σ-Fe{sub 50}Cr{sub 50}. - Abstract: In this work we report a study of the kinetic of the formation of the σ-Fe{sub 50}Cr{sub 50} alloy which is obtained by heat treatment of α-FeCr samples with different atomic ordering. Two α-FeCr alloys were obtained, one by mechanical alloying and the other by arc-melting. Both alloys were heated at 925 K for 170 h and then quenched into ice water. Before heat treatment both alloys exhibit α-FeCr disordered structure with greater ferromagnetic behavior in the alloy obtained by mechanical alloying due to its higher atomic disorder. The sigma phase precipitation is influenced by the atomic ordering of the bcc samples: in the alloy obtained by mechanical alloying, the bcc phase is completely transformed into the σ phase; in the alloy obtained by melted the α–σ transformation is partial.

A facile approach to pure-phase Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles sensitive to visible light

Energy Technology Data Exchange (ETDEWEB)

Wang, X., E-mail: xiongwang@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Zhang, M.; Tian, P. [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Chin, W.S. [Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Zhang, C.M. [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

2014-12-01

Graphical abstract: - Highlights: • Pure-phase Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles were prepared by a facile and environmentally benign sol–gel method. • The multiband characteristic of the nanoparticles greatly expands the visible light absorption. • The visible-light-driven photocatalytic activity of the obtained nanoparticles was improved by 30-fold as compared to the bulk. - Abstract: Pure-phase Bi{sub 2}Fe{sub 4}O{sub 9} nanoparticles with mullite-type structure were successfully fabricated through a facile and environmentally benign sol–gel process. According to the UV–Vis diffuse reflection spectrum, the multiband structure and the band edge position of the nanoparticles were confirmed, indicating the prominent absorption in the expanded visible-light region. As compared to the bulk, the visible-light-driven photocatalytic activity of the obtained nanoparticles was improved by 30-fold. The much improved photocatalytic efficiency of the sample mainly owed to the small crystal size and the multiband characteristic as well as the adding of H{sub 2}O{sub 2} as electron scavenger and a source of hydroxide free radicals instead of Fenton-like reaction, leading to a low recombination of the photogenerated e{sup −}/h{sup +} pairs.

Si{sub 2}Sb{sub 2}Te{sub 5} phase change material studied by an atomic force microscope nano-tip

Energy Technology Data Exchange (ETDEWEB)

Liu Yanbo; Min Guoquan; Zhang Jing; Zhou Weimin; Wan Yongzhong; Zhang Jianping; Li Xiaoli [Laboratory of Nano-Technology, Shanghai Nanotechnology Promotion Center, Shanghai 200237 (China); Zhang Ting; Niu Xiaoming; Song Zhitang; Feng Songlin, E-mail: liuyanbo@snpc.org.c, E-mail: tzhang@mail.sim.ac.c [State Key Laboratory of Functional Materials for Informatics, Laboratory of Nanotechnology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

2009-06-01

The Si{sub 2}Sb{sub 2}Te{sub 5} phase change material has been studied by applying a nano-tip (30 nm in diameter) on an atomic force microscopy system. Memory switching from a high resistance state to a low resistance state has been achieved, with a resistance change of about 1000 times. In a typical I-V curve, the current increases significantly after the voltage exceeds approx4.3 V. The phase transformation of a Si{sub 2}Sb{sub 2}Te{sub 5} film was studied in situ by means of in situ X-ray diffraction and temperature dependent resistance measurements. The thermal stability of Si{sub 2}Sb{sub 2}Te{sub 5} and Ge{sub 2}Sb{sub 2}Te{sub 5} was characterized and compared as well.

Liquid CO<sub>2sub>/Coal Slurry for Feeding Low Rank Coal to Gasifiers

Energy Technology Data Exchange (ETDEWEB)

Marasigan, Jose [Electric Power Research Institute, Inc., Palo Alto, CA (United States); Goldstein, Harvey [Electric Power Research Institute, Inc., Palo Alto, CA (United States); Dooher, John [Electric Power Research Institute, Inc., Palo Alto, CA (United States)

2013-09-30

This study investigates the practicality of using a liquid CO<sub>2sub>/coal slurry preparation and feed system for the E-Gas™ gasifier in an integrated gasification combined cycle (IGCC) electric power generation plant configuration. Liquid CO<sub>2sub> has several property differences from water that make it attractive for the coal slurries used in coal gasification-based power plants. First, the viscosity of liquid CO<sub>2sub> is much lower than water. This means it should take less energy to pump liquid CO<sub>2sub> through a pipe compared to water. This also means that a higher solids concentration can be fed to the gasifier, which should decrease the heat requirement needed to vaporize the slurry. Second, the heat of vaporization of liquid CO<sub>2sub> is about 80% lower than water. This means that less heat from the gasification reactions is needed to vaporize the slurry. This should result in less oxygen needed to achieve a given gasifier temperature. And third, the surface tension of liquid CO<sub>2sub> is about 2 orders of magnitude lower than water, which should result in finer atomization of the liquid CO<sub>2sub> slurry, faster reaction times between the oxygen and coal particles, and better carbon conversion at the same gasifier temperature. EPRI and others have recognized the potential that liquid CO<sub>2sub> has in improving the performance of an IGCC plant and have previously conducted systemslevel analyses to evaluate this concept. These past studies have shown that a significant increase in IGCC performance can be achieved with liquid CO<sub>2sub> over water with certain gasifiers. Although these previous analyses had produced some positive results, they were still based on various assumptions for liquid CO<sub>2sub>/coal slurry properties.

Synthesis, characterization and photocatalytic activity of WO{sub 3}/TiO{sub 2} for NO removal under UV and visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Luévano-Hipólito, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Martínez-de la Cruz, A., E-mail: azael.martinezdl@uanl.edu.mx [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); López-Cuellar, E. [CIIDIT, Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Yu, Q.L.; Brouwers, H.J.H. [Department of the Built Environment, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)

2014-11-14

Samples with different proportions WO{sub 3}/TiO{sub 2} were prepared by co-precipitation method followed by a heat treatment. The samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS), and adsorption–desorption N{sub 2} isotherms (BET). The photocatalytic properties of WO{sub 3}/TiO{sub 2} samples were evaluated in the photo-oxidation reaction of nitric oxide (NO) under UV and visible light irradiation. The highest photocatalytic activity was observed in the WO{sub 3}/TiO{sub 2} sample with a composition of 80% mole of TiO{sub 2}. Among the different substrates used for supporting the photocatalyst, the best results were reached over concrete and glass when it was exposed to UV and visible light irradiation, respectively. In overall, the photocatalytic efficiency of the synthesized materials was higher under UV than visible light irradiation. - Highlights: • WO{sub 3}/TiO{sub 2} prepared in simple way show high photocatalytic activity for NO removal. • The concrete was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with UV radiation. • The glass was the best substrate to the performance of WO{sub 3}/TiO{sub 2} with visible radiation.

Comparison of Atom Interferometers and Light Interferometers as Space-Based Gravitational Wave Detectors

Science.gov (United States)

Baker, John G.

2012-01-01

We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe.

Comparative Sensitivities of Gravitational Wave Detectors Based on Atom Interferometers and Light Interferometers

Science.gov (United States)

Baker, John G.; Thorpe, J. I.

2012-01-01

We consider a class of proposed gravitational wave detectors based on multiple atomic interferometers separated by large baselines and referenced by common laser systems. We compute the sensitivity limits of these detectors due to intrinsic phase noise of the light sources, non-inertial motion of the light sources, and atomic shot noise and compare them to sensitivity limits for traditional light interferometers. We find that atom interferometers and light interferometers are limited in a nearly identical way by intrinsic phase noise and that both require similar mitigation strategies (e.g. multiple arm instruments) to reach interesting sensitivities. The sensitivity limit from motion of the light sources is slightly different and favors the atom interferometers in the low-frequency limit, although the limit in both cases is severe. Whether this potential advantage outweighs the additional complexity associated with including atom interferometers will require further study.

The influence of Ti doping and annealing on Ce{sub 2}Ti{sub 2}O{sub 7} flash memory devices

Energy Technology Data Exchange (ETDEWEB)

Kao, Chyuan Haur [Department of Electronic Engineering, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC (China); Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Department of Electronic Engineering, Ming Chi University of Technology, Taiwan, ROC (China); Chen, Su Zhien [Department of Electronic Engineering, Chang Gung University, No. 259, Wenhua 1st Rd., Guishan Dist., Taoyuan City 33302, Taiwan, ROC (China); Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Luo, Yang; Chiu, Wang Ting; Chiu, Shih Wei; Chen, I Chien [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, No. 1, University Rd., Puli, Nantou Country 54561, Taiwan, ROC (China); Lin, Chan-Yu [Kidney Research Center, Department of Nephrology, Chang Gung Memorial Hospital, Chang Gung University, College of Medicine, Taoyuan, Taiwan, ROC (China); Chen, Hsiang, E-mail: hchen@ncnu.edu.tw [Department of Applied Materials and Optoelectronic Engineering, National Chi Nan University, No. 1, University Rd., Puli, Nantou Country 54561, Taiwan, ROC (China)

2017-02-28

Highlights: • Ce{sub 2}Ti{sub 2}O{sub 7} flash memories have been fabricated. • Material quality can be improved by annealing. • The memory performance can be enhanced by Ti doping. • Ti doping and annealing can reinforce crystallization. - Abstract: In this research, a CeO{sub 2} film with Ti doping was used as a trapping layer in metal oxide high-K-oxide-Si (MOHOS)-type memory devices. Since incorporation of Ti atoms into the film could fix dangling bonds and defects, the Ce{sub 2}Ti{sub 2}O{sub 7} trapping layer with annealing treatment could have a larger memory window and a faster programming/erasing speed. To confirm the origin, multiple material analyses indicate that annealing at an appropriate temperature and Ti doping could enhance crystallization. The Ce{sub 2}Ti{sub 2}O{sub 7}-based memory device is promising for future industrial flash memory applications.

Controlled hydrothermal synthesis of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites exhibiting visible-light photocatalytic degradation of crystal violet

Energy Technology Data Exchange (ETDEWEB)

Jiang, Yu-Rou; Lin, Ho-Pan [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China); Chung, Wen-Hsin [Department of Plant Pathology, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Dai, Yong-Ming [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China); Lin, Wan-Yu [Department of Plant Pathology, National Chung Hsing University, Taichung 402, Taiwan, ROC (China); Chen, Chiing-Chang, E-mail: ccchen@ms3.ntcu.edu.tw [Department of Science Application and Dissemination, National Taichung University of Education, Taichung 403, Taiwan, ROC (China)

2015-02-11

Highlights: • This is the first report on a series of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} heterojunctions. • The BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composition was controlled by adjusting the growth parameters. • The BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} were indirect semiconductors with a 1.78–2.95-eV bandgap. • The new photocatalysts removed CV at a much faster rate than TiO{sub 2}. • Mechanisms were determined by separating the intermediates using HPLC-MS. - Abstract: A series of BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites were prepared using autoclave hydrothermal methods. The composition and morphologies of the BiO{sub x}Cl{sub y}/BiO{sub m}I{sub n} composites were controlled by adjusting the experimental conditions: the reaction pH value, temperature, and KCl/KI molar ratio. The products were characterized using X-ray diffraction, scanning electron microscopy-electron dispersive X-ray spectroscopy, UV–vis diffuse reflectance spectroscopy, Brunauer–Emmett–Teller specific surface areas, cathodoluminescence, high-resolution transmission electron microscopy, and high-resolution X-ray photoelectron spectroscopy. The photocatalytic efficiencies of composite powder suspensions were evaluated by monitoring the crystal violet (CV) concentrations. In addition, the quenching effects of various scavengers indicated that the reactive O{sub 2}·{sup −} played a major role, and OH· or h{sup +} played a minor role in CV degradation. The intermediates formed during the decomposition process were isolated, identified, and characterized using high performance liquid chromatography-photodiode array-electrospray ionization-mass spectrometry to elucidate the CV decomposition mechanism.

Enhancing visible light photocatalytic and photocharge separation of (BiO){sub 2}CO{sub 3} plate via dramatic I{sup −} ions doping effect

Energy Technology Data Exchange (ETDEWEB)

Liang, Lei [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Cao, Jing [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Anhui Collaborative Innovation Center of Advanced Functional Composite, Huaibei, 235000, Anhui (China); Lin, Haili, E-mail: linhaili@mail.ipc.ac.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Guo, Xiaomin; Zhang, Meiyu [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); Chen, Shifu, E-mail: chshifu@chnu.edu.cn [College of Chemistry and Materials Science, Huaibei Normal University, Huaibei, 235000, Anhui (China); College of Chemistry and Materials Engineering, Anhui Science and Technology University, Fengyang, 233100, Anhui (China)

2016-08-15

Highlights: • Novel I-(BiO){sub 2}CO{sub 3} was prepared by a facile chemical precipitation method. • I{sup −} ions impurity level located on the top of valence band of (BiO){sub 2}CO{sub 3}. • I{sup −} ions doping largely improved photocatalytic activity of I-(BiO){sub 2}CO{sub 3}. • I-(BiO){sub 2}CO{sub 3} displayed excellent photocharge separation efficiency. - Abstract: Novel I{sup −} ions doped (BiO){sub 2}CO{sub 3} (I-(BiO){sub 2}CO{sub 3}) photocatalysts were successfully synthesized via a facile chemical precipitation method. Under visible light (λ > 400 nm), I-(BiO){sub 2}CO{sub 3} displayed much higher activity for rhodamine B and dichlorophenol degradation than the undoped (BiO){sub 2}CO{sub 3}. The pseudo-first-order rate constant k{sub app} of RhB degradation over 15.0% I-(BiO){sub 2}CO{sub 3} was 0.54 h{sup −1}, which is 11.3 times higher than that of (BiO){sub 2}CO{sub 3}. The doped I{sup −} ions formed an impurity level on the top of valence band of (BiO){sub 2}CO{sub 3} and induced much more visible light to be absorbed. The enhanced photocurrent and surface photovoltage properties were detected, which strongly ensures the efficient separation of electrons and holes in I-(BiO){sub 2}CO{sub 3} system under visible light. It provides a facile way to improve the photocatalytic activity of the wide-band-gap (BiO){sub 2}CO{sub 3} via intense doping effect of I{sup −} ions.

Broadband sensitized white light emission of g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphor under near ultraviolet excitation

Energy Technology Data Exchange (ETDEWEB)

Han, Bing, E-mail: hanbing@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Xue, Yongfei; Li, Pengju [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jingtao [School of Food and Bioengineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Zhang, Jie [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China); Shi, Hengzhen, E-mail: shihz@zzuli.edu.cn [School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 (China)

2015-12-15

The g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphors were synthesized and characterized by X-ray diffraction, Fourier transform-infrared spectroscopy, ultraviolet visible diffuse reflection spectra, photoluminescence spectra and luminescence decay curves. Under the excitation of 360 nm near ultraviolet light, these composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained in term of appropriate quality proportion of Y{sub 2}MoO{sub 6}:Eu{sup 3+} relative to g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+}. In addition, the emission color can be also dependent on the excitation wavelength in g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphor. - Graphical abstract: Under the excitation of 360 nm near ultraviolet light, the g-C{sub 3}N{sub 4}/Y{sub 2}MoO{sub 6}:Eu{sup 3+} composite phosphors show tunable emission from blue to red region, in which white light emission can be obtained. - Highlights: • The g-C3N4/Y2MoO6:Eu{sup 3+} composite phosphors were synthesized and characterized. • White light emission was realized in the g-C3N4/Y2MoO6:Eu{sup 3+} composites under UV excitation. • A novel idea to realize the broadband sensitized white light emission in phosphors was provided.

Faster-than-real-time robot simulation for plan development and robot safety

International Nuclear Information System (INIS)

Crane, C.D. III; Dalton, R.; Ogles, J.; Tulenko, J.S.; Zhou, X.

1990-01-01

The University of Florida, in cooperation with the Universities of Texas, Tennessee, and Michigan and Oak Ridge National Laboratory (ORNL), is developing an advanced robotic system for the US Department of Energy under the University Program for Robotics for Advanced Reactors. As part of this program, the University of Florida has been pursuing the development of a faster-than-real-time robotic simulation program for planning and control of mobile robotic operations to ensure the efficient and safe operation of mobile robots in nuclear power plants and other hazardous environments

Ultra-Deep Adsorptive Desulfurization of Light-Irradiated Diesel Fuel over Supported TiO<sub>2sub>-CeO>2sub> Adsorbents

Energy Technology Data Exchange (ETDEWEB)

Xiao, Jing; Wang, Xiaoxing; Chen, Yongsheng; Fujii, Mamoru; Song, Chunshan [SCUT-China; (Penn)

2014-02-13

This study investigates ultra-deep adsorptive desulfurization (ADS) from light-irradiated diesel fuel over supported TiO<sub>2sub>–CeO>2sub> adsorbents. A 30-fold higher desulfurization capacity of 95 mL of fuel per gram of adsorbent (mL-F/g-sorb) or 1.143 mg of sulfur per gram of adsorbent (mg-S/g-sorb) was achieved from light-irradiated fuel over the original low-sulfur fuel containing about 15 ppm by weight (ppmw) of sulfur. The sulfur species on spent TiO<sub>2sub>–CeO>2sub>/MCM-48 adsorbent was identified by sulfur K-edge XANES as sulfones and the adsorption selectivity to different compounds tested in a model fuel decreases in the order of indole > dibenzothiophenesulfone → dibenzothiophene > 4-methyldibenzothiophene > benzothiophene > 4,6-dimethyldibenzothiophene > phenanthrene > 2-methylnaphthalene ~ fluorene > naphthalene. The results suggest that during ADS of light-irradiated fuel, the original sulfur species were chemically transformed to sulfones, resulting in the significant increase in desulfurization capacity. For different supports for TiO2–CeO2 oxides, the ADS capacity increases with a decrease in the point of zero charge (PZC) value; for silica-supported TiO<sub>2sub>–CeO>2sub> oxides (the lowest PZC value of 2–4) with different surface areas, the ADS capacity increases monotonically with increasing surface area. The supported TiO<sub>2sub>–CeO>2sub>/MCM-48 adsorbent can be regenerated using oxidative air treatment. The present study provides an attractive new path to achieve ultraclean fuel more effectively.

Enhancing photocatalytic CO{sub 2} reduction by coating an ultrathin Al{sub 2}O{sub 3} layer on oxygen deficient TiO{sub 2} nanorods through atomic layer deposition

Energy Technology Data Exchange (ETDEWEB)

Zhao, Huilei; Chen, Jiatang; Rao, Guiying; Deng, Wei; Li, Ying, E-mail: yingli@tamu.edu

2017-05-15

Highlights: • Oxygen deficient TiO{sub 2} anatase nanorods are coated with an ultrathin Al{sub 2}O{sub 3} layer by ALD. • Exposed {100} facets and oxygen vacancies promote CO{sub 2} photoreduction to CO and CH{sub 4}. • Al{sub 2}O{sub 3} overlayer passivates surface states and mitigates surface charge recombination. • Two cycles of ALD coating lead to maximum photocatalytic CO{sub 2} reduction. • More than five cycles of ALD coating prohibits electron transfer to the surface. - Abstract: In this work, anatase nanorods (ANR) of TiO{sub 2} with active facet {100} as the major facet were successfully synthesized, and reducing the ANR by NaBH{sub 4} led to the formation of gray colored oxygen deficient TiO{sub 2-x} (ReANR). On the surface of ReANR, a thin layer of Al{sub 2}O{sub 3} was deposited using atomic layer deposition (ALD), and the thickness of Al{sub 2}O{sub 3} varied by the number of ALD cycles (1, 2, 5, 10, 50, 100, or 200). The growth rate of Al{sub 2}O{sub 3} was determined to be 0.25 Å per cycle based on high-resolution TEM analysis, and the XRD result showed the amorphous structure of Al{sub 2}O{sub 3}. All the synthesized photocatalysts (ANR, ReANR, and Al{sub 2}O{sub 3} coated ReANR) were tested for CO{sub 2} photocatalytic reduction in the presence of water vapor, with CO detected as the major reduction product and CH{sub 4} as the minor product. Compared with ANR, ReANR had more than 50% higher CO production and more than ten times higher CH{sub 4} production due to the oxygen vacancies that possibly enhanced CO{sub 2} adsorption and activation. By applying less than 5 cycles of ALD, the Al{sub 2}O{sub 3} coated ReANR had enhanced overall production of CO and CH{sub 4} than uncoated ReANR, with 2 cycles being the optimum, about 40% higher overall production than ReANR. Whereas, both CO and CH{sub 4} production decreased with increasing number of ALD cycles when more than 5 cycles were applied. Photoluminescence (PL) analysis showed an

Atom distribution and interactions in Ag{sub x}Pt{sub 1-x} and Au{sub x}Pt{sub 1-x} surface alloys on Pt(111)

Energy Technology Data Exchange (ETDEWEB)

Roetter, Ralf T.; Bergbreiter, Andreas; Hoster, Harry E.; Behm, R. Juergen [Institute of Surface Chemistry and Catalysis, Ulm University, D-89069 Ulm (Germany)

2009-07-01

The atom distributions in Ag{sub x}Pt{sub 1-x}/Pt(111) and Au{sub x}Pt{sub 1-x}/Pt(111) surface alloys were studied by high resolution UHV-STM. These surfaces were prepared by submonolayer Ag (Au) metal deposition on Pt(111), followed by annealing at 900 K or 1000 K, respectively, which in both cases results in surface confined 2D alloys, with equilibrated distribution of the components. Both systems show a tendency towards two-dimensional clustering, which fits well to their known bulk immiscibility. Effective cluster interactions (ECIs) will be derived by a quantitative evaluation of the 2D atom distributions in the surface alloys. By comparing the ECIs for PtAg and PtAu on Pt(111), and considering that Ag and Au have almost similar lattice constants, the results allow conclusion on the physical origin of the tendency for clustering.

Solution-processed n-ZnO nanorod/p-Co{sub 3}O{sub 4} nanoplate heterojunction light-emitting diode

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong-Woo; Lee, Su Jeong; Biswas, Pranab [Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722 (Korea, Republic of); Lee, Tae Il [Department of BioNano Technology, Gachon University, 1342 Seongnam Daero, Seongnam 13120 (Korea, Republic of); Myoung, Jae-Min, E-mail: jmmyoung@yonsei.ac.kr [Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722 (Korea, Republic of)

2017-06-01

Highlights: • The n-ZnO nanorods were epitaxially grown on p-Co{sub 3}O{sub 4} nanoplates. • The heteroepitaxial p-n junction was fabricated by using hydrothermal process. • The LEDs emitted reddish-orange and violet light related to ZnO point defects. • The Co{sub 3}O{sub 4} nanoplates function as a hole injection layer. • Junction between 1D NRs and 2D NPs provides a new approach to design nanostructures. - Abstract: A heterojunction light-emitting diode (LED) based on p-type cobalt oxide (Co{sub 3}O{sub 4}) nanoplates (NPs)/n-type zinc oxide (ZnO) nanorods (NRs) is demonstrated. Using a low-temperature aqueous solution process, the n-type ZnO NRs were epitaxially grown on Co{sub 3}O{sub 4} NPs which were two-dimensionally assembled by a modified Langmuir-Blodgett process. The heterojunction LEDs exhibited a typical rectifying behavior with a turn-on voltage of about 2 V and emitted not only reddish-orange light at 610 nm but also violet light at about 400 nm. From the comparative analyses of electroluminescence and photoluminescence, it was determined that the reddish-orange light emission was related to the electronic transitions from zinc interstitials (Zn{sub i}) to oxygen interstitials (O{sub i}) or conduction-band minimum (CBM) to oxygen vacancies (V{sub O}), and the violet light emission was attribute to the transition from CBM to valence-band maximum (VBM) or Zn{sub i} to zinc vacancies (V{sub Zn}).

Facile synthesis of MoS{sub 2}/Bi{sub 2}WO{sub 6} nanocomposites for enhanced CO{sub 2} photoreduction activity under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Dai, Weili, E-mail: wldai81@126.com [Key Laboratory of Jiangxi Province for Persistant Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, Jiangxi (China); Yu, Juanjuan [Key Laboratory of Jiangxi Province for Persistant Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, Jiangxi (China); Deng, Yiqiang, E-mail: dyq3211@126.com [College of Chemical Engineering, Guangdong University of Petrochemical Technology, Maoming 525000 Guangdong (China); Hu, Xu; Wang, Tengyao; Luo, Xubiao [Key Laboratory of Jiangxi Province for Persistant Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, Jiangxi (China)

2017-05-01

Highlights: • MoS{sub 2}/Bi{sub 2}WO{sub 6} nanocomposites (MB) were fabricated by a facile two-step approach. • MoS{sub 2} was first used as a cocatalyst coupling with Bi{sub 2}WO{sub 6} for CO{sub 2} photoreduction. • MoS{sub 2} significantly enhanced the photoelectric properties and photoactivity. • The CO{sub 3}{sup 2−}, HCO{sub 3}{sup −} and H{sub 2}CO{sub 3} in CO{sub 2} solution actually act as the reactive substrates. - Abstract: A novel composite material, MoS{sub 2}/Bi{sub 2}WO{sub 6}, has been fabricated via a facile two-step approach. The few layered MoS{sub 2} as a cocatalyst has intimate interactions with the hierarchical flower-like Bi{sub 2}WO{sub 6} microspheres, which boosts the visible light harvesting and charge transferring, and promotes the separation of electron-hole pairs, thus leading to the superior photocatalytic activity. It was found that the as-synthesized MoS{sub 2}/Bi{sub 2}WO{sub 6} nanocomposites exhibited significantly enhanced performance for the photoreduction of CO{sub 2} into hydrocarbons, i.e. methanol and ethanol, as compared with pure Bi{sub 2}WO{sub 6}. The yields of methanol and ethanol obtained over the composite with optimal content of MoS{sub 2} (0.4 wt%) were 36.7 and 36.6 μmol gcat{sup −1} after 4 h of visible light irradiation, respectively, which were 1.94 times higher than that over pure Bi{sub 2}WO{sub 6}. Furthermore, the mechanism of CO{sub 2} photoreduction was also investigated. It indicates that the CO{sub 3}{sup 2−}, HCO{sub 3}{sup −} and H{sub 2}CO{sub 3} generated in CO{sub 2} aqueous solution would be the reactive substrates during the photoreduction reaction, proving the thermodynamic feasibility of CO{sub 2} photoreduction. This work demonstrated that MoS{sub 2} is a very promising candidate for development of highly active photocatalysts, and supplied a facile and simple strategy for designing environmentally benign, cheap non-noble metal, and highly efficient semiconductor

Fabrication of heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalyst and efficient photodegradation of organic contaminants under visible-light

Energy Technology Data Exchange (ETDEWEB)

Sun, Meng; Li, Shuangli; Yan, Tao; Ji, Pengge; Zhao, Xia; Yuan, Kun; Wei, Dong [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Du, Bin, E-mail: dubin61@gmail.com [School of Resources and Environment, University of Jinan, Jinan 250022 (China); Key Laboratory of Chemical Sensing & Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

2017-07-05

Highlights: • The product shows efficient activity in photodegradation of RhB, BPA, and phenol. • The BBOC-10 heterojunction exhibits the best activity under visible light. • Suppressed recombination of photo-generated carriers lead to the activity enhancement. - Abstract: Heterostructured Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts were fabricated by a facile one-pot hydrothermal method, in which melem served as the sacrificial reagent to supply carbonate anions. The as-synthesized Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction catalysts were characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, scanning electron microscope, and transmission electron microscope. The XRD patterns of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} catalysts showed the distinctive peaks of Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}. The SEM and TEM results showed that the pure Bi{sub 2}O{sub 2}CO{sub 3} possessed large plate morphology, while Bi{sub 2}O{sub 4} were composed of various nanorods and particles. As for Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction, it was obviously observed that Bi{sub 2}O{sub 4} nanorods and particles were grown on the surfaces of Bi{sub 2}O{sub 2}CO{sub 3} plates. The visible light driven photocatalytic activity of Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} heterojunction photocatalyst was evaluated by decomposing dyes, phenol, and bisphenol A in water. Compared with Bi{sub 2}O{sub 2}CO{sub 3} and Bi{sub 2}O{sub 4}, the Bi{sub 2}O{sub 2}CO{sub 3}/Bi{sub 2}O{sub 4} photocatalysts have exhibited remarkable enhanced activity under visible light. The excellent activity can be mainly attributed to the enhanced separation efficiency of photo-generated carriers. Controlled experiments using different radical scavengers proved that ·O{sub 2}{sup −} and h{sup +} played the main role in decomposing organic pollutants. The results of this work would

Surface texture of single-crystal silicon oxidized under a thin V{sub 2}O{sub 5} layer

Energy Technology Data Exchange (ETDEWEB)

Nikitin, S. E., E-mail: nikitin@mail.ioffe.ru; Verbitskiy, V. N.; Nashchekin, A. V.; Trapeznikova, I. N.; Bobyl, A. V.; Terukova, E. E. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

2017-01-15

The process of surface texturing of single-crystal silicon oxidized under a V{sub 2}O{sub 5} layer is studied. Intense silicon oxidation at the Si–V{sub 2}O{sub 5} interface begins at a temperature of 903 K which is 200 K below than upon silicon thermal oxidation in an oxygen atmosphere. A silicon dioxide layer 30–50 nm thick with SiO{sub 2} inclusions in silicon depth up to 400 nm is formed at the V{sub 2}O{sub 5}–Si interface. The diffusion coefficient of atomic oxygen through the silicon-dioxide layer at 903 K is determined (D ≥ 2 × 10{sup –15} cm{sup 2} s{sup –1}). A model of low-temperature silicon oxidation, based on atomic oxygen diffusion from V{sub 2}O{sub 5} through the SiO{sub 2} layer to silicon, and SiO{sub x} precipitate formation in silicon is proposed. After removing the V{sub 2}O{sub 5} and silicon-dioxide layers, texture is formed on the silicon surface, which intensely scatters light in the wavelength range of 300–550 nm and is important in the texturing of the front and rear surfaces of solar cells.

Nitrogen-modified nano-titania: True phase composition, microstructure and visible-light induced photocatalytic NO{sub x} abatement

Energy Technology Data Exchange (ETDEWEB)

Tobaldi, D.M., E-mail: david.tobaldi@ua.pt [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Pullar, R.C. [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Gualtieri, A.F. [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, I-41121 Modena (Italy); Otero-Irurueta, G.; Singh, M.K. [Center for Mechanical Technology and Automation – TEMA, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal); Seabra, M.P.; Labrincha, J.A. [Department of Materials and Ceramic Engineering / CICECO−Aveiro Institute of Materials, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro (Portugal)

2015-11-15

Titanium dioxide (TiO{sub 2}) is a popular photocatalyst used for many environmental and anti-pollution applications, but it normally operates under UV light, exploiting ∼5% of the solar spectrum. Nitrification of titania to form N-doped TiO{sub 2} has been explored as a way to increase its photocatalytic activity under visible light, and anionic doping is a promising method to enable TiO{sub 2} to harvest visible-light by changing its photo-absorption properties. In this paper, we explore the insertion of nitrogen into the TiO{sub 2} lattice using our green sol–gel nanosynthesis method, used to create 10 nm TiO{sub 2} NPs. Two parallel routes were studied to produce nitrogen-modified TiO{sub 2} nanoparticles (NPs), using HNO{sub 3}+NH{sub 3} (acid-precipitated base-peptised) and NH{sub 4}OH (totally base catalysed) as nitrogen sources. These NPs were thermally treated between 450 and 800 °C. Their true phase composition (crystalline and amorphous phases), as well as their micro-/nanostructure (crystalline domain shape, size and size distribution, edge and screw dislocation density) was fully characterised through advanced X-ray methods (Rietveld-reference intensity ratio, RIR, and whole powder pattern modelling, WPPM). As pollutants, nitrogen oxides (NO{sub x}) are of particular concern for human health, so the photocatalytic activity of the NPs was assessed by monitoring NO{sub x} abatement, using both solar and white-light (indoor artificial lighting), simulating outdoor and indoor environments, respectively. Results showed that the onset of the anatase-to-rutile phase transformation (ART) occurred at temperatures above 450 °C, and NPs heated to 450 °C possessed excellent photocatalytic activity (PCA) under visible white-light (indoor artificial lighting), with a PCA double than that of the standard P25 TiO{sub 2} NPs. However, higher thermal treatment temperatures were found to be detrimental for visible-light photocatalytic activity, due to the effects

Coherent storage of temporally multimode light using a spin-wave atomic frequency comb memory

International Nuclear Information System (INIS)

Gündoğan, M; Mazzera, M; Ledingham, P M; Cristiani, M; De Riedmatten, H

2013-01-01

We report on the coherent and multi-temporal mode storage of light using the full atomic frequency comb memory scheme. The scheme involves the transfer of optical atomic excitations in Pr 3+ :Y 2 SiO 5 to spin waves in hyperfine levels using strong single-frequency transfer pulses. Using this scheme, a total of five temporal modes are stored and recalled on-demand from the memory. The coherence of the storage and retrieval is characterized using a time-bin interference measurement resulting in visibilities higher than 80%, independent of the storage time. This coherent and multimode spin-wave memory is promising as a quantum memory for light. (paper)

Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO{sub 2} overlay coating on TiO{sub 2} nanoparticle working electrode

Energy Technology Data Exchange (ETDEWEB)

Liu, Xueyang; Fang, Jian [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia); Gao, Mei [CSIRO Materials Science and Engineering, Melbourne, VIC 3169 (Australia); Wang, Hongxia [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia); Yang, Weidong [CSIRO Materials Science and Engineering, Melbourne, VIC 3169 (Australia); Lin, Tong, E-mail: tong.lin@deakin.edu.au [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia)

2015-02-01

Novel TiO{sub 2} single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO{sub 2} nanorods on TiO{sub 2} nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO{sub 2} nanorods had lower dye loading than TiO{sub 2} nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO{sub 2} nanorods received less resistance than that in TiO{sub 2} nanoparticle aggregation. By just applying a thin layer of TiO{sub 2} nanorods on TiO{sub 2} nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO{sub 2} nanoparticle layer covered with 3 μm thick TiO{sub 2} nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs. - Highlights: • Single crystalline TiO{sub 2} nanorods were prepared for DSSC application. • TiO{sub 2} nanorods show effective light scattering performance. • TiO{sub 2} nanorods have higher electron transfer efficiency than TiO{sub 2} nanoparticles. • TiO{sub 2} nanorods on TiO{sub 2} nanoparticle electrode improve DSSC efficiency.

Sprayed films of europium complexes toward light conversion devices

Energy Technology Data Exchange (ETDEWEB)

Camacho, Sabrina A.; Aoki, Pedro H.B.; Constantino, Carlos J.L.; Pires, Ana Maria, E-mail: anapires@fct.unesp.br

2014-09-15

Rare-earth complexes have become subject of intensive research due to the high quantum efficiency of their emission, very narrow bands, and excellent fluorescence monochromaticity. The chemical design and characterization of Eu complexes based on β-diketone ligands hexafluoroacetylacetate (hfac) and dibenzoylmetanate (dbm) is reported here. K[Eu(dbm){sub 4}] and K[Eu(hfac){sub 4}] complexes were immobilized as thin films by using the spray technique, a promising methodology for practical applications. The latter provides not only a faster layer deposition but also larger coated areas compared to conventional methods, such as layer-by-layer (LbL) and Langmuir–Blodgett (LB). The growth of the sprayed films was monitored through microbalance (QCM) and ultraviolet–visible (UV–Vis) absorption spectroscopy, which reveal a higher mass and absorbance per deposited layer of K[Eu(dbm){sub 4}] film. Micro-Raman images display a more homogeneous spatial distribution of the K[Eu(dbm){sub 4}] complex throughout the film, when compared to K[Eu(hfac){sub 4}] film. At nanometer scale, atomic force microscopy (AFM) images indicate that the roughness of the K[Eu(hfac){sub 4}] film is approximately one order of magnitude higher than that for the K[Eu(dbm){sub 4}] film, which pattern is kept at micrometer scale according to micro-Raman measurements. The photoluminescence data show that the complexes remain as pure red emitters upon spray immobilization. Besides, the quantum efficiency for the sprayed films are found equivalent to the values achieved for the powders, highlighting the potential of the films for application in light conversion devices. - Highlights: • Rare earth complexes thin films based on β-diketone ligands. • Spraying procedures to fabricate layer-by-layer (LbL) luminescent thin films. • Chemical design of Eu complexes based on hfac and dbm β-diketones ligands immobilized as sprayed films. • Pure red emitters upon spray immobilization. • Sprayed

Light harvesting enhancement for dye-sensitized solar cells by novel anode containing cauliflower-like TiO{sub 2} spheres

Energy Technology Data Exchange (ETDEWEB)

Yang, Lei [Beijing National Laboratory for Molecular Science, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Graduate University of the Chinese Academy of Sciences, Beijing 100049 (China); Lin, Yuan; Xiao, Xurui; Li, Xueping; Zhou, Xiaowen [Beijing National Laboratory for Molecular Science, Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China); Jia, Jianguang [Department of Chemistry, School of Science, Beijing University of Chemical Technology, Beijing 100029 (China)

2008-07-15

Cauliflower-like TiO{sub 2} rough spheres, which are about 200 nm large, have greatly enhanced light harvesting efficiency and energy conversion efficiency of dye-sensitized solar cells (DSC), due to their high light scattering effect and large BET surface area (80.7 m{sup 2} g{sup -1}) even after calcinations at 450 C for 30 min. The large size TiO{sub 2} rough and smooth spheres, produced at different initial temperatures by hydrolysis of Ti(OBu){sub 4} with P105 (EO{sub 37}PO{sub 56}EO{sub 37}) or F68 (EO{sub 78}PO{sub 30}EO{sub 78}) tri-block copolymer as structural agents, have nearly the same diameter of {proportional_to}275 nm and strong light scattering effects in the wavelength of 400-750 nm. However, rough spheres have even higher light scattering effect and larger BET surface area than smooth spheres for the roughness of the surface. By adding 25 wt.% large TiO{sub 2} spheres into the over-layer of TiO{sub 2} film composed of {proportional_to}20 nm TiO{sub 2} particles as light scattering centers, the energy conversion efficiency of the film containing rough spheres reaches 7.36%, much larger than that of smooth spheres (6.25%). From another point of view, the TiO{sub 2} rough spheres may have the satisfying ability in other fields of application such as photo-catalysis, drug carriers and so on. (author)

Assessment of undiscovered oil and gas resources in the Paradox Basin Province, Utah, Colorado, New Mexico, and Arizona, 2011

Science.gov (United States)

Whidden, Katherine J.

2012-01-01

Using a geology-based assessment methodology, the U.S. Geological Survey estimated means of 560 million barrels of undiscovered oil, 12,701 billion cubic feet of undiscovered natural gas, and 490 million barrels of undiscovered natural gas liquids in the Paradox Basin of Utah, Colorado, New Mexico, and Arizona.

First-principles study of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuan Xu [Computational Materials Science Center, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Institute for Computational Materials Science, School of Physics and Electronics, Henan University, Kaifeng 475004 (China)

2008-06-15

We have theoretically investigated basic properties of the (001) surface of cubic Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} (BST) by the plane-wave pseudopotential method within the local-density approximation. For the BaSrO{sub 2}-terminated surface, the surface-layer Sr atoms move inward and the surface-layer Ba atoms move outward. Moreover, the displacement of the surface-layer Sr atoms is much larger than the surface-layer Ba atoms. The rumpling of the BaSrO{sub 2}-terminated surface is much larger than that of the Ti{sub 2}O{sub 4}-terminated one. The surface state appears in the band structure of the Ti{sub 2}O{sub 4}-terminated surface of BST. Based on the results of the calculated grand thermodynamic potential, only the BaSrO{sub 2}-terminated surface can exist in the (001) surface of cubic BST. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

New theoretical approaches to atomic and molecular dynamics triggered by ultrashort light pulses on the atto- to picosecond time scale

Energy Technology Data Exchange (ETDEWEB)

Pabst, Stefan Ulf

2013-04-15

The concept of atoms as the building blocks of matter has existed for over 3000 years. A revolution in the understanding and the description of atoms and molecules has occurred in the last century with the birth of quantum mechanics. After the electronic structure was understood, interest in studying the dynamics of electrons, atoms, and molecules increased. However, time-resolved investigations of these ultrafast processes were not possible until recently. The typical time scale of atomic and molecular processes is in the picosecond to attosecond realm. Tremendous technological progress in recent years makes it possible to generate light pulses on these time scales. With such ultrashort pulses, atomic and molecular dynamics can be triggered, watched, and controlled. Simultaneously, the need rises for theoretical models describing the underlying mechanisms. This doctoral thesis focuses on the development of theoretical models which can be used to study the dynamical behavior of electrons, atoms, and molecules in the presence of ultrashort light pulses. Several examples are discussed illustrating how light pulses can trigger and control electronic, atomic, and molecular motions. In the first part of this work, I focus on the rotational motion of asymmetric molecules, which happens on picosecond and femtosecond time scales. Here, the aim is to align all three axes of the molecule as well as possible. To investigate theoretically alignment dynamics, I developed a program that can describe alignment motion ranging from the impulsive to the adiabatic regime. The asymmetric molecule SO{sub 2} is taken as an example to discuss strategies of optimizing 3D alignment without the presence of an external field (i.e., field-free alignment). Field-free alignment is particularly advantageous because subsequent experiments on the aligned molecule are not perturbed by the aligning light pulse. Wellaligned molecules in the gas phase are suitable for diffraction experiments. From the

“Glass-like” thermal conductivity gradually induced in thermoelectric Sr{sub 8}Ga{sub 16}Ge{sub 30} clathrate by off-centered guest atoms

Energy Technology Data Exchange (ETDEWEB)

Christensen, Sebastian; Schmøkel, Mette Stokkebro; Borup, Kasper Andersen; Christensen, Mogens, E-mail: mch@chem.au.dk, E-mail: bo@chem.au.dk; Iversen, Bo Brummerstedt, E-mail: mch@chem.au.dk, E-mail: bo@chem.au.dk [Department of Inorganic Chemistry & iNANO, Center for Materials Crystallography, Aarhus University, Langelandsgade 140, 8000 Aarhus C (Denmark); Madsen, Georg K. H. [ICAMS, Ruhr-Universität Bochum, Bochum (Germany); McIntyre, Garry J.; Capelli, Silvia C. [Institut Laue-Langevin, 71 Avenue des Martyrs, CS 20156, Grenoble Cedex 9 (France)

2016-05-14

The origin of the “glass-like” plateau in thermal conductivity of inorganic type I clathrates has been debated for more than a decade. Here, it is demonstrated that the low temperature thermal conductivity of Sr{sub 8}Ga{sub 16}Ge{sub 30} can be controlled by the synthesis method: A flux-grown sample has a “glass-like” plateau in thermal conductivity at low temperature, while a zone-melted sample instead has a crystalline peak. A combination of flux-growth and zone-melting produces an intermediate thermal conductivity. In a comprehensive study of three single crystal samples, it is shown by neutron diffraction that the transition from crystalline peak to “glass-like” plateau is related to an increase in Sr guest atom off-centering distance from 0.24 Å to 0.43 Å. By modifying ab initio calculated force constants for the guest atom to an isotropic model, we reproduce both measured heat capacity and inelastic neutron scattering data. The transition from peak to plateau in the thermal conductivity can be modeled by a combined increase of Rayleigh and disorder scattering. Measurement of heat capacity refutes simple models for tunneling of Sr between off-center sites. Furthermore, the electronic properties of the same samples are characterized by Hall carrier density, Seebeck coefficient, and resistivity. The present comprehensive analysis excludes tunneling and charge carrier scattering as dominant contributors to the “glass-like” plateau. The increased guest atom off-centering distance controlled by synthesis provides a possible microscopic mechanism for reducing the low temperature thermal conductivity of clathrates.

The control of superluminal group velocity in a system equivalent to the Y-type four-level atomic system

International Nuclear Information System (INIS)

Li Luming; Guo Hong; Xiao Feng; Peng Xiang; Chen Xuzong

2005-01-01

We study a new way to control the superluminal group velocity of light pulse in hot atomic gases with the five-level atomic configuration. The model of an equivalent Y-type four-level is applied and shows that the light goes faster by using an additional incoherent pumping field. The experiment is performed and shows in good agreement with our theoretical predictions

Atomic layer deposition of W{sub x}N/TiN and WN{sub x}C{sub y}/TiN nanolaminates

Energy Technology Data Exchange (ETDEWEB)

Elers, K.-E.; Saanila, V.; Li, W.-M.; Soininen, P.J.; Kostamo, J.T.; Haukka, S.; Juhanoja, J.; Besling, W.F.A

2003-06-23

Diffusion barrier materials, such as TiN, W{sub x}N, WN{sub x}C{sub y} and their nanolaminates were deposited by atomic layer deposition method. TiN film exhibited excellent properties, but W{sub x}N film exhibited high resistivity despite the low residue concentration. Both TiN and W{sub x}N films suffered from serious incompatibility with the copper metal. WN{sub x}C{sub y} film was deposited by introducing triethylboron as a reducing agent for tungsten. Excellent film properties were obtained, including very good compatibility with the copper metal, evident as strong adhesion and no pitting on the copper surface. Nanolaminate barrier stacks of W{sub x}N/TiN and WN{sub x}C{sub y}/TiN were successfully deposited. TiN deposition did not cause copper pitting when thin WN{sub x}C{sub y} film was deposited underneath.

Biomimetic fabrication of WO{sub 3} for water splitting under visible light with high performance

Energy Technology Data Exchange (ETDEWEB)

Yin, Chao; Zhu, Shenmin, E-mail: smzhu@sjtu.edu.cn; Yao, Fan; Gu, Jiajun; Zhang, Wang [Shanghai Jiao Tong University, State Key Laboratory of Metal Matrix Composites (China); Chen, Zhixin [University of Wollongong, Faculty of Engineering (Australia); Zhang, Di, E-mail: zhangdi@sjtu.edu.cn [Shanghai Jiao Tong University, State Key Laboratory of Metal Matrix Composites (China)

2013-08-15

Inspired by the high light-harvesting properties of typical butterfly wings, ceramic WO{sub 3} butterfly wings with hierarchical structures of bio-butterfly wings was fabricated using a template of PapilioParis butterfly wings through a sol-gel method. The effect of calcination temperatures on the structures of the ceramic butterfly wings was investigated and the results showed that the WO{sub 3} butterfly wing replica calcined at 550 Degree-Sign C (WO{sub 3} replica-550) is a single phase and has a high crystallinity and relatively fine hierarchical structure. The average grain size of WO{sub 3} replica-550 and WO{sub 3} powder are around 32.6 and 42.2 nm, respectively. Compared with pure WO{sub 3} powder, WO{sub 3} replica-550 demonstrated a higher light-harvesting capability in the region from 460 to 700 nm and more importantly the higher charge separation rate, as evidenced by electron paramagnetic resonance measurements. Photocatalytic O{sub 2} evolutions from water were investigated on the ceramic butterfly wings and pure WO{sub 3} powder under visible light ({lambda} > 420 nm). The results showed that the amount of O{sub 2} produced from WO{sub 3} replica-550 is 50 % higher than that of the pure WO{sub 3} powder. The improved photocatalytic performance of WO{sub 3} replica-550 is attributed to the quasi-honeycomb structure inherited from the PapilioParis butterfly wings, providing both high light-harvesting efficiency and efficient charge transport through the WO{sub 3}.

Assessment of undiscovered oil and gas resources of the Susitna Basin, southern Alaska, 2017

Science.gov (United States)

Stanley, Richard G.; Potter, Christopher J.; Lewis, Kristen A.; Lillis, Paul G.; Shah, Anjana K.; Haeussler, Peter J.; Phillips, Jeffrey D.; Valin, Zenon C.; Schenk, Christopher J.; Klett, Timothy R.; Brownfield, Michael E.; Drake II, Ronald M.; Finn, Thomas M.; Haines, Seth S.; Higley, Debra K.; Houseknecht, David W.; Le, Phuong A.; Marra, Kristen R.; Mercier, Tracey J.; Leathers-Miller, Heidi M.; Paxton, Stanley T.; Pearson, Ofori N.; Tennyson, Marilyn E.; Woodall, Cheryl A.; Zyrianova, Margarita V.

2018-05-01

The U.S. Geological Survey (USGS) recently completed an assessment of undiscovered, technically recoverable oil and gas resources in the Susitna Basin of southern Alaska. Using a geology-based methodology, the USGS estimates that mean undiscovered volumes of about 2 million barrels of oil and nearly 1.7 trillion cubic feet of gas may be found in this area.

Magnetic-field-dependent slow light in strontium atom-cavity system

Science.gov (United States)

Liu, Zeng-Xing; Wang, Bao; Kong, Cui; Xiong, Hao; Wu, Ying

2018-03-01

Realizing and controlling a long-lived slow light is of fundamental importance in physics and may find applications in quantum router and quantum information processing. In this work, we propose a feasible scheme to realize the slow light in a strontium atom-cavity system, in which the value of group delay can be continuously adjusted within a range of different Zeeman splittings and vacuum Rabi frequencies by varying the applied static magnetic field and the atom number instead of a strong coherent field. In our scheme, the major limitations of the slow-light structure, namely, dispersion and loss, can be effectively resolved, and so our scheme may help to achieve the practical application of slow light relevant to the optical communication network.

Epitaxial growth of topological insulator Bi{sub 2}Se{sub 3} film on Si(111) with atomically sharp interface

Energy Technology Data Exchange (ETDEWEB)

Bansal, Namrata [Department of Electrical and Computer Engineering, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Kim, Yong Seung [Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of); Edrey, Eliav; Brahlek, Matthew; Horibe, Yoichi [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Iida, Keiko; Tanimura, Makoto [Research Department, Nissan Arc, Ltd. Yokosuka, Kanagawa 237-0061 (Japan); Li Guohong; Feng Tian; Lee, Hang-Dong; Gustafsson, Torgny; Andrei, Eva [Department of Physics and Astronomy, Rutgers, State University of New Jersey, Piscataway, NJ 08854 (United States); Oh, Seongshik, E-mail: ohsean@physics.rutgers.edu [Department of Physics and Astronomy, Rutgers, the State University of New Jersey, Piscataway, NJ 08854 (United States)

2011-10-31

Atomically sharp epitaxial growth of Bi{sub 2}Se{sub 3} films is achieved on Si(111) substrate with molecular beam epitaxy. Two-step growth process is found to be a key to achieve interfacial-layer-free epitaxial Bi{sub 2}Se{sub 3} films on Si substrates. With a single-step high temperature growth, second phase clusters are formed at an early stage. On the other hand, with low temperature growth, the film tends to be disordered even in the absence of a second phase. With a low temperature initial growth followed by a high temperature growth, second-phase-free atomically sharp interface is obtained between Bi{sub 2}Se{sub 3} and Si substrate, as verified by reflection high energy electron diffraction (RHEED), transmission electron microscopy (TEM) and X-ray diffraction. The lattice constant of Bi{sub 2}Se{sub 3} is observed to relax to its bulk value during the first quintuple layer according to RHEED analysis, implying the absence of strain from the substrate. TEM shows a fully epitaxial structure of Bi{sub 2}Se{sub 3} film down to the first quintuple layer without any second phase or an amorphous layer.

Applicability of light sources and the inner filter effect in UV/acetylacetone and UV/H{sub 2}O{sub 2} processes

Energy Technology Data Exchange (ETDEWEB)

Wu, Bingdang; Yang, Minghui [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China); Yin, Ran [Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Zhang, Shujuan, E-mail: sjzhang@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, 210023 (China)

2017-08-05

Highlights: • Acetylacetone (AA) could directly use solar irradiation to decolorize dyes. • AA had a wider applicability than H{sub 2}O{sub 2} to a variety of light sources. • The photonic efficiency in the UV/AA process was target-dependent. • An accurate calculation approach for the inner filter effect was developed. - Abstract: Light source is a crucial factor in the application of a photochemical process, which determines the energy efficiency. The performances of acetylacetone (AA) in conversion of aqueous contaminants under irradiation with a low-pressure mercury lamp, a medium-pressure mercury lamp, a xenon lamp, and natural sunlight were investigated and compared with those of H{sub 2}O{sub 2} as reference. In all cases, AA was superior to H{sub 2}O{sub 2} in the degradation of Acid Orange 7. Using combinations of the different light sources with various cut-off and band-pass filters, the spectra responses of the absorbed photons in the UV/AA and UV/H{sub 2}O{sub 2} processes were determined for two colored and two colorless compounds. The photonic efficiency (φ) of the two photochemical processes was found to be target-dependent. A calculation approach for the inner filter effect was developed by taking the obtained φ into account, which provides a more accurate indication of the reaction mechanisms.

Light element opacities of astrophysical interest from ATOMIC

Energy Technology Data Exchange (ETDEWEB)

Colgan, J.; Kilcrease, D. P.; Magee, N. H. Jr.; Armstrong, G. S. J.; Abdallah, J. Jr.; Sherrill, M. E. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Fontes, C. J.; Zhang, H. L.; Hakel, P. [Computational Physics Division, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-07-11

We present new calculations of local-thermodynamic-equilibrium (LTE) light element opacities from the Los Alamos ATOMIC code for systems of astrophysical interest. ATOMIC is a multi-purpose code that can generate LTE or non-LTE quantities of interest at various levels of approximation. Our calculations, which include fine-structure detail, represent a systematic improvement over previous Los Alamos opacity calculations using the LEDCOP legacy code. The ATOMIC code uses ab-initio atomic structure data computed from the CATS code, which is based on Cowan's atomic structure codes, and photoionization cross section data computed from the Los Alamos ionization code GIPPER. ATOMIC also incorporates a new equation-of-state (EOS) model based on the chemical picture. ATOMIC incorporates some physics packages from LEDCOP and also includes additional physical processes, such as improved free-free cross sections and additional scattering mechanisms. Our new calculations are made for elements of astrophysical interest and for a wide range of temperatures and densities.

A piece of paper falling faster than free fall

International Nuclear Information System (INIS)

Vera, F; Rivera, R

2011-01-01

We report a simple experiment that clearly demonstrates a common error in the explanation of the classic experiment where a small piece of paper is put over a book and the system is let fall. This classic demonstration is used in introductory physics courses to show that after eliminating the friction force with the air, the piece of paper falls with acceleration g. To test if the paper falls behind the book in a nearly free fall motion or if it is dragged by the book, we designed a version of this experiment that includes a ball and a piece of paper over a book that is forced to fall using elastic cords. We recorded a video of our experiment using a high-speed video camera at 300 frames per second that shows that the book and the paper fall faster than the ball, which falls well behind the book with an acceleration approximately equal to g. Our experiment shows that the piece of paper is dragged behind the book and therefore the paper and book demonstration should not be used to show that all objects fall with acceleration g independently of their mass.

A piece of paper falling faster than free fall

Energy Technology Data Exchange (ETDEWEB)

Vera, F; Rivera, R, E-mail: fvera@ucv.cl [Instituto de Fisica, Pontificia Universidad Catolica de ValparaIso, Av. Universidad 330, Curauma, ValparaIso (Chile)

2011-09-15

We report a simple experiment that clearly demonstrates a common error in the explanation of the classic experiment where a small piece of paper is put over a book and the system is let fall. This classic demonstration is used in introductory physics courses to show that after eliminating the friction force with the air, the piece of paper falls with acceleration g. To test if the paper falls behind the book in a nearly free fall motion or if it is dragged by the book, we designed a version of this experiment that includes a ball and a piece of paper over a book that is forced to fall using elastic cords. We recorded a video of our experiment using a high-speed video camera at 300 frames per second that shows that the book and the paper fall faster than the ball, which falls well behind the book with an acceleration approximately equal to g. Our experiment shows that the piece of paper is dragged behind the book and therefore the paper and book demonstration should not be used to show that all objects fall with acceleration g independently of their mass.

Propagation and storing of light in optically modified atomic media

International Nuclear Information System (INIS)

Zaremba, Jaroslaw

2010-01-01

Coherent interactions of laser light with atomic ensembles allow one to modify dispersive properties of a medium and lead to new optical phenomena. Studies of the controlled light propagation and storing in such media have recently become a dynamically developing field of research motivated both by the fundamental character of the processes and by potential applications. This article briefly reviews basic theoretical approach to the dynamics of the propagation of laser pulses in optically modified media. The method and the physical processes are discussed that allow one to slow down the group velocity of laser pulse to zero (stopping of light), to transfer the state of a light pulse to atomic coherences and to restore the pulse. The interpretation of these phenomena in the formalism of dark-state polaritons is presented. Examples of possible coherent manipulations on a stored light are also discussed.

Propagation and storing of light in optically modified atomic media

Energy Technology Data Exchange (ETDEWEB)

Zaremba, Jaroslaw, E-mail: zaremba@fizyka.iomk.p [Institute of Physics Nicolaus Copernicus University ul. Grudziadzka 5/7 87 100 Torun (Poland)

2010-03-01

Coherent interactions of laser light with atomic ensembles allow one to modify dispersive properties of a medium and lead to new optical phenomena. Studies of the controlled light propagation and storing in such media have recently become a dynamically developing field of research motivated both by the fundamental character of the processes and by potential applications. This article briefly reviews basic theoretical approach to the dynamics of the propagation of laser pulses in optically modified media. The method and the physical processes are discussed that allow one to slow down the group velocity of laser pulse to zero (stopping of light), to transfer the state of a light pulse to atomic coherences and to restore the pulse. The interpretation of these phenomena in the formalism of dark-state polaritons is presented. Examples of possible coherent manipulations on a stored light are also discussed.

Exploring the thermoelectric and magnetic properties of uranium selenides: Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Azam, Sikander; Khan, Saleem Ayaz [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 30614 Pilsen (Czech Republic); Din, Haleem Ud [Department of Physics, Hazara University, Mansehra (Pakistan); Khenata, Rabah [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria); Goumri-Said, Souraya, E-mail: sosaid@alfaisal.edu [College of Science, Physics department, Alfaisal University, P.O. Box 50927, Riyadh 11533 (Saudi Arabia)

2016-09-01

The electronic, magnetic and thermoelectric properties of Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} compounds were investigated using the full potential linear augmented plane wave (FP-LAPW) method based on the density functional theory (DFT). The exchange correlation was treated with the generalized gradient approximation plus optimized effective Hubbard parameter and spin–orbit coupling (GGA+U+SOC). The present uranium selenides show narrow direct energy band gap values of 0.7 and 0.875 eV for Tl{sub 2}Ag{sub 2}USe{sub 4} and Tl{sub 3}Cu{sub 4}USe{sub 6} respectively. For both selenides U-d/f states are responsible for electrical transport properties. Uranium atoms were the most contributors in the magnetic moment compared to other atoms and show ferromagnetic nature. The spin density isosurfaces show the polarization of neighboring atoms of Uranium, such as silver/copper and selenium. Thermoelectric calculations reveal that Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}. - Highlights: • Electronic, magnetic and thermoelectric properties of uranium selenides are investigated with DFT. • They show a narrow direct energy band gap of 0.7 and 0.875 eV. • U-d/f states are responsible for electrical transport properties. • Tl{sub 3}Cu{sub 4}USe{sub 6} is more suitable for thermoelectric device applications than Tl{sub 2}Ag{sub 2}USe{sub 4}.

Maximizing growth of vegetable seedlings in controlled environments at elevated temperature, light and CO/sub 2/

Energy Technology Data Exchange (ETDEWEB)

Krizek, D.T.; Bailey, W.A.; Klueter, H.; Liu, R.C.

1974-01-01

Seedlings of cucumber Burpee Hybrid, tomato Michigan-Ohio and lettuce Grand Rapids were germinated in the greenhouse for 5, 8, and 11 days respectively, and then grown for 15 days at elevated temperature (30/24/sup 0/C), light (43.1 klx), and CO/sub 2/ (2000 ppm) a 16-hr photoperiod, 65% relative humidity, and fertilized 4 times daily. At the end of this time, they weighed 2 to 4.6 times those grown at standard environmental conditions in the growth chamber (24/18/sup 0/C, 21.5 klx, and 400 ppm CO/sub 2/) and 10 to 25 times those of greenhouse controls kept on natural days (24/18/sup 0/C, 350 ppm CO/sub 2/, and ca 12-hr photoperiod). Leaf expansion of seedlings grown under elevated growth chamber conditions was double that of seedlings in standard growth chamber conditions, and 6 to 7 times greater than under natural days in the greenhouse. Temperature was the most limiting factor for seedling growth. At the levels of light and CO/sub 2/ used in the experiment, CO/sub 2/ was more limiting than light intensity. In general, optimum seedling growth was obtained when temperature, light, and CO/sub 2/ were increased simultaneously. The most striking effects of CO/sub 2/ enrichment were precocious flower bud formation in tomato and cucumber and extensive growth of the lateral buds in all three species.

Atom probe tomography of a commercial light emitting diode

International Nuclear Information System (INIS)

Larson, D J; Prosa, T J; Olson, D; Lawrence, D; Clifton, P H; Kelly, T F; Lefebvre, W

2013-01-01

The atomic-scale analysis of a commercial light emitting diode device purchased at retail is demonstrated using a local electrode atom probe. Some of the features are correlated with transmission electron microscopy imaging. Subtle details of the structure that are revealed have potential significance for the design and performance of this device

Y{sub 2}O{sub 3} modified TiO{sub 2} nanosheets enhanced the photocatalytic removal of 4-chlorophenol and Cr (VI) in sun light

Energy Technology Data Exchange (ETDEWEB)

Zhao, Xiaona; Wu, Pei [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Liu, Min [State Grid Zhejiang Electric Power Research Institute, Hangzhou, Zhejiang 310007 (China); Lu, Dingze [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Ming, Junlan [State Grid Zhejiang Electric Power Research Institute, Hangzhou, Zhejiang 310007 (China); Li, Chunhe; Ding, Junqian; Yan, Qiuyang [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China); Fang, Pengfei, E-mail: fangpf@whu.edu.cn [Department of Physics and Key Laboratory of Artificial Micro-and Nano-structures of Ministry of Education, Wuhan University, Wuhan 430072 (China)

2017-07-15

Highlights: • Y{sub 2}O{sub 3}@TNSswithsynergisticphotocatalyticactivitywerepreparedbyone-potmethod. • Y{sub 2}O{sub 3} loading resulted in the structure evolution of TNSs and content increment of Ti{sup 3+} ions. • Modification on TNSs led to an obvious red shift of the optical absorption edge. • Appropriate amount of Y{sub 2}O{sub 3} can effectively improve the separation efficiency of the h{sup +}/e{sup −} pairs. - Abstract: Y{sub 2}O{sub 3} modified TiO{sub 2} nanosheets (Y{sub 2}O{sub 3}@TNSs), capable of exhibiting sun light, were synthesized through one pot/hydrothermal method using Y (NO{sub 3}){sub 3} as precursor. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of the as-prepared samples. The Y{sub 2}O{sub 3}@TNSs, with thickness of approximately 3–4 nm, large surface area of 240–350 m{sup 2}/g, were full of Y{sub 2}O{sub 3} nanoparticles highly dispersed on the surface. The introduction of Y{sub 2}O{sub 3} influenced the crystallinity and the structure evolution of TNSs, besides, improved the light absorption ability. The surface photo-current and fluorescence spectral studies revealed that the photo-generated charge carrier separation efficiency could be improved by an appropriate modification. The degradation activity of this sun-light-induced photocatalytic has enhanced apparently on 4-Chlorophenol and K{sub 2}Cr{sub 2}O{sub 7} solution, the degradation efficiency of 4-Chlorophenol reached 5.69 times than that of P25, and the maximum TOC removal obtained after 120 min was 67.6%, indicating that most organic compounds were released from the solution. The enhancement in the photocatalytic activity was attributed to the synergetic effect of the Y{sub 2}O{sub 3} and TNSs, which led to a fast separation and slow recombination of photo-induced electron-hole pairs. Consequently, the high efficiency in the experiments showed a promising application of

Visible-light wavelength matched microsphere assembly of TiO{sub 2} superfine nanorods and the enhanced photovoltaic performance

Energy Technology Data Exchange (ETDEWEB)

Tao, Xiyun; Wang, Yumin; Zhang, Xiang; Sun, Hongxia; Zhang, Qingsong; Niu, Laiyou; Liu, Juan; Zhou, Xingfu, E-mail: Zhouxf@njtech.edu.cn

2015-05-15

Graphical abstract: A novel visible-light wavelength matched microspheres assembly of TiO{sub 2} superfine nanorods with a diameter of ∼5 nm was fabricated via a hydrothermal method. The as-prepared rutile TiO{sub 2} microspheres have a uniform diameter of ∼450 nm and show a good light-trapping performance. Dye-sensitized solar cell based on this sample shows a satisfactory energy conversion efficiency of 6.59% and is the highest PCE reported for intrinsic rutile TiO{sub 2}. The further optimized DSSC shows a conversion efficiency of 8.3%, though the internal resistance is higher and the dye absorption is lower than that of widely used anatase TiO{sub 2} nanoparticles. - Highlights: • Microsphere assembly of TiO{sub 2} nanorods with a diameter of ∼5 nm was fabricated. • TiO{sub 2} microspheres size is well matched with the visible light wavelength. • TiO{sub 2} microsphere enhances the light-scattering ability. • Rutile TiO{sub 2} microsphere shows an energy conversion efficiency of 6.59%. • The highest PCE reported for intrinsic rutile TiO{sub 2} is obtained. - Abstract: According to the Mie scattering theory, spheres with the size matched with light wavelength are most suitable for light scattering and enhance the light trapping ability. In this paper, a novel visible-light wavelength matched sphere assembly of TiO{sub 2} superfine nanorods was fabricated via a simple one-step hydrothermal method. The morphology and the structure were examined by field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). The visible subwavelength TiO{sub 2} microsphere resembling an immature chinese chestnut is composed of countless superfine TiO{sub 2} nanorods, the diameter of these building blocks of superfine TiO{sub 2} nanorods is ∼5 nm. The obtained TiO{sub 2} sphere has an average diameter of ca. 450 nm, which matches well with the visible light wavelength and cause the

Ternary ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites: Novel visible-light-driven photocatalysts with excellent activity in degradation of different water pollutants

Energy Technology Data Exchange (ETDEWEB)

Golzad-Nonakaran, Behrouz; Habibi-Yangjeh, Aziz, E-mail: ahabibi@uma.ac.ir

2016-12-01

ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites with different Ag{sub 2}CO{sub 3} contents were fabricated by a facile ultrasonic-irradiation method. The resultant samples were fairly characterized using XRD, EDX, SEM, TEM, UV–vis DRS, FT-IR, and PL techniques to reveal their microstructure, purity, morphology, and spectroscopic properties. Photocatalytic activity of the prepared samples was investigated by photodegradation of four dye pollutants (rhodamine B, methyl orange, methylene blue, and fuchsine) under visible-light irradiation. The photocatalytic experiments in degradation of rhodamine B showed that the ternary ZnO/AgI/Ag{sub 2}CO{sub 3} (30%) nanocomposite has an enhanced activity nearly 19 and 14 times higher than those of the binary ZnO/Ag{sub 2}CO{sub 3} and ZnO/AgI photocatalysts, respectively. Based on the obtained results, the highly enhanced activity was attributed to generation of more electron-hole pairs under visible-light irradiation and separation of the photogenerated charge carriers due to formation of tandem n-n heterojunctions between counterparts of the nanocomposite. The active species trapping experiments were also examined and it was showed that superoxide ion radicals play a vital role in the photocatalytic degradation reaction. More importantly, the ternary photocatalyst demonstrated good photostability. - Highlights: • ZnO/AgI/Ag{sub 2}CO{sub 3} nanocomposites were fabricated by an ultrasonic-irradiation method. • The activity was investigated by photodegradation of four dyes under visible light. • ZnO/AgI/Ag{sub 2}CO{sub 3} (30%) nanocomposite has the best activity under visible light. • Activity is 19 and 14-folds higher than ZnO/Ag{sub 2}CO{sub 3} and ZnO/AgI in degradation of RhB.

Visible light driven photocatalysis and antibacterial activity of AgVO{sub 3} and Ag/AgVO{sub 3} nanowires

Energy Technology Data Exchange (ETDEWEB)

Singh, Anamika [Department of Life Sciences, University of Mumbai, Santacruz (E), Mumbai 400 098 (India); Dutta, Dimple P., E-mail: dimpled@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Ballal, A. [Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India); Fulekar, M.H. [School of Environment and Sustainable Development, Central University of Gujarat, Gandhinagar 382 030, Gujarat (India)

2014-03-01

Graphical abstract: - Highlights: • Ag/AgVO{sub 3} and pure AgVO{sub 3} nanowires synthesized by sonochemical process. • Characterization done using XRD, SEM, TEM, EDX and BET analysis. • Visible light degradation of RhB by Ag/AgVO{sub 3} within 45 min. • Antibacterial activity of Ag/AgVO{sub 3} demonstrated. - Abstract: Ag/AgVO{sub 3} nanowires and AgVO{sub 3} nanorods were synthesized in aqueous media via a facile sonochemical route. The as-synthesized products were characterized by X-ray diffraction, Brunauer–Emmett–Teller surface area analysis, scanning electron microscopy together with an energy dispersion X-ray spectrum analysis, transmission electron microscopy and UV–vis diffuse reflectance spectroscopy. The results revealed that inert atmosphere promotes the formation of Ag/AgVO{sub 3} nanowires. The photocatalytic studies revealed that the Ag/AgVO{sub 3} nanowires exhibited complete photocatalytic degradation of Rhodamine B within 45 min under visible light irradiation. The antibacterial activity of Ag/AgVO{sub 3} nanowires was tested against Escherechia coli and Bacillus subtilis. The minimum growth inhibitory concentration value was found to be 50 and 10 folds lower than for the antibiotic ciprofloxacin for E. coli and B. subtilis, respectively. The antibacterial properties of the β-AgVO{sub 3} nanorods prove that in case of the Ag dispersed Ag/AgVO{sub 3} nanowires, the enhanced antibacterial action is also due to contribution from the AgVO{sub 3} support.

Facile one-pot construction of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} heterojunction for arsenic removal by synchronous visible light catalysis oxidation and adsorption

Energy Technology Data Exchange (ETDEWEB)

Sun, Suwen; Ji, Chunnuan, E-mail: 1842355613@qq.com; Wu, Lingling; Chi, Shenghua; Qu, Rongjun; Li, Yan; Lu, Yangxiao; Sun, Changmei; Xue, Zhongxin

2017-06-15

α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites with heterojunction were prepared by facile one-pot synthesis using ferric chloride and dicyandiamide as precursors. The newly formed composites were applied to remove arsenic from aqueous solution for the first time through synchronous visible light catalysis oxidation and adsorption. α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites were characterized by wide-angle X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectroscopy, and BET surface analysis. Under visible light irradiation, As(III) was oxidized to As(V) efficiently on the surface of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4}. In addition, the oxidized arsenic could be adsorbed in situ, resulting in the effective arsenic removal. The enhancement of photocatalytic activity the composites was attributed to the construction of heterojunction between α-Fe{sub 2}O{sub 3} and g-C{sub 3}N{sub 4}. A possible oxidation mechanism of the as-composites for As(III) under visible light irradiation was also elucidated. - Highlights: • α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites with heterojunction was prepared by facile one-pot synthesis. • The photocatalytic activity of α-Fe{sub 2}O{sub 3}/g-C{sub 3}N{sub 4} composites under visible light irradiation for As(III) was evaluated. • Synchronous visible light catalysis oxidation and adsorption were achieved for the removal of arsenic. • The reasonable oxidation mechanism of the composites for As(III) under visible light irradiation was investigated.

A light-powered sub-threshold microprocessor

Energy Technology Data Exchange (ETDEWEB)

Liu Ming; Chen Hong; Zhang Chun; Li Changmeng; Wang Zhihua, E-mail: lium02@mails.tsinghua.edu.cn [Institute of Microelectronics, Tsinghua University, Beijing 100084 (China)

2010-11-15

This paper presents an 8-bit sub-threshold microprocessor which can be powered by an integrated photosensitive diode. With a custom designed sub-threshold standard cell library and 1 kbit sub-threshold SRAM design, the leakage power of 58 nW, dynamic power of 385 nW - 165 kHz, EDP 13 pJ/inst and the operating voltage of 350 mV are achieved. Under a light of about 150 kLux, the microprocessor can run at a rate of up to 500 kHz. The microprocessor can be used for wireless-sensor-network nodes.

On the efficient warm white-light emission from nano-sized Y{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Cesaria, M., E-mail: maura.cesaria@le.infn.it [Department of Mathematics and Physics “E. De Giorgi”, University of Salento, Lecce (Italy); Collins, J. [Wheaton College, Norton, MA (United States); Di Bartolo, B. [Department of Physics, Boston College, Chestnut Hill, MA (United States)

2016-01-15

We consider the reported emission of white light (WL) in the spectral range from 400 to beyond 900 nm induced by monochromatic infrared light (803.5 and 975 nm) continuous wave excitation of nominally un-doped yttrium oxide (Y{sub 2}O{sub 3}) nano-powders. Based on the experimental evidence, such an emission feature is a nano-scale phenomenon, resembles very closely the emission from an incandescent lamp (mimicking the sunlight, i.e., the most comfortable light to human eyes) and exhibits very high efficiency (864 lum/W) and nearly theoretical (i.e., 99) color rendering index. At the fundamental level, the origin of this phenomenon is still unexplained. In this paper we address the fundamental questions raised by the reported occurrence of WL emission from Y{sub 2}O{sub 3} nanopowders and attempt an interpretation at a more fundamental level. In particular we focus on the multiphoton-absorption and nonexponential decay patterns of the reported WL emission as starting points to formulate models and interpretations of the experimental occurrences still lacking in the literature. Our discussion invokes the electronic dispersion of Y{sub 2}O{sub 3} and nanoscale effects, which is supported by the experimental evidence according to which the observed warm WL emission is a nanoscale phenomenon with properties that only can be explained by nanoscale physics. - Highlights: • Emission of white light from 400 to beyond 900 nm induced by infrared light of un-doped Y{sub 2}O{sub 3} nano-powders. • The emission feature resembles very closely the emission from an incandescent lamp. • The observed emission properties only can be explained by nanoscale physics.

Light emission efficiency and imaging performance of Lu{sub 2}O{sub 3}:Eu nanophosphor under X-ray radiography conditions: Comparison with Gd{sub 2}O{sub 2}S:Eu

Energy Technology Data Exchange (ETDEWEB)

Seferis, I. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece); Michail, C.; Valais, I. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Zeler, J. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Liaparinos, P.; Fountos, G.; Kalyvas, N.; David, S. [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Stromatia, F. [Department of Radiology and Nuclear Medicine, “IASO” General Hospital, Mesogion 264, 15562 Holargos (Greece); Zych, E. [Faculty of Chemistry, Wroclaw University, 14F Joliot-Curie Street, 50-383 Wroclaw (Poland); Kandarakis, I., E-mail: kandarakis@teiath.gr [Department of Biomedical Engineering, Technological Educational Institute of Athens, 122 10 Athens (Greece); Panayiotakis, G. [Department of Medical Physics, Medical School, University of Patras, 265 00 Patras (Greece)

2014-07-01

Nanocrystallic europium-activated lutetium oxide (Lu{sub 2}O{sub 3}:Eu) is a strong candidate for use in digital medical imaging applications, due to its spectroscopic and structural properties. The aim of the present study was to investigate the imaging and efficiency properties of a 33.3 mg/cm{sup 2} Lu{sub 2}O{sub 3}:Eu scintillating screen coupled to a high resolution RadEye HR CMOS photodetector under radiographic imaging conditions. Since Lu{sub 2}O{sub 3}:Eu emits light in the red wavelength range, the light emission efficiency and the imaging performance were compared with results for a Gd{sub 2}O{sub 2}S:Eu phosphor screen. Parameters such as the Absolute Efficiency (AE), the X-ray Luminescence Efficiency (XLE), and the Detector Quantum Gain (DQG), were investigated. The imaging characteristics of Lu{sub 2}O{sub 3}:Eu nanophosphor screen were investigated in terms of the Modulation Transfer Function (MTF), the Normalized Noise Power Spectrum (NNPS) and the Detective Quantum Efficiency (DQE). It was found that Lu{sub 2}O{sub 3}:Eu nanophosphor has higher AE and XLE by a factor of 1.32 and 1.37 on average, respectively, in the whole radiographic energy range in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. DQG was also found higher in the energy range from 50 kVp to 100 kVp and comparable thereafter. The imaging quality of Lu{sub 2}O{sub 3}:Eu nanophosphor coupled to the CMOS sensor was found to outmatch in any aspect in comparison with the Gd{sub 2}O{sub 2}S:Eu screen. These results indicate that Lu{sub 2}O{sub 3}:Eu nanophosphor could be considered for further research in order to be used in medical imaging applications. - Highlights: • AE and XLE of Lu{sub 2}O{sub 3}:Eu nanophosphor were higher by a factor of 1.32 and 1.37 than Gd{sub 2}O{sub 2}S:Eu. • DQG was higher from 50 to 100 kVp and comparable thereafter. • Imaging performance of Lu{sub 2}O{sub 3}:Eu/CMOS was better than that of Gd{sub 2}O{sub 2}S:Eu/CMOS.

Electrodeposition synthesis of MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites and their visible light photocatalytic activity

Energy Technology Data Exchange (ETDEWEB)

Xu, Xuyao [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China); Zhou, Xiaosong, E-mail: zxs801213@163.com [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China); Li, Xiaoyu, E-mail: lixiaoyu@iga.ac.cn [Key Laboratory of Wetland Ecology and Environment, Northeast Institute of Geography and Agroecology, Chinese Academy of Science, Changchun 130012 (China); Yang, Fei [The State Key Laboratory of Resources and Environmental Information System, Institute of Geographic Sciences and Natural Resources Research of Chinese Academy of Sciences, 11A, Datun Road, Chaoyang District, Beijing 100101 (China); Jin, Bei; Xu, Tan; Li, Guosheng; Li, Manyi [School of Chemistry Science and Technology, and Institute of Physical Chemistry, Zhanjiang Normal University, Zhanjiang 524048 (China)

2014-11-15

Highlights: • MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposites are prepared by electrodeposition. • MnO{sub 2}/TiO{sub 2} exhibits high visible light photocatalytic activity. • The results of XRD show the depositions are attributed to α-MnO{sub 2}. • A photocatalytic mechanism is discussed under visible light irradiation. - Abstract: MnO{sub 2}/TiO{sub 2} nanotube arrays nanocomposite photocatalysts have been synthesized through an electrodeposition method. X-ray powder diffraction analysis and X-ray photoelectron spectroscopy measurements reveal that the products of electrodeposition method are MnO{sub 2}. Scanning electron microscopy measurements suggest that the depositions are deposited on the surface or internal of the nanotube. UV–vis light absorbance spectra demonstrate the excellent adsorption properties of MnO{sub 2}/TiO{sub 2} over the whole region of visible light, which enables this novel photocatalytic material to possess remarkable activity in the photocatalytic degradation of acid Orange II under visible light radiation. Moreover, a possible photocatalytic mechanism is discussed.

Sensitization by UV light of α-Al{sub 2}O{sub 3}:C polycrystalline detectors

Energy Technology Data Exchange (ETDEWEB)

Meira B, L. C.; Rubio F, H.; Neres de A, E. [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Dosimetria Termoluminicente, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil); Santos, A., E-mail: hrf@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear - CNEN, Laboratorio de Microesferas Gel, Av. Antonio Carlos 6627, Campus UFMG, CEP 31270-901, Belo Horizonte (Brazil)

2014-08-15

This paper describes an increase in sensitivity to gamma and beta radiation on α-Al{sub 2}O{sub 3}:C polycrystalline detector, which has been produced by a sol-gel process, following previous exposure to ultraviolet light. The increased sensitivity of the detector as a function of the exposure time and ultraviolet wavelength was studied. Since the main luminescent centers have emission peaks at different wavelengths, selective measurements of thermoluminescent emission intensity were done, in order to investigate the possible conversion of centers as a result of the exposition to ultraviolet light. Experimental results indicate that the nature and parameters of the luminescent centers in α-Al{sub 2}O{sub 3}:C sol-gel material can be very different of those in α-Al{sub 2}O{sub 3}:C single crystal. (author)

Element-resolved atomic structure imaging of rocksalt Ge{sub 2}Sb{sub 2}Te{sub 5} phase-change material

Energy Technology Data Exchange (ETDEWEB)

Zhang, Bin; Chen, Yongjin; Han, Xiaodong, E-mail: wzhang0@mail.xjtu.edu.cn, E-mail: ema@jhu.edu, E-mail: xdhan@bjut.edu.cn [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Zhang, Wei, E-mail: wzhang0@mail.xjtu.edu.cn, E-mail: ema@jhu.edu, E-mail: xdhan@bjut.edu.cn [Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an 710049 (China); I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen (Germany); Institute for Theoretical Solid-State Physics, RWTH Aachen University, 52056 Aachen (Germany); Shen, Zhenju; Li, Jixue [Department of Materials Science and Engineering, Center of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Zhang, Shengbai [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, Changchun 130012 (China); Zhang, Ze [Institute of Microstructure and Property of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Department of Materials Science and Engineering, Center of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Wuttig, Matthias [I. Institute of Physics (IA), RWTH Aachen University, 52056 Aachen (Germany); Mazzarello, Riccardo [Institute for Theoretical Solid-State Physics, RWTH Aachen University, 52056 Aachen (Germany); and others

2016-05-09

Disorder-induced electron localization and metal-insulator transitions (MITs) have been a very active research field starting from the seminal paper by Anderson half a century ago. However, pure Anderson insulators are very difficult to identify due to ubiquitous electron-correlation effects. Recently, an MIT has been observed in electrical transport measurements on the crystalline state of phase-change GeSbTe compounds, which appears to be exclusively disorder driven. Subsequent density functional theory simulations have identified vacancy disorder to localize electrons at the Fermi level. Here, we report a direct atomic scale chemical identification experiment on the rocksalt structure obtained upon crystallization of amorphous Ge{sub 2}Sb{sub 2}Te{sub 5}. Our results confirm the two-sublattice structure resolving the distribution of chemical species and demonstrate the existence of atomic disorder on the Ge/Sb/vacancy sublattice. Moreover, we identify a gradual vacancy ordering process upon further annealing. These findings not only provide a structural underpinning of the observed Anderson localization but also have implications for the development of novel multi-level data storage within the crystalline phases.

Bactericidal effect of blue LED light irradiated TiO{sub 2}/Fe{sub 3}O{sub 4} particles on fish pathogen in seawater

Energy Technology Data Exchange (ETDEWEB)

Cheng, T.C. [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Taiwan (China); Yao, K.S. [Department of Horticulture, National Taitung Junior College, Taiwan (China); Yeh, N. [Mingdao University, Taiwan (China); Chang, C.I. [Aquaculture Division, Fisheries Research Institute, Council of Agriculture, Taiwan (China); Hsu, H.C. [Department of Life Science, Mingdao University, Taiwan (China); Gonzalez, F. [Department of Tropical Agriculture and International Cooperation, National Pingtung University of Science and Technology, Taiwan (China); Chang, C.Y., E-mail: cyc1136@yahoo.com.tw [Center of General Education, National Taitung Junior College, Taiwan (China)

2011-05-31

This study uses blue LED light ({lambda}{sub max} = 475 nm) activated TiO{sub 2}/Fe{sub 3}O{sub 4} particles to evaluate the particles' photocatalytic activity efficiency and bactericidal effects in seawater of variable salinities. Different TiO{sub 2} to Fe{sub 3}O{sub 4} mole ratios have been synthesized using sol-gel method. The synthesized particles contain mainly anatase TiO{sub 2}, Fe{sub 3}O{sub 4} and FeTiO{sub 3}. The study has identified TiO{sub 2}/Fe{sub 3}O{sub 4}'s bactericidal effect to marine fish pathogen (Photobacterium damselae subsp. piscicida BCRC17065) in seawater. The SEM photo reveals the surface destruction in bacteria incubated with blue LED irradiated TiO{sub 2}/Fe{sub 3}O{sub 4}. The result of this study indicates that 1) TiO{sub 2}/Fe{sub 3}O{sub 4} acquires photocatalytic activities in both the freshwater and the seawater via blue LED irradiation, 2) higher photocatalytic activities appear in solutions of higher TiO{sub 2}/Fe{sub 3}O{sub 4} mole ratio, and 3) photocatalytic activity decreases as salinity increases. These results suggest that the energy saving blue LED light is a feasible light source to activate TiO{sub 2}/Fe{sub 3}O{sub 4} photocatalytic activities in both freshwater and seawater.

EXAFS study of Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound with first-order phase transition

Energy Technology Data Exchange (ETDEWEB)

L, Yingjie; Huliyageqi, B; Haschaolu, W; Song, Zhiqiang [Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, Physics and Electronic Information College, Inner Mongolia Normal University, Hohhot 010022 (China); Tegus, O, E-mail: tegusph@imnu.edu.cn [Inner Mongolia Key Laboratory for Physics and Chemistry of Functional Materials, Physics and Electronic Information College, Inner Mongolia Normal University, Hohhot 010022 (China); Nakai, Ikuo [Department of Electrical and Electronic Engineering, Tottori University, Tottori 680-8552 (Japan)

2014-10-15

Highlights: • We have investigated the Fe and Mn K edge XAFS spectra of the Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound at 25 K and 295 K. • The site occupation of the Fe and Mn atoms and local structure of Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} are determined. • The atomic distances between Fe–Fe in c-plane for the ferromagnetic state are larger than those in the paramagnetic state. - Abstract: The Fe{sub 2}P-type MnFe(P,Si) compounds are investigated by means of magnetic measurements and X-ray absorption fine structure spectroscopy. Magnetic measurements show that the Mn{sub 1.28}Fe{sub 0.67}P{sub 0.46}Si{sub 0.54} compound undergoes a first-order phase transition at the Curie temperature of 254 K. The Fe K-edge and Mn K-edge X-ray absorption fine structure spectra show that Mn atom mainly located at the 3g sites, while the 3f sites are occupied by Fe atoms and Mn atom randomly. The distances between the Fe atom and its nearest neighbor atoms in a triangle Fe–Mn–Fe change from 2.80 Å at 25 K to 2.74 Å at 300 K. On the other hand, the distances between Fe atom and its second neighbor atoms change from 4.06 Å at 25 K to 4.02 Å at 300 K.

Synergic effect of the TiO{sub 2}-CeO{sub 2} nanoconjugate system on the band-gap for visible light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Contreras-García, M.E. [Instituto de Investigaciones Metalúrgicas, edificio “U”, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, C.P. 58060, Morelia, Michoacán (Mexico); García-Benjume, M. Lorena, E-mail: lbenjume@yahoo.com [Instituto de Investigaciones Metalúrgicas, edificio “U”, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, C.P. 58060, Morelia, Michoacán (Mexico); Macías-Andrés, Víctor I. [Instituto de Investigaciones Metalúrgicas, edificio “U”, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, C.P. 58060, Morelia, Michoacán (Mexico); Barajas-Ledesma, E. [Universidad de La Ciénega del Estado de Michoacán de Ocampo, Avenida Universidad 3000, C.P. 59000, Sahuayo, Michoacán (Mexico); Medina-Flores, A. [Instituto de Investigaciones Metalúrgicas, edificio “U”, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, C.P. 58060, Morelia, Michoacán (Mexico); Espitia-Cabrera, M.I. [Facultad de Ingeniería Química, edificio “M”, Ciudad Universitaria, Universidad Michoacana de San Nicolás de Hidalgo, C.P. 58060, Morelia, Michoacán (Mexico)

2014-04-01

Graphical abstract: - Highlights: • Nanostructured TiO{sub 2}-CeO{sub 2} films are successfully synthesized by combining of sputtering and electrophoresis methods. • Synergic effect of CeO{sub 2} on TiO{sub 2} band gap was demonstrated, CeO{sub 2} diminishes it from 3.125 to 2.74. • Morphologic characterization of the nanoconjugate TiO{sub 2}-CeO{sub 2} films by different microscopy techniques. - Abstract: The TiO{sub 2}-CeO{sub 2} photocatalytic system in films is proposed here, in order to obtain photocatalytic systems that can be excited by solar light. The films were obtained through the electrophoretic deposition (EPD) of TiO{sub 2}-CeO{sub 2} gel on sputtered Ti Corning glass substrates. The synergic effect of CeO{sub 2} in TiO{sub 2} films was analyzed as a function of the optical band gap reduction at different concentrations (1, 5, 10, and 15 mol%). The effect of two thermal treatments was also evaluated. The lowest band gap value was obtained for the sample with 5 mol% ceria that was thermally treated at 700 °C. The nanostructured films were characterized by Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high angle annular dark field (HAADF), high resolution transmission electron microscopy (HRTEM), and atomic force microscopy (AFM). The nanocomposites were formed by TiO{sub 2} and CeO{sub 2} nanoparticles in the anatase and fluorite type phases, respectively.

Ultrasound assisted synthesis of heterogeneous g-C{sub 3}N{sub 4}/BiVO{sub 4} composites and their visible-light-induced photocatalytic oxidation of NO in gas phase

Energy Technology Data Exchange (ETDEWEB)

Ou, Man; Zhong, Qin, E-mail: zq304@mail.njust.edu.cn; Zhang, Shule; Yu, Lemeng

2015-03-25

Highlights: • The g-C{sub 3}N{sub 4}/BiVO{sub 4} composites were prepared via ultrasonic and calcination methods. • The conversion of NO of G6B4 was 4 times larger than that of the pure phases. • There were only NO{sub 2}{sup −} and NO{sub 3}{sup −} produced in the PCO reaction process. • The promotional mechanism on the g-C{sub 3}N{sub 4}/BiVO{sub 4} heterojunctions was proposed. - Abstract: The visible light active g-C{sub 3}N{sub 4}/BiVO{sub 4} catalysts were synthesized via facile ultrasonic dispersion and calcination methods and used in the study for photocatalytic oxidation (PCO) of NO in gas phase. The as-synthesized samples were analyzed by various characterization techniques. The results exhibited that an interaction between BiVO{sub 4} and g-C{sub 3}N{sub 4} was confirmed and a heterojunction was formed on the surface of g-C{sub 3}N{sub 4}/BiVO{sub 4} composite, which enhanced the separation and transfer of photogenerated electron–hole pairs. The mechanism on the heterojunction effect to improve the PCO ability was also proposed. The activity test showed that the optimum content of g-C{sub 3}N{sub 4} was 50 wt%. And the maximum conversion of NO was four times larger than that of the pure components when the inlet concentration of NO was about 400 ppm under the visible light (VL) irradiation. The ion chromatography (IC) showed that NO was removed in the oxidation formation of NO{sub 2}{sup −} and NO{sub 3}{sup −}.

Fluorocarbon assisted atomic layer etching of SiO{sub 2} and Si using cyclic Ar/C{sub 4}F{sub 8} and Ar/CHF{sub 3} plasma

Energy Technology Data Exchange (ETDEWEB)

Metzler, Dominik; Oehrlein, Gottlieb S., E-mail: oehrlein@umd.edu [Department of Materials Science and Engineering, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20740 (United States); Li, Chen [Department of Physics, and Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20740 (United States); Engelmann, Sebastian; Bruce, Robert L.; Joseph, Eric A. [IBM T. J. Watson Research Center, Yorktown Heights, New York 10598 (United States)

2016-01-15

The need for atomic layer etching (ALE) is steadily increasing as smaller critical dimensions and pitches are required in device patterning. A flux-control based cyclic Ar/C{sub 4}F{sub 8} ALE based on steady-state Ar plasma in conjunction with periodic, precise C{sub 4}F{sub 8} injection and synchronized plasma-based low energy Ar{sup +} ion bombardment has been established for SiO{sub 2} [Metzler et al., J. Vac. Sci. Technol. A 32, 020603 (2014)]. In this work, the cyclic process is further characterized and extended to ALE of silicon under similar process conditions. The use of CHF{sub 3} as a precursor is examined and compared to C{sub 4}F{sub 8}. CHF{sub 3} is shown to enable selective SiO{sub 2}/Si etching using a fluorocarbon (FC) film build up. Other critical process parameters investigated are the FC film thickness deposited per cycle, the ion energy, and the etch step length. Etching behavior and mechanisms are studied using in situ real time ellipsometry and x-ray photoelectron spectroscopy. Silicon ALE shows less self-limitation than silicon oxide due to higher physical sputtering rates for the maximum ion energies used in this work, ranged from 20 to 30 eV. The surface chemistry is found to contain fluorinated silicon oxide during the etching of silicon. Plasma parameters during ALE are studied using a Langmuir probe and establish the impact of precursor addition on plasma properties.

Inter-atomic force constants of BaF{sub 2} by diffuse neutron scattering measurement

Energy Technology Data Exchange (ETDEWEB)

Sakuma, Takashi, E-mail: sakuma@mx.ibaraki.ac.jp; Makhsun,; Sakai, Ryutaro [Institute of Applied Beam Science, Ibaraki University, Mito 310-8512 (Japan); Xianglian [College of Physics and Electronics Information, Inner Mongolia University for the Nationalities, Tongliao 028043 (China); Takahashi, Haruyuki [Institute of Applied Beam Science, Ibaraki University, Hitachi 316-8511 (Japan); Basar, Khairul [Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Bandung 40132 (Indonesia); Igawa, Naoki [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai 319-1195 (Japan); Danilkin, Sergey A. [Bragg Institute, Australian Nuclear Science and Technology Organisation, Kirrawee DC NSW 2232 (Australia)

2015-04-16

Diffuse neutron scattering measurement on BaF{sub 2} crystals was performed at 10 K and 295 K. Oscillatory form in the diffuse scattering intensity of BaF{sub 2} was observed at 295 K. The correlation effects among thermal displacements of F-F atoms were obtained from the analysis of oscillatory diffuse scattering intensity. The force constants among neighboring atoms in BaF{sub 2} were determined and compared to those in ionic crystals and semiconductors.

The Sun as a sub-GeV dark matter accelerator

DEFF Research Database (Denmark)

Emken, Timon; Kouvaris, Chris; Nielsen, Niklas Grønlund

2018-01-01

Sub-GeV halo dark matter that enters the Sun can potentially scatter off hot solar nuclei and be ejected much faster than its incoming velocity. We derive an expression for the rate and velocity distribution of these reflected particles, taking into account the Sun's temperature and opacity. We...... further demonstrate that future direct-detection experiments could use these energetic reflected particles to probe light dark matter in parameter space that cannot be accessed via ordinary halo dark matter....

LiBSi{sub 2}: a tetrahedral semiconductor framework from boron and silicon atoms bearing lithium atoms in the channels

Energy Technology Data Exchange (ETDEWEB)

Zeilinger, Michael; Faessler, Thomas F. [Department of Chemistry, Technische Universitaet Muenchen, Garching (Germany); Wuellen, Leo van [Department of Physics, University of Augsburg (Germany); Benson, Daryn [Department of Physics, Arizona State University, Tempe, AZ (United States); Kranak, Verina F.; Konar, Sumit; Haeussermann, Ulrich [Department of Materials and Environmental Chemistry, Stockholm University (Sweden)

2013-06-03

Silicon swallows up boron. The novel open tetrahedral framework structure (OTF) of the Zintl phase LiBSi{sub 2} was made by applying high pressure to a mixture of LiB and elemental silicon. The compound represents a new topology in the B-Si net (called tum), which hosts Li atoms in the channels. LiBSi{sub 2} is the first example where B and Si atoms form an ordered common framework structure with B engaged exclusively in heteronuclear B-Si contacts. (Copyright copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Comparison of thermal compatibility between atomized and comminuted U{sub 3}Si dispersion fuels

Energy Technology Data Exchange (ETDEWEB)

Ryu, Woo-Seog; Park, Jong-Man; Kim, Chang-Kyu; Kuk, II-Hyun [Korea Atomic Research Institute, Taejon (Korea, Republic of)

1997-08-01

Thermal compatibility of atomized U{sub 3}Si dispersion fuels were evaluated up to 2600 hours in the temperature range from 250 to 500{degrees}C, and compared with that of comminuted U{sub 3}Si. Atomized U{sub 3}Si showed better performance in terms of volume expansion of fuel meats. The reaction zone of U{sub 3}Si and Al occurred along the grain boundaries and deformation bands in U{sub 3}Si particles. Pores around fuel particles appeared at high temperature or after long-term annealing tests to remain diffusion paths over the trench of the pores. The constraint effects of cladding on fuel rod suppressed the fuel meat, and reduced the volume expansion.

Facile preparation of Z-scheme WO{sub 3}/g-C{sub 3}N{sub 4} composite photocatalyst with enhanced photocatalytic performance under visible light

Energy Technology Data Exchange (ETDEWEB)

Cui, Lifeng, E-mail: lifeng.cui@gmail.com [School of Chemistry and Environmental Engineering, Dongguan University of Technology, Guangdong 523808 (China); Ding, Xiang; Wang, Yangang; Shi, Huancong; Huang, Lihua; Zuo, Yuanhui [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China); Kang, Shifei, E-mail: sfkang@usst.edu.cn [Department of Environmental Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)

2017-01-01

Highlights: • WO{sub 3}/g-C{sub 3}N{sub 4} composites were synthesized through a facile mixing-and-heating method. • The composite showed improved visible light response. • The composite showed high activity for MB degradation. • Z-scheme charge carrier transfer pathways in the composite are proposed. - Abstract: Visible-light-driven WO{sub 3}/g-C{sub 3}N{sub 4} composites photocatalysts were synthesized via a facile one-step simultaneously heating procedure with urea as the main precursor. These prepared catalyst samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), transmission electron microscopy (TEM), N{sub 2} adsorption, ultraviolet-visible diffuse reflection spectroscopy (UV–vis), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and electrochemical impedance spectroscopy (EIS). The photocatalytic activity of the WO{sub 3}/g-C{sub 3}N{sub 4} composites was evaluated by the photo-degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the composites with 25 wt.% WO{sub 3} content exhibited highest photocatalytic activity compared to pure WO{sub 3}, bare g-C{sub 3}N{sub 4} and other WO{sub 3}/g-C{sub 3}N{sub 4} composites. The favorable photocatalytic activity of WO{sub 3}/g-C{sub 3}N{sub 4} composites was mainly attributed to the excellent surface properties, enhanced visible-light absorption and the desirable band positions. A possible Z-scheme photocatalytic mechanism was proposed based on structure and electrochemical characterizations results, which can well explain the enhanced migration rate of photogenerated electrons and holes in WO{sub 3}/g-C{sub 3}N{sub 4} heterojunctions.

Atomic partial charges on CH{sub 3}NH{sub 3}PbI{sub 3} from first-principles electronic structure calculations

Energy Technology Data Exchange (ETDEWEB)

Madjet, Mohamed E., E-mail: mmadjet@qf.org.qa; El-Mellouhi, Fedwa; Carignano, Marcelo A.; Berdiyorov, Golibjon R. [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, Qatar Foundation, P. O. Box 5825, Doha (Qatar)

2016-04-28

We calculated the partial charges in methylammonium (MA) lead-iodide perovskite CH{sub 3}NH{sub 3}PbI{sub 3} in its different crystalline phases using different first-principles electronic charge partitioning approaches, including the Bader, ChelpG, and density-derived electrostatic and chemical (DDEC) schemes. Among the three charge partitioning methods, the DDEC approach provides chemically intuitive and reliable atomic charges for this material, which consists of a mixture of transition metals, halide ions, and organic molecules. The DDEC charges are also found to be robust against the use of hybrid functionals and/or upon inclusion of spin–orbit coupling or dispersive interactions. We calculated explicitly the atomic charges with a special focus on the dipole moment of the MA molecules within the perovskite structure. The value of the dipole moment of the MA is reduced with respect to the isolated molecule due to charge redistribution involving the inorganic cage. DDEC charges and dipole moment of the organic part remain nearly unchanged upon its rotation within the octahedral cavities. Our findings will be of both fundamental and practical importance, as the accurate and consistent determination of the atomic charges is important in order to understand the average equilibrium distribution of the electrons and to help in the development of force fields for larger scale atomistic simulations to describe static, dynamic, and thermodynamic properties of the material.

Narrow band gap and visible light-driven photocatalysis of V-doped Bi{sub 6}Mo{sub 2}O{sub 15} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Xu, Jian; Qin, Chuanxiang; Huang, Yanlin [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wang, Yaorong, E-mail: yrwang@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2017-02-28

Highlights: • V{sup 5+}-doped Bi{sub 6}Mo{sub 2}O{sub 15} was synthesized by the electrospinning preparation. • The band gap energy of Bi{sub 6}Mo{sub 2}O{sub 15} was greatly reduced by V-doping in the lattices. • V-doped Bi{sub 6}Mo{sub 2}O{sub 15} shows high activity in RhB degradation under visible light. • Crystal structure of Bi{sub 6}Mo{sub 2}O{sub 15} is favorable for high photocatalytic capacity. - Abstract: Pure and V{sup 5+}-doped Bi{sub 6}Mo{sub 2}O{sub 15} (3Bi{sub 2}O{sub 3}·2MoO{sub 3}) photocatalysts were synthesized through electrospinning, followed by low-temperature heat treatment. The samples developed into nanoparticles with an average size of approximately 50 nm. The crystalline phases were verified via X-ray powder diffraction measurements (XRD). The surface properties of the photocatalysts were studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) analyses. The UV–vis spectra showed that V doping in Bi{sub 6}Mo{sub 2}O{sub 15} shifted the optical absorption from the UV region to the visible-light wavelength region. The energy of the band gap of Bi{sub 6}Mo{sub 2}O{sub 15} was reduced by V doping in the lattices. The photocatalytic activities of the pure and V-doped Bi{sub 6}Mo{sub 2}O{sub 15} were tested through photodegradation of rhodamine B (RhB) dye solutions under visible light irradiation. Results showed that 20 mol% V-doped Bi{sub 6}Mo{sub 2}O{sub 15} achieved efficient photocatalytic ability. RhB could be degraded by V-doped Bi{sub 6}Mo{sub 2}O{sub 15} in 2 h. The photocatalytic activities and mechanisms were discussed according to the characteristics of the crystal structure and the results of EIS and XPS measurements.

Fabrication of a direct Z-scheme type WO{sub 3}/Ag{sub 3}PO{sub 4} composite photocatalyst with enhanced visible-light photocatalytic performances

Energy Technology Data Exchange (ETDEWEB)

Lu, Jinsuo, E-mail: lujinsuo@xauat.edu.cn [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Wang, Yujing [School of Materials and Chemical Engineering, Xi’an Technological University, Xi’an, Shaanxi 710032 (China); Liu, Fei [School of Environmental and Municipal Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Zhang, Liang [College of Sciences, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Chai, Shouning, E-mail: s.n.chai@xauat.edu.cn [College of Sciences, Xi’an University of Architecture and Technology, Xi’an 710055 (China)

2017-01-30

Highlights: • A solid direct Z-scheme type photocatalyst WO{sub 3}/Ag{sub 3}PO{sub 4} was synthesized. • The WO{sub 3}/Ag{sub 3}PO{sub 4} composite showed enhanced photocatalytic activity and stability. • Nearly complete removal of organic dyes was achieved in a short time. • The reasonable Z-scheme mechanism of WO{sub 3}/Ag{sub 3}PO{sub 4} composite was proposed. - Abstract: A direct Z-scheme type photocatalyst WO{sub 3}/Ag{sub 3}PO{sub 4} composite (molar ration 1:1, 1W/1Ag) was prepared by hydrothermal method. The 1W/1Ag was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), UV–vis diffuse reflection spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and photoluminescence emission spectroscopy (PL) etc. technologies. The photocatalytic performances were evaluated by degradation of methylene blue (MB) and methyl orange (MO), and their removal rates were up to 95% after 60 min and 90% after 180 min, respectively. The prepared 1W/1Ag exhibits a much higher photocatalytic activity than pure Ag{sub 3}PO{sub 4} and pure WO{sub 3} under visible light irradiation. The apparent rate constants of MB and MO degradation on 1W/1Ag are about 2.4 and 2.5 times that of pure Ag{sub 3}PO{sub 4}, respectively. The enhanced performance of the 1W/1Ag is attributed to a synergistic effect including relatively high surface area, strong light absorption, matched energy band structure, and the improved separation of photogenerated charge carriers between the two components. A reasonable Z-scheme mechanism referring to directed migration of photoinduced carriers was proposed. Thus, it can be suggested that the 1W/1Ag can serve as a promising photocatalyst for environmental purification and clean energy utilization.

CsPbBr{sub 3} QD/AlO{sub x} inorganic nanocomposites with exceptional stability in water, light, and heat

Energy Technology Data Exchange (ETDEWEB)

Loiudice, Anna; Saris, Seryio; Buonsanti, Raffaella [Department of Chemical Sciences and Engineering, EPFL Valais Wallis, Sion (Switzerland); Oveisi, Emad; Alexander, Duncan T.L. [Interdisciplinary Centre for Electron Microscopy (CIME), EPFL, Lausanne (Switzerland)

2017-08-28

Herein, the assembly of CsPbBr{sub 3} QD/AlO{sub x} inorganic nanocomposites, by using atomic layer deposition (ALD) for the growth of the amorphous alumina matrix (AlO{sub x}), is described as a novel protection scheme for such QDs. The nucleation and growth of AlO{sub x} on the QD surface was thoroughly investigated by miscellaneous techniques, which highlighted the importance of the interaction between the ALD precursors and the QD surface to uniformly coat the QDs while preserving the optoelectronic properties. These nanocomposites show exceptional stability towards exposure to air (for at least 45 days), irradiation under simulated solar spectrum conditions (for at least 8 h), and heat (up to 200 C in air), and finally upon immersion in water. This method was extended to the assembly of CsPbBr{sub x}I{sub 3-x} QD/AlO{sub x} and CsPbI{sub 3} QD/AlO{sub x} nanocomposites, which were more stable than the pristine QD films. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

The CeO{sub 2}/Ag{sub 3}PO{sub 4} photocatalyst with stability and high photocatalytic activity under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Song, Yanhua [School of Environmental and Chemical Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003 (China); Zhao, Haozhu; Chen, Zhigang; Huang, Liying; Xu, Hui; Li, Huaming [School of the Environment, Institute for Energy Research, Jiangsu University, Zhenjiang, 212013 (China); Wang, Weiren [Department of Chemistry, Rice University, Houston, Texas, 77005 (United States)

2016-09-15

The CeO{sub 2}/Ag{sub 3}PO{sub 4} composite photocatalysts are synthesized by an in situ precipitation method. The XRD, FT-IR, XPS, TEM, EDS, and DRS are used to characterize the structure of the samples. The photocatalytic performance of the prepared samples is evaluated by the photocatalytic degradation of methylene blue (MB), rhodamine B (RhB), and ciprofloxacin (CIP). The results show that CeO{sub 2}/Ag{sub 3}PO{sub 4} hybrid materials exhibit much higher photocatalytic activity than the Ag{sub 3}PO{sub 4} alone. The optimal CeO{sub 2} content in CeO{sub 2}/Ag{sub 3}PO{sub 4} composites is found to be molar ratio 1 wt%. Photocurrent response of CeO{sub 2}/Ag{sub 3}PO{sub 4} (1 wt%) is about 1.5 times as high as that of the pure Ag{sub 3}PO{sub 4}. The increase of photocatalytic activity of CeO{sub 2}/Ag{sub 3}PO{sub 4} composites could be mainly attributed to the heterojunction between CeO{sub 2} and Ag{sub 3}PO{sub 4}. The trapping experiment has demonstrated that holes serve as the main active species for the degradation of MB under visible light irradiation. A photocatalytic mechanism is also proposed. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Low-temperature atomic layer deposition of MoS{sub 2} films

Energy Technology Data Exchange (ETDEWEB)

Jurca, Titel; Wang, Binghao; Tan, Jeffrey M.; Lohr, Tracy L.; Marks, Tobin J. [Department of Chemistry and the Materials Research Center, Northwestern University, Evanston, IL (United States); Moody, Michael J.; Henning, Alex; Emery, Jonathan D.; Lauhon, Lincoln J. [Department of Materials Science and Engineering, and the Materials Research Center, Northwestern University, Evanston, IL (United States)

2017-04-24

Wet chemical screening reveals the very high reactivity of Mo(NMe{sub 2}){sub 4} with H{sub 2}S for the low-temperature synthesis of MoS{sub 2}. This observation motivated an investigation of Mo(NMe{sub 2}){sub 4} as a volatile precursor for the atomic layer deposition (ALD) of MoS{sub 2} thin films. Herein we report that Mo(NMe{sub 2}){sub 4} enables MoS{sub 2} film growth at record low temperatures - as low as 60 C. The as-deposited films are amorphous but can be readily crystallized by annealing. Importantly, the low ALD growth temperature is compatible with photolithographic and lift-off patterning for the straightforward fabrication of diverse device structures. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

To test photon statistics by atomic beam deflection

International Nuclear Information System (INIS)

Wang Yuzhu; Chen Yudan; Huang Weigang; Liu Liang

1985-02-01

There exists a simple relation between the photon statistics in resonance fluorescence and the statistics of the momentum transferred to an atom by a plane travelling wave [Cook, R.J., Opt. Commun., 35, 347(1980)]. Using an atomic beam deflection by light pressure, we have observed sub-Poissonian statistics in resonance fluorescence of two-level atoms. (author)

Enhanced visible light photocatalytic performance of polyaniline modified mesoporous single crystal TiO{sub 2} microsphere

Energy Technology Data Exchange (ETDEWEB)

Deng, Yaocheng [College of Environmental Science and Engineering, Hunan University, Changsha, 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Tang, Lin, E-mail: tanglin@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha, 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha, 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Dong, Haoran; Yan, Ming; Wang, Jingjing [College of Environmental Science and Engineering, Hunan University, Changsha, 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China); Hu, Wei [College of Physics and Microelectronics Science, Hunan University, Changsha, 410082 (China); Wang, Jiajia; Zhou, Yaoyu; Tang, Jing [College of Environmental Science and Engineering, Hunan University, Changsha, 410082 (China); Key Laboratory of Environmental Biology and Pollution Control, Hunan University, Ministry of Education, Changsha 410082 (China)

2016-11-30

Highlights: • The mesoporous single crystal microsphere of PANI/MS-TiO{sub 2} improved the light absorption. • The mesoporous structure of MS-TiO{sub 2} can increase the loading amount of PANI. • The synergistic effect between PANI and MS-TiO{sub 2} promoted the separation of charges. • Improved photocatalysis was achieved via PANI modified mesoporous single crystal TiO{sub 2} microsphere. - Abstract: Polyaniline (PANI) modified mesoporous single crystal TiO{sub 2} microsphere (PANI/MS-TiO{sub 2}) with excellent photocatalytic activity was successfully prepared by a simple method of solution evaporation and chemisorption. The X-ray diffraction characterization demonstrated that the whole MS-TiO{sub 2} kept the crystal type of anatase. The nitrogen adsorption-desorption characterization coupled with scanning electron microscopy indicated that the MS-TiO{sub 2} possessed a unique mesoporous structure with high specific surface area, which resulted in the increased load of PANI on the surface of MS-TiO{sub 2} and multiple light reflection in the photocatalyst. The UV–vis diffuse reflectance spectra confirmed that PANI/MS-TiO{sub 2} presented more absorption ability in the visible light range than that of the pristine MS-TiO{sub 2}. The transient photocurrent responses and electrochemical impedance spectroscopy (EIS) indicated the high photo responses and fast photogenerated charge separation efficiency of PANI/MS-TiO{sub 2}. The photocatalytic activity of the PANI/MS-TiO{sub 2} was evaluated by the photodegradation of RhB and MB under visible light irradiation. MS-TiO{sub 2} photocatalyst with different molar ration of PANI had been prepared, and the results showed that the optimal photocatalyst (PANI/MS-TiO{sub 2} (1:40)) exhibited the highest photocatalytic efficiency which is nearly three times as great as that of pristine MS-TiO{sub 2} for the degradation of the RhB and MB under visible light irradiation. The remarkable performance of the PANI/MS-TiO{sub

Effects of halogens on interactions between a reduced TiO{sub 2} (110) surface and noble metal atoms: A DFT study

Energy Technology Data Exchange (ETDEWEB)

Tada, Kohei, E-mail: k-tada@aist.go.jp [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Research Institute of Electrochemical Energy, National Institute of Advanced Industrial Science and Technology (AIST), 1-8-31, Midorigaoka, Ikeda, Osaka, 563-8577 (Japan); Koga, Hiroaki [Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan); Hayashi, Akihide; Kondo, Yudai; Kawakami, Takashi; Yamanaka, Shusuke [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Okumura, Mitsutaka [Department of Chemistry, Graduate School of Science, Osaka University, 1-1, Machikaneyama, Toyonaka, Osaka, 560-0043 (Japan); Element Strategy Initiative for Catalysts and Batteries (ESICB), Kyoto University, 1-30 Goryo Ohara, Nishikyo, Kyoto, 615-8245 (Japan)

2017-07-31

Highlights: • We investigated the halogen effect on the interactions of noble metals with TiO{sub 2}. • Halogen atoms inhibit electron transfer from TiO{sub 2} to noble metals. • Iodine stabilizes the adsorption of noble metals especially for Ag and Cu. • Electron transfer from the TiO{sub 2} is effective in anchoring Au and Pt atoms. • Covalent interaction with the support is effective in anchoring Ag and Cu atoms. - Abstract: Using DFT calculation, we investigate the effects of halogens on the interactions between rutile TiO{sub 2} (110) and noble metal atoms (Au, Ag, Cu, Pt, and Pd). Fluorine, chlorine, and bromine atoms occupy the oxygen defect sites of TiO{sub 2}, decreasing the stability of noble metal atoms on the surface. This decrease occurs because the halogens inhibit electron transfer from TiO{sub 2} to the noble metal atoms; the electron transfer from reduced TiO{sub 2} to the noble metal atom stabilizes the noble metal atom adsorption. In contrast, iodine strengthens the interactions between TiO{sub 2} and some noble metal atoms, namely Ag and Cu. This stabilization occurs because of the covalent interaction between iodine-doped TiO{sub 2} and the noble metal atom. Therefore, the stabilization is explained well by chemical hardness. This result suggests that iodine-doping of a TiO{sub 2} surface would be an effective method for the preparation of highly stabilized noble metal clusters.

A One-Dimensional Quantum Interface between a Few Atoms and Weak Light

DEFF Research Database (Denmark)

Béguin, Jean-Baptiste Sylvain

Quantum interfaces between light and the collective degrees of freedom of an ensemble of identical atoms have been proposed as a valuable and promising alternative to cavity quantum electrodynamics enhanced interaction with single particles. Many features of the quantum world (e. g. multipartite...... entanglement, squeezed states), which are central to the future developments of Quantum Information Science and Metrology, can be explored with mesoscopic collective states of atoms. An efficient quantum interface needs a high optical depth for the atomic ensemble and a measurement sensitivity limited by both...... the intrinsic quantum noise of light and the quantum projection noise of atoms. This was achieved in the past in a free space optical dipole trap ensemble of Nat ∼ 10^6 atoms, which triggered the operation of a collective Ramsey atomic clock assisted by entanglement. We have characterized and prepared non...

Adsorption of SO{sub 2} on Li atoms deposited on MgO (1 0 0) surface: DFT calculations

Energy Technology Data Exchange (ETDEWEB)

Eid, Kh.M., E-mail: Kheid98@hotmail.com [Physics Department, Faculty of Education, Ain Shams University, Cairo 11757 (Egypt); Ammar, H.Y. [Department of Physics, Faculty of Science, Najran University, Najran 1988 (Saudi Arabia)

2011-05-01

The adsorption of sulfur dioxide molecule (SO{sub 2}) on Li atom deposited on the surfaces of metal oxide MgO (1 0 0) on both anionic and defect (F{sub s}-center) sites located on various geometrical defects (terrace, edge and corner) has been studied using density functional theory (DFT) in combination with embedded cluster model. The adsorption energy (E{sub ads}) of SO{sub 2} molecule (S-atom down as well as O-atom down) in different positions on both of O{sup -2} and F{sub s} sites is considered. The spin density (SD) distribution due to the presence of Li atom is discussed. The geometrical optimizations have been done for the additive materials and MgO substrate surfaces (terrace, edge and corner). The oxygen vacancy formation energies have been evaluated for MgO substrate surfaces. The ionization potential (IP) for defect free and defect containing of the MgO surfaces has been calculated. The adsorption properties of SO{sub 2} are analyzed in terms of the E{sub ads}, the electron donation (basicity), the elongation of S-O bond length and the atomic charges on adsorbed materials. The presence of the Li atom increases the catalytic effect of the anionic O{sup -2} site of MgO substrate surfaces (converted from physisorption to chemisorption). On the other hand, the presence of the Li atom decreases the catalytic effect of the F{sub s}-site of MgO substrate surfaces. Generally, the SO{sub 2} molecule is strongly adsorbed (chemisorption) on the MgO substrate surfaces containing F{sub s}-center.

Assessment of undiscovered sandstone copper deposits of the Kodar-Udokan area, Russia: Chapter M in Global mineral resource assessment

Science.gov (United States)

Zientek, Michael L.; Chechetkin, Vladimir S.; Parks, Heather L.; Box, Stephen E.; Briggs, Deborah A.; Cossette, Pamela M.; Dolgopolova, Alla; Hayes, Timothy S.; Seltmann, Reimar; Syusyura, Boris; Taylor, Cliff D.; Wintzer, Niki E.

2014-01-01

Mineral resource assessments integrate and synthesize available information as a basis for estimating the location, quality, and quantity of undiscovered mineral resources. This probabilistic mineral resource assessment of undiscovered sandstone copper deposits within Paleoproterozoic metasedimentary rocks of the Kodar-Udokan area in Russia is a contribution to a global assessment led by the U.S. Geological Survey (USGS). The purposes of this study are to (1) delineate permissive areas (tracts) to indicate where undiscovered sandstone-hosted copper deposits may occur within 2 km of the surface, (2) provide a database of known sandstone copper deposits and significant prospects, (3) estimate numbers of undiscovered deposits within these permissive tracts at several levels of confidence, and (4) provide probabilistic estimates of amounts of copper (Cu) and mineralized rock that could be contained in undiscovered deposits within each tract. The workshop for the assessment, held in October 2009, used a three-part form of mineral resource assessment as described by Singer (1993) and Singer and Menzie (2010).

Preparation of CdS@CeO{sub 2} core/shell composite for photocatalytic reduction of CO{sub 2} under visible-light irradiation

Energy Technology Data Exchange (ETDEWEB)

Ijaz, Sana [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190 (China); Institute of Chemical Sciences, Bahauddin Zakaryia University, Multan 60800 (Pakistan); Ehsan, Muhammad Fahad [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190 (China); Ashiq, Muhammad Naeem, E-mail: naeemashiqqau@yahoo.com [Institute of Chemical Sciences, Bahauddin Zakaryia University, Multan 60800 (Pakistan); Karamat, Nazia [Institute of Chemical Sciences, Bahauddin Zakaryia University, Multan 60800 (Pakistan); He, Tao, E-mail: het@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China)

2016-12-30

Highlights: • CdS@CeO{sub 2}core(*)/shell composite is fabricated using a two-step method. • CdS@CeO{sub 2} can photoreduce CO{sub 2} into CH{sub 4} and CH{sub 3}OH under visible-light irradiation. • CdS@CeO{sub 2} can enhance photocatalytic activity due to increased charge separation. • Core shell strategy for photocatalyst preparation can improve photostability. - Abstract: Present work demonstrates fabrication of CdS@CeO{sub 2} core/shell composite and its application in the photocatalytic reduction of CO{sub 2} under visible-light irradiation (λ ≥ 420 nm). CdS@CeO{sub 2} composite has been successfully prepared by two-step chemical method, while CeO{sub 2} and CdS have been synthesized by one-step hydrothermal method. X-ray diffraction analysis confirms the formation of fluorite cubic structure of CeO{sub 2} and cubic phase of CdS. High resolution transmission electron microscopy and scanning electron microscopy reveal the microsphere morphology of CdS, while CeO{sub 2} (shell) is in the form of spherical particles that surround the CdS (core) in case of the composite. X-ray photoelectron spectroscopy has been used to confirm the composition, oxidation state of the elements and valance band of the obtained materials. The CdS@CeO{sub 2} core/shell composite and CdS can convert CO{sub 2} into methane and methanol under visible-light irradiation. The CdS@CeO{sub 2} composite shows higher yield for both methane and methanol than CdS due to low recombination rate of photogenerated electron/hole pairs, as well as a larger BET specific surface area. Moreover, the CdS@CeO{sub 2} core/shell composite also shows improved stability upon photocatalysis.

Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy

Energy Technology Data Exchange (ETDEWEB)

Idrobo, Juan C., E-mail: idrobojc@ornl.gov [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Walkosz, Weronika [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States); Klie, Robert F.; Oeguet, Serdar [Department of Physics, University of Illinois at Chicago, Chicago, IL 60607 (United States)

2012-12-15

In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si{sub 3}N{sub 4}/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si{sub 3}N{sub 4}/SiO{sub 2} interface and in bulk Si{sub 3}N{sub 4} using aberration-corrected scanning transmission electron microscopy. -- Highlights: Black-Right-Pointing-Pointer Revealing the atomic structure of the {alpha}-Si{sub 3}N{sub 4}/SiO{sub 2} interface. Black-Right-Pointing-Pointer Identification and lattice location of oxygen impurities in bulk {alpha}-Si{sub 3}N{sub 4}. Black-Right-Pointing-Pointer Short range ordering of nitrogen and oxygen at the {beta}-Si{sub 3}N{sub 4}/SiO{sub 2} interface.

Future projects of light kaonic atom X-ray spectroscopy

International Nuclear Information System (INIS)

Tatsuno, H.; Bazzi, M.; Beer, G.; Bellotti, G.; Berucci, C.; Bragadireanu, A.M.; Bosnar, D.; Cargnelli, M.; Curceanu, C.; Butt, A.D.; D’Uffizi, A.; Fiorini, C.; Ghio, F.; Guaraldo, C.; Hayano, R.S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Sandri, P. Levi; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Vidal, A. Romero; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D.L.; Sirghi, F.; Doce, O. Vazquez; Widmann, E.; Zmeskal, J.

2016-01-01

X-ray spectroscopy of light kaonic atoms is a unique tool to provide precise information on the fundamental K̄N interaction at the low-energy limit and the in-medium nuclear interaction of K"−. The future experiments of kaonic deuterium strong-interaction shift and width (SIDDHARTA-2 and J-PARC E57) can extract the isospin dependent K"−N interaction at threshold. The high-resolution X-ray spectroscopy of kaonic helium with microcalorimeters (J-PARC E62) has the possibility to solve the long-standing potential-strength problem of the attractive K"−-nucleus interaction. Here, the recent experimental results and the future projects of X-ray spectroscopy of light kaonic atoms are presented.

Microbial inactivation kinetics and mechanisms of carbon-doped TiO{sub 2} (C-TiO{sub 2}) under visible light

Energy Technology Data Exchange (ETDEWEB)

Shim, Jaehong [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan, Jeonbuk 570-752 (Korea, Republic of); School of Natural Resources, University of Nebraska–Lincoln, Lincoln, NE 68583-0817 (United States); Seo, Young-Seok; Oh, Byung-Taek [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan, Jeonbuk 570-752 (Korea, Republic of); Cho, Min, E-mail: cho317@jbnu.ac.kr [Division of Biotechnology, Advanced Institute of Environment and Bioscience, College of Environmental and Bioresource Sciences, Chonbuk National University, Iksan, Jeonbuk 570-752 (Korea, Republic of)

2016-04-05

Highlights: • Carbon modified TiO{sub 2} photocatalysts prepared by sol–gel methods. • C-TiO{sub 2} was highly effective in the inactivation of L. monocytogenes. • C-TiO{sub 2} was shown to be more synergistic inactivation effect under visible light. • C-TiO{sub 2} be useful in the development of alternative disinfectants for environmental application. - Abstract: In this study, titanium dioxide nanoparticles doped with carbon (C-TiO{sub 2}) were synthesized by means of sol–gel methods, and the synthesis was verified by means of X-ray photoelectron spectroscopy. The nanoparticles’ photocatalytic disinfection activity of Listeria monocytogenes was tested under UV and visible light. The observed inactivation levels for 150 min of visible light exposure with and without UV cutoff filters were 2.10 and 2.45 log, respectively. We also found that traditional reactive oxygen species had insignificant actions on C-TiO{sub 2} photocatalysts and that L. monocytogenes inactivation in the C-TiO{sub 2} system under visible light was induced in large part by the midgap states (h{sub mid}{sup +}) that was produced photochemically from the visible light response. C-TiO{sub 2} was found to accelerate bacterial inactivation (of L. monocytogenes) in the presence of visible light. Our data suggests that the C-TiO{sub 2} may be useful in the development of alternative disinfectants for environmental applications.

Photocatalysis and characterization of the gel-derived TiO{sub 2} and P-TiO{sub 2} transparent thin films

Energy Technology Data Exchange (ETDEWEB)

Yu, Hsuan-Fu, E-mail: hfyu@mail.tku.edu.tw [Department of Chemical and Materials Engineering, Ceramic Materials Laboratory, Tamkang University, Taipei 25137, Taiwan (China); Energy and Opto-Electronic Materials Research Center, Tamkang University, Taipei 25137, Taiwan (China); Wang, Chang-Wen [Department of Chemical and Materials Engineering, Ceramic Materials Laboratory, Tamkang University, Taipei 25137, Taiwan (China)

2011-07-29

The gel-derived TiO{sub 2} and P-TiO{sub 2} transparent films coated on fused-SiO{sub 2} substrates were prepared using a spin-coating technique. Effects of phosphorus dopants and calcination temperature on crystal structure, crystallite size, microstructure, light transmittance and photocatalytic activity of the films were investigated. By introducing P atoms to Ti-O framework, the growth of anatase crystallites was hindered and the crystal structure of anatase-TiO{sub 2} could withstand temperature up to 900 deg. C. The photocatalytic activities of the prepared films were characterized using the characteristic time constant ({tau}) for the photocatalytic reaction. The titania film with a smaller {tau} value possesses a higher photocatalytic ability. After exposing to 365-nm UV light for 12 h, the P-TiO{sub 2} films calcined between 600 deg. C and 900 deg. C can photocatalytically decomposed {>=} 84 mol% of the methylene blue in water with corresponding {tau} {<=} 7.1 h, which were better than the pure TiO{sub 2} films prepared at the same calcination temperature.

Chemical kinetics in H{sub 2}O and D{sub 2}O under hydrothermal conditions

Energy Technology Data Exchange (ETDEWEB)

Ghandi, K.; Alcorn, C.D.; Legate, G. [Mount Allison Univ., Sackville, New Brunswick (Canada); Percival, P.W.; Brodovitch, J.-C. [Simon Fraser Univ., Burnaby, British Columbia (Canada)

2010-07-01

Muonium (Mu = μ{sup +}e{sup -}) is a light analogue of the H-atom. Studies of Mu chemical kinetics have been extended to supercritical water, a medium in some designs of future generation nuclear reactors. The Supercritical-Water-Cooled Reactor (SCWR) would operate at higher temperatures than current pressurized water-cooled reactors, and the lack of knowledge of water radiolysis under supercritical conditions constitutes a technology gap for SCWR development. Accurate modeling of chemistry in a SCWR requires data on kinetics of reactions involved in the radiolysis of water. In this paper, we first review our measurements of kinetics in H{sub 2}O and then describe new data for D{sub 2}O under sub- and supercritical conditions. (author)

Internal conversion coefficients for atomic numbers Z less than or equal to 30

International Nuclear Information System (INIS)

Band, I.M.; Trzhaskovskaya, M.B.; Listengarten, M.A.

1976-01-01

Presented here are internal conversion coefficients (ICC) of gamma rays for 20 values of atomic number, Z, in the range 3 less than or equal to Z less than or equal to 30, including all Z greater than or equal to 14. The tables provide the previously missing data for light elements. Coefficients are given for 19 values of gamma-ray transition energies up to 6 MeV for the K-electron shell and 18 values up to 2 MeV for three L-subshells. The minimum enegy is 15 keV. The first five electric and magnetic nuclear transition multipolarities are covered. The calculations are relativistic, with screening and finite nuclear size effect taken into account

Lactococcus lactis Thioredoxin Reductase Is Sensitive to Light Inactivation

DEFF Research Database (Denmark)

Björnberg, Olof; Viennet, Thibault; Skjoldager, Nicklas

2015-01-01

Thioredoxin, involved in numerous redox pathways, is maintained in the dithiol state by the nicotinamide adenine dinucleotide phosphate-dependent flavoprotein thioredoxin reductase (TrxR). Here, TrxR from Lactococcus lactis is compared with the well-characterized TrxR from Escherichia coli. The two...... enzymes belong to the same class of low-molecular weight thioredoxin reductases and display similar kcat values (∼25 s-1) with their cognate thioredoxin. Remarkably, however, the L. lactis enzyme is inactivated by visible light and furthermore reduces molecular oxygen 10 times faster than E. coli Trx......-resolution mass spectrometric analysis of heat-extracted FAD from light-damaged TrxR revealed a mass increment of 13.979 Da, relative to that of unmodified FAD, corresponding to the addition of one oxygen atom and the loss of two hydrogen atoms. Tandem mass spectrometry confined the increase in mass...

Scanning tunneling microscopy of the atomically smooth (001) surface of vanadium pentoxide V{sub 2}O{sub 5} crystals

Energy Technology Data Exchange (ETDEWEB)

Muslimov, A. E., E-mail: amuslimov@mail.ru; Butashin, A. V.; Kanevsky, V. M. [Russian Academy of Sciences, Shubnikov Institute of Crystallography, Federal Research Centre “Crystallography and Photonics” (Russian Federation)

2017-01-15

The (001) cleavage surface of vanadium pentoxide (V{sub 2}O{sub 5}) crystal has been studied by scanning tunneling spectroscopy (STM). It is shown that the surface is not reconstructed; the STM image allows geometric lattice parameters to be determined with high accuracy. The nanostructure formed on the (001) cleavage surface of crystal consists of atomically smooth steps with a height multiple of unit-cell parameter c = 4.37 Å. The V{sub 2}O{sub 5} crystal cleavages can be used as references in calibration of a scanning tunneling microscope under atmospheric conditions both along the (Ñ…, y) surface and normally to the sample surface (along the z axis). It is found that the terrace surface is not perfectly atomically smooth; its roughness is estimated to be ~0.5 Å. This circumstance may introduce an additional error into the microscope calibration along the z coordinate.

Visible light photoreduction of CO.sub.2 using heterostructured catalysts

Science.gov (United States)

Matranga, Christopher; Thompson, Robert L; Wang, Congjun

2015-03-24

The method provides for use of sensitized photocatalyst for the photocatalytic reduction of CO.sub.2 under visible light illumination. The photosensitized catalyst is comprised of a wide band gap semiconductor material, a transition metal co-catalyst, and a semiconductor sensitizer. The semiconductor sensitizer is photoexcited by visible light and forms a Type II band alignment with the wide band gap semiconductor material. The wide band gap semiconductor material and the semiconductor sensitizer may be a plurality of particles, and the particle diameters may be selected to accomplish desired band widths and optimize charge injection under visible light illumination by utilizing quantum size effects. In a particular embodiment, CO.sub.2 is reduced under visible light illumination using a CdSe/Pt/TiO2 sensitized photocatalyst with H.sub.2O as a hydrogen source.

Effect of Cu insertion on structural, local electronic/atomic structure and photocatalyst properties of TiO{sub 2}, ZnO and Ni(OH){sub 2} nanostructures: XANES-EXAFS study

Energy Technology Data Exchange (ETDEWEB)

Sharma, Aditya; Varshney, Mayora [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul, 02792 (Korea, Republic of); Shin, Hyun Joon, E-mail: shj001@postech.ac.kr [Pohang Accelerator Laboratory (POSTECH), Pohang, 37673 (Korea, Republic of); Lee, Byeong-Hyeon [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul, 02792 (Korea, Republic of); Chae, Keun Hwa, E-mail: khchae@kist.re.kr [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul, 02792 (Korea, Republic of); Won, Sung Ok, E-mail: sowon@kist.re.kr [Advanced Analysis Centre, Korea Institute of Science and Technology, Seoul, 02792 (Korea, Republic of)

2017-04-15

We report detailed investigations on the synthesis, structural, morphology, electronic/atomic structure and photocatalyst properties of Cu doped TiO{sub 2}, ZnO and Ni(OH){sub 2} nanostructures. All of the samples were synthesized by using the chemical precipitation method. Samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS) and photocatalyst measurements. XRD studies revealed single phase nature of the samples and omitted the presence of trivial metallic or binary oxide phases. TiO{sub 2} set of samples have shown nanorod kind of morphology, however TEM images of ZnO and Ni(OH){sub 2} set of samples depicted the spherical morphology of particles. XANES spectra at the Cu K-edge and Cu L-edge, along with the atomic multiplet calculations, revealed the predominance of Cu{sup 2+} ions in all of the samples, within the entire doping range. Ti L-edge and Ti K-edge XANES confirmed the existence of Ti{sup 4+} ions in the pure and Cu doped TiO{sub 2} samples with anatase local structure. Zn L-edge XANES results confirmed the divalent character of Zn ions in the pure and Cu doped ZnO, which is further validated by the Zn K-edge XANES. Ni L-edge and Ni K-edge XANES conveyed the +2 valence state of Ni ions in the pure and Cu doped Ni (OH){sub 2} samples. EXAFS analysis at the Cu K-edge nullifies the formation of Cu metallic clusters and other trivial phases, suggesting random distribution of Cu atoms in the oxide materials. Though, local atomic arrangement of Cu ions is disparate in the different oxide compounds. As an application of the pure and Cu doped TiO{sub 2}, ZnO and Ni(OH){sub 2} nanostructures, towards the degradation of water pollutant dyes, we demonstrate that all of the samples can serve as effective photocatalyst materials towards the degradation of methyl orange aqueous pollutant dye under the UV-light irradiation

Atomic layer deposition of two dimensional MoS{sub 2} on 150 mm substrates

Energy Technology Data Exchange (ETDEWEB)

Valdivia, Arturo; Conley, John F., E-mail: jconley@eecs.oregonstate.edu [School of EECS, Oregon State University, Corvallis, Oregon 97331 (United States); Tweet, Douglas J. [Sharp Labs of America, Camas, Washington 98607 (United States)

2016-03-15

Low temperature atomic layer deposition (ALD) of monolayer to few layer MoS{sub 2} uniformly across 150 mm diameter SiO{sub 2}/Si and quartz substrates is demonstrated. Purge separated cycles of MoCl{sub 5} and H{sub 2}S precursors are used at reactor temperatures of up to 475 °C. Raman scattering studies show clearly the in-plane (E{sup 1}{sub 2g}) and out-of-plane (A{sub 1g}) modes of MoS{sub 2}. The separation of the E{sup 1}{sub 2g} and A{sub 1g} peaks is a function of the number of ALD cycles, shifting closer together with fewer layers. X-ray photoelectron spectroscopy indicates that stoichiometry is improved by postdeposition annealing in a sulfur ambient. High resolution transmission electron microscopy confirms the atomic spacing of monolayer MoS{sub 2} thin films.

The Sun as a sub-GeV dark matter accelerator

OpenAIRE

Emken, Timon; Kouvaris, Chris; Nielsen, Niklas Grønlund

2018-01-01

Sub-GeV halo dark matter that enters the Sun can potentially scatter off hot solar nuclei and be ejected much faster than its incoming velocity. We derive an expression for the rate and velocity distribution of these reflected particles, taking into account the Sun’s temperature and opacity. We further demonstrate that future direct-detection experiments could use these energetic reflected particles to probe light dark matter in parameter space that cannot be accessed via ordinary halo dark m...

Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction as a highly efficient and stable visible light photocatalyst

Energy Technology Data Exchange (ETDEWEB)

Liu, Chengbin, E-mail: chem_cbliu@hnu.edu.cn [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Cao, Chenghao [State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China); Luo, Xubiao [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); Luo, Shenglian [Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063 (China); State Key Laboratory of Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082 (China)

2015-03-21

Graphical abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction was fabricated by simple electrochemical method. The heterostructures exhibit high photocatalytic activity and excellent recycling performance. - Highlights: • Ag-bridged Ag{sub 2}O nanowire network self-stability structure. • Ag{sub 2}O nanowire network/TiO{sub 2} nanotube p–n heterojunction. • High visible light photocatalytic activity. • Highly stable recycling performance. - Abstract: A unique Ag-bridged Ag{sub 2}O nanowire network/TiO{sub 2} nanotube array p–n heterojunction (Ag–Ag{sub 2}O/TiO{sub 2} NT) was fabricated by simple electrochemical method. Ag nanoparticles were firstly electrochemically deposited onto the surface of TiO{sub 2} NT and then were partly oxidized to Ag{sub 2}O nanowires while the rest of Ag mother nanoparticles were located at the junctions of Ag{sub 2}O nanowire network. The Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure exhibited strong visible-light response, effective separation of photogenerated carriers, and high adsorption capacity. The integration of Ag–Ag{sub 2}O self-stability structure and p–n heterojunction permitted high and stable photocatalytic activity of Ag–Ag{sub 2}O/TiO{sub 2} NT heterostructure photocatalyst. Under 140-min visible light irradiation, the photocatalytic removal efficiency of both dye acid orange 7 (AO7) and industrial chemical p-nitrophenol (PNP) over Ag–Ag{sub 2}O/TiO{sub 2} NT reached nearly 100% much higher than 17% for AO7 or 13% for PNP over bare TiO{sub 2} NT. After 5 successive cycles under 600-min simulated solar light irradiation, Ag–Ag{sub 2}O/TiO{sub 2} NT remained highly stable photocatalytic activity.

Ternary g-C{sub 3}N{sub 4}/ZnO/AgCl nanocomposites: Synergistic collaboration on visible-light-driven activity in photodegradation of an organic pollutant

Energy Technology Data Exchange (ETDEWEB)

Akhundi, Anise; Habibi-Yangjeh, Aziz, E-mail: ahabibi@uma.ac.ir

2015-12-15

Graphical abstract: - Highlights: • Novel ternary g-C{sub 3}N{sub 4}/ZnO/AgCl nanocomposites were prepared using a facile method. • g-C{sub 3}N{sub 4}/ZnO/AgCl (40%) has superior activity in degradation of RhB under visible-light. • The activity is 7.5 and 6-fold higher than g-C{sub 3}N{sub 4}/ZnO and g-C{sub 3}N{sub 4}/AgCl, respectively. • There are synergistic collaboration between ZnO and AgCl in enhancing the activity. - Abstract: The present work demonstrates the preparation of ternary g-C{sub 3}N{sub 4}/ZnO/AgCl nanocomposites, as novel visible-light-driven photocatalysts, using a facile large-scale methodology. The microstructure, morphology, purity, thermal, and spectroscopic properties of the prepared samples were studied using XRD, TEM, EDX, TG, UV–vis DRS, FT-IR, and PL techniques. Compared with the g-C{sub 3}N{sub 4}/ZnO and g-C{sub 3}N{sub 4}/AgCl nanocomposites, the g-C{sub 3}N{sub 4}/ZnO/AgCl nanocomposites displayed higher photocatalytic activity for degradation of rhodamine B under visible-light irradiation. Photocatalytic activity of the g-C{sub 3}N{sub 4}/ZnO/AgCl (40%) nanocomposite is about 9.5, 7.5, and 6-fold higher than those of the g-C{sub 3}N{sub 4}, g-C{sub 3}N{sub 4}/ZnO, and g-C{sub 3}N{sub 4}/AgCl samples, respectively. The enhanced photocatalytic activity of the nanocomposites was mainly attributed to efficiently separation of the charge carriers by synergistic collaboration of ZnO and AgCl in removing photogenerated electrons from g-C{sub 3}N{sub 4}. Furthermore, the results showed that the photocatalytic activity of the nanocomposite considerably depends on the preparation time, calcination temperature, and scavengers of the reactive species. Finally, the nanocomposite was found to be a reusable photocatalyst.

Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and Λ atom-light coupling scheme

International Nuclear Information System (INIS)

Hamedi, H R; Ruseckas, J; Juzeliūnas, G

2017-01-01

We consider propagation of a probe pulse in an atomic medium characterized by a combined tripod and Lambda (Λ) atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by five light fields. It is demonstrated that dark states can be formed for such an atom-light coupling. This is essential for formation of the electromagnetically induced transparency (EIT) and slow light. In the limiting cases the scheme reduces to conventional Λ- or N -type atom-light couplings providing the EIT or absorption, respectively. Thus, the atomic system can experience a transition from the EIT to the absorption by changing the amplitudes or phases of control lasers. Subsequently the scheme is employed to analyze the nonlinear pulse propagation using the coupled Maxwell–Bloch equations. It is shown that a generation of stable slow light optical solitons is possible in such a five-level combined tripod and Λ atomic system. (paper)

Detecting and locating light atoms from high-resolution STEM images: The quest for a single optimal design

Energy Technology Data Exchange (ETDEWEB)

Gonnissen, J.; De Backer, A. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Dekker, A.J. den [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Delft Center for Systems and Control (DCSC), Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands); Sijbers, J. [iMinds-Vision Lab, University of Antwerp, Universiteitsplein 1, 2610 Wilrijk (Belgium); Van Aert, S., E-mail: sandra.vanaert@uantwerpen.be [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

2016-11-15

In the present paper, the optimal detector design is investigated for both detecting and locating light atoms from high resolution scanning transmission electron microscopy (HR STEM) images. The principles of detection theory are used to quantify the probability of error for the detection of light atoms from HR STEM images. To determine the optimal experiment design for locating light atoms, use is made of the so-called Cramér–Rao Lower Bound (CRLB). It is investigated if a single optimal design can be found for both the detection and location problem of light atoms. Furthermore, the incoming electron dose is optimised for both research goals and it is shown that picometre range precision is feasible for the estimation of the atom positions when using an appropriate incoming electron dose under the optimal detector settings to detect light atoms. - Highlights: • The optimal detector design to detect and locate light atoms in HR STEM is derived. • The probability of error is quantified and used to detect light atoms. • The Cramér–Rao lower bound is calculated to determine the atomic column precision. • Both measures are evaluated and result in the single optimal LAADF detector regime. • The incoming electron dose is optimised for both research goals.

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.

Efficient visible light photocatalytic NO{sub x} removal with cationic Ag clusters-grafted (BiO){sub 2}CO{sub 3} hierarchical superstructures

Energy Technology Data Exchange (ETDEWEB)

Feng, Xin [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 40067 (China); Zhang, Wendong [Department of Scientific Research Management, Chongqing Normal University, Chongqing 401331 (China); Deng, Hua [State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Ni, Zilin [Department of Scientific Research Management, Chongqing Normal University, Chongqing 401331 (China); Dong, Fan, E-mail: dfctbu@126.com [Chongqing Key Laboratory of Catalysis and Functional Organic Molecules, College of Environment and Resources, Engineering Research Center for Waste Oil Recovery Technology and Equipment of Ministry of Education, College of Environment and Resources, Chongqing Technology and Business University, Chongqing 40067 (China); Zhang, Yuxin, E-mail: zhangyuxin@cqu.edu.cn [College of Materials Science and Engineering, National Key Laboratory of Fundamental Science of Micro/Nano-Devices and System Technology, Chongqing University, Chongqing 400044 (China)

2017-01-15

Graphical abstract: The cationic Ag clusters-grafted (BiO){sub 2}CO{sub 3} hierarchical superstructures exhibits highly enhanced visible light photocatalytic air purification through an interfacial charge transfer process induced by Ag clusters. - Highlights: • Microstructural optimization and surface cluster-grafting were firstly combined. • Cationic Ag clusters were grafted on the surface of (BiO){sub 2}CO{sub 3} superstructures. • The Ag clusters-grafted BHS displayed enhanced visible light photocatalysis. • Direct interfacial charge transfer (IFCT) from BHS to Ag clusters was proposed. • The charge transfer process and the dominant reactive species were revealed. - Abstract: A facile method was developed to graft cationic Ag clusters on (BiO){sub 2}CO{sub 3} hierarchical superstructures (BHS) surface to improve their visible light activity. Significantly, the resultant Ag clusters-grafted BHS displayed a highly enhanced visible light photocatalytic performance for NOx removal due to the direct interfacial charge transfer (IFCT) from BHS to Ag clusters. The chemical and coordination state of the cationic Ag clusters was determined with the extended X-ray absorption fine structure (EXAFS) and a theoretical structure model was proposed for this unique Ag clusters. The charge transfer process and the dominant reactive species (·OH) were revealed on the basis of electron spin resonance (ESR) trapping. A new photocatalysis mechanism of Ag clusters-grafted BHS under visible light involving IFCT process was uncovered. In addition, the cationic Ag clusters-grafted BHS also demonstrated high photochemical and structural stability under repeated photocatalysis runs. The perspective of enhancing photocatalysis through combination of microstructural optimization and IFCT could provide a new avenue for the developing efficient visible light photocatalysts.

Population of collective modes in light scattering by many atoms

Science.gov (United States)

Guerin, William; Kaiser, Robin

2017-05-01

The interaction of light with an atomic sample containing a large number of particles gives rise to many collective (or cooperative) effects, such as multiple scattering, superradiance, and subradiance, even if the atomic density is low and the incident optical intensity weak (linear optics regime). Tracing over the degrees of freedom of the light field, the system can be well described by an effective atomic Hamiltonian, which contains the light-mediated dipole-dipole interaction between atoms. This long-range interaction is at the origin of the various collective effects, or of collective excitation modes of the system. Even though an analysis of the eigenvalues and eigenfunctions of these collective modes does allow distinguishing superradiant modes, for instance, from other collective modes, this is not sufficient to understand the dynamics of a driven system, as not all collective modes are significantly populated. Here, we study how the excitation parameters, i.e., the driving field, determines the population of the collective modes. We investigate in particular the role of the laser detuning from the atomic transition, and demonstrate a simple relation between the detuning and the steady-state population of the modes. This relation allows understanding several properties of cooperative scattering, such as why superradiance and subradiance become independent of the detuning at large enough detuning without vanishing, and why superradiance, but not subradiance, is suppressed near resonance. We also show that the spatial properties of the collective modes allow distinguishing diffusive modes, responsible for radiation trapping, from subradiant modes.

Synthesize and characterize of Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods photocatalysts and its photocatalytic activity under visible light irradiation

Energy Technology Data Exchange (ETDEWEB)

Zou, Xuejun [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China); Dong, Yuying, E-mail: dongy@dlnu.edu.cn [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China); Zhang, Xiaodong, E-mail: fatzhxd@126.com [Environment and Low-Carbon Research Center, School of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093 (China); Cui, Yubo [Department of Environmental Science and Technology, Dalian Nationalities University, Dalian 116600 (China)

2016-03-15

Graphical abstract: - Highlights: • Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods were prepared by sol–gel with hydrothermal method. • Toluene removal efficiency was 70% in 4 h using the Ag{sub 3}VO{sub 4}/TiO{sub 2}. • Benzyl alcohol and benzaldehyde were intermediates, and partially mineralized. - Abstract: In this paper, in order to expand the light response range of TiO{sub 2}, Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods photocatalysts were fabricated by a simple sol–gel method with microwave and hydrothermal method. The as-prepared samples were characterized by XRD, SEM, DRS, XPS and N{sub 2} adsorption–desorption. Meanwhile, their photocatalytic properties were investigated by the degradation of toluene under visible light irradiation. The degradation conversation of toluene had gotten to about 70% in 1% Ag{sub 3}VO{sub 4}/TiO{sub 2} nanorods after reaction 4 h. The predominant photocatalytic activity can be attributed to its strong absorption in visible light region and excellent charge separation characteristics. By using in situ FTIR, benzyl alcohol and benzaldehyde species could be observed during the reaction and the formed intermediates would be partially oxidized into CO{sub 2} and H{sub 2}O. Electron spin resonance confirmed that OH· and O{sub 2}·{sup −} were involved in the photocatalytic degradation of toluene.

Fluorescent Protein Voltage Probes Derived from ArcLight that Respond to Membrane Voltage Changes with Fast Kinetics

Science.gov (United States)

Han, Zhou; Jin, Lei; Platisa, Jelena; Cohen, Lawrence B.; Baker, Bradley J.; Pieribone, Vincent A.

2013-01-01

We previously reported the discovery of a fluorescent protein voltage probe, ArcLight, and its derivatives that exhibit large changes in fluorescence intensity in response to changes of plasma membrane voltage. ArcLight allows the reliable detection of single action potentials and sub-threshold activities in individual neurons and dendrites. The response kinetics of ArcLight (τ1-on ~10 ms, τ2-on ~ 50 ms) are comparable with most published genetically-encoded voltage probes. However, probes using voltage-sensing domains other than that from the Ciona intestinalis voltage sensitive phosphatase exhibit faster kinetics. Here we report new versions of ArcLight, in which the Ciona voltage-sensing domain was replaced with those from chicken, zebrafish, frog, mouse or human. We found that the chicken and zebrafish-based ArcLight exhibit faster kinetics, with a time constant (τ) less than 6ms for a 100 mV depolarization. Although the response amplitude of these two probes (8-9%) is not as large as the Ciona-based ArcLight (~35%), they are better at reporting action potentials from cultured neurons at higher frequency. In contrast, probes based on frog, mouse and human voltage sensing domains were either slower than the Ciona-based ArcLight or had very small signals. PMID:24312287

Fluorescent protein voltage probes derived from ArcLight that respond to membrane voltage changes with fast kinetics.

Directory of Open Access Journals (Sweden)

Zhou Han

Full Text Available We previously reported the discovery of a fluorescent protein voltage probe, ArcLight, and its derivatives that exhibit large changes in fluorescence intensity in response to changes of plasma membrane voltage. ArcLight allows the reliable detection of single action potentials and sub-threshold activities in individual neurons and dendrites. The response kinetics of ArcLight (τ1-on ~10 ms, τ2-on ~ 50 ms are comparable with most published genetically-encoded voltage probes. However, probes using voltage-sensing domains other than that from the Ciona intestinalis voltage sensitive phosphatase exhibit faster kinetics. Here we report new versions of ArcLight, in which the Ciona voltage-sensing domain was replaced with those from chicken, zebrafish, frog, mouse or human. We found that the chicken and zebrafish-based ArcLight exhibit faster kinetics, with a time constant (τ less than 6 ms for a 100 mV depolarization. Although the response amplitude of these two probes (8-9% is not as large as the Ciona-based ArcLight (~35%, they are better at reporting action potentials from cultured neurons at higher frequency. In contrast, probes based on frog, mouse and human voltage sensing domains were either slower than the Ciona-based ArcLight or had very small signals.

Segregation of solute atoms to interphase boundaries in GdNi{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Murray, Ryan; Banerjee, Debashis; Collins, Gary S., E-mail: collins@wsu.edu [Washington State University, Department of Physics and Astronomy (United States); Zacate, Matthew O. [Northern Kentucky University, Department of Physics and Geology (United States)

2017-11-15

Lattice locations of {sup 111}In impurity probe atoms in intermetallic GdNi{sub 2} were studied as a function of alloy composition and temperature using perturbed angular correlation spectroscopy (PAC). Measurements were made on a pair of samples that were richer and poorer in Gd. Three nuclear quadrupole interaction signals were detected and their equilibrium site fractions were measured up to 700 {sup ∘}C. Two signals have well-defined electric field gradients (EFGs) and are attributed to In-probes on Gd- and Ni-sites in a well-ordered lattice. A third signal exhibiting strong inhomogeneous broadening was observed at low temperature in Gd-richer samples. This is attributed to segregation of the In-probes to phase boundaries (PB) of minor volume fractions of the neighboring GdNi phase. A measurement made on a stoichiometric GdNi sample exhibited the same inhomogeneously broadened signal, indicating that In-probes prefer to occupy PB and/or grain boundary sites in GdNi rather than the well-defined Gd- and Ni-sites. Changes in site fractions were reversible above 300 {sup ∘}C, indicating that probe atoms equilibrate among all lattice locations within a time period of one day. Thus, PB sites provide lower enthalpy environments for In-probes than either crystallographic site in GdNi{sub 2}. Enthalpy differences between the levels were determined from measurements of temperature dependences of ratios of site fractions. The enthalpy of transfer of In-probes from the Gd- to Ni-sublattice, which is coupled to intrinsic disorder in the compound, was found to be much smaller in the Gd-richer sample than in the Gd-poorer sample. This can be explained by differing temperature dependences of intrinsic defect concentrations at the two compositions. Among those probes that remain within the GdNi{sub 2} phase, there is a temperature dependence of the ratio of site fractions of In-probes on Gd- and Ni-sites. Taking this into account, a macroscopic segregation enthalpy is

How to cool down cold atoms using laser light? Principles and techniques

International Nuclear Information System (INIS)

Guellati-Khelifa, Saida; Clade, Pierre

2012-01-01

This article is devoted to the description of various mechanisms of the laser cooling of neutral atoms. These mechanisms are all based on the interaction between a photon, an entity of light, and an atom, an entity of matter. One of the macroscopic manifestations of this interaction is the pressure of radiation force. The effect of this force is strongly amplified when the source of photon is a laser. We will describe how it is possible to use this force with the Doppler effect in order to slow an atomic beam and also to reduce considerably the thermal agitation of atoms. We will explain how by shaping the light potentials and magnetic fields it is possible to reach extremely low temperatures of some nano-kelvin. At these temperatures, very near to the absolute zero, it is possible for certain kind of atoms, called bosons, to achieve a new state of matter, where quantum behaviour of atoms became apparent on a macroscopic scale. (authors)

The Dopants and Doping Level Dependence of the Structure and Magnetic Properties of the Eu (BA<sub>1-xsub>LR_x)>2sub>Cu>3sub>O>7+δsub>

Energy Technology Data Exchange (ETDEWEB)

Lin, Yu [Iowa State Univ., Ames, IA (United States)

2002-12-31

Eu(Ba<sub>1-xsub>LR_x)>2sub>Cu>3sub>O>7+δsub> were systematically studied in order to understand how the valence of the rear earth elements, ionic sizes and magnetic moment affect the crystal structure and magnetic and electrical properties. Differential thermal analyses were carried out to check the phase purity, X-ray data were least-squares fitted to determine the lattice parameters, and DC-SQUID magnetometry was used to characterize the superconducting properties. These results showed that the crystallography is consistent with other EuLR123ss series, LR = La, Pr, Eu. The lattice parameters vary with the ionic radii of the rare earth ions. Unlike the uniform change in lattice parameter, the superconducting transition did not vary systematically with the ionic size of the dopants. Although the general trend was for T<sub>c> to decrease with decreasing ionic size of the dopant, for the same doping level, Pr was anomalous, depressing T<sub>c> faster. Although the exact mechanism is not clear, this result is consistent with the depression of T<sub>c> for Pr substitution for the rare earth in R123. The critical current J<sub>c> was determined using the Bean model from magnetization versus field measurements as a function of temperature and field. The effect of the dopants on J<sub>c> with the increasing of temperature or applied field was determined. For T < 77 K and small values of x, the value of J<sub>c> was increased over that of the x = 0 sample. In addition, the smaller the substituting atom, the higher the J<sub>c> becomes. For instance, at x = 0.025, Eu123 < EuLa.025 < EuPr.025 < EuNd.025 < EuEu.025. The enhancement of J<sub>c> disappears for x > 0.05 and T > 0.5T<sub>c>.

Optically stimulated luminescence study on gamma-irradiated ice frozen from H sub 2 O and D sub 2 O

CERN Document Server

Yada, T; Hirai, M; Yamanaka, C; Ikeya, M

2002-01-01

Optically stimulated luminescence (OSL) and thermoluminescence (TL) for gamma-irradiated ice samples have been investigated as future dating techniques for icy bodies in the solar system. The OSL around 400nm lasted more than 600s for gamma-irradiated H sub 2 O ice and D sub 2 O ice under 623-nm-light stimulation at 90 K; the latter was used to study the migration of hydrogen atoms. A defect containing trapped electrons is the most suitable explanation of the OSL emissions. The intensity of the TL peak at 120 K increased linearly with gamma-dosage increasing up to 15 kGy for both D sub 2 O ice and H sub 2 O ice. Intensities of both OSL and TL for D sub 2 O ice were larger than those for H sub 2 O ice. The TL peak related to H sub 2 O was observed but its thermal characteristics did not agree with those of OH and HO sub 2 radicals measured by ESR. The OSL method should be employed in future surveys in the solar system.