The influence of biosurfactant adsorption on the physicochemical behaviour of carbon steel surfaces using contact angle measurements and X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Shubina, V., E-mail: varvara.shubina2014@gmail.com [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Gaillet, L. [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Ababou-Girard, S. [Institut de Physique de Rennes, Département Matériaux et Nanosciences, UMR 6251 CNRS, Université Rennes 1, 35000 Rennes-Cedex (France); Gaudefroy, V. [LUNAM Université, IFSTTAR, MAST, SMC, F-44340 Bouguenais (France); Chaussadent, T.; Farças, F. [Université Paris-Est, IFSTTAR, MAST, CPDM, F-77447 Marne-la-Vallée (France); Meylheuc, T. [INRA, UMR1319 Micalis, F-78352 Jouy-en-Josas (France); AgroParisTech, UMR Micalis, F-78352 Jouy-en-Josas (France); Dagbert, C. [2 Chemin de la Grand’côte, 36270 Éguzon-Chantôme (France); Creus, J. [LaSIE, UMR7356, Université de La Rochelle, Pôle Sciences et Technologie, Bâtiment Marie Curie, Avenue Michel Crépeau, 17000 La Rochelle (France)

2015-10-01

Highlights: • Surface modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells were investigated using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). • CAM allowed to establish an increase of electron-donating properties of steel surface due to the biosurfactant adsorption. • XPS demonstrated that biosurfactant molecules change the stoichiometry of mixted-oxide layer and the new outer layer mostly composed of magnetite. • Thickness and density of adsorbed biosurfactants layers were highlighted using a semiquantitative approach for 3 different concentrations of biomolecules. - Abstract: We investigated modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). After conditioning carbon steel in solutions with three different concentrations of biosurfactant molecules: 0.05, 0.3 and 1 g L{sup −1}, the average thickness of the biosurfactant layer on the carbon steel specimens was 7.9 ± 0.3, 12.1 ± 0.5 and 16.4 ± 0.7 Å, respectively. The biosurfactants changed the composition of both the Fe{sup 2+} and Fe{sup 3+} mixed-oxide layer and the outer layer, mostly composed of Fe{sup 3+} associated with magnetite. Contact angle measurements indicate decreased hydrophobic properties after the carbon steel was modified by biosurfactant. It was shown that the carbon steel surface free energy depends on the biosurfactant concentration, due to an acquisition of strong electron-donating properties.

The influence of biosurfactant adsorption on the physicochemical behaviour of carbon steel surfaces using contact angle measurements and X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Shubina, V.; Gaillet, L.; Ababou-Girard, S.; Gaudefroy, V.; Chaussadent, T.; Farças, F.; Meylheuc, T.; Dagbert, C.; Creus, J.

2015-01-01

Highlights: • Surface modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells were investigated using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). • CAM allowed to establish an increase of electron-donating properties of steel surface due to the biosurfactant adsorption. • XPS demonstrated that biosurfactant molecules change the stoichiometry of mixted-oxide layer and the new outer layer mostly composed of magnetite. • Thickness and density of adsorbed biosurfactants layers were highlighted using a semiquantitative approach for 3 different concentrations of biomolecules. - Abstract: We investigated modifications to carbon steel surfaces due to the adsorption of a biosurfactant derived from Pseudomonas fluorescens bacteria cells using contact angle measurements (CAM) and X-ray photoelectron spectroscopy (XPS). After conditioning carbon steel in solutions with three different concentrations of biosurfactant molecules: 0.05, 0.3 and 1 g L −1 , the average thickness of the biosurfactant layer on the carbon steel specimens was 7.9 ± 0.3, 12.1 ± 0.5 and 16.4 ± 0.7 Å, respectively. The biosurfactants changed the composition of both the Fe 2+ and Fe 3+ mixed-oxide layer and the outer layer, mostly composed of Fe 3+ associated with magnetite. Contact angle measurements indicate decreased hydrophobic properties after the carbon steel was modified by biosurfactant. It was shown that the carbon steel surface free energy depends on the biosurfactant concentration, due to an acquisition of strong electron-donating properties

Modification of carbon fiber surfaces via grafting with Meldrum's acid

International Nuclear Information System (INIS)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-01-01

Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Modification of carbon fiber surfaces via grafting with Meldrum's acid

Energy Technology Data Exchange (ETDEWEB)

Cuiqin, Fang; Jinxian, Wu [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Julin, Wang, E-mail: wjl@mail.buct.edu.cn [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Tao, Zhang [Beijing Institute of Ancient Architecture, Beijing 100050 (China)

2015-11-30

Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

Adsorption of thiophene on a Si(0 0 1)-2 x 1 surface studied by photoelectron spectroscopy and diffraction

Energy Technology Data Exchange (ETDEWEB)

Shimomura, M. [Research Institute of Electronics, Shizuoka University, Johoku, Hamamatsu 432-8011 (Japan)]. E-mail: romshimo@rie.shizuoka.ac.jp; Ikejima, Y. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yajima, K. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Yagi, T. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Goto, T. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Gunnella, R. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); UdR INFM, Department of Physics, University of Camerino, Camerino 62032 (Italy); Abukawa, T. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan); Fukuda, Y. [Research Institute of Electronics, Shizuoka University, Johoku, Hamamatsu 432-8011 (Japan); Kono, S. [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira, Aoba-ku, Sendai 980-8577 (Japan)

2004-10-15

Chemisorption of thiophene on a Si(0 0 1) surface has been studied by synchrotron radiation induced photoelectron spectroscopy (SRPES). Two adsorption-related components in Si 2p and S 2p spectra are observed after exposure of thiophene. It is suggested that the two components of Si 2p are ascribed to silicon bonded to hydrocarbon and sulfur. The core-level shift resolved photoelectron diffraction (PED) result indicates that the low-kinetic-energy component of S 2p can be ascribed to 2,5-dihydrothiophehe (DHT)-like species. Another S 2p component could be assigned to dissociated sulfur based on the results of PED and time evolution of the spectrum under irradiation. These assignments are consistent with the core-level shift of S 2p.

Adsorption of thiophene on a Si(0 0 1)-2 x 1 surface studied by photoelectron spectroscopy and diffraction

International Nuclear Information System (INIS)

Shimomura, M.; Ikejima, Y.; Yajima, K.; Yagi, T.; Goto, T.; Gunnella, R.; Abukawa, T.; Fukuda, Y.; Kono, S.

2004-01-01

Chemisorption of thiophene on a Si(0 0 1) surface has been studied by synchrotron radiation induced photoelectron spectroscopy (SRPES). Two adsorption-related components in Si 2p and S 2p spectra are observed after exposure of thiophene. It is suggested that the two components of Si 2p are ascribed to silicon bonded to hydrocarbon and sulfur. The core-level shift resolved photoelectron diffraction (PED) result indicates that the low-kinetic-energy component of S 2p can be ascribed to 2,5-dihydrothiophehe (DHT)-like species. Another S 2p component could be assigned to dissociated sulfur based on the results of PED and time evolution of the spectrum under irradiation. These assignments are consistent with the core-level shift of S 2p

Determination of the bonding of alkyl monolayers to the Si(111) surface using chemical-shift, scanned-energy photoelectron diffraction

Energy Technology Data Exchange (ETDEWEB)

Terry, J.; Linford, M.R.; Wigren, C.; Cao, R.; Pianetta, P.; Chidsey, C.E. [Stanford University, Stanford, California 94309 (United States)

1997-08-01

The bonding of alkyl monolayers to Si(111) surfaces has been studied by conventional x-ray photoelectron spectroscopy (XPS) and chemical-shift, scanned-energy photoelectron diffraction (PED) using synchrotron radiation. Two very different wet-chemical methods have been used to prepare the alkyl monolayers: (i) olefin insertion into the H{endash}Si bond on the H{endash}Si(111) surface, and (ii) replacement of Cl on the Cl{endash}Si(111) surface by an alkyl group from an alkyllithium reagent. In both cases, XPS has revealed a C 1s signal chemically shifted to lower binding energy, which we have assigned to carbon bonded to silicon. PED has shown that both preparative methods result in carbon bonded in an atop site with the expected C{endash}Si bond length of 1.85{plus_minus}0.05{Angstrom}. Chemical-shift, scanned-energy photoelectron diffraction is a particularly valuable probe of local structure at surfaces that contain the same element in multiple, chemically distinct environments. {copyright} {ital 1997 American Institute of Physics.}

Determination of the bonding of alkyl monolayers to the Si(111) surface using chemical-shift, scanned-energy photoelectron diffraction

International Nuclear Information System (INIS)

Terry, J.; Linford, M.R.; Wigren, C.; Cao, R.; Pianetta, P.; Chidsey, C.E.

1997-01-01

The bonding of alkyl monolayers to Si(111) surfaces has been studied by conventional x-ray photoelectron spectroscopy (XPS) and chemical-shift, scanned-energy photoelectron diffraction (PED) using synchrotron radiation. Two very different wet-chemical methods have been used to prepare the alkyl monolayers: (i) olefin insertion into the H endash Si bond on the H endash Si(111) surface, and (ii) replacement of Cl on the Cl endash Si(111) surface by an alkyl group from an alkyllithium reagent. In both cases, XPS has revealed a C 1s signal chemically shifted to lower binding energy, which we have assigned to carbon bonded to silicon. PED has shown that both preparative methods result in carbon bonded in an atop site with the expected C endash Si bond length of 1.85±0.05 Angstrom. Chemical-shift, scanned-energy photoelectron diffraction is a particularly valuable probe of local structure at surfaces that contain the same element in multiple, chemically distinct environments. copyright 1997 American Institute of Physics

A porous carbon material from pyrolysis of fructus cannabis’s shells for supercapacitor electrode application

Science.gov (United States)

Li, Kai; Zhang, Wei-Bin; Zhao, Zhi-Yun; Zhao, Yue; Chen, Xi-Wen; Kong, Ling-Bin

2018-02-01

The porous carbon material is obtained via pyrolysis and activation of fructus cannabis’s shells, an easy-to-get biomass source, and is used as an active electrode material for supercapacitors. The obtained carbon exhibit a high specific surface area of 2389 m2 g-1. And the result of x-ray photoelectron spectroscopy (XPS) shows that the obtained porous carbon possess numerous oxygen groups, which can facilitate the wettability of the electrode. The prepared porous carbon also exhibit remarkable electrochemical properties, such as high specific capacitance of 357 F g-1 at a current density of 0.5 A g-1 in 6 mol L-1 aqueous KOH electrolyte, good rate capability of 77% capacitance retention as the current density increase from 0.5 A g-1 to 10 A g-1. In addition, it also presents a superior cycling stability of 100% capacitance retention after 10 000 cycles at the current density of 1 A g-1.

(He 1) photoelectron spectra of vinyl- and (1-dimethylaminovinyl)pyridines

International Nuclear Information System (INIS)

Baidin, V.N.; Koikov, L.N.; Terent'ev, P.B.; Gloriozov, I.P.

1985-01-01

The (He 1) photoelectron spectra of α=, β-, γ-vinyl, α-, β-, and γ-(1-dimethylvinyl)-pyridines, 1-dimethyl- and 1-diethylaminostyrenes were obtained and interpreted within the framework of the molecular orbital perturbation theory. In both pyridine derivative series, there is a regular increase in the ionization energy of the 1α 2 , π/sub C=C/ and n/sub en/ orbitals and decrease in the ionization energy of the 2b 1 orbitals in the order α 2 and 2b 1 is found for γ-vinylpyridine). The splitting of the energy levels of the heterocycle in dimethylaminovinylpyridines is less than in the corresponding vinyl derivatives, which indicates a weakening of the interaction between the aromatic (or heteroaromatic) ring and the enamine fragment extruding from the ring plane. The ionization energy of the unshared electron pair of the nitrogen atom of the pyridine ring for all the compounds except for α- (1-dimethylaminovinyl)pyridine (which displays an ortho effect) is close to that for pyridine. The photoelectron spectral data are compared with the MO energies calculated by the MINDO/3 method

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

International Nuclear Information System (INIS)

Liu, Yuzhu; Knopp, Gregor; Qin, Chaochao; Gerber, Thomas

2015-01-01

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S 2 to S 1 is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S 2 state to the vibrationally hot S 1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S 1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding

High resolution X-ray photoelectron spectroscopy of styrene oxide adsorption and reaction on Ag(1 1 1)

Science.gov (United States)

Piao, H.; Enever, M. C. N.; Adib, K.; Hrbek, J.; Barteau, M. A.

2004-11-01

Synchrotron-based X-ray photoelectron spectroscopy (XPS) has been used to investigate the adsorption and reaction of styrene oxide on Ag(1 1 1). When adsorption is carried out at 250 K or above, ring opening of styrene oxide forms a stable surface oxametallacycle intermediate which eventually reacts at 485 K to regenerate styrene oxide. High resolution XPS is capable of distinguishing the oxametallacycle from molecularly adsorbed and condensed styrene oxide on the basis of different C1s peak separations. The observed separations are well accounted for by the results of DFT calculations.

Lineshape of Ne 1s photoionization satellite [1s2s]({sup 3}S)3s and its valence Auger decay spectrum

Energy Technology Data Exchange (ETDEWEB)

Yarzhemsky, V.G.; Amusia, M.Ya.; Chernysheva, L.V

2002-12-15

Lineshape of Ne1s photoionization satellite [1s2s]({sup 3}S)3s({sup 2}S) and lineshapes of corresponding low-energy Auger spectra are calculated using the Many-Body Perturbation Theory. The results obtained reproduce the experimentally observed asymmetrical lineshape of photoelectron satellite and its intensity.

Polarization Effects in Attosecond Photoelectron Spectroscopy

DEFF Research Database (Denmark)

Baggesen, Jan Conrad; Madsen, Lars Bojer

2010-01-01

following the field instead. We show that polarization effects may lead to an apparent temporal shift that needs to be properly accounted for in the analysis. The effect may be isolated and studied by angle-resolved photoelectron spectroscopy from oriented polar molecules. We also show that polarization...... effects will lead to an apparent temporal shift of 50 as between photoelectrons from a 2p and 1s state in atomic hydrogen....

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

Energy Technology Data Exchange (ETDEWEB)

Liu, Yuzhu, E-mail: yuzhu.liu@gmail.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Knopp, Gregor [Paul Scherrer Institute, Villigen 5232 (Switzerland); Qin, Chaochao [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Gerber, Thomas [Paul Scherrer Institute, Villigen 5232 (Switzerland)

2015-01-13

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S{sub 2} to S{sub 1} is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S{sub 2} state to the vibrationally hot S{sub 1} state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S{sub 1} state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding.

Occupied and unoccupied electronic structures of an L-cysteine film studied by core-absorption and resonant photoelectron spectroscopies

Science.gov (United States)

Kamada, M.; Hideshima, T.; Azuma, J.; Yamamoto, I.; Imamura, M.; Takahashi, K.

2016-04-01

Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4, m ≥ 3) orbitals. Resonant photoelectron spectra at S-L23 and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively.

Occupied and unoccupied electronic structures of an L-cysteine film studied by core-absorption and resonant photoelectron spectroscopies

Energy Technology Data Exchange (ETDEWEB)

Kamada, M., E-mail: kamada@cc.saga-u.ac.jp; Hideshima, T.; Azuma, J.; Yamamoto, I.; Imamura, M.; Takahashi, K. [Synchrotron Light Application Center, Saga University, Honjo 1, Saga 840-8502 (Japan)

2016-04-15

Unoccupied and occupied electronic structures of an L-cysteine film have been studied by absorption and resonant photoelectron spectroscopies. Core absorptions at S-L, C-K, N-K, and O-K levels indicate that the lower unoccupied states are predominantly composed of oxygen-2p, carbon-2p, and sulfur-4s+3d orbitals, while higher unoccupied states may be attributed dominantly to nitrogen-np (n ≥ 3), oxygen-np (n ≥ 3), and sulfur-ns+md (n ≥ 4,  m ≥ 3) orbitals. Resonant photoelectron spectra at S-L{sub 23} and O-K levels indicate that the highest occupied state is originated from sulfur-3sp orbitals, while oxygen-2sp orbitals contribute to the deeper valence states. The delocalization lifetimes of the oxygen-1s and sulfur-2p excited states are estimated from a core-hole clock method to be about 9 ± 1 and 125 ± 25 fs, respectively.

Biomass-derived porous carbon modified glass fiber separator as polysulfide reservoir for Li-S batteries.

Science.gov (United States)

Selvan, Ramakrishnan Kalai; Zhu, Pei; Yan, Chaoi; Zhu, Jiadeng; Dirican, Mahmut; Shanmugavani, A; Lee, Yun Sung; Zhang, Xiangwu

2018-03-01

Biomass-derived porous carbon has been considered as a promising sulfur host material for lithium-sulfur batteries because of its high conductive nature and large porosity. The present study explored biomass-derived porous carbon as polysulfide reservoir to modify the surface of glass fiber (GF) separator. Two different carbons were prepared from Oak Tree fruit shells by carbonization with and without KOH activation. The KOH activated porous carbon (AC) provides a much higher surface area (796 m 2  g -1 ) than pyrolized carbon (PC) (334 m 2  g -1 ). The R factor value, calculated from the X-ray diffraction pattern, revealed that the activated porous carbon contains more single-layer sheets with a lower degree of graphitization. Raman spectra also confirmed the presence of sp 3 -hybridized carbon in the activated carbon structure. The COH functional group was identified through X-ray photoelectron spectroscopy for the polysulfide capture. Simple and straightforward coating of biomass-derived porous carbon onto the GF separator led to an improved electrochemical performance in Li-S cells. The Li-S cell assembled with porous carbon modified GF separator (ACGF) demonstrated an initial capacity of 1324 mAh g -1 at 0.2 C, which was 875 mAh g -1 for uncoated GF separator (calculated based on the 2nd cycle). Charge transfer resistance (R ct ) values further confirmed the high ionic conductivity nature of porous carbon modified separators. Overall, the biomass-derived activated porous carbon can be considered as a promising alternative material for the polysulfide inhibition in Li-S batteries. Copyright © 2017 Elsevier Inc. All rights reserved.

Transient photoelectron spectroscopy of the dissociative Br2(1Piu) state.

Science.gov (United States)

Strasser, Daniel; Goulay, Fabien; Leone, Stephen R

2007-11-14

Photodissociation of bromine on the Br2(1Piu) state is probed with ultrafast extreme ultraviolet (53.7 nm) single-photon ionization. Time-resolved photoelectron spectra show simultaneously the depletion of ground state bromine molecules as well as the rise of Br(2P3/2) products due to 402.5 nm photolysis. A partial photoionization cross-section ratio of atomic versus molecular bromine is obtained. Transient photoelectron spectra of a dissociative wave packet on the excited state are presented in the limit of low-power-density, single-photon excitation to the dissociative state. Transient binding energy shifts of "atomic-like" photoelectron peaks are observed and interpreted as photoionization of nearly separated Br atom pairs on the Br2(1Piu) state to repulsive dissociative ionization states.

X-ray photoelectron spectra of γ-irradiated perfluorobenzene

International Nuclear Information System (INIS)

Sunder, S.; Sagert, N.H.; Wood, D.D.; Miller, N.H.

1990-01-01

The effect of γ-radiolysis on perfluorobenzene (PFB) was investigated using low-temperature X-ray photoelectron spectroscopy (XPS). PFB was irradiated in fluorine-passivated nickel cells using Co 60 γ-rays in an Atomic Energy of Canada Limited Gammacell at a dose rate of about 2.6 Gy·s -1 and for a total dose of about 50 kGy. The γ-radiolysis of PFB not only results in cross-linkage but also in the formation of saturated carbon centers in the PFB, as indicated by the presence of CF 2 and CF 3 groups. The relative abundance of CF, CF 2 and CF 3 groups, in the irradiated PFB, was estimated to be about 86, 9 and 5%, respectively

Near threshold behavior of photoelectron satellite intensities

International Nuclear Information System (INIS)

Shirley, D.A.; Becker, U.; Heimann, P.A.; Langer, B.

1987-09-01

The historical background and understanding of photoelectron satellite peaks is reviewed, using He(n), Ne(1s), Ne(2p), Ar(1s), and Ar(3s) as case studies. Threshold studies are emphasized. The classification of electron correlation effects as either ''intrinsic'' or ''dynamic'' is recommended. 30 refs., 7 figs

Assigning Oxidation States to Organic Compounds via Predictions from X-ray Photoelectron Spectroscopy: A Discussion of Approaches and Recommended Improvements

Energy Technology Data Exchange (ETDEWEB)

Gupta, Vipul; Ganegoda, Hasitha; Engelhard, Mark H.; Terry, Jeff H.; Linford, Matthew R.

2014-02-11

The traditional assignment of oxidation numbers to organic molecules is problematic. Accordingly, in 1999, Calzaferri proposed a simple and elegant solution that is based on the similar electronegativities of carbon and hydrogen: hydrogen would be assigned an oxidation number of zero when bonded to carbon. Here we show that X-ray photoelectron spectroscopy (XPS), a core electron spectroscopy that is sensitive to oxidation states of elements, confirms his suggestion. In particular, in this work we: (i) list the typical rules for assigning oxidation numbers, (ii) discuss the traditional assignment of oxidation numbers to organic molecules, (iii) review Calzaferri’s solution, (iv) introduce X-ray photoelectron spectroscopy (XPS), (v) show the consistency of Calzaferri’s suggestion with XPS results, (vi) provide supporting examples from the literature, (vii) provide examples from our own research, and (viii) further confirm the Calzaferri suggestion/photoelectron spectroscopy results by discussing two organic well-known reactions. We end by reechoing Calzaferri’s suggestion that the traditional rules for assigning oxidation numbers to organic molecules be modified.

Derivation of Hamaker Dispersion Energy of Amorphous Carbon Surfaces in Contact with Liquids Using Photoelectron Energy-Loss Spectra

Science.gov (United States)

Godet, Christian; David, Denis

2017-12-01

Hamaker interaction energies and cutoff distances have been calculated for disordered carbon films, in contact with purely dispersive (diiodomethane) or polar (water) liquids, using their experimental dielectric functions ɛ ( q, ω) obtained over a broad energy range. In contrast with previous works, a q-averaged q is derived from photoelectron energy-loss spectroscopy (XPS-PEELS) where the energy loss function (ELF) q is a weighted average over allowed transferred wave vector values, q, given by the physics of bulk plasmon excitation. For microcrystalline diamond and amorphous carbon films with a wide range of (sp3/sp2 + sp3) hybridization, non-retarded Hamaker energies, A 132 ( L < 1 nm), were calculated in several configurations, and distance and wavenumber cutoff values were then calculated based on A 132 and the dispersive work of adhesion obtained from contact angles. A geometric average approximation, H 0 CVL = ( H 0 CVC H 0 LVL )1/2, holds for the cutoff separation distances obtained for carbon-vacuum-liquid (CVL), carbon-vacuum-carbon (CVC) and liquid-vacuum-liquid (LVL) equilibrium configurations. The linear dependence found for A CVL, A CLC and A CLV values as a function of A CVC, for each liquid, allows predictive relationships for Hamaker energies (in any configuration) using experimental determination of the dispersive component of the surface tension, {γ}_{CV}^d , and a guess value of the cutoff distance H 0 CVC of the solid. [Figure not available: see fulltext.

Nondipole effects in attosecond photoelectron streaking

DEFF Research Database (Denmark)

Spiewanowski, Maciek; Madsen, Lars Bojer

2012-01-01

The influence of nondipole terms on the time delay in photoionization by an extreme-ultraviolet attosecond pulse in the presence of a near-infrared femtosecond laser pulse from 1s, 2s, and 2p states in hydrogen is investigated. In this attosecond photoelectron streaking process, the relative...

Interpretation of the photoelectron spectra of FeS(2)(-) by a multiconfiguration computational approach.

Science.gov (United States)

Clima, Sergiu; Hendrickx, Marc F A

2007-11-01

The ground states of FeS(2) and FeS(2)(-), and several low-lying excited electronic states of FeS(2) that are responsible for the FeS(2)(-) photoelectron spectrum, are calculated. At the B3LYP level an open, quasi-linear [SFeS](-) conformation is found as the most stable structure, which is confirmed at the ab initio CASPT2 computational level. Both the neutral and the anionic unsaturated complexes possess high-spin electronic ground states. For the first time a complete assignment of the photoelectron spectrum of FeS(2)(-) is proposed. The lowest energy band in this spectrum is ascribed to an electron detachment from the two highest-lying 3dpi antibonding orbitals (with respect to the iron-sulfur bonding) of iron. The next-lowest experimental band corresponds to an electron removal from nonbonding, nearly pure sulfur orbitals. The two highest bands in the spectra are assigned as electron detachments from pi and sigma bonding mainly sulfur orbitals.

Photoelectron spectroscopic and microspectroscopic probes of ferroelectrics

Science.gov (United States)

Tǎnase, Liviu C.; Abramiuc, Laura E.; Teodorescu, Cristian M.

2017-12-01

This contribution is a review of recent aspects connected with photoelectron spectroscopy of free ferroelectric surfaces, metals interfaced with these surfaces, graphene-like layers together with some exemplifications concerning molecular adsorption, dissociations and desorptions occurring from ferroelectrics. Standard photoelectron spectroscopy is used nowadays in correlation with other characterization techniques, such as piezoresponse force microscopy, high resolution transmission electron spectroscopy, and ferroelectric hysteresis cycles. In this work we will concentrate mainly on photoelectron spectroscopy and spectro-microscopy characterization of ferroelectric thin films, starting from atomically clean ferroelectric surfaces of lead zirco-titanate, then going towards heterostructures using this material in combination with graphene-like carbon layers or with metals. Concepts involving charge accumulation and depolarization near surface will be revisited by taking into account the newest findings in this area.

Role of nuclear dynamics in the asymmetric molecular-frame photoelectron angular distributions for C 1s photoejection from CO2

International Nuclear Information System (INIS)

Miyabe, S.; Haxton, D. J.; Rescigno, T. N.; McCurdy, C. W.

2011-01-01

We report the results of semiclassical calculations of the asymmetric molecular-frame photoelectron angular distributions for C 1s ionization of CO 2 measured with respect to the CO + and O + ions produced by subsequent Auger decay, and show how the decay event can be used to probe ultrafast molecular dynamics of the transient cation. The fixed-nuclei photoionization amplitudes were constructed using variationally obtained electron-molecular-ion scattering wave functions. The amplitudes are then used in a semiclassical manner to investigate their dependence on the nuclear dynamics of the cation. The method introduced here can be used to study other core-level ionization events.

Cobalt Oxide on N-Doped Carbon for 1-Butene Oligomerization to Produce Linear Octenes

Energy Technology Data Exchange (ETDEWEB)

Zhao, Dongting [Department; Xu, Zhuoran [Department; Chada, Joseph P. [Department; Carrero, Carlos A. [Department; Rosenfeld, Devon C. [The Dow Chemical Company, 2301 N. Brazosport Boulevard, Freeport, Texas 77541-3257, United States; Rogers, Jessica L. [The Dow Chemical Company, 2301 N. Brazosport Boulevard, Freeport, Texas 77541-3257, United States; Hermans, Ive [Department; Huber, George W. [Department

2017-10-02

Cobalt oxide supported on N-doped carbon catalysts were investigated for 1-butene oligomerization. The materials were synthesized by treating activated carbon with nitric acid and subsequently with NH3 at 200, 400, 600, and 800 °C, followed by impregnation with cobalt. The 1-butene oligomerization selectivity increased with ammonia treatment temperature of the carbon support. The oligomerization selectivity of cobalt oxide on N-doped carbon synthesized at 800 °C (800A-CoOx/N-C) is 2.6 times higher than previously reported cobalt oxide on N-doped carbon synthesized with NH4OH (2A-CoOx/N-C). Over 70% of the butene dimers were linear C8 olefins for all catalysts. The oligomerization selectivity increased with 1-butene conversion. The catalysts were characterized by elemental analysis, N2 adsorption, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS). The nitrogen content of the catalysts increases with ammonia treatment temperature as confirmed by elemental analysis. The surface content of pyridinic nitrogen with a binding energy of 398.4 ± 0.1 eV increased with ammonia treatment temperature as evidenced by deconvolution of N 1s XPS spectra.

Observation of atomic arrangement by using photoelectron holography and atomic stereo-photograph

International Nuclear Information System (INIS)

Matsushita, Tomohiro; Guo, Fang Zhun; Agui, Akane; Matsui, Fumihiko; Daimon, Hiroshi

2006-01-01

Both a photoelectron holography and atomic stereo-photograph are the atomic structure analysis methods on the basis of photoelectron diffraction. They have six special features such as 1) direct determination of atomic structure, 2) measurement of three dimensional atomic arrangements surrounding of specific element in the sample, 3) determination of position of atom in spite of electron cloud, 4) unnecessary of perfect periodic structure, 5) good sensitivity of structure in the neighborhood of surface and 6) information of electron structure. Photoelectron diffraction, the principle and measurement system of photoelectron holography and atomic stereo-photograph is explained. As application examples of atomic stereo-photograph, the single crystal of cupper and graphite are indicated. For examples of photoelectron holography, Si(001)2p and Ge(001)3s are explained. (S.Y.)

Angle resolved photoelectron distribution of the 1{pi} resonance of CO/Pt(111)

Energy Technology Data Exchange (ETDEWEB)

Haarlammert, Thorben; Wegner, Sebastian; Tsilimis, Grigorius; Zacharias, Helmut [Physikalisches Institut, Westfaelische Wilhelms Universitaet, Muenster (Germany); Golovin, Alexander [Institute of Physics, St. Petersburg State University (Russian Federation)

2009-07-01

The CO 1{pi} level of a c(4 x 2)-2CO/Pt(111) reconstruction shows a significant resonance when varying the photon energy between h{nu}=23 eV and h{nu}=48 e V. This resonance has not been observed in gas phase measurements or on the Pt(1 10) surface. To investigate the photoelectron distribution of the 1{pi} level high harmonic radiaton has been used. By conversion in rare gases like argon, neon, or helium photon energies of up to 100 eV have been generated at repetition r ates of up to 10 kHz. The single harmonics have been separated and focused by a toroidal grating and directed to the sample surface. A time-of-flight detector with multiple anodes registers the kinetic energies of the emitted photoelectrons and enables the simultaneous detection of multiple emission angles. The angular distributions of photoelectrons emitted from the CO 1{pi} level have been measured for a variety of initial photon energies. Further the angular distributions of the CO 1{pi} level photoelectrons emitted from a CO-Pt{sub 7} cluster have been calculated using the MSX{alpha}-Method which shows good agreement with the ex perimental data.

Photoelectron spectroscopy an introduction to ultraviolet photoelectron spectroscopy in the gas phase

CERN Document Server

Eland, J H D

2013-01-01

Photoelectron Spectroscopy: An Introduction to Ultraviolet Photoelectronspectroscopy in the Gas Phase, Second Edition Photoelectron Spectroscopy: An Introduction to Ultraviolet PhotoelectronSpectroscopy in the Gas Phase, Second Edition aims to give practical approach on the subject of photoelectron spectroscopy, as well as provide knowledge on the interpretation of the photoelectron spectrum. The book covers topics such as the principles and literature of photoelectron microscopy; the main features and analysis of photoelectron spectra; ionization techniques; and energies from the photoelectron spectra. Also covered in the book are topics suc as photoelectron band structure and the applications of photoelectron spectroscopy in chemistry. The text is recommended for students and practitioners of chemistry who would like to be familiarized with the concepts of photoelectron spectroscopy and its importance in the field.

Photoelectron and photodissociation studies of free atoms and molecules, using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Medhurst, L.J.

1991-11-01

High resolution synchrotron radiation and Zero-Kinetic-Energy Photoelectron spectroscopy were used to study two-electron transitions in atomic systems at their ionization thresholds. Using this same technique the core-ionized mainline and satellite states of N{sub 2} and CO were studied with vibrational resolution. Vibrationally resolved synchrotron radiation was used to study the dissociation of N{sub 2}, C{sub 2}H{sub 4}, and CH{sub 3}Cl near the N 1s and C 1s thresholds. The photoelectron satellites of the argon 3s, krypton 4s and xenon 4d subshells were studied with zero kinetic energy photoelectron spectroscopy at their ionization thresholds. In all of these cases, satellites with lower binding energies are enhanced at their thresholds while those closer to the double ionization threshold are suppressed relative to their intensities at high incident light energies.

Photoelectron and photodissociation studies of free atoms and molecules, using synchrotron radiation

International Nuclear Information System (INIS)

Medhurst, L.J.

1991-11-01

High resolution synchrotron radiation and Zero-Kinetic-Energy Photoelectron spectroscopy were used to study two-electron transitions in atomic systems at their ionization thresholds. Using this same technique the core-ionized mainline and satellite states of N 2 and CO were studied with vibrational resolution. Vibrationally resolved synchrotron radiation was used to study the dissociation of N 2 , C 2 H 4 , and CH 3 Cl near the N 1s and C 1s thresholds. The photoelectron satellites of the argon 3s, krypton 4s and xenon 4d subshells were studied with zero kinetic energy photoelectron spectroscopy at their ionization thresholds. In all of these cases, satellites with lower binding energies are enhanced at their thresholds while those closer to the double ionization threshold are suppressed relative to their intensities at high incident light energies

Photoelectron Diffraction Imaging for C2H2 and C2H4 Chemisorbed on Si(100) Reveals a New Bonding Configuration

International Nuclear Information System (INIS)

Xu, S. H.; Keeffe, M.; Yang, Y.; Chen, C.; Yu, M.; Lapeyre, G. J.; Rotenberg, E.; Denlinger, J.; Yates, J. T. Jr.

2000-01-01

A new adsorption site for adsorbed acetylene on Si(100) is observed by photoelectron imaging based on the holographic principle. The diffraction effects in the carbon 1s angle-resolved photoemission are inverted (including the small-cone method) to obtain an image of the atom's neighboring carbon. The chemisorbed acetylene molecule is bonded to four silicon surface atoms. In contrast to the C 2 H 2 case, the image for adsorbed C 2 H 4 shows it bonded to two Si surface atoms. (c) 2000 The American Physical Society

Polarization and dipole effects in hard X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Novak, M. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Pauly, N., E-mail: nipauly@ulb.ac.be [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium); Dubus, A. [Universite Libre de Bruxelles, Service de Metrologie Nucleaire (CP 165/84), 50 av. F. D. Roosevelt, B-1050 Brussels (Belgium)

2012-03-15

Highlights: Black-Right-Pointing-Pointer X-rays are unpolarized or linearly polarized. Black-Right-Pointing-Pointer A difference of polarization implies a variation in path travelled by the photoelectrons. Black-Right-Pointing-Pointer We show the influence of the polarization on the partial intensity distributions. Black-Right-Pointing-Pointer We also point out the influence of the dipole approximation. Black-Right-Pointing-Pointer We use Monte Carlo simulations. - Abstract: Hard X-ray photoelectron spectroscopy (HXPS) using X-rays in the 1.5-15 keV energy range generated by synchrotron sources becomes an increasingly important analysis technique due to its potential for bulk sensitive measurements. However, besides their high energy, another characteristic of photons generated by synchrotron sources is their linear polarization while X-rays from Al K{alpha} or Mg K{alpha} for instance are unpolarized. This difference implies a possible variation in total path travelled by the photoelectrons generated by the X-rays inside the medium and consequently a modification of the resulting spectrum shape. We show the influence of the polarization on the partial intensity distributions, namely the number of electrons escaping after n inelastic scattering events, for photoelectron with energies of 0.5, 1, 2, 3, 4 and 5 keV and originating from Si 1s{sub 1/2}, Cu 1s{sub 1/2}, Cu 2p{sub 3/2}, Au 4d{sub 3/2} and Au 4f{sub 7/2} subshells. Moreover, we point out the influence of the dipole approximation leading to an underestimation of the partial intensity distributions due to the neglect of the forward-backward asymmetry of the angular photoelectron distribution.

Photoelectron and photodissociation studies of free atoms and molecules, using synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Medhurst, Laura Jane [Univ. of California, Berkeley, CA (United States)

1991-11-01

High resolution synchrotron radiation and Zero-Kinetic-Energy Photoelectron spectroscopy were used to study two-electron transitions in atomic systems at their ionization thresholds. Using this same technique the core-ionized mainline and satellite states of N₂ and CO were studied with vibrational resolution. Vibrationally resolved synchrotron radiation was used to study the dissociation of N₂, C₂H₄, and CH₃Cl near the N 1s and C 1s thresholds. The photoelectron satellites of the argon 3s, krypton 4s and xenon 4d subshells were studied with zero kinetic energy photoelectron spectroscopy at their ionization thresholds. In all of these cases, satellites with lower binding energies are enhanced at their thresholds while those closer to the double ionization threshold are suppressed relative to their intensities at high incident light energies.

Core level photoelectron spectroscopy of LiGaS2 and Ga-S bonding in complex sulfides

International Nuclear Information System (INIS)

Atuchin, V.V.; Isaenko, L.I.; Kesler, V.G.; Lobanov, S.I.

2010-01-01

The electronic parameters of the lithium thiogallate LiGaS 2 have been evaluated by X-ray photoelectron spectroscopy (XPS). Spectral features of all constituent element core levels and Auger lines have been considered. The Ga-S bonding effects in Ga-bearing sulfide crystals have been discussed using binding energy difference Δ 2p (S-Ga) = BE(S 2p) - BE(Ga 3d) as a representative parameter to quantify the valence electron shift from gallium to sulfur atoms. The value Δ 2p (S-Ga) = 141.9 eV found for LiGaS 2 is very close to that evaluated for AgGaS 2 . This relation is an indicator of closely coincident ionicity of Ga-S bonds in LiGaS 2 and AgGaS 2 .

Structure determination of Ga As (110) p (1 x 1) - Sb using scanned-energy photoelectron diffraction

International Nuclear Information System (INIS)

Ascolani, H.; Asensio, M.C.; Fritzsche, W.

1996-01-01

Photoelectron diffraction (PD) in the scanned-energy mode has proven to be a powerfull tool for structural determination of the first few surface layers. The scanned-energy mode involves the measurement of the intensity of photoelectrons emitted from a core level as a function of the incident photon energy for different emission directions. The atom specificity of PD allows the investigation of the local structure of adsorbed atoms without interference of the substrate. In addition, if a measurable chemical shift exists, this technique is also able to discriminate between atoms of the same species adsorbed in inequivalent sites. The Ga As (110) p (1x1)-Sb (1 ML) surface represents a prototype system to study atom adsorption on III-V semiconductors. The epitaxial continued layer structure (ECLS) is generally accepted as the geometry corresponding to this surface, although some authors have claimed that the p 3 model forms a stable geometry equivalent to the ECLS, and that it provides an equally good description of their experimental results. So far, the conclusions about the atomic structure of this surface had been derived on the basis of indirect methods. This work exploits to the utmost the possibilities of analysis offered by the scanned-energy PD technique, namely, chemical shift analysis and direct inversion. The energy spectrum of Sb-4d photoelectrons emitted from the Ga As (110)-p (1x1) Sb surface has two chemically-shifted components. We have inverted the scanned-energy photoelectron diffraction data corresponding to these two components to obtain the positions of the Ga and As atoms which are nearest neighbors of two inequivalent Sb atoms. Our results contradict various models proposed for this surface and are consistent only with the ECLS. For a more detailed atomic structure determination, the best fit between experiment and multiple-scattering calculations was determined by a trial-and-error procedure. (author)

Photoelectron spectroscopy and spectro-microscopy of Pb(Zr,Ti)O{sub 3} (1 1 1) thin layers: Imaging ferroelectric domains with binding energy contrast

Energy Technology Data Exchange (ETDEWEB)

Huşanu, Marius A.; Popescu, Dana G.; Tache, Cristian A. [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele-Ilfov (Romania); Apostol, Nicoleta G. [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele-Ilfov (Romania); Elettra Sincrotrone Trieste, S.S. 14 – km 163,5, Area Science Park, 34169 Basovizza-Trieste (Italy); Barinov, Alexei; Lizzit, Silvano; Lacovig, Paolo [Elettra Sincrotrone Trieste, S.S. 14 – km 163,5, Area Science Park, 34169 Basovizza-Trieste (Italy); Teodorescu, Cristian M., E-mail: teodorescu@infim.ro [National Institute of Materials Physics, Atomistilor 105b, 077125 Magurele-Ilfov (Romania)

2015-10-15

Graphical abstract: - Highlights: • Achievement of well ordered PZT(1 1 1) surfaces with reasonable low energy electron diffraction patterns and good stoichiometry. • Ability of photoelectron spectromicroscopy to visualize ferroelectric domains with contrast of binding energy. • Model taking into account the influence of photogenerated carriers on the depolarization field and its torque on the polarization vector. • Evidence of domain wall migration induced by photogenerated carriers. • Segregation of metal Pb only on areas with out-of-plane component of the polarization pointing outwards. - Abstract: The ability of photoelectron spectro-microscopy with sub-micrometer lateral resolution to identify ferroelectric domains by analysis of surface band bendings is demonstrated on lead zirco-titanate PZT(1 1 1) thin films grown by pulsed laser deposition. Conventional synchrotron radiation X-ray photoelectron spectroscopy allowed one to derive the surface composition of the sample and evidenced shifts toward higher binding energy when the sample is subject to intense soft X-ray beam. A basic model is developed which supposes that photogenerated carriers reduce the depolarization field, yielding a lower torque applied to the ferroelectric polarization. As a consequence, the out-of-plane component of the polarization increases. Domain migration during irradiation with soft X-ray is inferred from the relative amplitude of the components with different binding energy. When the flux density of soft X-ray is on the order of 10{sup 11} photons/(s μm{sup 2}), metal Pb clusters are formed at the surface on areas with the out-of-plane component of the polarization pointing outwards only.

Emission Depth Distribution Function of Al 2s Photoelectrons in Al2O3

Science.gov (United States)

Hucek, S.; Zemek, J.; Jablonski, A.; Tilinin, I. S.

The escape probability of Al 2s photoelectrons leaving an aluminum oxide sample (Al2O3) has been studied as a function of depth of origin. It has been found that the escape probability (the so-called emission depth distribution function - DDF) depends strongly on the photoelectron emission direction with respect to that of the incident X-ray beam. In particular, in the emission direction close to that of photon propagation, the DDF differs substantially from the simple Beer-Lambert law and exhibits a nonmonotonic behavior with a maximum in the near-surface region at a depth of about 10 Å. Experimental results are in good agreement with theoretical predictions based on Monte Carlo simulations of the electron transport and with analytical solution of the linearized Boltzmann kinetic equation with appropriate boundary conditions. Both theoretical approaches take into account multiple elastic scattering of photoelectrons on their way out of the sample. It is shown that the commonly used straight line approximation (SLA), which neglects elastic scattering effects, fails to describe adequately experimental data at emission directions close to minima of the differential photoelectric cross section.

Internal structure of InP/ZnS nanocrystals unraveled by high-resolution soft X-ray photoelectron spectroscopy.

Science.gov (United States)

Huang, Kai; Demadrille, Renaud; Silly, Mathieu G; Sirotti, Fausto; Reiss, Peter; Renault, Olivier

2010-08-24

High-energy resolution photoelectron spectroscopy (DeltaE InP/ZnS core/shell nanocrystals synthesized using a single-step procedure (core and shell precursors added at the same time), a homogeneously alloyed InPZnS core structure is evidenced by quantitative analysis of their In3d(5/2) spectra recorded at variable excitation energy. When using a two-step method (core InP nanocrystal synthesis followed by subsequent ZnS shell growth), XPS analysis reveals a graded core/shell interface. We demonstrate the existence of In-S and S(x)-In-P(1-x) bonding states in both types of InP/ZnS nanocrystals, which allows a refined view on the underlying reaction mechanisms.

Classical ultraviolet photoelectron spectroscopy of polymers

International Nuclear Information System (INIS)

Salaneck, W.R.

2009-01-01

Although X-ray photoelectron spectroscopy of polymers was well established by Clark and coworkers in the 1970s, ultraviolet photoelectron spectroscopy of polymer films, was developed later. Previous to the 1970s, the first attempts to use ultraviolet light on polymer films took the form of appearance potential (valence band edge) measurements. Only some years later could the full valence band region of thin polymer films, including insulating polymers, semiconducting polymers and electrically conducting polymers. The development of what might be termed 'classical ultraviolet photoelectron spectroscopy' of polymer films may be loosely based upon a variety of issues, including adapting thin polymer film technology to ultra high vacuum studies, the widespread use of helium resonance lamps for studies of solid surfaces, the combined advent of practical and sufficient theoretical-computational methods. The advent of, and the use of, easily available synchrotron radiation for multi-photon spectroscopies, nominally in the area of the near UV, is not included in the term 'classical'. At the same time, electrically conducting polymers were discovered, leading to applications of the corresponding semiconducting polymers, which added technologically driven emphasis to this development of ultraviolet photoelectron spectroscopy for polymer materials. This paper traces a limited number of highlights in the evolution of ultraviolet photoelectron spectroscopy of polymers, from the 1970s through to 2008. Also, since this issue is dedicated to Prof. Kazuhiko Seki, who has been a friend and competitor for over two decades, the author relies on some of Prof. Seki's earlier research, unpublished, on who-did-what-first. Prof. Seki's own contributions to the field, however, are discussed in other articles in this issue.

Inner-shell photoelectron angular distributions from fixed-in-space OCS molecules: comparison between experiment and theory

Energy Technology Data Exchange (ETDEWEB)

Golovin, A V [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Institute of Physics, St Petersburg State University, 198504 St Petersburg (Russian Federation); Adachi, J [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan); Motoki, S [Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033, (Japan); Takahashi, M [Institute for Molecular Science, Okazaki 444-8585 (Japan); Yagishita, A [Photon Factory, Institute of Materials Structure Science, Tsukuba 305-0801 (Japan); Graduate School of Science, University of Tokyo, Bunkyo-ku, Tokyo 113-0033 (Japan)

2005-10-28

Photoelectron angular distributions (PADs) for O 1s, C 1s and S 2p{sub 1/2}, 2p{sub 3/2} ionization of OCS molecules have been measured in shape resonance regions. These PAD results are compared with the results for O 1s and C 1s ionization of CO molecules, and multi-scattering X{alpha} (MSX{alpha}) calculations. The mechanism of the PAD formation both for parallel and perpendicular transitions differs very significantly in these molecules and a step from a two-centre potential (CO) to a three-centre potential (OCS) plays a principal role in electron scattering and the formation of the resulting PAD. For parallel transitions, it is found that for the S 2p and O 1s ionization the photoelectrons are emitted preferentially in a hemisphere directed to the ionized S and O atom, respectively. In OCS O 1s ionization, the S-C fragment plays the role of a strong 'scatterer' for photoelectrons, and in the shape resonance region most intensities of the PADs are concentrated on the region directed to the O atom. The MSX{alpha} calculations for perpendicular transitions reproduce the experimental data, but not so well as in the case of parallel transitions. The results of PAD, calculated with different l{sub max} on different atomic centres, reveal the important role of the d (l = 2) partial wave for the S atom in the partial wave decompositions of photoelectron wavefunctions.

Photoelectron imaging spectroscopy for (2+1) resonance-enhanced multiphoton ionization of atomic bromine

International Nuclear Information System (INIS)

Kim, Yong Shin; Jung, Young Jae; Kang, Wee Kyung; Jung, Kyung Hoon

2002-01-01

Two-photon resonant third photon ionization of atomic bromine (4p 5 2 P 3/2 and 2 P 1/2 ) has been studied using a photoelectron imaging spectroscopy in the wavelength region 250-278 nm. The technique has yielded simultaneously both relative branching ratios to the three levels of Br + ( 3 P 2 , 3 P 0,1 and 1 D 2 ) with 4p 4 configuration and the angular distributions of outgoing photoelectrons. The product branching ratios reveal a strong propensity to populate particular levels in many cases. Several pathways have been documented for selective formation of Br + ( 3 P 2 ) and Br + ( 3 P 0,1 ) ions. In general, the final ion level distributions are dominated by the preservation of the ion core configuration of a resonant excited state. Some deviations from this simple picture are discussed in terms of the configuration interaction of resonant states and the autoionization in the continuum. The photoelectron angular distributions are qualitatively similar for all transitions, with a positive A 2 anisotropy coefficient of 1.0 - 2.0 and negligible A 4 in most cases, which suggests that the angular distribution is mainly determined by the single-photon ionization process of a resonant excited state induced from the third photon absorption

X-ray photoelectron spectroscopy study on Ba1-xEuxTiO3

International Nuclear Information System (INIS)

Lu, D.-Y.; Sugano, Mikio; Sun Xiuyun; Su Wenhui

2005-01-01

X-ray photoelectron spectroscopy is employed to study inner-shell core-level binding energies Eu 4d, Ti 2p and O 1s, Ba 3d for new single-phase Ba 1-x Eu x TiO 3 (0.1 ≤ x ≤ 0.4) samples prepared by solid state reaction at 4.0 GPa and 1090 deg. C. The peak positions of binding energies determined by linear background subtraction and Gaussian fit are presented. XPS analysis indicates that the mixed-valent Eu 3+ /Eu 2+ ions at A-site and Ti 4+ /Ti 3+ ions at B-site coexisted in the Ba 1-x Eu x TiO 3 powder surface, and the amount of Eu 2+ ions is equal to Eu 3+ ions

Dissociative photoionization of the NO molecule studied by photoelectron-photon coincidence technique

International Nuclear Information System (INIS)

Kivimaeki, A.; Alvarez-Ruiz, J.; Coreno, M.; Simone, M. de; Moise, A.; Partanen, L.; Richter, R.; Stankiewicz, M.

2010-01-01

Low-energy photoelectron-vacuum ultraviolet (VUV) photon coincidences have been measured using synchrotron radiation excitation in the inner-valence region of the nitric oxide molecule. The capabilities of the coincidence set-up were demonstrated by detecting the 2s -1 → 2p -1 radiative transitions in coincidence with the 2s photoelectron emission in Ne. In NO, the observed coincidence events are attributed to dissociative photoionization with excitation, whereby photoelectron emission is followed by fragmentation of excited NO + ions into O + + N* or N + + O* and VUV emission from an excited neutral fragment. The highest coincidence rate occurs with the opening of ionization channels which are due to correlation satellites of the 3σ photoionization. The decay time of VUV photon emission was also measured, implying that specific excited states of N atoms contribute significantly to observed VUV emission.

Investigation of photoelectronic processes in CdIn2S4 by photoinduced current transient spectroscopy

International Nuclear Information System (INIS)

Serpi, A.

1986-01-01

Photoelectronic processes in CdIn 2 S 4 are investigated by four-gate photoinduced current transient spectroscopy. In general the photocurrent decay transients are non-exponential because of a nonlinear multichannel recombination mechanism. Nevertheless suitable extrinsic excitation allows to open one recombination channel only and so to evidence a purely exponential relaxation. The detailed analysis of this process leads to the interpretation that the defects associated with the energy levels continuously distributed below the conduction band act as relay centres for radiative recombination of photoelectrons rather than as thermal emitting traps. An electron trapping level located at about 0.6 eV from the bottom of the conduction band is also evidenced. (author)

X-ray photoelectron spectroscopy study of CO2 reaction with polycrystalline uranium surface

International Nuclear Information System (INIS)

Liu Kezhao; Yu Yong; Zhou Juesheng; Wu Sheng; Wang Xiaolin; Fu Yibei

1999-10-01

The adsorption of CO 2 on 'clean' depleted polycrystalline uranium metal surface has been studied by X-ray photoelectron spectroscopy (XPS) at 300 K. The 'clean' surface were prepared by Ar + ion sputtering under ultra-high vacuum (UHV) condition with a base pressure 6.7 x 10 -8 Pa. The result s shows that adsorption of CO 2 on 'clean' uranium metal took place in total dissociation, and leads to the formation of uranium dioxide, uranium carbides and free carbon. The total dissociation of CO 2 produced carbon, oxygen species, CO 2 2- and CO 3 2- species. The diffusion tendency of carbon was much stronger than that of oxygen, and led to form a carbide in oxide-metal interface while the oxygen remained on their surface as an oxide

The threshold photoelectron spectrum of mercury

International Nuclear Information System (INIS)

Rojas, H; Dawber, G; Gulley, N; King, G C; Bowring, N; Ward, R

2013-01-01

The threshold photoelectron spectrum of mercury has been recorded over the energy range (10–40 eV) which covers the region from the lowest state of the singly charged ion, 5d 10 6s( 2 S 1/2 ), to the double charged ionic state, 5d 9 ( 2 D 3/2 )6s( 1 D 2 ). Synchrotron radiation has been used in conjunction with the penetrating-field threshold-electron technique to obtain the spectrum with high resolution. The spectrum shows many more features than observed in previous photoemission measurements with many of these assigned to satellite states converging to the double ionization limit. (paper)

Core level photoelectron spectroscopy of LiGaS{sub 2} and Ga-S bonding in complex sulfides

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V., E-mail: atuchin@thermo.isp.nsc.r [Laboratory of Optical Materials and Structures, Institute of Semiconductor Physics, SB RAS, 13, Lavrentieva Ave., Novosibirsk 90, 630090 (Russian Federation); Isaenko, L.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Kesler, V.G. [Laboratory of Physical Bases of Integrated Microelectronics, Institute of Semiconductor Physics, SB RAS, Novosibirsk 90, 630090 (Russian Federation); Lobanov, S.I. [Laboratory of Crystal Growth, Institute of Geology and Mineralogy, SB RAS, Novosibirsk 90, 630090 (Russian Federation)

2010-05-14

The electronic parameters of the lithium thiogallate LiGaS{sub 2} have been evaluated by X-ray photoelectron spectroscopy (XPS). Spectral features of all constituent element core levels and Auger lines have been considered. The Ga-S bonding effects in Ga-bearing sulfide crystals have been discussed using binding energy difference {Delta}{sub 2p}(S-Ga) = BE(S 2p) - BE(Ga 3d) as a representative parameter to quantify the valence electron shift from gallium to sulfur atoms. The value {Delta}{sub 2p}(S-Ga) = 141.9 eV found for LiGaS{sub 2} is very close to that evaluated for AgGaS{sub 2}. This relation is an indicator of closely coincident ionicity of Ga-S bonds in LiGaS{sub 2} and AgGaS{sub 2}.

A coupled bunch instability due to beam-photoelectron interactions in KEKB-LER

Energy Technology Data Exchange (ETDEWEB)

Ohmi, Kazuhito [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan)

1996-08-01

LER of KEKB is designed to storage the positron beam of 2.6 A with multibunch operation. Nb = 3.3 x 10{sup 10} positrons are filled in a bunch and the bunch passes every 2ns through a beam chamber. The photoelectron instability may be serious for KEKB-LER. We consider a motion of photoelectrons produced by a bunch with a computer simulation technic. A cylindrical chamber with a diameter of 10 cm was used as a model chamber. About 15 times of the photoelectrons were produced by a bunch. The wake force was calculated for the loading bunches with displacements of 0.5 mm and 1 mm. The wake characteristics seems to be caused by the trapped electrons kicked by the loading bunch. The wake was saturated with the loading displacement of 0.5 mm. We obtained a growth rate by the wake force. It is very high rate, 2500s{sup -1} which exceeds damping rates of various mechanism, radiation, head-tail and feedback. Perhaps it is essential to remove the photoelectrons around the positron beam explicitly. If we apply magnetic field fo about 20 G, the growth rate will be reduced. (S.Y.)

A Photoelectron Spectroscopic Study of Di-t-butylphosphazene

DEFF Research Database (Denmark)

Elbel, S.; Ellis, A.; Niecke, E.

1985-01-01

Gaseous trans-ButPNBut, generated by mild gas-phase thermolysis of its more stable [2 + 1] cyclodimer, has been characterized by field-ionization mass spectrometry and U.V. photoelectron spectroscopy. The photoelectron spectrum has been assigned based on SCC-Xα model calculations for representat......Gaseous trans-ButPNBut, generated by mild gas-phase thermolysis of its more stable [2 + 1] cyclodimer, has been characterized by field-ionization mass spectrometry and U.V. photoelectron spectroscopy. The photoelectron spectrum has been assigned based on SCC-Xα model calculations...

Imaging photoelectron photoion coincidence spectroscopy with velocity focusing electron optics

International Nuclear Information System (INIS)

Bodi, Andras; Johnson, Melanie; Gerber, Thomas; Gengeliczki, Zsolt; Sztaray, Balint; Baer, Tomas

2009-01-01

An imaging photoelectron photoion coincidence spectrometer at the vacuum ultraviolet (VUV) beamline of the Swiss Light Source is presented and a few initial measurements are reported. Monochromatic synchrotron VUV radiation ionizes the cooled or thermal gas-phase sample. Photoelectrons are velocity focused, with better than 1 meV resolution for threshold electrons, and also act as start signal for the ion time-of-flight analysis. The ions are accelerated in a relatively low, 40-80 V cm -1 field, which enables the direct measurement of rate constants in the 10 3 -10 7 s -1 range. All electron and ion events are recorded in a triggerless multiple-start/multiple-stop setup, which makes it possible to carry out coincidence experiments at >100 kHz event frequencies. As examples, the threshold photoelectron spectrum of the argon dimer and the breakdown diagrams for hydrogen atom loss in room temperature methane and the chlorine atom loss in cold chlorobenzene are shown and discussed.

Energy- and angled-resolved photoelectron spectroscopy of negative ions

International Nuclear Information System (INIS)

Pegg, D.J.; Thompson, J.S.; Compton, R.N.; Alton, G.D.

1988-01-01

Energy- and angle-resolved photoelectron detachment spectroscopy is currently being used to investigate the structure of negative ions and their interaction with radiation. Measurements of the electron affinity of the Ca atom and the partial cross sections for photodetachment of the metastable negative ion, He - (1s2s2p 4 P), are reported. 5 refs., 5 figs

GaN polarity determination by photoelectron diffraction

Czech Academy of Sciences Publication Activity Database

Romanyuk, Olexandr; Jiříček, Petr; Paskova, T.; Bieloshapka, Igor; Bartoš, Igor

2013-01-01

Roč. 103, č. 9 (2013), "091601-1"-"091601-4" ISSN 0003-6951 R&D Projects: GA ČR(CZ) GBP108/12/G108 Grant - others:AV ČR(CZ) M100101201 Institutional support: RVO:68378271 Keywords : GaN * photoelectron diffraction * wurtzite * surface polarity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.515, year: 2013 http://apl.aip.org/resource/1/applab/v103/i9/p091601_s1?isAuthorized=no

Local carbon diffusion coefficient measurement in the S-1 spheromak

International Nuclear Information System (INIS)

Mayo, R.M.; Levinton, F.M.; Meyerhofer, D.D.; Chu, T.K.; Paul, S.F.; Yamada, M.

1988-10-01

The local carbon diffusion coefficient was measured in the S - 1 spheromak by detecting the radial spread of injected carbon impurity. The radial impurity density profile is determined by the balance of ionization and diffusion. Using measured local electron temperature T/sub e/ and density n/sub e/, the ionization rate is determined from which the particle diffusion coefficient is inferred. The results found in this work are consistent with Bohm diffusion. The absolute magnitude of D/sub /perpendicular// was determined to be (4/approximately/6) /times/ D/sub Bohm/. 25 refs., 13 figs., 2 tabs

Proline adsorption on TiO 2(1 1 0) single crystal surface: A study by high resolution photoelectron spectroscopy

Science.gov (United States)

Fleming, G. J.; Adib, K.; Rodriguez, J. A.; Barteau, M. A.; Idriss, H.

2007-12-01

The surface chemistry and binding of DL-proline were investigated on the oxidised (stoichiometric) and reduced (sub-stoichiometric) TiO 2(1 1 0) single crystal surfaces. TiO 2 was chosen as the substrate as it best represents the surface of a biomedical implant, which bio-molecules interact with during the healing of bone/teeth fractures (molecular recognition). High resolution X-ray photoelectron spectroscopy (HR-XPS) studies of the C1s and N1s regions revealed that DL-proline is present in two forms (dissociated and zwitterionic) on the oxidised TiO 2 surface. On TiO 2(1 1 0) surfaces reduced by Ar + sputtering, a significant increase in the amount of zwitterionic proline at the surface was detected when compared with the oxidised surface. Study of the temperature effect showed that in both cases the zwitterionic structure was the less stable structure. The reason for its relative instability appears to be thermodynamic.

Communication: Remarkable electrophilicity of the oxalic acid monomer: An anion photoelectron spectroscopy and theoretical study

International Nuclear Information System (INIS)

Buonaugurio, Angela; Graham, Jacob; Buytendyk, Allyson; Bowen, Kit H.; Ryder, Matthew R.; Gutowski, Maciej; Keolopile, Zibo G.; Haranczyk, Maciej

2014-01-01

Our experimental and computational results demonstrate an unusual electrophilicity of oxalic acid, the simplest dicarboxylic acid. The monomer is characterized by an adiabatic electron affinity and electron vertical detachment energy of 0.72 and 1.08 eV (±0.05 eV), respectively. The electrophilicity results primarily from the bonding carbon-carbon interaction in the singly occupied molecular orbital of the anion, but it is further enhanced by intramolecular hydrogen bonds. The well-resolved structure in the photoelectron spectrum is reproduced theoretically, based on Franck-Condon factors for the vibronic anion → neutral transitions

Impact of water vapour and carbon dioxide on surface composition of C{sub 3}A polymorphs studied by X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Dubina, E.; Plank, J. [Technische Universität München, Lehrstuhl für Bauchemie, Lichtenbergstr. 4, 85747 Garching bei München (Germany); Black, L., E-mail: l.black@leeds.ac.uk [Institute for Resilient Infrastructure, School of Civil Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom)

2015-07-15

The surface specific analytical method, X-ray photoelectron spectroscopy (XPS), has been used to study the effects of water vapour and CO{sub 2} on the cubic and orthorhombic polymorphs of C{sub 3}A. Significant differences between the two polymorphs were observed in the XPS spectra. Upon exposure to water vapour, both polymorphs produced C{sub 4}AH{sub 13} on their surfaces. Additionally, the sodium-doped o-C{sub 3}A developed NaOH and traces of C{sub 3}AH{sub 6} on its surface. Subsequent carbonation yielded mono carboaluminate on both polymorphs. Large amounts of Na{sub 2}CO{sub 3} also formed on the surface of o-C{sub 3}A as a result of carbonation of NaOH. Furthermore, the extent of carbonation was much more pronounced for o-C{sub 3}A{sub o} than for c-C{sub 3}A.

Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

Energy Technology Data Exchange (ETDEWEB)

Embong, Zaidi, E-mail: zaidi@uthm.edu.my [Faculty of Science, Technology and Human Development, Universiti Tun Hussien Onn Malaysia (UTHM) 86400, Parit Raja, Batu, Johor (Malaysia); Research Centre for Soft Soils (RECESS), Office for Research, Innovation, Commercialization and Consultancy Management (ORICC), Universiti Tun Hussien Onn Malaysia UTHM 86400, Parit Raja, Batu, Johor (Malaysia); Johar, Saffuwan [Faculty of Science, Technology and Human Development, Universiti Tun Hussien Onn Malaysia (UTHM) 86400, Parit Raja, Batu, Johor (Malaysia); Tajudin, Saiful Azhar Ahmad [Research Centre for Soft Soils (RECESS), Office for Research, Innovation, Commercialization and Consultancy Management (ORICC), Universiti Tun Hussien Onn Malaysia UTHM 86400, Parit Raja, Batu, Johor (Malaysia); Sahdan, Mohd Zainizan [Microelectronics and Nanotechnology Centre (MiNT-SRC), Office for Research, Innovation, Commercialization and Consultancy Management (ORICC), Universiti Tun Hussien Onn Malaysia UTHM 86400, Parit Raja, Batu, Johor (Malaysia)

2015-04-29

Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si{sup 2+} and Al{sup 2+} cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail.

Surface study of stainless steel electrode deposition from soil electrokinetic (EK) treatment using X-ray photoelectron spectroscopy (XPS)

International Nuclear Information System (INIS)

Embong, Zaidi; Johar, Saffuwan; Tajudin, Saiful Azhar Ahmad; Sahdan, Mohd Zainizan

2015-01-01

Electrokinetic (EK) remediation relies upon application of a low-intensity direct current through the soil between stainless steel electrodes that are divided into a cathode array and an anode array. This mobilizes charged species, causing ions and water to move toward the electrodes. Metal ions and positively charged organic compounds move toward the cathode. Anions such as chloride, fluoride, nitrate, and negatively charged organic compounds move toward the anode. Here, this remediation techniques lead to a formation of a deposition at the both cathode and anode surface that mainly contributed byanion and cation from the remediated soil. In this research, Renggam-Jerangau soil species (HaplicAcrisol + RhodicFerralsol) with a surveymeter reading of 38.0 ± 3.9 μR/hr has been investigation in order to study the mobility of the anion and cation under the influence electric field. Prior to the EK treatment, the elemental composition of the soil and the stainless steel electrode are measured using XRF analyses. Next, the soil sample is remediated at a constant electric potential of 30 V within an hour of treatment period. A surface study for the deposition layer of the cathode and anode using X-ray Photoelectron spectroscopy (XPS) revealed that a narrow photoelectron signal from oxygen O 1s, carbon, C 1s silica, Si 2p, aluminium, Al 2p and chromium, Cr 2p exhibited on the electrode surface and indicate that a different in photoelectron intensity for each element on both electrode surface. In this paper, the mechanism of Si 2+ and Al 2+ cation mobility under the influence of voltage potential between the cathode and anode will be discussed in detail

Photoelectron emission from thin overlayers

International Nuclear Information System (INIS)

Jablonski, A.

2012-01-01

Highlights: ► Weak influence of the support on photoemission from an overlayer. ► Accurate description of photoelectron intensity from overlayer by analytical theory. ► Method for overlayer thickness measurements based on analytical formalism. ► Influence of photoelectron elastic scattering on calculated thickness. -- Abstract: Photoelectron signal intensities calculated for a thin overlayer from theoretical models taking elastic photoelectron collisions into account are shown to be very weakly dependent on the substrate material. This result has been obtained for photoelectrons analyzed in XPS spectrometers equipped with typical X-ray sources, i.e. sources of Mg Kα and Al Kα radiation. Low sensitivity to the substrate material is due to the fact that trajectories of photoelectrons emitted in the overlayer and entering the substrate have a low probability to reach the analyzer without energy loss. On the other hand, the signal intensity of photoelectrons emitted in the overlayer is found to be distinctly affected by elastic photoelectron scattering. Consequently, a theoretical model that can accurately describe the photoelectron intensity from an overlayer deposited on any material (e.g. on a substrate of the same material as the overlayer) can be a useful basis for a universal and convenient method for determination of the overlayer thickness. It is shown that the formalism derived from the kinetic Boltzmann equation within the so-called transport approximation satisfies these requirements. This formalism is postulated for use in overlayer-thickness measurements to avoid time-consuming Monte Carlo simulations of photoelectron transport, and also to circumvent problems with determining the effective attenuation lengths for overlayer/substrate systems.

Surface cleaning and preparation in AlGaN/GaN-based HEMT processing as assessed by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Gonzalez-Posada, Fernando; Bardwell, Jennifer A.; Moisa, Simona; Haffouz, Soufien; Tang, Haipeng; Brana, Alejandro F.; Munoz, Elias

2007-01-01

The chemical composition of the AlGaN/GaN surface during typical process steps in transistor fabrication was studied using X-ray photoelectron spectroscopy (XPS). The steps studied included organic solvent cleaning, 1:1 HCl:H 2 O dip, buffered oxide etch dip, oxygen plasma descum and rapid thermal annealing (RTA). The surface composition was calculated after correction for the interference of the Ga Auger lines in the N 1s portion of the spectra. The buffered oxide etched (BOE) surface showed a greater tendency for Al (compared to Ga) to be oxidized in the surface, under a layer of adventitious carbon. Three different treatments were found to yield a combination of low C and O levels in the surface. Both plasma cleaning and RTA were highly effective at reducing the carbon contamination of the surface, but did increase the oxygen levels. The RTA treated surface was found to have low levels of oxygen incorporation to a depth of 2-6 nm

Multi-walled carbon nanotube supported CdS-DETA nanocomposite for efficient visible light photocatalysis

Energy Technology Data Exchange (ETDEWEB)

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

2017-01-15

Designing high performance functional nanomaterials by tuning their dimension at nanoscale and constructing novel interface has been a hot topic in recent years. In this work, multi-walled carbon nanotube (MWCNT)/CdS-diethylenetriamine (DETA) composite photocatalyst was synthesized via hydrothermal method. The structure, morphology, optical property and core level analysis of MWCNT/CdS-DETA nanocomposite were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy spectra (EDS), UV–Vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron spectrum (XPS). CdS-DETA can be uniformly dispersed on the surface of MWCNT. Photocatalytic properties of as-prepared photocatalysts were investigated under 410 nm LED light irradiation for photodegradation of methylene bule (MB). The k{sub app} of MWCNT/CdS-DETA is 0.034 min{sup −1}, which is about 6 times more than pure CdS-DETA. Photostability test indicated that MWCNT/CdS-DETA hybrid can be reused for degradation of organic pollution, suggesting the possible application of MWCNT/CdS-DETA hybrid is the most promising strategy for advanced photocatalyst material design. - Highlights: • Novel MWCNT/CdS-DETA photocatalyst was prepared. • MWCNT/CdS-DETA showed high photocatalytic activity. • MWCNT/CdS-DETA showed long reusable life.

Photoelectron spectroscopy of supersonic molecular beams

International Nuclear Information System (INIS)

Pollard, J.E.

1982-05-01

A new technique for performing high resolution molecular photoelectron spectroscopy is described, beginning with its conceptual development, through the construction of a prototypal apparatus, to the initial applications on a particularly favorable molecular system. The distinguishing features of this technique are: (1) the introduction of the sample in the form of a collimated supersonic molecular beam; and (2) the use of an electrostatic deflection energy analyzer which is carefully optimized in terms of sensitivity and resolution. This combination makes it possible to obtain photoelectron spectra at a new level of detail for many small molecules. Three experiments are described which rely on the capability to perform rotationally-resolved photoelectron spectroscopy on the hydrogen molecule and its isotopes. The first is a measurement of the ionic vibrational and rotational spectroscopic constants and the vibrationally-selected photoionization cross sections. The second is a determination of the photoelectron asymmetry parameter, β, for selected rotational transitions. The third is an investigation of the rotational relaxation in a free jet expansion, using photoelectron spectroscopy as a probe of the rotational state population distributions. In the closing chapter an assessment is made of the successes and limitations of the technique, and an indication is given of areas for further improvement in future spectrometers

Effect of oxide charge trapping on x-ray photoelectron spectroscopy of HfO2/SiO2/Si structures

International Nuclear Information System (INIS)

Abe, Yasuhiro; Miyata, Noriyuki; Suzuki, Haruhiko; Kitamura, Koji; Igarashi, Satoru; Nohira, Hiroshi; Ikenaga, Eiji

2009-01-01

We examined the effects of interfacial SiO 2 layers and a surface metal layer on the photoelectron spectra of HfO 2 /SiO 2 /Si structures by hard X-ray photoemission spectroscopy with synchrotron radiation as well as conventional X-ray photoelectron spectroscopy (XPS). The Hf 4f and Hf 3d photoelectron peaks broadened and shifted toward a higher binding energy with increasing thickness of the interfacial SiO 2 layer, even though photoelectrons may have been emitted from the HfO 2 layer with the same chemical composition. Thinning the interfacial Si oxide layer to approximately one monolayer and depositing a metal layer on the HfO 2 surface suppressed these phenomena. The O 1s photoelectron spectra revealed marked differences between the metal- and nonmetal-deposited HfO 2 /SiO 2 /Si structures; HfO 2 and SiO 2 components in the O 1s photoelectron spectra for the metal-deposited structures were observed at reasonably separated binding energies, but those for the nonmetal-deposited structures were not separated clearly. From this behavior concerning the effects of interfacial SiO 2 and surface metal layers, we concluded that the Hf 4f, Hf 3d, and O 1s spectra measured from the HfO 2 /SiO 2 /Si structures did not reflect actual chemical bonding states. We consider that potential variations in the HfO 2 film owing to charge trapping strongly affect the measured photoelectron spectra. On the basis of angle-resolved XPS measurements, we propose that positive charges are trapped at the HfO 2 surface and negative charges are trapped inside the HfO 2 layer. (author)

Many-electron effects in photoelectron spectroscopy

International Nuclear Information System (INIS)

Martin, R.L.

1976-06-01

The deviations from Koopmans' one-electron model of photoionization which lead to satellite structure in the photoelectron spectrum are examined within the formalism of configuration interaction (CI). The mechanisms which contribute to satellite intensity may be classified as continuum state configuration interaction, final ionic state configuration interaction, and initial state configuration interaction. The discussion centers around the last two mechanisms, these being the prime contributors to the satellite intensity well above threshold. Specific examples of theoretical ''spectra'' are presented for the F(1s) region of HF and the 1s region of neon. The agreement between theory and experiment is found to be excellent. In these two instances, initial state configuration interaction contributions increase the satellite intensity and are of nearly equal importance to the final ionic state mixing

Development of laser Raman and x-ray photoelectron spectroscopic parameters as an additional thermal maturity indicator to the conodont alteration index

International Nuclear Information System (INIS)

Marshall, C.P.; Wilson, M.A.

1999-01-01

Full text: Laser Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) was applied in an attempt to quantify and elucidate the chemical transformations of the conodont alteration index (CAI) in artificially matured conodonts. Coniform elements of the genus Drepanodus from the Ordovician Emanuel Formation and pectiniform elements of the genus Polygnathus from the Devonian Napier Formation, both from the Canning Basin were used in this investigation. Samples where specifically chosen to study the effects of genus, element morphology, geological age, lithology and depositional environment upon the CAI. The first order Raman spectra (900-1800 cm-1) of both sets of conodonts show three bands. These are assigned to apatite at 965 cm-1, D band (defects present in the structural units and disorder) at 1345 cm-1 and the G band (carbon-carbon in plane stretching vibration or structural ordered carbon) at 1600 cm-1. The Raman spectra recorded for both sample sets, CAI range of 1-7 are characteristic of poorly/ highly disordered carbon within the conodont organic matter. Further more, the D band becomes progressively narrower and more intense the higher the thermal treatment. The G band becomes narrower until CAI 4 and after that has no systematic change apart from the intensity decreasing with temperature. The most noteworthy spectral characteristic in relation to thermal maturity is the clearly defined linear trend of decreasing D band line-width with increasing rank. The carbon 1s photoelectron regions acquired from both sample sets contain three peaks. These peaks are assigned to carbon bonded to sp3 and sp2 hybridized carbon (284.7 eV), alcohol (287.2 eV) and carboxyl (288.3 eV) functional groups. With increasing thermal treatment all the carbon constituents show a linear decrease in abundance. The poorly/ highly disordered carbon shows no progressive ordering with increasing thermal treatment. This is also in agreement with the XPS results, in which the aliphatic

Photoelectron angular distribution from free SiO2 nanoparticles as a probe of elastic electron scattering.

Science.gov (United States)

Antonsson, E; Langer, B; Halfpap, I; Gottwald, J; Rühl, E

2017-06-28

In order to gain quantitative information on the surface composition of nanoparticles from X-ray photoelectron spectroscopy, a detailed understanding of photoelectron transport phenomena in these samples is needed. Theoretical results on the elastic and inelastic scattering have been reported, but a rigorous experimental verification is lacking. We report in this work on the photoelectron angular distribution from free SiO 2 nanoparticles (d = 122 ± 9 nm) after ionization by soft X-rays above the Si 2p and O 1s absorption edges, which gives insight into the relative importance of elastic and inelastic scattering channels in the sample particles. The photoelectron angular anisotropy is found to be lower for photoemission from SiO 2 nanoparticles than that expected from the theoretical values for the isolated Si and O atoms in the photoelectron kinetic energy range 20-380 eV. The reduced angular anisotropy is explained by elastic scattering of the outgoing photoelectrons from neighboring atoms, smearing out the atomic distribution. Photoelectron angular distributions yield detailed information on photoelectron elastic scattering processes allowing for a quantification of the number of elastic scattering events the photoelectrons have undergone prior to leaving the sample. The interpretation of the experimental photoelectron angular distributions is complemented by Monte Carlo simulations, which take inelastic and elastic photoelectron scattering into account using theoretical values for the scattering cross sections. The results of the simulations reproduce the experimental photoelectron angular distributions and provide further support for the assignment that elastic and inelastic electron scattering processes need to be considered.

Photoelectron emission as a tool to assess dose of electron radiation received by ZrO2:PbS films

International Nuclear Information System (INIS)

Krumpane, Diana; Dekhtyar, Yury; Surkova, Indra; Romanova, Marina

2013-01-01

PbS nano dots embedded in ZrO 2 thin film matrix (ZrO 2 :PbS films) were studied for application in nanodosimetry of electron radiation used in radiation therapy. ZrO 2 :PbS films were irradiated with 9 MeV electron radiation with doses 3, 7 and 10 Gy using medical linear accelerator. Detection of the dosimetric signal was made by measuring and comparing photoelectron emission current from ZrO 2 :PbS films before and after irradiation. It was found that electron radiation decreased intensity of photoemission current from the films. Derivatives of the photoemission spectra were calculated and maximums at photon energies 5.65 and 5.75 eV were observed. Amplitude of these maximums decreased after irradiation with electrons. Good linear correlation was found between the relative decrease of the intensity of these maximums and dose of electron radiation. Observed changes in photoemission spectra from ZrO 2 :PbS films under influence of electron radiation suggested that the films may be considered to be effective material for electron radiation dosimetry. Photoelectron emission is a tool that allows to read the signal from such dosimeter. (authors)

Calculated characteristics of multichannel photoelectron multipliers

International Nuclear Information System (INIS)

Vasil'chenko, V.G.; Dajkovskij, A.G.; Milova, N.V.; Rakhmatov, V.E.; Rykalin, V.I.

1990-01-01

Structural features and main calculated characteristics of some modifications of position-sensitive two-coordinate multichannel photoelectron multipliers (PEM) with plate-type multiplying systems are described. The presented PEM structures are free from direct optical and ion feedbacks, provide coordinate resolution ≅ 1 mm with efficiency of photoelectron detection ≅ 90%. Capabilities for using silicon field-effect photocathodes, providing electron extraction into vacuum, as well as prospects of using multichannel multiplying systems for readout of the data from solid detectors are considered

X-ray photoelectron spectroscopy of HUPA organic substances: natural and synthetic humic compounds

International Nuclear Information System (INIS)

Barre, N.; Mercier-Bion, F.; Reiller, P.

2004-01-01

X-ray photoelectron spectroscopy (XPS) results on the characterisation of the HUPA organic materials, i.e. natural humic substances ''GOHY 573'' (fulvic acid FA and humic acid HA) extracted from the Gorleben ground waters, and synthetic humic acids ''M1'' and ''M42'' obtained from a standard melanoidin preparation from FZ Rossendorf, are presented in this paper. XPS investigations were focused on the determination of the chemical environment of the major elements as carbon, nitrogen, oxygen and sulphur, and on the identification of trace metals trapped by these organic compounds. (orig.)

Polarity of wurtzite crystals by photoelectron diffraction

Czech Academy of Sciences Publication Activity Database

Bartoš, Igor; Romanyuk, Olexandr

2014-01-01

Roč. 315, OCT (2014), s. 506-509 ISSN 0169-4332 Grant - others:AVČR(CZ) M100101201 Institutional support: RVO:68378271 Keywords : wurtzite semiconductors * surface polarity * X-ray photoelectron diffraction * XPD Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.711, year: 2014 http://www.sciencedirect.com/science/article/pii/S016943321400066X

X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Attekum, P.M.T.M. van.

1979-01-01

The methods and results of X-ray photoelectron spectroscopy in the study of plasmons, alloys and gold compounds are discussed. After a comprehensive introduction, seven papers by the author, previously published elsewhere, are reprinted and these cover a wide range of the uses of X-ray photoelectron spectroscopy. (W.D.L.)

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

International Nuclear Information System (INIS)

Bradforth, S.E.

1992-11-01

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound → bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN - , NCO - and NCS - . Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH 3 0H,F + C 2 H 5 OH,F + OH and F + H 2 . A time dependent framework for the simulation and interpretation of the bound → free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH → O( 3 P, 1 D) + HF and F + H 2 . The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H 2 system, comparisons with three-dimensional quantum calculations are made

Carbon isotope fractionation of 1,1,1-trichloroethane during base-catalyzed persulfate treatment

International Nuclear Information System (INIS)

Marchesi, Massimo; Thomson, Neil R.; Aravena, Ramon; Sra, Kanwartej S.; Otero, Neus; Soler, Albert

2013-01-01

Highlights: • Treatability and C fractionation of 1,1,1-TCA by base-catalyzed S 2 O 8 2− was studied. • The rate of degradation of 1,1,1-TCA increased with a higher OH − :S 2 O 8 2− ratio. •Base-catalyzed S 2 O 8 2− can potentially treat recalcitrant compound like 1,1,1-TCA. • An enrichment factor of −7.0‰ independent of the OH − :S 2 O 8 2− ratio was obtained. • Carbon isotope can potentially be used to estimate the ISCO treatment efficacy. -- Abstract: The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S 2 O 8 2− ) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S 2 O 8 2− molar ratio from 0.2:1 to 8:1 enhanced the reaction rate of 1,1,1-TCA by a factor of ∼5 to yield complete (>99.9%) destruction. An average carbon isotope enrichment fractionation factor which was independent of the NaOH:S 2 O 8 2− molar ratio of −7.0 ± 0.2‰ was obtained. This significant carbon isotope fractionation and the lack of dependence on changes in the NaOH:S 2 O 8 2− molar ratio demonstrates that carbon isotope analysis can potentially be used in situ as a performance assessment tool to estimate the degradation effectiveness of 1,1,1-TCA by a base-catalyzed persulfate system

Band alignment of ZnO/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Liu, Xinke, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn; He, Jiazhu; Chen, Le; Li, Kuilong; Jia, Fang; Zeng, Yuxiang; Lu, Youming; Zhu, Deliang; Liu, Wenjun, E-mail: xkliu@szu.edu.cn, E-mail: liuwj@szu.edu.cn [College of Materials Science and Engineering, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Zhang, Yuan [School of Physics and Electronic Information, Hua Bei Normal University, 100 Dongshan Road, Huai Bei 235000 (China); Liu, Qiang; Yu, Wenjie [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS, 865 Chang Ning Road, Shanghai 200050 (China); Wu, Jing [Institute of Materials research and Engineering (IMRE), 2 Fusionopolis Way, Innovis, #08-03, 138634 Singapore (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117583 Singapore (Singapore)

2016-08-15

The energy band alignment between ZnO and multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The ZnO film was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 3.32 eV and a conduction band offset (CBO) of 1.12 eV were obtained for the ZnO/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the ZnO/ML-MoS{sub 2} interface were found to be 3.54 eV and 1.34 eV, respectively. With the CHF{sub 3} plasma treatment, the band alignment of the ZnO/ML-MoS{sub 2} interface has been changed from type II or staggered band alignment to type III or misaligned one, which favors the electron-hole pair separation. The band alignment difference is believed to be dominated by the down-shift in the core level of Zn 2p or the interface dipoles, which is caused by the interfacial layer rich in F.

Revealing the 1 nm/s Extensibility of Nanoscale Amorphous Carbon in a Scanning Electron Microscope

DEFF Research Database (Denmark)

Zhang, Wei

2013-01-01

In an ultra-high vacuum scanning electron microscope, the edged branches of amorphous carbon film (∼10 nm thickness) can be continuously extended with an eye-identifying speed (on the order of ∼1 nm/s) under electron beam. Such unusual mobility of amorphous carbon may be associated with deformation...... promoted by the electric field, which resulted from an inner secondary electron potential difference from the main trunk of carbon film to the tip end of branches under electron beam. This result demonstrates importance of applying electrical effects to modify properties of carbon materials. It may have...... positive implications to explore some amorphous carbon as electron field emission device. SCANNING 35: 261-264, 2013. © 2012 Wiley Periodicals, Inc....

Projection methods for the analysis of molecular-frame photoelectron angular distributions

International Nuclear Information System (INIS)

Lucchese, R.R.; Montuoro, R.; Grum-Grzhimailo, A.N.; Liu, X.-J.; Pruemper, G.; Morishita, Y.; Saito, N.; Ueda, K.

2007-01-01

The analysis of the molecular-frame photoelectron angular distributions (MFPADs) is discussed within the dipole approximation. The general expressions are reviewed and strategies for extracting the maximum amount of information from different types of experimental measurements are considered. The analysis of the N 1s photoionization of NO is given to illustrate the method

Carbon isotope fractionation of 1,1,1-trichloroethane during base-catalyzed persulfate treatment

Energy Technology Data Exchange (ETDEWEB)

Marchesi, Massimo, E-mail: m2marche@uwaterloo.ca [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Thomson, Neil R. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Aravena, Ramon [Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Sra, Kanwartej S. [Department of Civil and Environmental Engineering, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1 (Canada); Golder Associates Inc, Toronto, Ontario, Canada L5N 5Z7 (Canada); Otero, Neus; Soler, Albert [Departament de Cristal.lographia, Mineralogia i Diposits Minerals, Facultat de Geologia, Universitat de Barcelona, Barcelona, Spain 08028 (Spain)

2013-09-15

Highlights: • Treatability and C fractionation of 1,1,1-TCA by base-catalyzed S{sub 2}O{sub 8}{sup 2−} was studied. • The rate of degradation of 1,1,1-TCA increased with a higher OH{sup −}:S{sub 2}O{sub 8}{sup 2−} ratio. •Base-catalyzed S{sub 2}O{sub 8}{sup 2−} can potentially treat recalcitrant compound like 1,1,1-TCA. • An enrichment factor of −7.0‰ independent of the OH{sup −}:S{sub 2}O{sub 8}{sup 2−} ratio was obtained. • Carbon isotope can potentially be used to estimate the ISCO treatment efficacy. -- Abstract: The extent of carbon isotope fractionation during degradation of 1,1,1-trichloroethane (1,1,1-TCA) by a base-catalyzed persulfate (S{sub 2}O{sub 8}{sup 2−}) treatment system was investigated. Significant destruction of 1,1,1-TCA was observed at a pH of ∼12. An increase in the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio from 0.2:1 to 8:1 enhanced the reaction rate of 1,1,1-TCA by a factor of ∼5 to yield complete (>99.9%) destruction. An average carbon isotope enrichment fractionation factor which was independent of the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio of −7.0 ± 0.2‰ was obtained. This significant carbon isotope fractionation and the lack of dependence on changes in the NaOH:S{sub 2}O{sub 8}{sup 2−} molar ratio demonstrates that carbon isotope analysis can potentially be used in situ as a performance assessment tool to estimate the degradation effectiveness of 1,1,1-TCA by a base-catalyzed persulfate system.

X-ray photoelectron spectroscopy study of β-BaB2O4 optical surface

International Nuclear Information System (INIS)

Atuchin, V.V.; Kesler, V.G.; Kokh, A.E.; Pokrovsky, L.D.

2004-01-01

An X-ray photoelectron spectroscopy (XPS) study has been performed for (0 0 1) BaB 2 O 4 . The crystal surface has been polished mechanically and cleaned by chemical etching. In XPS observation, depth profiling has been produced by sputtering with Ar + 3 keV ions. Photoelectron binding energies of original element core levels and valence band have been measured as a function of sputtering time. The persistence of binding energies of barium and boron core levels and valence band structure has been found. For O 1 s core level the formation of new spectral components with lower binding energies has been revealed

Negative-Ion source for mass selective photodetachment photoelectron spectroscopy

International Nuclear Information System (INIS)

Kaesmaier, R.; Baemann, C.; Drechsler, G.; Boesl, U.

1995-01-01

We have designed and constructed a negative ion source for mass spectrometry and mass selective photodetachement photoelectron spectroscopy. The characteristics of the source are high anion densities and a large variety of accessible systems. Thus, mass spectra and photoelectron spectra of large unvolatile moelcules (biomolecules), of metal-organic compounds and of molecule water clusters, especially mentioned in this article, have been measured. Combining mass spectrometry, photoelectron spectroscopy (PES) and high resolution ZEKE (zero kinetic energy)-PES (1) should make the apparatus to an ideal diagnostic tool for structural assignment

Femtosecond x-ray photoelectron diffraction on gas-phase dibromobenzene molecules

International Nuclear Information System (INIS)

Rolles, D; Boll, R; Epp, S W; Erk, B; Foucar, L; Hömke, A; Adolph, M; Gorkhover, T; Aquila, A; Chapman, H N; Coppola, N; Delmas, T; Gumprecht, L; Holmegaard, L; Bostedt, C; Bozek, J D; Coffee, R; Decleva, P; Filsinger, F; Johnsson, P

2014-01-01

We present time-resolved femtosecond photoelectron momentum images and angular distributions of dissociating, laser-aligned 1,4-dibromobenzene (C 6 H 4 Br 2 ) molecules measured in a near-infrared pump, soft-x-ray probe experiment performed at an x-ray free-electron laser. The observed alignment dependence of the bromine 2p photoelectron angular distributions is compared to density functional theory calculations and interpreted in terms of photoelectron diffraction. While no clear time-dependent effects are observed in the angular distribution of the Br(2p) photoelectrons, other, low-energy electrons show a pronounced dependence on the time delay between the near-infrared laser and the x-ray pulse. (paper)

Nanoporous carbon derived from agro-waste pineapple leaves for supercapacitor electrode

Science.gov (United States)

Sodtipinta, Jedsada; Amornsakchai, Taweechai; Pakawatpanurut, Pasit

2017-09-01

By using KOH as the chemical activating agent in the synthesis, the activated carbon derived from pineapple leaf fiber (PALF) was prepared. The structure, morphology, and the surface functional groups of the as-prepared activated carbon were investigated using x-ray diffraction, field emission scanning electron microscope equipped with energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical behavior and performance of the as-synthesized activated carbon electrode were measured using the cyclic voltammetry and the electrochemical impedance spectroscopy in 1 M Na2SO4 electrolyte solution in three-electrode setup. The activated carbon electrode exhibited the specific capacitance of 131.3 F g-1 at a scan rate of 5 mV s-1 with excellent cycling stability. The capacitance retention after 1000 cycles was about 97% of the initial capacitance at a scan rate of 30 mV s-1. Given these good electrochemical properties along with the high abundance of PALF, this activated carbon electrode has the potential to be one of the materials for future large-scale production of the electrochemical capacitors. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

Liquid microjet for photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Winter, Bernd [Helmholtz-Zentrum Berlin fuer Materialien und Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany)], E-mail: bernd.winter@bessy.de

2009-03-21

Photoelectron spectroscopy from highly volatile liquids, especially from water and aqueous solutions, has recently become possible due to the development of the vacuum liquid microjet in combination of high-brilliance synchrotron radiation. The present status of this rapidly growing field is reported here, with an emphasize on the method's sensitivity for detecting local electronic structure, and for monitoring ultrafast dynamical processes in aqueous solution exploiting core-level resonant excitation.

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

Energy Technology Data Exchange (ETDEWEB)

Bradforth, Stephen Edmund [Univ. of California, Berkeley, CA (United States)

1992-11-01

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound {yields} bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN^-, NCO^- and NCS^-. Transition state photoelectron spectra are presented for the following systems Br + HI, Cl + HI, F + HI, F + CH₃0H,F + C₂H₅OH,F + OH and F + H₂. A time dependent framework for the simulation and interpretation of the bound → free transition state photoelectron spectra is subsequently developed and applied to the hydrogen transfer reactions Br + HI, F + OH → O(³P, ¹D) + HF and F + H₂. The theoretical approach for the simulations is a fully quantum-mechanical wave packet propagation on a collinear model reaction potential surface. The connection between the wavepacket time evolution and the photoelectron spectrum is given by the time autocorrelation function. For the benchmark F + H₂ system, comparisons with three-dimensional quantum calculations are made.

Band alignment at the Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4}/CdS interface

Energy Technology Data Exchange (ETDEWEB)

Haight, Richard; Barkhouse, Aaron; Gunawan, Oki; Shin, Byungha; Copel, Matt; Hopstaken, Marinus; Mitzi, David B [IBM TJ Watson Research Center, P.O. Box 218, Yorktown Hts., New York 10598 (United States)

2011-06-20

Energy band alignments between CdS and Cu{sub 2}ZnSn(S{sub x}Se{sub 1-x}){sub 4} (CZTSSe) grown via solution-based and vacuum-based deposition routes were studied as a function of the [S]/[S+Se] ratio with femtosecond laser ultraviolet photoelectron spectroscopy, photoluminescence, medium energy ion scattering, and secondary ion mass spectrometry. Band bending in the underlying CZTSSe layer was measured via pump/probe photovoltage shifts of the photoelectron spectra and offsets were determined with photoemission under flat band conditions. Increasing the S content of the CZTSSe films produces a valence edge shift to higher binding energy and increases the CZTSSe band gap. In all cases, the CdS conduction band offsets were spikes.

Interlaminar and ductile characteristics of carbon fibers-reinforced plastics produced by nanoscaled electroless nickel plating on carbon fiber surfaces.

Science.gov (United States)

Park, Soo-Jin; Jang, Yu-Sin; Rhee, Kyong-Yop

2002-01-15

In this work, a new method based on nanoscaled Ni-P alloy coating on carbon fiber surfaces is proposed for the improvement of interfacial properties between fibers and epoxy matrix in a composite system. Fiber surfaces and the mechanical interfacial properties of composites were characterized by atomic absorption spectrophotometer (AAS), scanning electron microscopy (SEM), X-ray photoelectron spectrometry (XPS), interlaminar shear strength (ILSS), and impact strength. Experimental results showed that the O(1s)/C(1s) ratio or Ni and P amounts had been increased as the electroless nickel plating proceeded; the ILSS had also been slightly improved. The impact properties were significantly improved in the presence of Ni-P alloy on carbon fiber surfaces, increasing the ductility of the composites. This was probably due to the effect of substituted Ni-P alloy, leading to an increase of the resistance to the deformation and the crack initiation of the epoxy system.

Study of surface cleaning methods and pyrolysis temperatures on nanostructured carbon films using x-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kerber, Pranita; Porter, Lisa M.; McCullough, Lynne A.; Kowalewski, Tomasz; Engelhard, Mark; Baer, Donald [Department of Materials Science and Engineering, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213 (United States); Chemistry Department, Carnegie Mellon University, 5000 Forbes Avenue, Pittsburgh, Pennsylvania 15213 (United States); Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352 (United States)

2012-11-15

Nanostructured carbon (ns-C) films fabricated by stabilization and pyrolysis of diblock copolymers are of interest for a variety of electrical/electronic applications due to their chemical inertness, high-temperature insensitivity, very high surface area, and tunable electrical resistivity over a wide range [Kulkarni et al., Synth. Met. 159, 177 (2009)]. Because of their high porosity and associated high specific surface area, controlled surface cleaning studies are important for fabricating electronic devices from these films. In this study, quantification of surface composition and surface cleaning studies on ns-C films synthesized by carbonization of diblock copolymers of polyacrylonitrile-b-poly(n-butyl acrylate) at two different temperatures were carried out. X-ray photoelectron spectroscopy was used for elemental analysis and to determine the efficacy of various surface cleaning methods for ns-C films and to examine the polymer residues in the films. The in-situ surface cleaning methods included HF vapor treatment, vacuum annealing, and exposure to UV-ozone. Quantitative analysis of high-resolution XPS scans showed 11 at. % nitrogen was present in the films pyrolyzed at 600 Degree-Sign C, suggesting incomplete denitrogenation of the copolymer films. The nitrogen atomic concentration decreased significantly for films pyrolyzed at 900 Degree-Sign C confirming extensive denitrogenation at that temperature. Furthermore, quantitative analysis of nitrogen subpeaks indicated higher loss of nitrogen atoms residing at the edge of graphitic clusters relative to that of nitrogen atoms within the graphitic clusters, suggesting higher graphitization with increasing pyrolysis temperature. Of the surface cleaning methods investigated, in-situ annealing of the films at 300 Degree-Sign C for 40 min was found to be the most efficacious in removing adventitious carbon and oxygen impurities from the surface.

Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

International Nuclear Information System (INIS)

Arnold, D.W.

1994-08-01

Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O 3 - . A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO 2 , has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO 2 molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO 2 reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C 2 - - C 11 - ), and van der Waals clusters (X - (CO 2 ) n , X = I, Br, Cl; n ≤ 13 and I - (N 2 O) n=1--11 ). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X - (CO 2 )n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products

Photoelectron spectroscopy and the dipole approximation

Energy Technology Data Exchange (ETDEWEB)

Hemmers, O.; Hansen, D.L.; Wang, H. [Univ. of Nevada, Las Vegas, NV (United States)] [and others

1997-04-01

Photoelectron spectroscopy is a powerful technique because it directly probes, via the measurement of photoelectron kinetic energies, orbital and band structure in valence and core levels in a wide variety of samples. The technique becomes even more powerful when it is performed in an angle-resolved mode, where photoelectrons are distinguished not only by their kinetic energy, but by their direction of emission as well. Determining the probability of electron ejection as a function of angle probes the different quantum-mechanical channels available to a photoemission process, because it is sensitive to phase differences among the channels. As a result, angle-resolved photoemission has been used successfully for many years to provide stringent tests of the understanding of basic physical processes underlying gas-phase and solid-state interactions with radiation. One mainstay in the application of angle-resolved photoelectron spectroscopy is the well-known electric-dipole approximation for photon interactions. In this simplification, all higher-order terms, such as those due to electric-quadrupole and magnetic-dipole interactions, are neglected. As the photon energy increases, however, effects beyond the dipole approximation become important. To best determine the range of validity of the dipole approximation, photoemission measurements on a simple atomic system, neon, where extra-atomic effects cannot play a role, were performed at BL 8.0. The measurements show that deviations from {open_quotes}dipole{close_quotes} expectations in angle-resolved valence photoemission are observable for photon energies down to at least 0.25 keV, and are quite significant at energies around 1 keV. From these results, it is clear that non-dipole angular-distribution effects may need to be considered in any application of angle-resolved photoelectron spectroscopy that uses x-ray photons of energies as low as a few hundred eV.

Analysis of mechanism of carbon removal from GaAs(1 0 0) surface by atomic hydrogen

International Nuclear Information System (INIS)

Tomkiewicz, P.; Winkler, A.; Krzywiecki, M.; Chasse, Th.; Szuber, J.

2008-01-01

Etching of carbon contaminations from the GaAs(1 0 0) surface by irradiating with atomic hydrogen, which is one of the key reactions to promote high-quality thin films growth by molecular beam epitaxy (MBE), has been investigated by mass spectrometry (MS), Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS). It is shown that during the cleaning process at room temperature a total reduction of the Auger carbon signal, accompanied by desorption of methane as major reaction product, can be observed. The reaction pathways as well as the processes responsible for the observed carbon removal are discussed in detail to give a support for etching and growth quality enhancement not only in thin films epitaxy but in all atomic hydrogen promoted gas-phase III-V semiconductor processes

Photoelectron spectroscopy

International Nuclear Information System (INIS)

Bosch, A.

1982-01-01

In this work examples of the various aspects of photoelectron spectroscopy are given. The investigation was started with the development of an angle-resolved spectrometer so that the first chapters deal with angle-resolved ultra-violet photoelectron spectroscopy. To indicate the possibilities and pitfalls of the technique, in chapter II the theory is briefly reviewed. In chapter III the instrument is described. The system is based on the cylindrical mirror deflection analyzer, which is modified and improved for angle-resolved photoelectron spectroscopy. In combination with a position sensitive detector, a spectrometer is developed with which simultaneously several angle-resolved spectra can be recorded. In chapter IV, the results are reported of angle-integrated UPS experiments on dilute alloys. Using the improved energy resolution of the instrument the author was able to study the impurity states more accurately and shows that the photoemission technique has become an important tool in the study of impurities and the interactions involved. XPS and Auger results obtained from dilute alloys are presented in chapter V. It is shown that these systems are especially suited for the study of correlation effects and can provide interesting problems related to the satellite structure and the interaction of the impurity with the host. In chapter VI, the valence bands of ternary alloys are studied with UPS and compared to recent band structure calculation. The core level shifts are analyzed in a simple, thermodynamic scheme. (Auth.)

Excited state non-adiabatic dynamics of the smallest polyene, trans 1,3-butadiene. I. Time-resolved photoelectron-photoion coincidence spectroscopy

Science.gov (United States)

Boguslavskiy, Andrey E.; Schalk, Oliver; Gador, Niklas; Glover, William J.; Mori, Toshifumi; Schultz, Thomas; Schuurman, Michael S.; Martínez, Todd J.; Stolow, Albert

2018-04-01

The ultrafast excited state dynamics of the smallest polyene, trans-1,3-butadiene, were studied by femtosecond time-resolved photoelectron-photoion coincidence (TRPEPICO) spectroscopy. The evolution of the excited state wavepacket, created by pumping the bright 1Bu (ππ*) electronic state at its origin of 216 nm, is projected via one- and two-photon ionization at 267 nm onto several ionization continua. The results are interpreted in terms of Koopmans' correlations and Franck-Condon factors for the excited and cationic states involved. The known predissociative character of the cation excited states is utilized to assign photoelectron bands to specific continua using TRPEPICO spectroscopy. This permits us to report the direct observation of the famously elusive S1(21Ag) dark electronic state during the internal conversion of trans 1,3-butadiene. Our phenomenological analysis permits the spectroscopic determination of several important time constants. We report the overall decay lifetimes of the 11Bu and 21Ag states and observe the re-appearance of the hot ground state molecule. We argue that the apparent dephasing time of the S2(11Bu) state, which leads to the extreme breadth of the absorption spectrum, is principally due to large amplitude torsional motion on the 1Bu surface in conjunction with strong non-adiabatic couplings via conical intersections, whereupon nuclear wavepacket revivals to the initial Franck-Condon region become effectively impossible. In Paper II [W. J. Glover et al., J. Chem. Phys. 148, 164303 (2018)], ab initio multiple spawning is used for on-the-fly computations of the excited state non-adiabatic wavepacket dynamics and their associated TRPEPICO observables, allowing for direct comparisons of experiment with theory.

Conformational effects in photoelectron circular dichroism

Science.gov (United States)

Turchini, S.

2017-12-01

Photoelectron circular dichroism (PECD) is a novel type of spectroscopy, which presents surprising sensitivity to conformational effects in chiral systems. While classical photoelectron spectroscopy mainly responds to conformational effects in terms of energy level shifts, PECD provides a rich and detailed response to tiny changes in electronic and structural properties by means of the intensity dispersion of the circular dichroism as a function of photoelectron kinetic energy. In this work, the basics of PECD will be outlined, emphasizing the role of interference from the l,l+/- 1 outgoing partial wave of the photoelectron in the PECD transition matrix element, which is responsible for the extreme sensitivity to conformational effects. Examples using molecular systems and interfaces will shed light on the powerful application of PECD to classical conformational effects such as group substitution, isomerism, conformer population and clustering. Moreover, the PECD results will be reported in challenging new fields where conformations play a key role, such as vibrational effects, transient chirality and time- resolved experiments. To date, PECD has mostly been based on synchrotron radiation facilities, but it also has a future as a table-top lab experiment by means of multiphoton ionization. An important application of PECD as an analytical tool will be reported. The aim of this review is to illustrate that in PECD, the presence of conformational effects is essential for understanding a wide range of effects from a new perspective, making it different from classical spectroscopy.

Study of strontium- and magnesium-doped lanthanum gallate solid electrolyte surface by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Datta, Pradyot; Majewski, Peter; Aldinger, Fritz

2008-01-01

The chemical states of the surface of the oxygen ion conducting solid electrolyte La 0.9 Sr 0.1 Ga 0.85 Mg 0.15 O 3-δ (LSGM 1015) as prepared by solid-state synthesis was analyzed by X-ray photoelectron spectroscopy. It was found that adventitious carbon did not interact with any of the constituent elements of LSGM 1015. Ga and La were found to exist in trivalent states. But, due to ionic bombardment presence of Mg could not be detected in the electrolyte surface

A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO(-).

Science.gov (United States)

Roy, Soumendra K; Jian, Tian; Lopez, Gary V; Li, Wei-Li; Su, Jing; Bross, David H; Peterson, Kirk A; Wang, Lai-Sheng; Li, Jun

2016-02-28

The observation of the gaseous UFO(-) anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO(-) is linear with an O-U-F structure and a (3)H4 spectral term derived from a U 7sσ(2)5fφ(1)5fδ(1) electron configuration, whereas the ground state of neutral UFO has a (4)H(7/2) spectral term with a U 7sσ(1)5fφ(1)5fδ(1) electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

Projection methods for the analysis of molecular-frame photoelectron angular distributions

International Nuclear Information System (INIS)

Grum-Grzhimailo, A.N.; Lucchese, R.R.; Liu, X.-J.; Pruemper, G.; Morishita, Y.; Saito, N.; Ueda, K.

2007-01-01

A projection method is developed for extracting the nondipole contribution from the molecular frame photoelectron angular distributions of linear molecules. A corresponding convenient parametric form for the angular distributions is derived. The analysis was performed for the N 1s photoionization of the NO molecule a few eV above the ionization threshold. No detectable nondipole contribution was found for the photon energy of 412 eV

Anion photoelectron spectroscopy of radicals and clusters

Energy Technology Data Exchange (ETDEWEB)

Travis, Taylor R. [Univ. of California, Berkeley, CA (United States)

1999-12-01

Anion photoelectron spectroscopy is used to study free radicals and clusters. The low-lying ²Σ and ²π states of C_2nH (n = 1--4) have been studied. The anion photoelectron spectra yielded electron affinities, term values, and vibrational frequencies for these combustion and astrophysically relevant species. Photoelectron angular distributions allowed the author to correctly assign the electronic symmetry of the ground and first excited states and to assess the degree of vibronic coupling in C₂H and C₄H. Other radicals studied include NCN and I₃. The author was able to observe the low-lying singlet and triplet states of NCN for the first time. Measurement of the electron affinity of I₃ revealed that it has a bound ground state and attachment of an argon atom to this moiety enabled him to resolve the symmetric stretching progression.

Photoelectron-spectroscopic and reactivity investigation of thin Pd-Sn films prepared by magnetron sputtering

International Nuclear Information System (INIS)

Skala, T.; Veltruska, K.; Sedlacek, L.; Masek, K.; Matolinova, I.; Matolin, V.

2007-01-01

We have studied Pd-Sn layers with different composition prepared by magnetron sputtering. Layers were sputtered onto Al 2 O 3 and SiO 2 substrates and studied by X-ray photoelectron spectroscopy (XPS). Spectra confirmed that after vacuum annealing residual oxygen and carbon have been removed and bimetallic bonds have been created. The shift of Pd 3d 5/2 core level to higher binding energy followed by the peak narrowing in dependence on the composition was observed, accompanied by the shift of the Pd 4d in the valence band region, induced by hybridization of Pd-d and Sn-s,p states. Experiments carried out on a gas-flow reactor indicate increasing temperature of the CO oxidation with tin ratio in the alloy

Photoelectron and ICD electron angular distributions from fixed-in-space neon dimers

International Nuclear Information System (INIS)

Jahnke, T; Czasch, A; Schoeffler, M; Schoessler, S; Kaesz, M; Titze, J; Kreidi, K; Grisenti, R E; Staudte, A; Jagutzki, O; Schmidt, L Ph H; Semenov, S K; Cherepkov, N A; Schmidt-Boecking, H; Doerner, R

2007-01-01

We report on molecular frame angular distributions of 2s photoelectrons and electrons emitted by interatomic Coulombic decay from neon dimers. We found that the measured angular distribution of the photoelectron strongly depends on the environment of the cluster. The experimental results are in excellent agreement with frozen core Hartree-Fock calculations. The ICD electrons show slight variations in their angular distribution for different kinetic energies

Laser photoelectron spectrometry of Sc- and Y-

International Nuclear Information System (INIS)

Feigerle, C.S.; Herman, Z.; Lineberger, W.C.

1981-01-01

The photoelectron spectra of Sc - and Y - have been obtained in a crossed ion- and laser-beam experiment. Analysis of the Sc - spectrum yields two bound terms of 3d4s 2 4p configuration ( 1 D 0 and 3 D 0 ), with EA(Sc) = 0.189 +- 0.020 eV and an excited-state binding energy of 0.042 +- 0.020 eV. Similarly, the (4d5s 2 5p) 1 D 0 ground state of Y - is bound by 0.308 +- 0.012 eV and a (4d5s 2 5p) 3 D 0 excited term is bound by 0.165 +- 0.025 eV. With the determination of the bound electronic configuration of Sc - as 3d4s 2 4p, the order of filling of electron shells of the first transition series negative ions is found to be 4s 2 ep, 3d4s 2 4p, the order of filling of electron shells of the first transition series negative ions is found to be 4s 2 4p, 3d4s 2 4p, followed by 3dsup(k) 4s 2 (k = 3, 4, ..., 10). (orig.)

X-ray photoelectron spectroscopy study of {beta}-BaB{sub 2}O{sub 4} optical surface

Energy Technology Data Exchange (ETDEWEB)

Atuchin, V.V.; Kesler, V.G.; Kokh, A.E.; Pokrovsky, L.D

2004-02-29

An X-ray photoelectron spectroscopy (XPS) study has been performed for (0 0 1) BaB{sub 2}O{sub 4}. The crystal surface has been polished mechanically and cleaned by chemical etching. In XPS observation, depth profiling has been produced by sputtering with Ar{sup +} 3 keV ions. Photoelectron binding energies of original element core levels and valence band have been measured as a function of sputtering time. The persistence of binding energies of barium and boron core levels and valence band structure has been found. For O 1 s core level the formation of new spectral components with lower binding energies has been revealed.

Photoelectron diffraction of magnetic ultrathin films: Fe/Cu(001)

Energy Technology Data Exchange (ETDEWEB)

Tobin, J.G. (Lawrence Livermore National Lab., CA (USA)); Wagner, M.K. (Wisconsin Univ., Madison, WI (USA). Dept. of Chemistry); Guo, X.Q.; Tong, S.Y. (Wisconsin Univ., Milwaukee, WI (USA). Dept. of Physics)

1991-01-03

The preliminary results of an ongoing investigation of Fe/Cu(001) are presented here. Energy dependent photoelectron diffraction, including the spin-dependent variant using the multiplet split Fe3s state, is being used to investigate the nanoscale structures formed by near-monolayer deposits of Fe onto Cu(001). Core-level photoemission from the Fe3p and Fe3s states has been generated using synchrotron radiation as the tunable excitation source. Tentatively, a comparison of the experimental Fe3p cross section measurements with multiple scattering calculations indicates that the Fe is in a fourfold hollow site with a spacing of 3.6{Angstrom} between it and the atom directly beneath it, in the third layer. This is consistent with an FCC structure. The possibility of utilizing spin-dependent photoelectron diffraction to investigate magnetic ultrathin films will be demonstrated, using our preliminary spectra of the multiplet-split Fe3s os near-monolayer Fe/Cu(001). 18 refs., 10 figs.

Preparation and photoelectronic and electrochemical properties of oligo [(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)]s

Energy Technology Data Exchange (ETDEWEB)

Jung, Young Min; Park, Young Tae [Dept. of Chemistry, Keimyung University, Daegu (Korea, Republic of); Baek, Seong Ho [Div. of Green Energy Research, Daegu Gyeongbuk Institute of Science and Technology, Daegu (Korea, Republic of)

2017-01-15

We oligomerized 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole with dichloroalkylphenylsilanes utilizing n-BuLi to yield conjugated oligo [(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(alkylphenylsilylene)]s. Gel permeation chromatography measurements confirm that the synthesized materials are oligomeric. In addition, the prepared oligomers show characteristic diene stretching bands at 1579–1599 cm{sup −1} in their FT-IR spectra. Furthermore, the oligomers are highly soluble in common organic solvents such as tetrahydrofuran and chloroform. In tetrahydrofuran, the oligomers show strong maximum electronic absorption bands at 253–292 nm with molar absorptivities of 1.61 × 10{sup 2} to 2.57 × 10{sup 4} /cm M in their UV–vis electronic absorption spectra, indicating that the maxima are red-shifted by 5–8 nm compared to the 2,5-dibromo-1,1-diisopropyl-3,4-diphenyl-2,5-silole monomer, strong maximum electronic excitation bands at 292–312 nm, and strong maxima electronic emission bands at 385–396 nm in the emission fluorescence spectra. The emission and absorption spectra strongly suggest that the prepared silole-containing oligomers may be conjugated through the oligomer backbone. In particular, cyclic voltammetry measurements of oligo[(1,1-diisopropyl-3,4-diphenyl-2,5-silolene)-co-(diphenylsilylene)] deposited on a glassy carbon electrode in 1.0 M aqueous hydrogen chloride show two oxidation potentials at 0.98 and 1.61 V vs. Ag/Ag{sup +}, and two reduction potentials at 0.00 and −1.93 V vs. Ag/Ag{sup +}. The oligomers were stable on heating to 200 °C under nitrogen, as determined by thermogravimetric analysis, losing between 4% and 23% of their starting weights.

The threshold photoelectron spectrum of the geminal chloro-fluoro-ethene (1,1-C2H2FCl) isomer. Experiment and theory

International Nuclear Information System (INIS)

Locht, R; Leyh, B; Dehareng, D

2014-01-01

The threshold photoelectron spectrum (TPES) of 1,1-C 2 H 2 FCl has been measured for the first time using synchrotron radiation. It has been compared to the HeI PES obtained earlier (Tornow et al 1990 Chem. Phys. 146 115). Eight photoelectron bands have been observed at 10.22, 12.45, 13.28, 14.29, 14.99, 17.12, 17.67 and at 20.23 eV successively. Only the first three bands exhibit a rich and extensive vibrational structure. Their adiabatic ionization energies are measured and a detailed vibrational analysis is presented. The assignments of the electronic bands and of the vibrational wavenumbers were made by using ab initio quantum chemical calculations. These allowed us to provide the MO description of the eight electronic states in terms of ionization and double excitation. The good correlation between predicted vibrational wavenumbers and the experimental values provides a strong basis for the assignment of all the vibrational structures. (paper)

Activated carbon-supported CuO nanoparticles: a hybrid material for carbon dioxide adsorption

Science.gov (United States)

Boruban, Cansu; Esenturk, Emren Nalbant

2018-03-01

Activated carbon-supported copper(II) oxide (CuO) nanoparticles were synthesized by simple impregnation method to improve carbon dioxide (CO2) adsorption capacity of the support. The structural and chemical properties of the hybrid material were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (https://www.google.com.tr/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0CCsQFjAC&url=http%3A%2F%2Fwww.intertek.com%2Fanalytical-laboratories%2Fxrd%2F&ei=-5WZVYSCHISz7Aatqq-IAw&usg=AFQjCNFBlk-9wqy49foh8tskmbD-GGbG9g&sig2=eKrhYjO75rl_Id2sLGpq4w&bvm=bv.96952980,d.bGg) (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption spectroscopy (AAS), and Brunauer-Emmett-Teller (BET) analyses. The analyses showed that CuO nanoparticles are well-distributed on the activated carbon surface. The CO2 adsorption behavior of the activated carbon-supported CuO nanoparticles was observed by thermogravimetric analysis (TGA), temperature programmed desorption (TPD), Fourier transform infrared (FTIR), and BET analyses. The results showed that CuO nanoparticle loading on activated carbon led to about 70% increase in CO2 adsorption capacity of activated carbon under standard conditions (1 atm and 298 K). The main contributor to the observed increase is an improvement in chemical adsorption of CO2 due to the presence of CuO nanoparticles on activated carbon.

Distortion dependent intersystem crossing: A femtosecond time-resolved photoelectron spectroscopy study of benzene, toluene, and p-xylene

Directory of Open Access Journals (Sweden)

Anne B. Stephansen

2017-07-01

Full Text Available The competition between ultrafast intersystem crossing and internal conversion in benzene, toluene, and p-xylene is investigated with time-resolved photoelectron spectroscopy and quantum chemical calculations. By exciting to S2 out-of-plane symmetry breaking, distortions are activated at early times whereupon spin-forbidden intersystem crossing becomes (partly allowed. Natural bond orbital analysis suggests that the pinnacle carbon atoms distorting from the aromatic plane change hybridization between the planar Franck-Condon geometry and the deformed (boat-shaped S2 equilibrium geometry. The effect is observed to increase in the presence of methyl-groups on the pinnacle carbon-atoms, where largest extents of σ and π orbital-mixing are observed. This is fully consistent with the time-resolved spectroscopy data: Toluene and p-xylene show evidence for ultrafast triplet formation competing with internal conversion, while benzene appears to only decay via internal conversion within the singlet manifold. For toluene and p-xylene, internal conversion to S1 and intersystem crossing to T3 occur within the time-resolution of our instrument. The receiver triplet state (T3 is found to undergo internal conversion in the triplet manifold within ≈100–150 fs (toluene or ≈180–200 fs (p-xylene as demonstrated by matching rise and decay components of upper and lower triplet states. Overall, the effect of methylation is found to both increase the intersystem crossing probability and direct the molecular axis of the excited state dynamics.

High temperature and high resolution uv photoelectron spectroscopy using supersonic molecular beams

International Nuclear Information System (INIS)

Wang, Lai-Sheng; Reutt-Robey, J.E.; Niu, B.; Lee, Y.T.; Shirley, D.A.

1989-07-01

A high temperature molecular beam source with electron bombardment heating has been built for high resolution photoelectron spectroscopic studies of high temperature species and clusters. This source has the advantages of: producing an intense, continuous, seeded molecular beam, eliminating the interference of the heating mechanism from the photoelectron measurement. Coupling the source with our hemispherical electron energy analyzer, we can obtain very high resolution HeIα (584 angstrom) photoelectron spectra of high temperature species. Vibrationally-resolved photoelectron spectra of PbSe, As 2 , As 4 , and ZnCl 2 are shown to demonstrate the performance of the new source. 25 refs., 8 figs., 1 tab

The effect of gamma ray irradiation on PAN-based intermediate modulus carbon fibers

International Nuclear Information System (INIS)

Li, Bin; Feng, Yi; Qian, Gang; Zhang, Jingcheng; Zhuang, Zhong; Wang, Xianping

2013-01-01

Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) were conducted on PAN-based intermediate modulus carbon fibers to investigate the structure and surface hydrophilicity of the carbon fibers before and after gamma irradiation. Two methods were used to determine Young’s modulus of the carbon fibers. The results show that gamma ray irradiation improved the degree of graphitization and introduced compressive stress into carbon fiber surface. Gamma ray also improved the carbon fiber surface hydrophilicity through increasing the value of O/C and enhancing the quantity of oxygen functional groups on carbon fibers. No distinct morphology change was observed after gamma ray irradiation. The Young’s modulus of the fibers increased with increasing irradiation dose

Multiphoton ionization photoelectron spectroscopy of xenon: Experiment and theory

International Nuclear Information System (INIS)

Bajic, S.J.; Compton, R.N.; Tang, X.; L'Huiller, A.; Lambropoulos, P.

1988-11-01

Photoelectron energy and angular distributions for resonantly enhanced multiphoton ionization (REMPI) of xenon via the three-photon-allowed 7s[3/2] 1 0 and 5d[3/2] 1 0 states have been studied both experimentally and theoretically. The electron kinetic energy spectra give the probability of leaving Xe + in either the 2 P/sub 1/2/ or 2 P/sub 3/2/ core. The measured branching ratio for leaving each ionic core is used to test the theoretical description of the REMPI process. Measurements of both the angular distributions and the [3+1] REMPI via the 5d state are adequately reproduced by multichannel quantum defect theory. However, measurements of angular distributions for the electrons resulting from [3+1] via the 7s[3/2] 1 0 state into Xe + 2 P/sub 3/2/ (core preserving) or Xe + 2 P/sub 1/2/ (core changing) are in striking disagreement with theory. 1 ref., 2 figs

Forest biomass carbon stocks and variation in Tibet’s carbon-dense forests from 2001 to 2050

Science.gov (United States)

Sun, Xiangyang; Wang, Genxu; Huang, Mei; Chang, Ruiying; Ran, Fei

2016-01-01

Tibet’s forests, in contrast to China’s other forests, are characterized by primary forests, high carbon (C) density and less anthropogenic disturbance, and they function as an important carbon pool in China. Using the biomass C density data from 413 forest inventory sites and a spatial forest age map, we developed an allometric equation for the forest biomass C density and forest age to assess the spatial biomass C stocks and variation in Tibet’s forests from 2001 to 2050. The results indicated that the forest biomass C stock would increase from 831.1 Tg C in 2001 to 969.4 Tg C in 2050, with a net C gain of 3.6 Tg C yr−1 between 2001 and 2010 and a decrease of 1.9 Tg C yr−1 between 2040 and 2050. Carbon tends to allocate more in the roots of fir forests and less in the roots of spruce and pine forests with increasing stand age. The increase of the biomass carbon pool does not promote significant augmentation of the soil carbon pool. Our findings suggest that Tibet’s mature forests will remain a persistent C sink until 2050. However, afforestation or reforestation, especially with the larger carbon sink potential forest types, such as fir and spruce, should be carried out to maintain the high C sink capacity. PMID:27703215

Photoelectron spectroscopy principles and applications

CERN Document Server

Hüfner, Stefan

1995-01-01

Photoelectron Spectroscopy presents an up-to-date introduction to the field by treating comprehensively the electronic structures of atoms, molecules, solids and surfaces Brief descriptions are given of inverse photoemission, spin-polarized photoemission and photoelectron diffraction Experimental aspects are considered throughout the book, and the results are carefully interpreted by theory A wealth of measured data is presented in the form of tables for easy use by experimentalists

Scanned-energy mode photoelectron diffraction measurements at beamline 7.0.1

International Nuclear Information System (INIS)

Toomes, R.; Booth, N.A.; Woodruff, D.P.

1997-01-01

This report covers the results of the authors first experimental run, in May 1996, conducted to explore the advantages offered by the high spectral resolution available at the SpectroMicroscopy Facility on beam line 7.0 to conduct scanned-energy mode photoelectron diffraction (PhD). This technique is now a well-established method for the determination of local structure of atomic and molecular adsorbates on well-characterised surfaces. The directly-emitted component of an adsorbate core-level photoelectron wavefield interferes coherently with components of the same wavefield elastically scattered by surrounding atoms, leading to a modulation in the photoemission intensity as a function of kinetic energy in any specific emission direction. A series of such PhD modulation spectra, each typically covering energies from 50-500 eV, for a series of different emission directions, provides the basis for a quantitative structure determination of the emitter-scatterer geometry. Within the last years the authors have developed an integrated approach to extract the structural information from these photoelectron diffraction (PhD) spectra in a quantitative way. A direct data inversion technique (the so-called Projection method) provides a first-order estimate of the local adsorbate geometry in the form of an 'image' of the scatterer atoms which are nearest neighbours to the emitter. This information is then used as a starting model for optimisation of the structural parameters by comparing the experimental PhD spectra with the results of multiple scattering simulations using a code developed by Fritzsche. The optimisation uses an automated trial-and-error procedure by minimising a reliability factor which provides an objective measure of the quality of agreement between experiment and theory. The authors have successfully applied this approach to the structure determination of about 30 adsorption systems

Scanned-energy mode photoelectron diffraction measurements at beamline 7.0.1

Energy Technology Data Exchange (ETDEWEB)

Toomes, R.; Booth, N.A.; Woodruff, D.P. [Univ. of Warwick, Coventry (United Kingdom)] [and others

1997-04-01

This report covers the results of the authors first experimental run, in May 1996, conducted to explore the advantages offered by the high spectral resolution available at the SpectroMicroscopy Facility on beam line 7.0 to conduct scanned-energy mode photoelectron diffraction (PhD). This technique is now a well-established method for the determination of local structure of atomic and molecular adsorbates on well-characterised surfaces. The directly-emitted component of an adsorbate core-level photoelectron wavefield interferes coherently with components of the same wavefield elastically scattered by surrounding atoms, leading to a modulation in the photoemission intensity as a function of kinetic energy in any specific emission direction. A series of such PhD modulation spectra, each typically covering energies from 50-500 eV, for a series of different emission directions, provides the basis for a quantitative structure determination of the emitter-scatterer geometry. Within the last years the authors have developed an integrated approach to extract the structural information from these photoelectron diffraction (PhD) spectra in a quantitative way. A direct data inversion technique (the so-called Projection method) provides a first-order estimate of the local adsorbate geometry in the form of an `image` of the scatterer atoms which are nearest neighbours to the emitter. This information is then used as a starting model for optimisation of the structural parameters by comparing the experimental PhD spectra with the results of multiple scattering simulations using a code developed by Fritzsche. The optimisation uses an automated trial-and-error procedure by minimising a reliability factor which provides an objective measure of the quality of agreement between experiment and theory. The authors have successfully applied this approach to the structure determination of about 30 adsorption systems.

Plasma Treatment of Carbon Nanotubes Applied to Improve the High Performance of Carbon Nanofiber Supercapacitors

International Nuclear Information System (INIS)

Chang, Wei-Min; Wang, Cheng-Chien; Chen, Chuh-Yung

2015-01-01

Graphical abstract: This article focused on improving conductivity of carbon nanofibers (CNFs) by added plasma-treatment carbon nanotubes (CNTs). The plasma modification method avoided the destruction of the length and structure of the CNTs and maintained their good electrical properties. Through this method, the relation between conductivity and surface activity site of CNFs was investigated. The results shown that he CNTs-MA added to the CNFs successfully maintained the activity sites on the surface of the CNFs and provide a good electric network to enhance the supercapacitor performance of the CNFs. - Highlights: • The plasma modification method avoided the destruction of the length and structure of the CNTs and maintained their good electrical properties. • The highest conductivity of the CNTs-MA/CNF was 5.2 s/cm at 2.5 wt.% of CNTs-MA addition. It was increased to 8.7 time. • The CNTs-MA added to the CNFs successfully maintained the activity sites on the surface of the CNFs and provide a good electric network to enhance the supercapacitor performance of the CNFs. The highest capacitance was 382 F/g. - Abstract: Plasma-treatment carbon nanotubes (CNTs) grafted with maleic anhydride (MA) were embedded in polyacryonitrile nanofibers via electrospinning and subsequently carbonizated at 800 °C to fabricate carbon nanofibers (CNFs). The grafted degree of MA on CNTs (CNTs-MA) was determined via Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The morphology, surface composition and conductivity of the CNTs-MA/CNF were characterized using electron microscopy, X-ray photoelectron and electrochemical impedance spectroscopy, respectively. CNTs-MA not only affected the conductivity of the CNFs but also the types of the nitrogen functional groups that could be represented as active sites on the CNFs to enhance the performance of the supercapacitors. When 2.5 wt.% CNTs-MA was embedded in the CNFs, the highest conductivity was obtained at

Atomic photoelectron-spectroscopy studies using synchrotron radiation

International Nuclear Information System (INIS)

Kobrin, P.H.

1983-02-01

Photoelectron spectroscopy combined with tunable synchrotron radiation has been used to study the photoionization process in several atomic systems. The time structure of the synchrotron radiation source at the Stanford Synchrotron Radiation Laboratory (SSRL) was used to record time-of-flight (TOF) photoelectron spectra of gaseous Cd, Hg, Ne, Ar, Ba, and Mn. The use of two TOF analyzers made possible the measurement of photoelectron angular distributions as well as branching ratios and partial cross sections

Practical chemical analysis of Pt and Pd based heterogeneous catalysts with hard X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Yoshikawa, H., E-mail: YOSHIKAWA.Hideki@nims.go.jp [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Matolínová, I.; Matolín, V. [Charles University in Prague, Faculty of Mathematics and Physics, V Holešovičkách 2, 18000 Prague 8 (Czech Republic)

2013-10-15

Highlights: •Hard X-ray photoelectron spectroscopy (HAXPES) enables interface analysis of catalyst. •HAXPES enables overall analysis of porous film of Pt-doped CeO{sub 2} and related catalyst. •HAXPES enables analysis of trace elements for Pd and Pt{sub 3}Ni nanoparticle catalysts. -- Abstract: Interfacial properties including configuration, porosity, chemical states, and atomic diffusion greatly affect the performance of supported heterogeneous catalysts. Hard X-ray photoelectron spectroscopy (HAXPES) can be used to analyze the interfaces of heterogeneous catalysts because of its large information depth of more than 20 nm. We use HAXPES to examine Pt-doped CeO{sub 2} and related thin film catalysts evaporated on Si, carbon, and carbon nanotube substrates, because Pt-doped CeO{sub 2} has great potential as a noble metal-based heterogeneous catalyst for fuel cells. The HAXPES measurements clarify that the dopant material, substrate material, and surface pretreatment of substrate are important parameters that affect the interfacial properties of Pt-doped CeO{sub 2} and related thin film catalysts. Another advantage of HAXPES measurement of heterogeneous catalysts is that it can be used for chemical analysis of trace elements by detecting photoelectrons from deep core levels, which have large photoionization cross-sections in the hard X-ray region. We use HAXPES for chemical analysis of trace elements in Pd nanoparticle catalysts immobilized on sulfur-terminated substrates and Pt{sub 3}Ni nanoparticle catalysts enveloped by dendrimer molecules.

Full k-space visualization of photoelectron diffraction

International Nuclear Information System (INIS)

Denlinger, J.D.; Rotenberg, E.; Kevan, S.D.; Tonner, B.P.

1997-01-01

The development of photoelectron holography has promoted the need for larger photoelectron diffraction data sets in order to improve the quality of real-space reconstructed images (by suppressing transformational artifacts and distortions). The two main experimental and theoretical approaches to holography, the transform of angular distribution patterns for a coarse selection of energies or the transform of energy-scanned profiles for several directions, represent two limits to k-space sampling. The high brightness of third-generation soft x-ray synchrotron sources provides the opportunity to rapidly measure large high-density x-ray photoelectron diffraction (XPD) data sets with approximately uniform k-space sampling. In this abstract, the authors present such a photoelectron data set acquired for Cu 3p emission from Cu(001). Cu(001) is one of the most well-studied systems for understanding photoelectron diffraction structure and for testing photoelectron holography methods. Cu(001) was chosen for this study in part due to the relatively inert and unreconstructed clean surface, and it served to calibrate and fine-tune the operation of a new synchrotron beamline, electron spectrometer and sample goniometer. In addition to Cu, similar open-quotes volumeclose quotes XPD data sets have been acquired for bulk and surface core-level emission from W(110), from reconstructed Si(100) and Si(111) surfaces, and from the adsorbate system of c(2x2) Mn/Ni(100)

A combined photoelectron spectroscopy and relativistic ab initio studies of the electronic structures of UFO and UFO-

Science.gov (United States)

Roy, Soumendra K.; Jian, Tian; Lopez, Gary V.; Li, Wei-Li; Su, Jing; Bross, David H.; Peterson, Kirk A.; Wang, Lai-Sheng; Li, Jun

2016-02-01

The observation of the gaseous UFO- anion is reported, which is investigated using photoelectron spectroscopy and relativisitic ab initio calculations. Two strong photoelectron bands are observed at low binding energies due to electron detachment from the U-7sσ orbital. Numerous weak detachment bands are also observed due to the strongly correlated U-5f electrons. The electron affinity of UFO is measured to be 1.27(3) eV. High-level relativistic quantum chemical calculations have been carried out on the ground state and many low-lying excited states of UFO to help interpret the photoelectron spectra and understand the electronic structure of UFO. The ground state of UFO- is linear with an O-U-F structure and a 3H4 spectral term derived from a U 7sσ25fφ15fδ1 electron configuration, whereas the ground state of neutral UFO has a 4H7/2 spectral term with a U 7sσ15fφ15fδ1 electron configuration. Strong electron correlation effects are found in both the anionic and neutral electronic configurations. In the UFO neutral, a high density of electronic states with strong configuration mixing is observed in most of the scalar relativistic and spin-orbit coupled states. The strong electron correlation, state mixing, and spin-orbit coupling of the electronic states make the excited states of UFO very challenging for accurate quantum chemical calculations.

Nitrogen- and oxygen-enriched carbon with square tubular structure prepared from polyaniline as electrode for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Xiang, X.; Liu, E.; Wu, Y.; Tian, Y.; Xie, H.; Wu, Z.; Zhu, Y. [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan (China)

2012-10-15

Square tubular carbon with a large number of surface functional groups are prepared by carbonizing and activating polyaniline, which are synthesized by polymerization of aniline with a template-free self-assembly method in aqueous media. The physicochemical properties of the square tubular carbon is characterized by scanning and transmission electron microscopy, Brunauer-Emmett-Teller surface area measurements, Raman spectroscopy, and X-ray photoelectron spectroscopy measurements. When used as an electrode, the square tubular carbon exhibit a specific capacitance of 223 F g{sup -1} at a scan rate of 2 mV s{sup -1}, which could still stay over 90% when the scan rate increased by 10 times. The specific capacitance even hardly decrease at a current density of 3 A g{sup -1} after 10,000 cycles, which indicates that the square tubular carbon have good cycle durability and may be a promising candidate as an electrode for supercapacitors. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the wide-energy-range tuning of x-ray photoemission electron microscope optics for the observation of the photoelectrons excited by several keV x-rays

International Nuclear Information System (INIS)

Yasufuku, H.; Yoshikawa, H.; Kimura, M.; Vlaicu, A.M.; Kato, M.; Kudo, M.; Fujikata, J.; Fukushima, S.

2006-01-01

We have newly developed an x-ray photoemission electron microscope (XPEEM) which uses both soft x-rays and hard x-rays at the undulator beam line BL15XU in the synchrotron radiation (SR) facility SPring-8 to observe various practical materials. In combination with an energy analyzer and high brilliant x-ray source, the detection of high kinetic energy inner-shell photoelectrons is essential for revealing the chemical properties of specimen subsurfaces or buried interfaces, owing to long inelastic mean free path of the high kinetic energy photoelectrons. The most significant result in our design is the new combined electric and magnetic field objective lens in which the magnetic field penetrates up to the sample surface. This allows the measurement with high spatial resolution of both low intensity images of inner-shell photoelectrons with high kinetic energy and high intensity images of secondary electrons. By using the sample bias scan method, we can easily change the focus condition of the objective lens in order to allow the energy filtered imaging with photoelectrons having the kinetic energy in a wide range (1-10 000 eV). By the combination of high brilliant SR x-rays, the new objective lens, and sample bias method, our XPEEM can successfully obtain the microarea x-ray photoelectron spectra and energy filtered XPEEM images of inner-shell photoelectrons, such as Si 1s, without any surface cleaning procedure. The energy filtered XPEEM image using photoelectrons from deep inner shells, Si 1s, was obtained for the first time

Surface modification of pyrolyzed carbon fibres by cyclic voltammetry and their characterization with XPS and dye adsorption

International Nuclear Information System (INIS)

Georgiou, P.; Walton, J.; Simitzis, J.

2010-01-01

Commercial carbon fibres were pyrolyzed up to 1000 deg. C and were then electrochemically treated by cyclic voltammetry in aqueous electrolyte solutions of H 2 SO 4 , in two potential sweep ranges: a narrow region, N, and a wide region, W, avoiding and including water decomposition, respectively. The anodic and cathodic peaks were correlated with oxide formation and their partial reduction, respectively. The nature of oxygen containing groups on the fibre surfaces was determined by XPS. Wide scan spectra and high energy resolution spectra were recorded through the C 1s, O 1s, N 1s and S 2p photoelectron regions. The ability of the fibres to adsorb methylene blue and alizarin yellow dyes from their aqueous solutions indicates the presence of electron acceptor or donor groups on the fibres, respectively. The carbon fibres were classified into two categories. The first includes electrochemically untreated and treated in the N region, and the second those treated in the W region. The high oxygen concentration and effective dye adsorption on the carbon fibres in the second category indicates that their surfaces were effectively modified. The adsorption of dyes on carbon fibres constitutes a complementary method to XPS for an indirect estimation of oxygen and other groups present on the carbon fibre surfaces.

High-energy double photoeffect and photoionization with excitation from 2 {sup 1}S and 2 {sup 3}S states of helium-like ions

Energy Technology Data Exchange (ETDEWEB)

Amusia, M.Ya. [The Racah Institute of Physics, Hebrew University, 91904 Jerusalem (Israel); A F Ioffe Physical-Technical Institute, 194921 St Petersburg (Russian Federation); Mikhailov, A.I.; Mikhailov, I.A. [St Petersburg Nuclear Physics Institute, Gatchina, 188350 St Petersburg (Russian Federation)

1999-10-28

Double ionization and ionization with excitation of helium-like ions with Z>>1 from 2 {sup 1}S and 2 {sup 3}S states on the absorption of a high-frequency photon have been considered. The analytical calculation is performed in the non-relativistic photon energy range in the lowest order of perturbation theory in the inter-electron interaction. Coulomb wavefunctions and the Coulomb Green function are used as a zeroth-order approximation. Differential and total cross sections of the processes are expressed via the corresponding values for the single photoionization. The photoelectron energy spectrum is obtained in the marginal energy range (i.e. for p{sub 1}>>p{sub 2}, p{sub 1} and p{sub 2} momenta of photoelectrons) for the double-ionization process. Simple relations between the cross sections of double ionization and ionization with excitation are derived. (author)

Shake-up transitions in S 2p, S 2s and F 1s photoionization of the SF6 molecule

International Nuclear Information System (INIS)

Decleva, P; Fronzoni, G; Kivimaeki, A; Alvarez Ruiz, J; Svensson, S

2009-01-01

Shake-up transitions occurring upon core photoionization in the SF 6 molecule have been studied experimentally and theoretically. The S 2p, S 2s and F 1s shake-up satellite photoelectron spectra were measured using Al Ka radiation at 1487 eV photon energy. They have been interpreted with the aid of ab initio configuration interaction calculations in the sudden-limit approximation. For the S 2p spectrum, conjugate shake-up transitions were also calculated. Clear evidence of conjugate processes is observed in the S 2p shake-up spectrum measured at 230 eV photon energy. The experimental and theoretical S 2p and S 2s shake-up spectra show very similar structures mainly due to orbital relaxation involving S 3s and 3p participation. For the calculation of the F 1s shake-up spectrum, the symmetry lowering of the molecule in the final states was considered, resulting in a good agreement with the experiment.

Study of radicals, clusters and transition state species by anion photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Arnold, Don Wesley [Univ. of California, Berkeley, CA (United States)

1994-08-01

Free radicals, elemental and van der Waals clusters and transition state species for bimolecular chemical reactions are investigated using anion photoelectron spectroscopy. Several low-lying electronic states of ozone have been identified via photoelectron spectroscopy of O₃^-. A characterization of these states is important to models for atmospheric ozone reaction kinetics. The fluoroformyloxyl radical, FCO₂, has been investigated, providing vibrational frequencies and energies for two electronic states. The technique has also been employed to make the first direct observation and characterization of the NNO₂ molecule. Several electronic states are observed for this species which is believed to play a role as a reactive intermediate in the N + NO₂ reaction. The experimental results for all three of these radicals are supplemented by ab initio investigations of their molecular properties. The clusters investigations include studies of elemental carbon clusters (C₂^- - C₁₁^-), and van der Waals clusters (X^-(CO₂)_n, X = I, Br, Cl; n {le} 13 and I^- (N₂O)_n=1--11). Primarily linear clusters are observed for the smaller carbon clusters, while the spectra of the larger clusters contain contribution from cyclic anion photodetachment. Very interesting ion-solvent interactions are observed in the X^-(CO₂)n clusters. The transition state regions for several bimolecular chemical reactions have also been investigated by photodetachment of a negative ion precursor possessing a geometry similar to that of the transition state species. These spectra show features which are assigned to motions of the unstable neutral complex existing between reactants and products.

Probing deeper by hard x-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Risterucci, P.; Renault, O., E-mail: olivier.renault@cea.fr; Martinez, E.; Delaye, V. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); Detlefs, B. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Zegenhagen, J. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Gaumer, C. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles (France); Grenet, G. [Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, 36, avenue Guy de Collongue 69 134 Ecully Cedex (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

2014-02-03

We report an hard x-ray photoelectron spectroscopy method combining high excitation energy (15 keV) and improved modelling of the core-level energy loss features. It provides depth distribution of deeply buried layers with very high sensitivity. We show that a conventional approach relying on intensities of the core-level peaks is unreliable due to intense plasmon losses. We reliably determine the depth distribution of 1 ML La in a high-κ/metal gate stack capped with 50 nm a-Si. The method extends the sensitivity of photoelectron spectroscopy to depths beyond 50 nm.

Surface modification by vacuum annealing for field emission from heavily phosphorus-doped homoepitaxial (1 1 1) diamond

International Nuclear Information System (INIS)

Yamada, Takatoshi; Nebel, Christoph E.; Somu, Kumaragurubaran; Shikata, Shin-ichi

2008-01-01

The relationship between field emission properties and C 1s core level shifts of heavily phosphorus-doped homoepitaxial (1 1 1) diamond is investigated as a function of annealing temperature in order to optimize surface carbon bonding configurations for device applications. A low field emission threshold voltage is observed from surfaces annealed at 800 deg. C for hydrogen-plasma treated surface, while a low field emission threshold voltage of wet-chemical oxidized surface is observed after annealing at 900 deg. C. The C 1s core level by X-ray photoelectron spectroscopy (XPS) showed a shoulder peak at 1 eV below the main peak over 800 and 900 deg. C annealing temperature for hydrogen-plasma treated and wet-chemical oxidized surfaces, respectively. When the shoulder peak intensity is less than 10% of the main peak intensity, lower threshold voltages are observed. This is due to the carbon-reconstruction which gives rise to a small positive electron affinity. By increasing annealing temperature, the shoulder peak ratios also increase, which indicates that a surface graphitization takes place. This leads to higher threshold voltages

Structures of cycloserine and 2-oxazolidinone probed by X-ray photoelectron spectroscopy: theory and experiment.

Science.gov (United States)

Ahmed, Marawan; Wang, Feng; Acres, Robert G; Prince, Kevin C

2014-05-22

The electronic structures and properties of 2-oxazolidinone and the related compound cycloserine (CS) have been investigated using theoretical calculations and core and valence photoelectron spectroscopy. Isomerization of the central oxazolidine heterocycle and the addition of an amino group yield cycloserine. Theory correctly predicts the C, N, and O 1s core spectra, and additionally, we report theoretical natural bond orbital (NBO) charges. The valence ionization energies are also in agreement with theory and previous measurements. Although the lowest binding energy part of the spectra of the two compounds shows superficial similarities, further analysis of the charge densities of the frontier orbitals indicates substantial reorganization of the wave functions as a result of isomerization. The highest occupied molecular orbital (HOMO) of CS shows leading carbonyl π character with contributions from other heavy (non-H) atoms in the molecule, while the HOMO of 2-oxazolidinone (OX2) has leading nitrogen, carbon, and oxygen pπ characters. The present study further theoretically predicts bond resonance effects of the compounds, evidence for which is provided by our experimental measurements and published crystallographic data.

A microcomputer-controlled modulation technique for the detection of transient species in UV photoelectron spectroscopy

International Nuclear Information System (INIS)

Lonkhuyzen, H. van; Muller, H.G.; Lange, C.A. de

1980-01-01

A microcomputer-controlled modulation method is described to measure UV photoelectron spectra of transient species generated in a microwave discharge. Spectra at low and high microwave power levels are simultaneously recorded and afterwards linearly combined in order to remove parent compound signals. The method is applied to discharged oxygen where the transition O 2 + ( 2 PHIsub(u)) 2 ( 1 Δsub(g)) becomes visible without interference from the parent molecule O 2 ( 3 Σsub(g) - ), and to discharged sulphur dioxide where SO( 3 Σ - ) and S( 3 P) photoelectron spectra are obtained free from SO 2 bands. Finally the build-up of transient bands as a function of time is recorded. (orig.)

Bimolecular reaction dynamics from photoelectron spectroscopy of negative ions

Energy Technology Data Exchange (ETDEWEB)

Bradforth, S.E.

1992-11-01

The transition state region of a neutral bimolecular reaction may be experimentally investigated by photoelectron spectroscopy of an appropriate negative ion. The photoelectron spectrum provides information on the spectroscopy and dynamics of the short lived transition state and may be used to develop model potential energy surfaces that are semi-quantitative in this important region. The principles of bound [yields] bound negative ion photoelectron spectroscopy are illustrated by way of an example: a full analysis of the photoelectron bands of CN[sup [minus

Variable Mixed Orbital Character in the Photoelectron Angular Distribution of NO_{2}

Science.gov (United States)

Laws, Benjamin A.; Cavanagh, Steven J.; Lewis, Brenton R.; Gibson, Stephen T.

2017-06-01

NO_{2} a key component of photochemical smog and an important species in the Earth's atmosphere, is an example of a molecule which exhibits significant mixed orbital character in the HOMO. In photoelectron experiments the geometric properties of the parent anion orbital are reflected in the photoelectron angular distribution (PAD), an area of research that has benefited largely from the ability of velocity-map imaging (VMI) to simultaneously record both the energetic and angular information, with 100% collection efficiency. Photoelectron spectra of NO_{2}^{-}, taken over a range of wavelengths (355nm-520nm) with the ANU's VMI spectrometer, reveal an anomalous jump in the anisotropy parameter near threshold. Consequently, the orbital behavior of NO_{2}^{-} appears to be quite different near threshold compared to detachment at higher photon energies. This surprising effect is due to the Wigner Threshold law, which causes p orbital character to dominate the photodetachment cross-section near threshold, before the mixed s/d orbital character becomes significant at higher electron kinetic energies. By extending recent work on binary character models to form a more general expression, the variable mixed orbital character of NO_{2}^{-} is able to be described. This study provides the first multi-wavelength NO_{2} anisotropy data, which is shown to be in decent agreement with much earlier zero-core model predictions of the anisotropy parameter. K. J. Reed, A. H. Zimmerman, H. C. Andersen, and J. I. Brauman, J. Chem. Phys. 64, 1368, (1976). doi:10.1063/1.432404 D. Khuseynov, C. C. Blackstone, L. M. Culberson, and A. Sanov, J. Chem. Phys. 141, 124312, (2014). doi:10.1063/1.4896241 W. B. Clodius, R. M. Stehman, and S. B. Woo, Phys. Rev. A. 28, 760, (1983). doi:10.1103/PhysRevA.28.760 Research supported by the Australian Research Council Discovery Project Grant DP160102585

Co-implantation of carbon and nitrogen into silicon dioxide for synthesis of carbon nitride materials

CERN Document Server

Huang, M B; Nuesca, G; Moore, R

2002-01-01

Materials synthesis of carbon nitride has been attempted with co-implantation of carbon and nitrogen into thermally grown SiO sub 2. Following implantation of C and N ions to doses of 10 sup 1 sup 7 cm sup - sup 2 , thermal annealing of the implanted SiO sub 2 sample was conducted at 1000 degree sign C in an N sub 2 ambient. As evidenced in Fourier transform infrared measurements and X-ray photoelectron spectroscopy, different bonding configurations between C and N, including C-N single bonds, C=N double bonds and C=N triple bonds, were found to develop in the SiO sub 2 film after annealing. Chemical composition profiles obtained with secondary ion mass spectroscopy were correlated with the depth information of the chemical shifts of N 1s core-level electrons, allowing us to examine the formation of C-N bonding for different atomic concentration ratios between N and C. X-ray diffraction and transmission electron microscopy showed no sign of the formation of crystalline C sub 3 N sub 4 precipitates in the SiO ...

X-ray Photoelectron Spectroscopy study of CaV1-xMoxO3-δ

Science.gov (United States)

Belyakov, S. A.; Kuznetsov, M. V.; Shkerin, S. N.

2018-06-01

An investigation was carried out on perovskite-based derivatives of CaV1-xMoxO3-δ using X-ray Photoelectron Spectroscopy (XPS). According to the XRD pattern, the area of homogeneity covers the region from x = 0 to x = 0.6. Wide XPS-peaks of Ca, V, Mo and O are observed, signalling that elements are presented in multiple states. A model for explaining the large chemical shifts of XPS peaks due to different charging effects on different parts of the sample surface is proposed.

Comet C2012 S1 (ISON)s Carbon-rich and Micron-size-dominated Coma Dust

Science.gov (United States)

Wooden, D.; De Buizer, J.; Kelley, M.; Sitko, M.; Woodward, C.; Harker, D.; Reach, W.; Russell, R.; Kim, D.; Yanamadra-Fisher, P.;

Feasibility of photoelectron sources with sharp lines of stable energy between 20 and 80 keV

Czech Academy of Sciences Publication Activity Database

Dragoun, Otokar; Špalek, Antonín; Kašpar, Jaromír; Bonn, J.; Kovalík, Alojz; Otten, E.W.; Vénos, Drahoslav; Weinheimer, Ch.

2011-01-01

Roč. 69, č. 4 (2011), s. 672-677 ISSN 0969-8043 R&D Projects: GA MŠk LC07050 Institutional research plan: CEZ:AV0Z10480505 Keywords : Photoelectron * Neutrino mass * Electron spectrometer Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.172, year: 2011

Surface characterization of IM7/5260 composites by x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Ohno, Satomi; Lee, Moon-Hwan; Lin, Kuen Y.; Ohuchi, Fumio S.

2001-01-01

Surfaces of high-performance carbon fiber/bismeleimide (BMI) composites (IM7/5260) have been characterized by x-ray photoelectron spectroscopy. An experimental technique to separately examine the chemical natures of the carbon fibers and BMI resin in the composite form was developed. This technique uses a flood gun to establish differential charging conditions on the BMI resin. The binding energies from the BMI resin were shifted by an amount of voltage applied to the flood gun, whereas those from the carbon fibers were uniquely determined due to their electrically conducting nature. By adding external bias voltage to the sample, the binding energies for conducting fibers were further shifted from those of the BMI resin, thereby separating the IM7 phase completely from the BMI phase in the binding energy scale, allowing independent measurement of the chemical changes associated with those peaks. Using this technique, the effects of thermal aging and surface plasma treatment on the IM7/5260 composite were studied

An Assessment of Carbon Storage in China’s Arboreal Forests

Directory of Open Access Journals (Sweden)

Weiwei Shao

2017-04-01

Full Text Available In the years 2009–2013, China carried out its eighth national survey of forest resources. Based on the survey data, this paper used a biomass conversion function method to evaluate the carbon stores and carbon density of China’s arboreal forests. The results showed that: (1 By age group, the largest portion of carbon stores in China’s arboreal forests are in middle-aged forests. Over-mature forests have the least carbon storage; (2 By origin, natural forests of all age groups have higher carbon storage and carbon density than man-made forest plantations. The carbon density of natural forests and forest plantations increases gradually with the age of the trees; (3 By type (dominant tree species, the 18 most abundant types of arboreal forest in China account for approximately 94% of the nation’s total arboreal forest biomass and carbon storage. Among these, broadleaf mixed and Quercus spp. form the two largest portions. Taxus spp. forests, while comprising a very small portion of China’s forested area, have very high carbon density; (4 By region, the overall arboreal forest carbon storage is highest in the southwest part of China, and lowest in the northwest. However, because of differences in land use and forest coverage ratios, regions with arboreal forests of high carbon density are not necessarily the same regions that have high overall carbon storage; (5 By province, Heilongjiang, Yunnan, Tibet, Sichuan, Inner Mongolia, and Jilin have rather high carbon storage. The arboreal forests in Tibet, Jilin, Xinjiang, Sichuan, Yunnan, and Hainan have a rather high carbon density. This paper’s evaluation of carbon storage in China’s arboreal forests is a valuable reference for interpreting the role and function of Chinese ecosystems in coping with global climate change.

High-order multiphoton ionization photoelectron spectroscopy of NO

International Nuclear Information System (INIS)

Carman, H.S. Jr.; Compton, R.N.

1987-01-01

Photoelectron energy angular distributions of NO following three different high-order multiphoton ionization (MPI) schemes have been measured. The 3 + 3 resonantly enhanced multiphoton ionization (REMPI) via the A 2 Σ + (v=O) level yielded a distribution of electron energies corresponding to all accessible vibrational levels (v + =O-6) of the nascent ion. Angular distributions of electrons corresponding to v + =O and v + =3 were significantly different. The 3 + 2 REMPI via the A 2 Σ + (v=1) level produced only one low-energy electron peak (v + =1). Nonresonant MPI at 532 nm yielded a distribution of electron energies corresponding to both four- and five-photon ionization. Prominent peaks in the five-photon photoelectron spectrum (PES) suggest contributions from near-resonant states at the three-photon level. 4 refs., 3 figs

Photoelectron wave function in photoionization: plane wave or Coulomb wave?

Science.gov (United States)

Gozem, Samer; Gunina, Anastasia O; Ichino, Takatoshi; Osborn, David L; Stanton, John F; Krylov, Anna I

2015-11-19

The calculation of absolute total cross sections requires accurate wave functions of the photoelectron and of the initial and final states of the system. The essential information contained in the latter two can be condensed into a Dyson orbital. We employ correlated Dyson orbitals and test approximate treatments of the photoelectron wave function, that is, plane and Coulomb waves, by comparing computed and experimental photoionization and photodetachment spectra. We find that in anions, a plane wave treatment of the photoelectron provides a good description of photodetachment spectra. For photoionization of neutral atoms or molecules with one heavy atom, the photoelectron wave function must be treated as a Coulomb wave to account for the interaction of the photoelectron with the +1 charge of the ionized core. For larger molecules, the best agreement with experiment is often achieved by using a Coulomb wave with a partial (effective) charge smaller than unity. This likely derives from the fact that the effective charge at the centroid of the Dyson orbital, which serves as the origin of the spherical wave expansion, is smaller than the total charge of a polyatomic cation. The results suggest that accurate molecular photoionization cross sections can be computed with a modified central potential model that accounts for the nonspherical charge distribution of the core by adjusting the charge in the center of the expansion.

Eelectrochemical properties and corrosion resistance of carbon-ion-implanted magnesium

International Nuclear Information System (INIS)

Xu, Ruizhen; Yang, Xiongbo; Li, Penghui; Suen, Kai Wong; Wu, Guosong; Chu, Paul K.

2014-01-01

Highlights: • Carbon, as a biocompatible benign element, was implanted into Mg. • A protective amorphous carbon layer was formed after implantation. • Treated sample exhibits good corrosion resistance in two solutions. - Abstract: The corrosion resistance of magnesium-based biomaterials is critical to clinical applications. In this work, carbon as a biocompatible and benign nonmetallic element with high chemical inertness is implanted into pure magnesium to improve the corrosion behavior. X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HR-TEM), and Raman scattering reveal the formation of an amorphous carbon layer after ion implantation. Electrochemical studies demonstrate remarkable improvement in the corrosion resistance of magnesium in simulated body fluids (SBF) and Dulbecco’s Modified Eagle Medium (DMEM)

Oxidation Half-Reaction of Aqueous Nucleosides and Nucleotides via Photoelectron Spectroscopy Augmented by ab Initio Calculations

Czech Academy of Sciences Publication Activity Database

Schroeder, C. A.; Pluhařová, Eva; Seidel, R.; Schroeder, W. P.; Faubel, M.; Slavíček, P.; Winter, B.; Jungwirth, Pavel; Bradforth, S. E.

2015-01-01

Roč. 137, č. 1 (2015), s. 201-209 ISSN 0002-7863 R&D Projects: GA ČR GBP208/12/G016 Grant - others:GA ČR(CZ) GA13-34168S Institutional support: RVO:61388963 Keywords : DNA damage * photoelectron spectroscopy * DNA charge migration Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.038, year: 2015 http://pubs.acs.org/doi/10.1021/ja508149e

Surface characterization of colossal magnetoresistive manganites La1-xSr xMnO3 using photoelectron spectroscopy

International Nuclear Information System (INIS)

Mannella, N.; Rosenhahn, A.; Nambu, A.; Sell, B.C.; Mun, B.S.; Yang, S.-H.; Marchesini, S.; Watanabe, M.; Ibrahim, K.; Ritchey, S.B.; Tomioka, Y.; Fadley, C.S.

2006-01-01

We have studied the temperature and time dependence of Surface chemical composition and atomic structure of in situ fractured colossal magnetoresistive perovskites La 1-x Sr x MnO (x = 0.3, 0.4) using core-level photoelectron spectroscopy and diffraction, simultaneous with observing marked changes in both core and valence electronic structure on going above the Curie temperature [N. Mannella et al., Phys. Rev. Lett. 92 (2004) 166401]. Stoichiometric analyses via core-level intensity ratios show that the near-surface composition is very nearly the same as that of the nominal (bulk) stoichiometry and further show that, during duration of our experiments, the degree of surface stoichiometry alteration or contamination has been minimal. The effects of photoelectron diffraction on such analyses are also explored. We comment on the degree to which near-surface composition or atomic-structure alterations might influence spectroscopic investigations of these manganites, or other strongly correlated materials

Spin analysis of photoelectrons by using synchrotron radiation

International Nuclear Information System (INIS)

Yagishita, Akira

1983-03-01

This report is the proceedings of a workshop on ''Spin analysis of photoelectrons by using synchrotron radiation'' held at National Laboratory for High Energy Physics on October 21, 1982. The purpose of this workshop was to examine the feasibility of the experiment on the spin analysis of photoelectrons at the photon factory which has started the operation in 1982. The workshop covered the following subjects on the spin analysis of photoelectrons and on the detectors for spin polarization; the experiment and the theory on the spin analysis of photoelectrons emitted from gas and solid, the detectors for measuring the spin polarization of electron beam, the test experiment on a Mott detector, and further problems. The proceedings contain five papers related to the above subjects. (Asami, T.)

Analysis of Ti/Mo film by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Mou Fangming; Tu Bing; Yao Bing; Liu Jinhua; Long Xinggui

2002-01-01

Chemical elements and their electronic binding energy on surface of Ti film and bulk are analyzed by X-ray photoelectron spectroscopy (XPS) and Ar + etching. The results show that the surface of specimens is contaminated by carbon and oxygen. Mo on surface of Ti film is from substrate. The XPS spectra of Ti 2p of the etched specimens are fitted on. The results show that Ti chemical states on surface of Ti film are TiO 2 with a content of approaching to 100% and a little Ti. Some TiO 2 will be reduced to low chemical states with the increasing of etching time. The chemical states of Mo on surface of Ti film are MoO 3 and Mo. The content of Mo increases as etching time increasing. Chemical state of carbon on the surface of film is graphite and carbide with binding energy of 288.2-288.9 eV

The electronic states of 1,2,3-triazole studied by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy, and a comparison with ab initio configuration interaction methods

DEFF Research Database (Denmark)

Palmer, Michael H.; Hoffmann, Søren Vrønning; Jones, Nykola C.

2011-01-01

The Rydberg states in the vacuum ultraviolet photoabsorption spectrum of 1,2,3-triazole have been measured and analyzed with the aid of comparison to the UV valence photoelectron ionizations and the results of ab initio configuration interaction (CI) calculations. Calculated electronic ionization...... and excitation energies for singlet, triplet valence, and Rydberg states were obtained using multireference multiroot CI procedures with an aug-cc-pVTZ [5s3p3d1f] basis set and a set of Rydberg [4s3p3d3f] functions. Adiabatic excitation energies obtained for several electronic states using coupled...... are the excitations consistent with an f-series....

Economical and green synthesis of bagasse-derived fluorescent carbon dots for biomedical applications

International Nuclear Information System (INIS)

Du, Fengyi; Zhang, Miaomiao; Li, Xiaofeng; Jiang, Xinyi; Li, Zhang; Hua, Ye; Shao, Genbao; Jin, Jie; Shao, Qixiang; Gong, Aihua; Li, Jianan; Zhou, Ming

2014-01-01

Carbon quantum dots (CDs) are promising nanomaterials in biomedical, photocatalytical and photoelectronic applications. However, determining how to explore an ideal precursor for a renewable carbon resource is still an interesting challenge. Here, for the first time, we report that renewable wastes of bagasse as a new precursor were prepared for fluorescent CDs by a hydrothermal carbonization (HTC) process. The characterization results show that such bagasse-derived CDs are monodispersed, contain quasi spherical particles with a diameter of about 1.8 nm and exhibit favorable photoluminescence properties, super-high photostability and good dispersibility in water. Most importantly, bagasse-derived CDs have good biocompatibility and can be easily and quickly internalized by living cancer cells; they can also be used for multicolour biolabeling and bioimaging in cancer cells. It is suggested that bagasse-derived CDs might have potential applications in biomedical and photoelectronic fields. (paper)

Quantitative spectromicroscopy from inelastically scattered photoelectrons in the hard X-ray range

Energy Technology Data Exchange (ETDEWEB)

Renault, O., E-mail: olivier.renault@cea.fr; Zborowski, C.; Risterucci, P. [Univ. Grenoble Alpes, F-38000 Grenoble, France and CEA, LETI, MINATEC Campus, F-38054 Grenoble (France); Wiemann, C.; Schneider, C. M. [Peter Grünberg Institute (PGI-6) and JARA-FIT, Research Center Jülich, D-52425 Jülich (Germany); Grenet, G. [Institut des Nanotechnologies de Lyon, Ecole Centrale, 69134 Ecully Cedex (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

2016-07-04

We demonstrate quantitative, highly bulk-sensitive x-ray photoelectron emission microscopy by analysis of inelastically scattered photoelectrons in the hard X-ray range, enabling elemental depth distribution analysis in deeply buried layers. We show results on patterned structures used in electrical testing of high electron mobility power transistor devices with an epitaxial Al{sub 0.25}Ga{sub 0.75}N channel and a Ti/Al metal contact. From the image series taken over an energy range of up to 120 eV in the Ti 1s loss feature region and over a typical 100 μm field of view, one can accurately retrieve, using background analysis together with an optimized scattering cross-section, the Ti depth distribution from 14 nm up to 25 nm below the surface. The method paves the way to multi-elemental, bulk-sensitive 3D imaging and investigation of phenomena at deeply buried interfaces and microscopic scales by photoemission.

In situ photoelectron spectroscopy of LaMnO3 and La0.6Sr0.4MnO3 thin films grown by laser molecular beam expitaxy

International Nuclear Information System (INIS)

Oshima, M.; Kobayashi, D.; Horiba, K.; Ohguchi, H.; Kumigashira, H.; Ono, K.; Nakagawa, N.; Lippmaa, M.; Kawasaki, M.; Koinuma, H.

2004-01-01

We have constructed a high-resolution photoelectron spectroscopy system combined with a laser molecular beam epitaxy (laser-MBE) chamber and have characterized composition-controlled La 1-x Sr x MnO 3 (LSMO) thin films. The importance of atomically flat surfaces by in situ photoelectron spectroscopy for revealing the intrinsic electronic structures has been demonstrated by comparing O1s, O2s and valence band spectra from the laser-MBE-grown LaMnO 3 and LSMO films with those from the scraped samples. Even for the laser-MBE-grown LSMO films, core levels and band structure exhibit strong dependence on surface morphology. For atomically flat LSMO films, we have also elucidated the hole-doping features into Mn3d e g band by substituting La with Sr by resonant photoelectron spectra

A photoelectron and TPEPICO investigation of the acetone radical cation.

Science.gov (United States)

Rennie, Emma E; Boulanger, Anne-Marie; Mayer, Paul M; Holland, David M P; Shaw, David A; Cooper, Louise; Shpinkova, Larisa G

2006-07-20

The valence shell photoelectron spectrum, threshold photoelectron spectrum, and threshold photoelectron photoion coincidence (TPEPICO) mass spectra of acetone have been measured using synchrotron radiation. New vibrational progressions have been observed and assigned in the X 2B2 state photoelectron bands of acetone-h6 and acetone-d6, and the influence of resonant autoionization on the threshold electron yield has been investigated. The dissociation thresholds for fragment ions up to 31 eV have been measured and compared to previous values. In addition, kinetic modeling of the threshold region for CH3* and CH4 loss leads to new values of 78 +/- 2 kJ mol(-1) and 75 +/- 2 kJ mol(-1), respectively, for the 0 K activation energies for these two processes. The result for the methyl loss channel is in reasonable agreement with, but slightly lower than, that of 83 +/- 1 kJ mol(-1) derived in a recent TPEPICO study by Fogleman et al. The modeling accounts for both low-energy dissociation channels at two different ion residence times in the mass spectrometer. Moreover, the effects of the ro-vibrational population distribution, the electron transmission efficiency, and the monochromator band-pass are included. The present activation energies yield a Delta(f)H298 for CH3CO+ of 655 +/- 3 kJ mol(-1), which is 4 kJ mol(-1) lower than that reported by Fogleman et al. The present Delta(f)H298 for CH3CO+ can be combined with the Delta(f)H298 for CH2CO (-47.5 +/- 1.6 kJ mol(-1)) and H+ (1530 kJ mol(-1)) to yield a 298 K proton affinity for ketene of 828 +/- 4 kJ mol(-1), in good agreement with the value (825 kJ mol(-1)) calculated at the G2 level of theory. The measured activation energy for CH4 loss leads to a Delta(f)H298 (CH2CO+*) of 873 +/- 3 kJ mol(-1).

Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

Energy Technology Data Exchange (ETDEWEB)

Jordan, I.; Huppert, M.; Wörner, H. J., E-mail: hwoerner@ethz.ch [Laboratory of Physical Chemistry, ETH Zurich, Vladimir-Prelog-Weg 2, 8093 Zurich (Switzerland); Brown, M. A. [Laboratory for Surface Science and Technology, Department of Materials, ETH Zurich, Vladimir-Prelog-Weg 5, 8093 Zurich (Switzerland); Bokhoven, J. A. van [Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1, 8093 Zurich (Switzerland); Laboratory for Catalysis and Sustainable Chemistry, Paul Scherrer Institute, 5232 Villigen (Switzerland)

2015-12-15

A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

International Nuclear Information System (INIS)

Jordan, I.; Huppert, M.; Wörner, H. J.; Brown, M. A.; Bokhoven, J. A. van

2015-01-01

A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup

Photoelectron spectrometer for attosecond spectroscopy of liquids and gases

Science.gov (United States)

Jordan, I.; Huppert, M.; Brown, M. A.; van Bokhoven, J. A.; Wörner, H. J.

2015-12-01

A new apparatus for attosecond time-resolved photoelectron spectroscopy of liquids and gases is described. It combines a liquid microjet source with a magnetic-bottle photoelectron spectrometer and an actively stabilized attosecond beamline. The photoelectron spectrometer permits venting and pumping of the interaction chamber without affecting the low pressure in the flight tube. This pressure separation has been realized through a sliding skimmer plate, which effectively seals the flight tube in its closed position and functions as a differential pumping stage in its open position. A high-harmonic photon spectrometer, attached to the photoelectron spectrometer, exit port is used to acquire photon spectra for calibration purposes. Attosecond pulse trains have been used to record photoelectron spectra of noble gases, water in the gas and liquid states as well as solvated species. RABBIT scans demonstrate the attosecond resolution of this setup.

Angle-resolved photoelectron spectroscopy of formaldehyde and methanol

Science.gov (United States)

Keller, P. R.; Taylor, J. W.; Grimm, F. A.; Carlson, Thomas A.

1984-10-01

Angle-resolved photoelectron spectroscopy was employed to obtain the angular distribution parameter, β, for the valence orbitals (IP < 21.1 eV) of formaldehyde and methanol over the 10-30 eV photon energy range using dispersed polarized synchrotron radiation as the excitation source. It was found that the energy dependence of β in the photoelectron energy range between 2 and 10 eV can be related to the molecular-orbital type from which ionization occurs. This generalized energy behavior is discussed with regard to earlier energy-dependence studies on molecules of different orbital character. Evidence is presented for the presence of resonance photoionization phenomena in formaldehyde in agreement with theoretical cross-section calculations.

Photoelectron spectroscopy via electronic spectroscopy of molecular ions

International Nuclear Information System (INIS)

Khan, Z.H.

1990-01-01

In this work, a new aspect of the correlation between optical and photoelectron spectra is discussed on the basis of which the first ionization potentials of condensed-ring aromatics can be estimated from certain features in the electronic spectra of their positive ions. Furthermore, it is noticed that the first IP's are very sensitive to molecular size as the latter's inclusion in the regression formulas improves the results considerably. Once the first ionization potential for a molecule is determined, its higher IP's may be computed if the lower-energy electronic bands for its cation are known. This procedure is especially useful for such systems whose uv photoelectron spectra are unknown. (author). 11 refs, 10 figs, 1 tab

Photoelectron studies of machined brass surfaces

Science.gov (United States)

Potts, A. W.; Merrison, J. P.; Tournas, A. D.; Yacoot, A.

UV photoelectron spectroscopy has been used to determine the surface composition of machined brass. The results show a considerable change between the photoelectron surface composition and the bulk composition of the same sample determined by energy-dispersive X-ray fluorescence. On the surface the lead composition is increased by ˜900 G. This is consistent with the important part that lead is believed to play in improving the machinability of this alloy.

Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

Science.gov (United States)

2012-01-01

Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production) and industrial (net emissions from forest industry) forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1). The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100 years increases the strength of

Estimating the carbon budget and maximizing future carbon uptake for a temperate forest region in the U.S.

Directory of Open Access Journals (Sweden)

Peckham Scott D

2012-06-01

Full Text Available Abstract Background Forests of the Midwest U.S. provide numerous ecosystem services. Two of these, carbon sequestration and wood production, are often portrayed as conflicting. Currently, carbon management and biofuel policies are being developed to reduce atmospheric CO2 and national dependence on foreign oil, and increase carbon storage in ecosystems. However, the biological and industrial forest carbon cycles are rarely studied in a whole-system structure. The forest system carbon balance is the difference between the biological (net ecosystem production and industrial (net emissions from forest industry forest carbon cycles, but to date this critical whole system analysis is lacking. This study presents a model of the forest system, uses it to compute the carbon balance, and outlines a methodology to maximize future carbon uptake in a managed forest region. Results We used a coupled forest ecosystem process and forest products life cycle inventory model for a regional temperate forest in the Midwestern U.S., and found the net system carbon balance for this 615,000 ha forest was positive (2.29 t C ha-1 yr-1. The industrial carbon budget was typically less than 10% of the biological system annually, and averaged averaged 0.082 t C ha-1 yr-1. Net C uptake over the next 100-years increased by 22% or 0.33 t C ha-1 yr-1 relative to the current harvest rate in the study region under the optized harvest regime. Conclusions The forest’s biological ecosystem current and future carbon uptake capacity is largely determined by forest harvest practices that occurred over a century ago, but we show an optimized harvesting strategy would increase future carbon sequestration, or wood production, by 20-30%, reduce long transportation chain emissions, and maintain many desirable stand structural attributes that are correlated to biodiversity. Our results for this forest region suggest that increasing harvest over the next 100�

Photoionization and ionic dissociation of the C3 H3 NS molecule induced by soft X-ray near the C1s edge.

Science.gov (United States)

Lago, A F; Januário, R D; Cavasso Filho, R L; Simon, M; Dávalos, J Z

2017-10-01

Time of flight mass spectrometry, electron-ion coincidence, and ion yield spectroscopy were employed to investigate for the first time the thiazole (C 3 H 3 NS) molecule in the gas phase excited by synchrotron radiation in the soft X-ray domain. Total ion yield (TIY) and photoelectron-photoion coincidence (PEPICO) spectra were recorded as a function of the photon energy in the vicinity of the carbon K edge (C1s). The C1s resonant transitions as well as the core ionization thresholds have been determined from the profile of TIY spectrum, and the features were discussed. The corresponding partial ion yields were determined from the PEPICO spectra for the cation species produced upon the molecular photodissociation. Additional ab initio calculations have also been performed from where relevant structural and electronic configuration parameters were obtained for this molecule. Copyright © 2017 John Wiley & Sons, Ltd.

Threshold photoelectron spectroscopy of acetaldehyde and acrolein

International Nuclear Information System (INIS)

Yencha, Andrew J.; Siggel-King, Michele R.F.; King, George C.; Malins, Andrew E.R.; Eypper, Marie

2013-01-01

Highlights: •High-resolution threshold photoelectron spectrum of acetaldehyde. •High-resolution threshold photoelectron spectrum of acrolein. •High-resolution total photoion yield spectrum of acetaldehyde. •High-resolution total photoion yield spectrum of acrolein. •Determination of vertical ionization potentials in acetaldehyde and acrolein. -- Abstract: High-resolution (6 meV and 12 meV) threshold photoelectron (TPE) spectra of acetaldehyde and acrolein (2-propenal) have been recorded over the valence binding energy region 10–20 eV, employing synchrotron radiation and a penetrating-field electron spectrometer. These TPE spectra are presented here for the first time. All of the band structures observed in the TPE spectra replicate those found in their conventional HeI photoelectron (PE) spectra. However, the relative band intensities are found to be dramatically different in the two types of spectra that are attributed to the different dominant operative formation mechanisms. In addition, some band shapes and their vertical ionization potentials are found to differ in the two types of spectra that are associated with the autoionization of Rydberg states in the two molecules

Imaging photoelectron circular dichroism of chiral molecules by femtosecond multiphoton coincidence detection

Energy Technology Data Exchange (ETDEWEB)

Lehmann, C. Stefan; Ram, N. Bhargava; Janssen, Maurice H. M., E-mail: m.h.m.janssen@vu.nl [LaserLaB Amsterdam, VU University Amsterdam, De Boelelaan 1081, 1081 HV Amsterdam (Netherlands); Powis, Ivan [School of Chemistry, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

2013-12-21

Here, we provide a detailed account of novel experiments employing electron-ion coincidence imaging to discriminate chiral molecules. The full three-dimensional angular scattering distribution of electrons is measured after photoexcitation with either left or right circular polarized light. The experiment is performed using a simplified photoelectron-photoion coincidence imaging setup employing only a single particle imaging detector. Results are reported applying this technique to enantiomers of the chiral molecule camphor after three-photon ionization by circularly polarized femtosecond laser pulses at 400 nm and 380 nm. The electron-ion coincidence imaging provides the photoelectron spectrum of mass-selected ions that are observed in the time-of-flight mass spectra. The coincident photoelectron spectra of the parent camphor ion and the various fragment ions are the same, so it can be concluded that fragmentation of camphor happens after ionization. We discuss the forward-backward asymmetry in the photoelectron angular distribution which is expressed in Legendre polynomials with moments up to order six. Furthermore, we present a method, similar to one-photon electron circular dichroism, to quantify the strength of the chiral electron asymmetry in a single parameter. The circular dichroism in the photoelectron angular distribution of camphor is measured to be 8% at 400 nm. The electron circular dichroism using femtosecond multiphoton excitation is of opposite sign and about 60% larger than the electron dichroism observed before in near-threshold one-photon ionization with synchrotron excitation. We interpret our multiphoton ionization as being resonant at the two-photon level with the 3s and 3p Rydberg states of camphor. Theoretical calculations are presented that model the photoelectron angular distribution from a prealigned camphor molecule using density functional theory and continuum multiple scattering X alpha photoelectron scattering calculations

Two-color visible/vacuum ultraviolet photoelectron imaging dynamics of Br2.

Science.gov (United States)

Plenge, Jürgen; Nicolas, Christophe; Caster, Allison G; Ahmed, Musahid; Leone, Stephen R

2006-10-07

An experimental two-color photoionization dynamics study of laser-excited Br2 molecules is presented, combining pulsed visible laser excitation and tunable vacuum ultraviolet (VUV) synchrotron radiation with photoelectron imaging. The X 1Sigmag + -B 3Pi0+u transition in Br2 is excited at 527 nm corresponding predominantly to excitation of the v' = 28 vibrational level in the B 3Pi0+u state. Tunable VUV undulator radiation in the energy range of 8.40-10.15 eV is subsequently used to ionize the excited molecules to the X 2Pi32,12 state of the ion, and the ionic ground state is probed by photoelectron imaging. Similar experiments are performed using single-photon synchrotron ionization in the photon energy range of 10.75-12.50 eV without any laser excitation. Photoelectron kinetic energy distributions are extracted from the photoelectron images. In the case of two-color photoionization using resonant excitation of the intermediate B 3Pi0+u state, a broad distribution of photoelectron kinetic energies is observed, and in some cases even a bimodal distribution, which depends on the VUV photon energy. In contrast, for single-photon ionization, a single nearly Gaussian-shaped distribution is observed, which shifts to higher energy with photon energy. Simulated spectra based on Franck-Condon factors for the transitions Br2(X 1Sigmag+, v" = 0)-Br2 +(X 2Pi12,32, v+) and Br2(B 3Pi0+u, v' = 28)-Br2 +(X 2Pi12,32, v+) are generated. Comparison of these calculated spectra with the measured images suggests that the differences in the kinetic energy distributions for the two ionization processes reflect the different extensions of the vibrational wave functions in the v" = 0 electronic ground state (X 1Sigmag+) versus the electronically and vibrationally excited state (B 3Pi0+u, v' = 28).

Time-resolved photoelectron spectrometry of a dephasing process in pyrazine

International Nuclear Information System (INIS)

Pavlov, R.L.; Pavlov, L.I.; Delchev, Ya.I.; Pavlova, S.I.

2001-01-01

The first femtosecond time-resolved photoelectron imaging (PEI) is presented. The method is characterized by photoionization of NO and further applied to ultrafast dephasing in pyrazine. Intermediate case behaviour in radiationless transition is clearly observed in time-resolved photoelectron kinetic energy distribution. Femtosecond PEI is with much improved efficiency than conventional photoelectron spectroscopies. It is anticipated that the unifield approach of time-resolved photoelectron and photoion imaging opens the possibility of observing photon-induced dynamics in real time

GaN quantum dot polarity determination by X-ray photoelectron diffraction

Czech Academy of Sciences Publication Activity Database

Romanyuk, Olexandr; Bartoš, Igor; Brault, J.; De Mierry, P.; Paskova, T.; Jiříček, Petr

2016-01-01

Roč. 389, Dec (2016), s. 1156-1160 ISSN 0169-4332 R&D Projects: GA ČR GA15-01687S; GA MŠk LM2015088 Institutional support: RVO:68378271 Keywords : GaN * semipolar GaN * quantum dots * X-ray photoelectron diffraction * surface polarity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.387, year: 2016

Quadrupole effects in core and valence photoelectron emission from crystalline germanium measured via a spatially modulated x-ray interference field

International Nuclear Information System (INIS)

Nelson, E.J.; Woicik, J.C.; Pianetta, P.; Vartanyants, I.A.; Cooper, J.W.

2002-01-01

Near a crystal x-ray Bragg reflection, the incident and reflected x-ray beams that travel with opposite wave vectors create an x-ray standing-wave (XSW) interference field. The quadrupole (and higher order nondipole) contributions to the photoelectron emission matrix element differ for these two beams due to their different wave vectors. By monitoring the angle-resolved photoelectron yield as a function of photon energy near the (11-1) Bragg back-reflection condition of crystalline Ge, we measure the contribution of nondipole effects to Ge 3p, Ge 3d, and Ge valence-band (4s and 4p) XSW photoelectron emission. Significant changes due to nondipole emission are measured in both the apparent amplitude and phase of the Ge structure factor relative to the true Ge atomic distribution, and compared to theory

Adsorption removal of acid black 1 from aqueous solution using ordered mesoporous carbon

Energy Technology Data Exchange (ETDEWEB)

Peng, Xiaoming, E-mail: pengxiaoming70@126.com [School of Civil Engineering, Southeast University, Nanjing 210096 (China); Hu, Xijun [Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,China (China); Fu, Dafang, E-mail: fdf@seu.edu.cn [School of Civil Engineering, Southeast University, Nanjing 210096 (China); Lam, Frank L.Y. [Department of Chemical and Biomolecular Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong,China (China)

2014-03-01

Highlights: • Ordered mesoporous carbon was prepared using template. • Ordered mesoporous carbon was introduced of N-containing group by Chemical vapor deposition method. • Modified CMK-3 have better adsorption capacity and efficiency than virgin CMK-3 to removal AB1 dye. - Abstract: A novel ordered mesoporous carbon CMK-3 and synthetic CMK-3 containing nitrogen functional groups by ammonia-treated were applied for acid black 1(AB1) dye adsorption. The ammonia-treated(chemical vapor deposition method) before and after CMK-3 were characterized by using a Micrometitics ASAP 2020 surface area analyzer (ASAP 2020), Fourier transform infrared spectrophotometer (FT–IR), X-ray Photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscope (SEM) and equilibrium studies. This result indicates that the prepared CMK-3 and modified CMK-3 were almost uniform, as rope-like domains and their uniform mesopore with diameter centered at 3.2 nm and 3.7 nm. The FIIR analysis depicted that the presence of a variety of new basic functional groups on the modified CMK-3 surface. Several effect variables of pH, dye concentration and temperature were studied. The pseudo second-order model showed the fitter well to agree with the kinetic data. The experimental data were analyzed by the Langmuir and Freundlich models, with the latter found to closely the isotherm model. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The results show that CMK-3 using ammonia gas modified by thermal treatment system is an effective method to improvement capacity as it shows the highest adsorption capacity of AB1, as compared to the unmodified CMK-3 and the bamboo-based carbon, respectively.

Evidence of site-specific fragmentation on thioacetic acid, CH3C(O)SH, irradiated with synchrotron radiation around the S 2p and O 1s regions.

Science.gov (United States)

Erben, Mauricio F; Geronés, Mariana; Romano, Rosana M; Della Védova, Carlos O

2006-01-26

Site-specific fragmentations following S 2p and O 1s photoexcitation of thioacetic acid, CH3C(O)SH, have been studied by means of synchrotron radiation. Total ion yield (TIY) spectra were measured and multicoincidence techniques, which include photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion coincidence (PEPIPICO) time-of-flight mass spectrometry, were applied. The equivalent-core approximation was employed in order to estimate ionization transition values, and the observed peaks were tentatively assigned. A site-specific fragmentation is moderately observed by comparing the mass spectra collected at resonant energies around the inner and shallow inner shell S 2p and O 1s ionization edges. Beside H+ ion, the most abundant ions observed at the S 2p edge excitation were CH3CO+, SH+, S+, and CH3+. At the O 1s region the large CH3CO+ fragment was depressed, and small CHx+ (x = 0, 1, 2, 3), S+, and SH+ fragments were dominant. The dissociation dynamic for the main ion-pair production has been discussed. Two- and three-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms were proposed.

Effect of sizing on carbon fiber surface properties and fibers/epoxy interfacial adhesion

International Nuclear Information System (INIS)

Dai Zhishuang; Shi Fenghui; Zhang Baoyan; Li Min; Zhang Zuoguang

2011-01-01

This paper aims to study effect of sizing on surface properties of carbon fiber and the fiber/epoxy interfacial adhesion by comparing sized and desized T300B and T700SC carbon fibers. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the desized carbon fibers present less concentration of activated carbon, especially those connect with the hydroxyl and epoxy groups. Inverse gas chromatography (IGC) analysis reveals that the desized carbon fibers have larger dispersive surface energy γ S D and smaller polar component γ S SP than the commercial sized ones. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the desized carbon fiber/epoxy is higher than those of the T300B and T700SC. Variations of the IFSS for both the sized and desized carbon fibers correspond to γ S D /γ S tendency of the fiber surface, however the work of adhesion does not reveal close correlation with IFSS trend for different fiber/epoxy systems.

Study of fine films nature on the surface of copper band by photoelectron spectroscopy method

International Nuclear Information System (INIS)

Reznichenko, K.N.; Fedorov, V.N.; Shevakin, Yu.F.

1983-01-01

The composition of surface films formed on the copper band of industrial production under atmospheric conditions, its changes in thickness and determination of chemical state of the above films are studied. It has been found by the methods of X-ray photoelectronic and Auger-spectroscopy that defect formations on the surface of the copper band of industrial production represent copper oxides in the form of fine films, their change in colour from blue to dark blue probably is determined by different thickness of these defects. The said films on copper have practically identical chemical composition characterized by the presence of unequally valent copper, oxygen in various states (adsorbed and in the form of oxides), carbon and iron. By means of chemical shifts of the line Cu 2psub(3/2) and Ol s the presence in the external part of the film of CuO copper oxide is established and nearer to the interface surface film-metal-of Cu 2 O cuprous oxide which indicates a two-layer surface film structure. The presence of adsorbed carbon and iron in the film composition is a result of surface contamination

Electronic structure of the misfit layer compound (SnS)(1.20)TiS2 : Band structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, CM; deGroot, RA; Wiegers, GA; Haas, C

1996-01-01

In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)(1.20)TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

Electronic structure of the misfit layer compound (SnS)1.20TiS2 : band structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, C.M.; Groot, R.A. de; Wiegers, G.A.; Haas, C.

1996-01-01

In order to understand the electronic structure of the incommensurate misfit layer compound (SnS)1.20TiS2 we carried out an ab initio band structure calculation in the supercell approximation. The band structure is compared with that of the components 1T-TiS2 and hypothetical SnS with a similar

Photoelectron antibunching and absorber theory

International Nuclear Information System (INIS)

Pegg, D.T.

1980-01-01

The recently detected photoelectron antibunching effect is considered to be evidence for the quantised electromagnetic field, i.e. for the existence of photons. Direct-action quantum absorber theory, on the other hand, has been developed on the basis that the quantised field is illusory, with quantisation being required only for atoms. In this paper it is shown that photoelectron antibunching is readily explicable in terms of absorber theory and in fact is directly attributable to the quantum nature of the emitting and detecting atoms alone. The physical nature of the reduction of the wavepacket associated with the detection process is briefly discussed in terms of absorber theory. (author)

Photoelectron photoion molecular beam spectroscopy

International Nuclear Information System (INIS)

Trevor, D.J.

1980-12-01

The use of supersonic molecular beams in photoionization mass spectroscopy and photoelectron spectroscopy to assist in the understanding of photoexcitation in the vacuum ultraviolet is described. Rotational relaxation and condensation due to supersonic expansion were shown to offer new possibilities for molecular photoionization studies. Molecular beam photoionization mass spectroscopy has been extended above 21 eV photon energy by the use of Stanford Synchrotron Radiation Laboratory (SSRL) facilities. Design considerations are discussed that have advanced the state-of-the-art in high resolution vuv photoelectron spectroscopy. To extend gas-phase studies to 160 eV photon energy, a windowless vuv-xuv beam line design is proposed

Rapid and controllable perforation of carbon nanotubes by microwave radiation

Science.gov (United States)

Ojaghi, Neda; Mokhtarifar, Maryam; Sabaghian, Zahra; Arab, Hamed; Maghrebi, Morteza; Baniadam, Majid

2018-05-01

This study presents a new controlled approach to deep perforation of millimeter-long carbon nanotube arrays (CNTAs) by fast oxidative cutting. The approach is based on decorating CNTAs with silver (Ag) nanoparticles, followed by heating Ag-decorated CNTAs with microwave radiation (2.48 GHz, 300 W). The perforation was evaluated using different techniques such as transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller method. The results of the oxidation of carbonaceous materials indicated that the relative amount of oxygen functional groups increased without total oxidation of carbon up to 60 s. After 60 s, the amount of functional groups decreased as the total oxidation started suddenly. Afterwards, at around 120 and 420 s, the oxidation of Ag-decorated CNTAs reached the point of total perforation and total cutting, respectively. Though carbon decomposition terminated at around 420 s, the total pore volume and surface area increased continuously. This was attributed to the steady growth of Ag nanoparticles located between CNTAs.

Bonding in inorganic compounds: a study by x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Avanzino, S.C.

1978-10-01

Core electron binding energies were measured for a variety of inorganic and organometallic compounds using gas-phase X-ray photoelectron spectroscopy (XPS). The atomic charge distributions in these molecules are deduced from the binding energies, often leading to a better understanding of the bonding in these compounds. The XPS spectra of fifteen volatile tin compounds were recorded. The data suggest that the metal d orbitals are not significantly involved in the bonding. The oxygen ls XPS spectra of gaseous CH 3 Mn(CO) 5 , [π-C 5 H 5 Fe(CO) 2 ] 2 , and Co 4 (CO) 12 can be readily resolved into separate peaks due to bridging and terminal carbonyl groups. The C ls spectrum of Fe(CO) 5 consists of a single symmetric peak. The carbonyl ligand core binding energies of transition-metal carbonyl complexes are sensitive to differences in the metal-to-CO ligand bonding. Both C ls and O ls carbonyl binding energies correlate well with average C-O stretching force constants or average C-O stretching frequencies. The metal and carbonyl binding energies in a series of pentacarbonylmanganese complexes LMn(CO) 5 are a good measure of the relative electronegativities of the ligands L. High-quality X-ray photoelectron spectra have been obtained for compounds dissolved in glycerin solutions, and aqueous solutions were converted into glycerin solutions which gave good XRSspectra of the solutes. The technique appears promising as a future analytical application of X-ray photoelectron spectroscopy. The shifts in the binding energies of oxygen, chlorine, and carbon atoms in some isoelectronic isostructural compounds can be explained in terms of simple trends in atomic charges

Performance of the SRRC scanning photoelectron microscope

CERN Document Server

Hong, I H; Yin, G C; Wei, D H; Juang, J M; Dann, T E; Klauser, R; Chuang, T J; Chen, C T; Tsang, K L

2001-01-01

A scanning photoelectron microscope has been constructed at SRRC. This SPEM system consists primarily of a Fresnel zone plate (ZP) with an order-selection aperture, a flexure scanning stage, a hemispherical electron analyzer, and sample/ZP insertion system. The flexure stage is used to scan the sample. A hemispherical analyzer with Omni V lens and a 16-channel multichannel detector (MCD) is used to collect photoelectrons. A set of 16 photoelectron images at different kinetic energies can be simultaneously acquired in one single scan. The data acquisition system is designed to collect up to 32 images concurrently, including 16 MCD signals, total electron yield and transmitted photon flux. The design and some initial test results of this SPEM station are presented and discussed.

Performance of the SRRC scanning photoelectron microscope

Science.gov (United States)

Hong, I.-H.; Lee, T.-H.; Yin, G.-C.; Wei, D.-H.; Juang, J.-M.; Dann, T.-E.; Klauser, R.; Chuang, T. J.; Chen, C. T.; Tsang, K.-L.

2001-07-01

A scanning photoelectron microscope has been constructed at SRRC. This SPEM system consists primarily of a Fresnel zone plate (ZP) with an order-selection aperture, a flexure scanning stage, a hemispherical electron analyzer, and sample/ZP insertion system. The flexure stage is used to scan the sample. A hemispherical analyzer with Omni V lens and a 16-channel multichannel detector (MCD) is used to collect photoelectrons. A set of 16 photoelectron images at different kinetic energies can be simultaneously acquired in one single scan. The data acquisition system is designed to collect up to 32 images concurrently, including 16 MCD signals, total electron yield and transmitted photon flux. The design and some initial test results of this SPEM station are presented and discussed.

Performance of the SRRC scanning photoelectron microscope

International Nuclear Information System (INIS)

Hong, I.-H.; Lee, T.-H.; Yin, G.-C.; Wei, D.-H.; Juang, J.-M.; Dann, T.-E.; Klauser, R.; Chuang, T.J.; Chen, C.T.; Tsang, K.-L.

2001-01-01

A scanning photoelectron microscope has been constructed at SRRC. This SPEM system consists primarily of a Fresnel zone plate (ZP) with an order-selection aperture, a flexure scanning stage, a hemispherical electron analyzer, and sample/ZP insertion system. The flexure stage is used to scan the sample. A hemispherical analyzer with Omni V lens and a 16-channel multichannel detector (MCD) is used to collect photoelectrons. A set of 16 photoelectron images at different kinetic energies can be simultaneously acquired in one single scan. The data acquisition system is designed to collect up to 32 images concurrently, including 16 MCD signals, total electron yield and transmitted photon flux. The design and some initial test results of this SPEM station are presented and discussed

Screen-printed carbon electrode modified on its surface with amorphous carbon nitride thin film: Electrochemical and morphological study

Energy Technology Data Exchange (ETDEWEB)

Ghamouss, F. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France); Tessier, P.-Y. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Djouadi, A. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Besland, M.-P. [Universite de Nantes, UMR CNRS 6502, Institut des Materiaux Jean Rouxel - IMN Faculte des Sciences and des Techniques de Nantes, 2 rue de la Houssiniere, 44322 Nantes Cedex 3 (France); Boujtita, M. [Universite de Nantes, UMR 6006-CNRS, FR-2465-CNRS, Laboratoire d' Analyse isotopique et Electrochimique de Metabolismes (LAIEM) (France)]. E-mail: mohammed.boujtita@univ-nantes.fr

2007-04-20

The surface of a screen-printed carbon electrode (SPCE) was modified by using amorphous carbon nitride (a-CN {sub x}) thin film deposited by reactive magnetron sputtering. Scanning electron microscopy and photoelectron spectroscopy measurements were used to characterise respectively the morphology and the chemical structure of the a-CN {sub x} modified electrodes. The incorporation of nitrogen in the amorphous carbon network was demonstrated by X ray photoelectron spectroscopy. The a-CN {sub x} layers were deposited on both carbon screen-printed electrode (SPCE) and silicon (Si) substrates. A comparative study showed that the nature of substrate, i.e. SPCE and Si, has a significant effect on both the surface morphology of deposited a-CN {sub x} film and their electrochemical properties. The improvement of the electrochemical reactivity of SPCE after a-CN {sub x} film deposition was highlighted both by comparing the shapes of voltammograms and calculating the apparent heterogeneous electron transfer rate constant.

Graphene Membranes for Atmospheric Pressure Photoelectron Spectroscopy.

Science.gov (United States)

Weatherup, Robert S; Eren, Baran; Hao, Yibo; Bluhm, Hendrik; Salmeron, Miquel B

2016-05-05

Atmospheric pressure X-ray photoelectron spectroscopy (XPS) is demonstrated using single-layer graphene membranes as photoelectron-transparent barriers that sustain pressure differences in excess of 6 orders of magnitude. The graphene serves as a support for catalyst nanoparticles under atmospheric pressure reaction conditions (up to 1.5 bar), where XPS allows the oxidation state of Cu nanoparticles and gas phase species to be simultaneously probed. We thereby observe that the Cu(2+) oxidation state is stable in O2 (1 bar) but is spontaneously reduced under vacuum. We further demonstrate the detection of various gas-phase species (Ar, CO, CO2, N2, O2) in the pressure range 10-1500 mbar including species with low photoionization cross sections (He, H2). Pressure-dependent changes in the apparent binding energies of gas-phase species are observed, attributable to changes in work function of the metal-coated grids supporting the graphene. We expect atmospheric pressure XPS based on this graphene membrane approach to be a valuable tool for studying nanoparticle catalysis.

Photoelectronic properties of semiconductors

CERN Document Server

Bube, Richard H

1992-01-01

The interaction between light and electrons in semiconductors forms the basis for many interesting and practically significant properties. This book examines the fundamental physics underlying this rich complexity of photoelectronic properties of semiconductors, and will familiarise the reader with the relatively simple models that are useful in describing these fundamentals. The basic physics is also illustrated with typical recent examples of experimental data and observations. Following introductory material on the basic concepts, the book moves on to consider a wide range of phenomena, including photoconductivity, recombination effects, photoelectronic methods of defect analysis, photoeffects at grain boundaries, amorphous semiconductors, photovoltaic effects and photoeffects in quantum wells and superlattices. The author is Professor of Materials Science and Electrical Engineering at Stanford University, and has taught this material for many years. He is an experienced author, his earlier books having fo...

Mechanical Properties of Domestic T700 Grade Carbon Fibers/QY9611 BMI Matrix Composites

Directory of Open Access Journals (Sweden)

LI Guoli

2017-04-01

Full Text Available The morphologies,surface energies and surface chemical properties of the domestic T700 grade carbon fiber and the T700S carbon fiber were characterized by using scanning electronic microscopy (SEM, inverse gas chromatography(IGC and X-ray photoelectron spectroscopy (XPSrespectively.The mechanical properties of the two carbon fibers/QY9611 composites were also discussed. The results indicate that the surface properties of carbon fibers have an important influence on the interfacial properties of composites. The interfacial properties of domestic T700 grade carbon fibers/QY9611 composite at room temperature/dry conditions are superior to T700S/QY9611 composite. The toughness of domestic T700 grade carbon fibers/QY9611composite is outstanding as well. The value of CAI has reached the level of foreign advanced composite IM7/5250-4. After hydrothermal treatment,the interfacial strength of domestic T700 grade carbon fibers/QY9611 composite is equal to that of T700S/QY9611 composite. It shows that domestic T700 grade carbon fibers/QY9611 composite has good hydrothermal-resistant properties.

A scanning photoelectron microscope (SPEM) at the National Synchrotron Light Source (NSLS)

International Nuclear Information System (INIS)

Ade, H.; Kirz, J.; Hulbert, S.; Johnson, E.; Anderson, E.; Kern, D.; Brookhaven National Lab., Upton, NY; Lawrence Berkeley Lab., CA; International Business Machines Corp., Yorktown Heights, NY

1989-01-01

We are in the process of developing and commissioning a scanning photoelectron microscope (SPEM) at the X1A beamline of the National Synchrotron Light Source (NSLS). It is designed to make use of the Soft X-ray Undulator (SXU) at the NSLS. This high brightness source illuminates a Fresnel zone plate, which forms a focused probe, ≤ 0.2μm in size, on the specimen surface. A grating monochromator selects the photon energy in the 400-800 eV range with an energy resolution of better than 1 eV. The expected flux in the focus is in the 5 x 10 7 - 10 9 photons/s range. A single pass Cylindrical Mirror Analyzer (CMA) is used to record photoemission spectra, or to form an image within a fixed electron energy bandwidth as the specimen is mechanically scanned. As a first test, a 1000 mesh Au grid was successfully imaged with a resolution of about 1μm and the CMA tuned to the Au 4 f photoelectron peak. Once it is commissioned, a program is planned which will utilize the microscope to study beam sensitive systems, such as thin oxide/sub-oxide films of alumina and silica, and ultimately various adsorbates on these films. 14 refs., 4 figs

Crystal structure of a diaryl carbonate: 1,3-phenylene bis(phenyl carbonate

Directory of Open Access Journals (Sweden)

Marina A. Solomos

2017-12-01

Full Text Available The whole molecule of the title compound, C20H14O6, is generated by mirror symmetry, the mirror bisecting the central benzene ring. The carbonate groups adopt an s-cis-s-cis conformation, with torsion angles of 58.7 (2 and 116.32 (15°. The crystal structure of 1,3-phenylene bis(phenyl carbonate contains no strong hydrogen bonds, though weak C—H...O and offset π–π interactions are observed, forming layers parallel to the ac plane.

Alkyl-terminated Si(111) surfaces: A high-resolution, core level photoelectron spectroscopy study

Energy Technology Data Exchange (ETDEWEB)

Terry, J.; Linford, M.R.; Wigren, C.; Cao, R.; Pianetta, P.; Chidsey, C.E. [Stanford University, Stanford, California 94309 (United States)

1999-01-01

The bonding of alkyl monolayers to Si(111) surfaces has been studied with high-resolution core level photoelectron spectroscopy (PES). Two very different wet-chemical methods have been used to prepare the alkyl monolayers: (i) Olefin insertion into the H{endash}Si bond of the H{endash}Si(111) surface, and (ii) replacement of Cl on the Cl{endash}Si(111) surface by an alkyl group from an alkyllithium reagent. In both cases, PES has revealed a C 1s component shifted to lower binding energy and a Si 2p component shifted to higher binding energy. Both components are attributed to the presence of a C{endash}Si bond at the interface. Along with photoelectron diffraction data [Appl. Phys. Lett. {bold 71}, 1056, (1997)], these data are used to show that these two synthetic methods can be used to functionalize the Si(111) surface. {copyright} {ital 1999 American Institute of Physics.}

Observation of relaxation on time scale of core hole decay by coincidence photoelectron spectroscopy

International Nuclear Information System (INIS)

Ohno, Masahide

2007-01-01

It is shown by a many-body theory that when the relaxation time of a metastable core hole state(s) to the most stable one is comparable to or shorter than core hole decay time of the former state(s), a comparison between the singles (noncoincidence) photoelectron spectroscopy (PES) spectrum and the coincidence one provides a direct evidence of the relaxation. In principle the variation with photoelectron kinetic energy of relaxation (or charge transfer (CT)) time can be determined. By singles measurement the correlation of a photoelectron generated by creation of the metastable states not only with an Auger electron generated by annihilation of the same core hole state but also with an Auger electron generated by annihilation of the stable state via relaxation of the metastable state, is completely lost, unless only the metastable state is observed by PES, whereas the correlation often manifests directly in the coincidence spectra. Thus, compared to the coincidence spectroscopy the singles one is often much less capable of elucidating the competition between relaxation and core hole decay of a metastable state. Such examples are discussed

Coherent Control of Photoelectron Wavepacket Angular Interferograms

OpenAIRE

Hockett, Paul; Wollenhaupt, Matthias; Baumert, Thomas

2015-01-01

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the cohere...

Study of transition metal oxides by photoelectron spectroscopy

International Nuclear Information System (INIS)

Rao, C.N.R.; Sarma, D.D.; Vasudevan, S.; Hegde, M.S.

1979-01-01

Systematics in the X-ray photoelectron spectra (X.p.e.s.) of Ti, V, Cr, Mn and Nb oxides with the metal ion in different oxidation states as well as of related series of mono-, sesqui- and di-oxides of the first row of transition metals have been investigated in detail. Core level binding energies, spin-orbit splittings and exchange splittings are found to exhibit interesting variations with the oxidation state of the metal or the nuclear charge. The 3d binding energies of the monoxides show a proportionality to Goodenough's (R - RC). Other aspects of interest in the study are the satellite structure and final state effects in the X.p.e.s. of the oxides, and identification of different valence states in oxides of the general formulae Mn02n-1 and M304. The nature of changes in the 3d bands of oxides undergoing metal-insulator transitions is also indicated. (author)

Measurement of core level and band offsets at the interface of ITO/Hg_3In_2Te_6(1 1 0) heterojunction by synchrotron radiation photoelectron spectroscopy

International Nuclear Information System (INIS)

Li, Yapeng; Fu, Li; Sun, Jie; Ibrahim, Kurash; Wang, Jia-ou

2016-01-01

Highlights: • The valence band maximum of ITO film and MIT were measured to be 1.6 eV and 0.6 eV, respectively. • The concentration of In element presented a trend of increasing first and then decreasing from MIT to ITO. • The valence band offsets of the ITO/MIT(1 1 0) heterojunction was confirmed to be a type-II band alignment phenomenon. - Abstract: The Indium Tin Oxide (ITO) film was deposited on the surface of Hg_3In_2Te_6 (short for MIT) (1 1 0) for the fabrication of ITO/MIT(1 1 0) heterojunction by using the pulsed laser deposition method. In situ X-ray photoelectron spectroscopy was utilized to examine the band offsets and core level of ITO/MIT(1 1 0) heterojunctions. The result showed that the valence band maximum of ITO films and MIT(1 1 0) were 1.6 eV and 0.6 eV, respectively. Meanwhile, it was found that the binding energy of Te 3d, Sn 3d and Hg 4f remained unchanged during the ITO deposition process. However, the binding energy of O 1s and In 3d_5_/_2 increased about 0.3 eV and 0.2 eV, respectively, with the thickness increasing of ITO film from 3.5 nm to 5 nm. This may due to the elements diffusion at the interface region during the film growing process. According to the core level spectrum, it can be speculated that no significant chemical reaction occurred at the interface of ITO/MIT(1 1 0). In addition, the valence band offset of the ITO/MIT(1 1 0) heterojunction can be calculated to be −1 ± 0.15 eV by the means of the photoelectron spectroscopy methods. The conduction band offset is deduced to be −3.96 ± 0.15 eV from the known valence band offset value, indicating that the band offsets of ITO/MIT(1 1 0) heterojunction is a type-II band alignment.

Laser induced changes of As.sub.50./sub.Se.sub.50./sub. nanolayers studied by synchrotron radiation photoelectron spectroscopy

Czech Academy of Sciences Publication Activity Database

Kondrat, O.; Popovich, N.; Holomb, R.; Mitsa, V.; Lyamayev, V.; Tsud, N.; Cháb, Vladimír; Matolín, V.; Prince, K. C.

2012-01-01

Roč. 520, č. 24 (2012), s. 7224-7229 ISSN 0040-6090 R&D Projects: GA MŠk(CZ) LC06058 Institutional support: RVO:68378271 Keywords : chalcogenide glass * photostructural changes * photoelectron spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.604, year: 2012

Three-Dimensional X-Ray Photoelectron Tomography on the Nanoscale: Limits of Data Processing by Principal Component Analysis

DEFF Research Database (Denmark)

Hajati, S.; Walton, J.; Tougaard, S.

2013-01-01

In a previous article, we studied the influence of spectral noise on a new method for three-dimensional X-ray photoelectron spectroscopy (3D XPS) imaging, which is based on analysis of the XPS peak shape [Hajati, S., Tougaard, S., Walton, J. & Fairley, N. (2008). Surf Sci 602, 3064-3070]. Here, we...... study in more detail the influence of noise reduction by principal component analysis (PCA) on 3D XPS images of carbon contamination of a patterned oxidized silicon sample and on 3D XPS images of Ag covered by a nanoscale patterned octadiene layer. PCA is very efficient for noise reduction, and using...... acquisition time. A small additional amount of information is obtained by using up to five PCA factors, but due to the increased noise level, this information can only be extracted if the intensity of the start and end points for each spectrum are obtained as averages over several energy points....

Coherent control of photoelectron wavepacket angular interferograms

International Nuclear Information System (INIS)

Hockett, P; Wollenhaupt, M; Baumert, T

2015-01-01

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light–matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable. (paper)

Coherent control of photoelectron wavepacket angular interferograms

Science.gov (United States)

Hockett, P.; Wollenhaupt, M.; Baumert, T.

2015-11-01

Coherent control over photoelectron wavepackets, via the use of polarization-shaped laser pulses, can be understood as a time and polarization-multiplexed process, where the final (time-integrated) observable coherently samples all instantaneous states of the light-matter interaction. In this work, we investigate this multiplexing via computation of the observable photoelectron angular interferograms resulting from multi-photon atomic ionization with polarization-shaped laser pulses. We consider the polarization sensitivity of both the instantaneous and cumulative continuum wavefunction; the nature of the coherent control over the resultant photoelectron interferogram is thus explored in detail. Based on this understanding, the use of coherent control with polarization-shaped pulses as a methodology for a highly multiplexed coherent quantum metrology is also investigated, and defined in terms of the information content of the observable.

Atmospheric pressure plasma surface modification of carbon fibres

DEFF Research Database (Denmark)

Kusano, Yukihiro; Løgstrup Andersen, Tom; Michelsen, Poul

2008-01-01

Carbon fibres are continuously treated with dielectric barrier discharge plasma at atmospheric pressure in various gas conditions for adhesion improvement in mind. An x-ray photoelectron spectroscopic analysis indicated that oxygen is effectively introduced onto the carbon fibre surfaces by He, He...

MoS2 coated hollow carbon spheres for anodes of lithium ion batteries

International Nuclear Information System (INIS)

Zhang, Yufei; Wang, Ye; Shi, Wenhui; Yang, Huiying; Yang, Jun; Huang, Wei; Dong, Xiaochen

2016-01-01

With the assistance of resorcinol–formaldehyde, MoS 2 coated hollow carbon spheres (C@MoS 2 ) were synthesized through a facile hydrothermal route followed by heat and alkali treatments. The measurements indicate that the hollow carbon spheres with an average diameter of 300 nm and shell thickness of 20 nm. And the hollow core are uniformly covered by ultrathin MoS 2 nanosheets with a length increased to 400 nm. The unique hollow structure and the synergistic effect between carbon layer and MoS 2 nanosheets significantly enhance the rate capability and electrochemical stability of C@MoS 2 spheres as anode material of lithium-ion battery. The synthesized C@MoS 2 delivered a capacity of 750 mAh g −1 at a current density of 100 mA g −1 . More importantly, the C@MoS 2 maintained a reversible capacity of 533 mAh g −1 even at a high current density of 1000 mA g −1 . The study indicated that MoS 2 coated hollow carbon spheres can be promising anode material for next generation high-performance lithium-ion batteries. (paper)

Fabrication of multilayered-sandwich MoS2/c architectures with advanced lithium storage properties

International Nuclear Information System (INIS)

Du, Jinlong; Yang, Zhanxu; Wang, Xiaorong; Qi, Chengyuan; Li, Yue; Mao, Wei; Qiao, Haiyan; Yu, ZongBao; Ren, Tieqiang; Qiao, Qingdong

2017-01-01

MoS 2 /C nanocomposite with a multilayered sandwich structure based on few-layered MoS 2 and carbon layers in an alternating sequence, was successfully synthesized through a one-step synchronized carbonization and sulfuration method. The hybrids were characterized by X-ray diffraction, High-resolution transmission electron microscopy, Atomic force microscope, Raman and X-ray photoelectron spectroscopic methods. The as-obtained MoS 2 /C nanocomposite applied as lithium-ion batteries anode materials, showed a high initial discharge and charge capacities of 1678.5 and 1386.0 mAh g −1 , respectively. High specific reversible capacity is maintained at fast C rates, e.g., 1390, 1223, 1017, 566, and 450 mAh g −1 at 0.1C, 0.6C, 3C, 10C and 20C, respectively. The good performance of the composite is mainly attributed to the unique few layered composite architectures, which can improve ion/electron transportation and prevent aggregation and restacking during the lithiation/delithiation process.

Reduction of Kondo lattice effects in Yb1-xLuxAl3 observed by soft x-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Yamaguchi, J; Sekiyama, A; Imada, S; Yamasaki, A; Tsunekawa, M; Muro, T; Ebihara, T; Onuki, Y; Suga, S

2007-01-01

We have carried out the bulk-sensitive and high-resolution soft x-ray photoelectron spectroscopy on Lu substituted intermediate-valence compound Yb 1-x Lu x Al 3 (x = 0.4) at temperatures from 200 to 20 K. The temperature dependences of the bulk Yb 4f photoelectron spectra revealed in our preceding works on high purity YbAl 3 have not been observed in this Lu substituted system. The temperature dependences of the bulk Yb 4f peak positions and the Yb valence in this system can be well reproduced by the single impurity Anderson model (SIAM), whereas the spectral behaviors in YbAl 3 were not at all reproduced by the SIAM. These results confirm the importance of the Kondo lattice effects for YbAl 3 , for which the coherent lattice periodicity plays essential roles

Photoelectron interference fringes by super intense x-ray laser pulses

International Nuclear Information System (INIS)

Toyota, Koudai; Morishita, Toru; Watanabe, Shinichi; Tolstikhin, Oleg I

2009-01-01

The photoelectron spectra of H - produced by circularly polarized strong high-frequency laser pulses are theoretically studied. An oscillating substructure in the above-threshold ionization (ATI) peaks is observed, which extends the validity of the earlier findings in the 1D calculations [K. Toyota et al., Phys. Rev. A 76, 043418 (2007)] and 3D calculations for linear polarization [O. I. Tolstikhin, Phys. Rev. A 77, 032712 (2008)]. Its origin is due to an interference between a pair of photoelectron wave packets created in the rising and falling part of the pulse, which appears clearly in the stabilization regime.

The electronic states of 1,2,4-triazoles: A study of 1H- and1-methyl-1,2,4-triazole by vacuum ultraviolet photoabsorption and ultraviolet photoelectron spectroscopy and a comparison with ab initio configuration interaction computations

DEFF Research Database (Denmark)

Palmer, Michael H.; Camp, Philip J.; Hoffmann, Søren Vrønning

2012-01-01

The first vacuum ultraviolet absorption spectrum of a 1,2,4-triazole has been obtained and analyzed in detail, with assistance from both an enhanced UV photoelectron spectroscopic study and ab initio multi-reference multi-root configuration interaction procedures. For both 1H- and 1-methyl-1,2...

A doped activated carbon prepared from polyaniline for high performance supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Li, Limin; Liu, Enhui; Li, Jian; Yang, Yanjing; Shen, Haijie; Huang, Zhengzheng; Xiang, Xiaoxia; Li, Wen [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)

2010-03-01

A novel doped activated carbon has been prepared from H{sub 2}SO{sub 4}-doped polyaniline which is prepared by the oxypolymerization of aniline. The morphology, surface chemical composition and surface area of the carbon have been investigated by scanning electron microscope, X-ray photoelectron spectroscopy and Brunaner-Emmett-Teller measurement, respectively. Electrochemical properties of the doped activated carbon have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol l{sup -1} KOH. The specific capacitance of the carbon is as high as 235 F g{sup -1}, the specific capacitance hardly decreases at a high current density 11 A g{sup -1} after 10,000 cycles, which indicates that the carbon possesses excellent cycle durability and may be a promising candidate for supercapacitors. (author)

Hybridization and bond-orbital components in site-specific X-ray photoelectron spectra of rutile TiO2

International Nuclear Information System (INIS)

Woicik, J.C.; Nelson, E.J.; Kronik, Leeor; Jain, Manish; Chelikowsky, James R.; Heskett, D.; Berman, L.E.; Herman, G.S.

2002-01-01

We have determined the Ti and O components of the rutile TiO 2 valence band using the method of site-specific x-ray photoelectron spectroscopy. Comparisons with calculations based on pseudopotentials within the local density approximation reveal the hybridization of the Ti 3d, 4s, and 4p states, and the O 2s and 2p states on each site. These chemical effects are observed due to the large differences between the angular-momentum dependent matrix elements of the photoelectron process

Raman and photoelectron spectroscopic investigation of high-purity niobium materials: Oxides, hydrides, and hydrocarbons

Science.gov (United States)

Singh, Nageshwar; Deo, M. N.; Nand, Mangla; Jha, S. N.; Roy, S. B.

2016-09-01

We present investigations of the presence of oxides, hydrides, and hydrocarbons in high-purity (residual resistivity ratio, ˜300) niobium (Nb) materials used in fabrication of superconducting radio frequency (SRF) cavities for particle accelerators. Raman spectroscopy of Nb materials (as-received from the vendor as well as after surface chemical- and thermal processing) revealed numerous peaks, which evidently show the presence of oxides (550 cm-1), hydrides (1277 and 1385 cm-1: ˜80 K temperature), and groups of hydrocarbons (1096, 2330, 2710, 2830, 2868, and 3080 cm-1). The present work provides direct spectroscopic evidence of hydrides in the electropolished Nb materials typically used in SRF cavities. Raman spectroscopy thus can provide vital information about the near-surface chemical species in niobium materials and will help in identifying the cause for the performance degradation of SRF cavities. Furthermore, photoelectron spectroscopy was performed on the Nb samples to complement the Raman spectroscopy study. This study reveals the presence of C and O in the Nb samples. Core level spectra of Nb (doublet 3d5/2 and 3d3/2) show peaks near 206.6 and 209.4 eV, which can be attributed to the Nb5+ oxidation state. The core level spectra of C 1 s of the samples are dominated by graphitic carbon (binding energy, 284.6 eV), while the spectra of O 1 s are asymmetrically peaked near binding energy of ˜529 eV, and that indicates the presence of metal-oxide Nb2O5. The valence-band spectra of the Nb samples are dominated by a broad peak similar to O 2p states, but after sputtering (for 10 min) a peak appears at ˜1 eV, which is a feature of the elemental Nb atom.

DEVELOPMENT OF NEXT-GENERATION DETECTORS AND INSTRUMENTATION FOR PHOTOELECTRON SPECTROSCOPY, DIFFRACTION AND HOLOGRAPHY

International Nuclear Information System (INIS)

Charles S. Fadley, Principal Investigator

2005-01-01

We have developed a new multichannel detector for use in photoelectron spectroscopy (as well as other types of high-count-rate spectroscopy) that will operate at rates of up to 1 GHz. Such detectors are crucial to the full utilization of the high-brightness radiation generated by third-generation synchrotron radiation sources. In addition, new software and hardware has been developed to permit rapidly and accurately scanning photoelectron spectra that will be accumulated in as little as a 200 micros. A versatile next-generation sample goniometer permitting equally rapid scanning of specimen angles or photon energies for angle-resolved photoemission studies, photoelectron diffraction, and photoelectron holography measurements, and cooling to below 10K has also been designed and constructed. These capabilities have been incorporated into a unique photoelectron spectrometer/diffractometer at the Advanced Light Source of the Lawrence Berkeley National Laboratory; this experimental system includes ultrahigh energy resolution, in situ rotation, variable polarization, and optional spin detection. This overall system is now being used in studies of a variety of problems including magnetic metals and oxides; metal/metal, metal/metal oxide, and metal-oxide/metal-oxide multilayers; and systems exhibiting giant and colossal magnetoresistance

Single-photoelectron noise reduction in scintillation detectors

International Nuclear Information System (INIS)

Marvin, T.P.

1995-10-01

The 1994--95 search at SLAC for mulicharged particles used four 21 x 21 x 130-cm 3 Bicron 408 scintillation counters to detect a signal at the single-photoelectron level. The competing noise requiring minimization was due to a combination of PM tube (8-inch Thorne EMI 9353KA) afterpulsing and ambient radiation-induced scintillator luminescence. A very slow decay (> 30 μs) component was observed and received particular attention. Efforts to reduce the SPE noise included photomultiplier tube base modifications, detector shielding and cooling, signal amplification, and veto procedures

Molecular photoionisation using synchrotron radiation. Photoelectron photoion coincidence and circular dichroism

International Nuclear Information System (INIS)

Garcia-Macias, Gustavo Adolfo

2002-01-01

The first ionisation potential of the CF 3 radical has been determined in this work from the appearance potential of the CF 3 + fragment, formed in the photofragmentation of CF 3 Br. In obtaining this value special care has been taken in removing the contributions from second order light and internal energy of the fragmenting parent ion. The resulting ionisation potential was found to be in very good agreement with a number of recent theoretical calculations. The valence photoelectron spectra of three monoterpenes such as limonene, carvone and camphor have been recorded along with their mass spectra taken in coincidence with energy selected photoelectrons, providing information about state selected parent ion fragmentation channels. A new photoelectron spectrometer based on the Alien box design has been studied by ray-tracing simulations. It will include a two dimensional position sensitive detector system consisting in two micro channel plates in a chevron stack and a delay-line anode to encode the impact position. It is currently under construction and it is expected to be commissioned by summer 2002. Continuum molecular scattering calculations have been performed in the optically active carvone. We have looked for circular dichroism in the angular distributions of core and valence photoelectron spectra. The values have been found to be of at least four orders of magnitude bigger than the normal circular dichroism in absorption. Experimental results have been obtained for the circular dichroism in the valence and inner shells of camphor and carvone as a function of photon energy. The experiments were performed in the BESSY II and SACO storage rings in Berlin and Orsay respectively. The core results on camphor show a definite difference between the partial cross-sections of the carbonyl carbon Is orbital when switching the helicity of either the light or the enantiomer. The core results on carvone have yet to be properly analysed and are noisier but the circular

China’s carbon flow: 2008–2012

International Nuclear Information System (INIS)

Li, Huanan; Wei, Yi-Ming; Mi, Zhifu

2015-01-01

As the world’s largest CO 2 emitter, China’s CO 2 emissions have become one of the most popular issues concerned by domestic and foreign researchers. Therefore, analysis of the current status of China’s carbon emissions is very important. After drawing a chart of China’s carbon flow in 2012, based on the IPCC carbon emission inventory method and China’s energy balance table, this paper gives a detailed description of the current status of China’s carbon flow and compares the changing characteristics of China’s carbon flow between 2008 and 2012. The results show that 75.12% of total CO 2 emissions flow mainly into several sectors, such as ferrous sectors, and the chemical industry in the terminal sub-sectors. Although China’s thermoelectric efficiency increased dramatically during past four years, emissions from the heat and power production sector are still increasing due to China’s large demand for heat and power. In the ferrous metal and chemical industry sectors, CO 2 emissions are mainly energy-related, while in the non-metallic mineral sector, CO 2 emissions are mainly from process CO 2 emissions. In different terminal sub-sectors, the main carriers of CO 2 flow are different, thus, related CO 2 reduction policies should also be targeted. In addition, some valuable suggestions are given in this paper. - Highlights: • We compare the changing characteristics of China’s carbon flow from 2008 to 2012. • CO 2 flow carried by primary energy has significantly increased in 2012. • Majority of CO 2 flows into China’s the production and construction systems. • Process emissions from all four main sectors have increased significantly. • CO 2 reduction policies for different CO 2 carriers should be different

Photoelectron spectroscopy bulk and surface electronic structures

CERN Document Server

Suga, Shigemasa

2014-01-01

Photoelectron spectroscopy is now becoming more and more required to investigate electronic structures of various solid materials in the bulk, on surfaces as well as at buried interfaces. The energy resolution was much improved in the last decade down to 1 meV in the low photon energy region. Now this technique is available from a few eV up to 10 keV by use of lasers, electron cyclotron resonance lamps in addition to synchrotron radiation and X-ray tubes. High resolution angle resolved photoelectron spectroscopy (ARPES) is now widely applied to band mapping of materials. It attracts a wide attention from both fundamental science and material engineering. Studies of the dynamics of excited states are feasible by time of flight spectroscopy with fully utilizing the pulse structures of synchrotron radiation as well as lasers including the free electron lasers (FEL). Spin resolved studies also made dramatic progress by using higher efficiency spin detectors and two dimensional spin detectors. Polarization depend...

Sulfurized activated carbon for high energy density supercapacitors

Science.gov (United States)

Huang, Yunxia; Candelaria, Stephanie L.; Li, Yanwei; Li, Zhimin; Tian, Jianjun; Zhang, Lili; Cao, Guozhong

2014-04-01

Sulfurized activated carbon (SAC), made by coating the pore surface with thiophenic sulfur functional groups from the pyrolysis of sulfur flakes, were characterized and tested for supercapacitor applications. From X-ray photoelectron spectroscopy (XPS), the sulfur content in the SAC was found to be 2.7 at%. Electrochemical properties from potentiostatic and galvanostatic measurements, and electrochemical impedance spectroscopy (EIS) were used to evaluate the effect of sulfur on porous carbon electrodes. The SAC electrode exhibits better conductivity, and an obvious increase in specific capacitance that is almost 40% higher than plain activated carbons (ACs) electrode at a high current density of 1.4 A g-1. The proposed mechanism for improved conductivity and capacitive performance due to the sulfur functional groups on ACs will be discussed.

Core-level photoelectron study of Si(1 1 1) sq root 7x sq root 3-(Pb, Sn) surface

CERN Document Server

Soda, K; Takada, T; Yoshimoto, O; Kato, M; Yagi, S; Morita, K; Kamada, M

2003-01-01

The Sn 4d and Pb 5d core-level photoelectron spectra have been studied in order to clarify their bonding properties and atomic arrangement on a Si(1 1 1) sq root 7x sq root 3-(Pb, Sn) surface, which is formed by the coadsorption of 0.4 ML Pb and 0.4 ML Sn and shows two kinds of bright spots in the scanning tunneling microscopic (STM) images: (A) those aligned zigzag on the T sub 1 site and (B) those on the T sub 1 and H sub 3 sites along the [1 1 -2] direction. The Pb 5d spectrum shows a single spin-orbit-split feature with weak tailing towards the high binding energy side, while the Sn 4d spectrum exhibits shoulder structures at the high binding energy side of the main peaks. This definitely indicates at least two different Sn-Si bonds or inequivalent Sn adsorbing sites and single bond or site for Pb. Thus the spots A at the T sub 1 site and those B at the T sub 1 and H sub 3 sites in the STM images are ascribed to Pb and Sn adatoms, respectively. The formation process of this surface will be also discussed ...

The effect of promoters on the electronic structure of ruthenium catalysts supported on carbon

International Nuclear Information System (INIS)

Guraya, Monica; Sprenger, Susanne; Rarog-Pilecka, Wioletta; Szmigiel, Dariusz; Kowalczyk, Zbigniew; Muhler, Martin

2004-01-01

Alkali- and earth-alkali-promoted ruthenium catalysts supported on graphitized carbon were investigated by means of X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) in order to study the effect of promoters on the electronic structure of this metal-support system. Samples were measured as prepared and after thorough reduction in hydrogen. The C 1s spectra of reduced alkali-promoted catalysts showed a shift towards higher binding energies and an asymmetric broadening. Neither non-promoted nor Ba-promoted Ru/C samples exhibited such a behaviour after similar treatments. The most important feature in the UP spectra of the reduced alkali-promoted catalysts was the appearance of a well defined Fermi edge absent in the semimetal-like electronic structure of graphite. No significant effects appeared in the case of non-promoted or Ba-promoted catalysts. The increase in the density of occupied states at the Fermi energy indicates a shift of this level into the conduction band, due to a charge transfer from the promoter to the support. This interpretation also provides an explanation for the observed higher C 1s binding energy and asymmetric broadening, due to the off-set introduced in the binding energy scale and the increasing probability of inelastic excitations near the Fermi level. In addition to photoelectron spectroscopy, low energy ion scattering (ISS) was used to obtain information about the localisation of the promoters. Based on the mild sputtering effect during prolonged series of spectra, it was possible to conclude that potassium covers both the carbon support and the Ru metal particles

Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Anirban Das

2014-01-01

Full Text Available Attachment of PbS quantum dots (QD to single-walled carbon nanotubes (SWNT and multiwalled carbon nanotubes (MWCNT is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT by π-π stacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT was observed, indicating FRET from the QD to the CNT.

China's carbon mitigation strategies: Enough?

International Nuclear Information System (INIS)

Wang, Can; Lin, Jie; Cai, Wenjia; Liao, Hua

2014-01-01

As the largest CO 2 emitter in the world, China has made great achievements in carbon mitigation over the past eight years (2005–2013). Through a comprehensive and detailed overview of China's carbon mitigation strategies, this paper presents China's carbon mitigation achievements and strategies, including adjustment to the industrial structure, saving energy, optimizing energy structure, increasing forest carbon sinks, building foundational capacity, innovating technologies and practicing mitigation efforts in localities and sectors. Having been in place for some years already, the results of many of these measures and policies are now plateauing. China is facing challenges including inevitable emissions growth, shrinking of mitigation potential from technological progress, difficulty in further adjusting the industrial structure and economic development mode, continued dominance of coal in the energy mix, local governments’ reluctance to adopt measures to reduce carbon emissions, etc. Through policy diagnosis it is found that the root causes of these problems and challenges are the facts that policy-making is done primarily on the production side and there is an absence of co-benefits in the decision-making process. Therefore, it is recommended that translating mitigation targets to the consumption level and mainstreaming mitigations’ co-benefits into decision-making processes are needed to quickly enhance the results of mitigation work in China. - Highlights: • Key aspects of China's carbon mitigation strategies were outlined. • China's carbon mitigation achievements were summarized. • Challenges to meet further mitigation were investigated. • Strategic suggestions to quickly enhance China's mitigation ambition were given

Analysis of sensing properties of thermoelectric vapor sensor made of carbon nanotubes/ethylene-octene copolymer composites

Czech Academy of Sciences Publication Activity Database

Slobodian, P.; Říha, Pavel; Olejník, R.; Benlikaya, R.

2016-01-01

Roč. 110, December (2016), s. 257-266 ISSN 0008-6223 Grant - others:Ministerstvo školství, mládeže a tělovýchovy (MŠMT)(CZ) LO1504 Institutional research plan: CEZ:AV0Z20600510 Institutional support: RVO:67985874 Keywords : Multiwalled carbon nanotubes (MWCN) * aromatic hydrocarbons * carbon nanotubes * ethylene * fourier transform infrared spectroscopy * X ray photoelectron spectroscopy Subject RIV: BK - Fluid Dynamics OBOR OECD: Construction engineering, Municipal and structural engineering Impact factor: 6.337, year: 2016

Photoelectron spectra and electronic structure of nitrogen analogues of boron β-diketonates with aromatic substituents

Energy Technology Data Exchange (ETDEWEB)

Tikhonov, Sergey A., E-mail: allser@bk.ru [Far Eastern Federal University, 8 Sukhanova St., Vladivostok, 690950 (Russian Federation); Vovna, Vitaliy I. [Far Eastern Federal University, 8 Sukhanova St., Vladivostok, 690950 (Russian Federation); Borisenko, Aleksandr V. [Vladivostok Branch of Russian Customs Academy, 16v Strelkovaya St., Vladivostok, 690034 (Russian Federation)

2016-11-15

Highlights: • The electronic structures of three nitrogen analogues of boron β-diketonates have been investigated. • UV photoelectron spectra have been interpreted. • The structure of the UV photoelectron spectra is in good agreement with the energies and compositions of Kohn-Sham orbitals. - Abstract: The electronic structure of three nitrogen analogoues of boron β-diketonates containing aromatic substituents was studied by the ultraviolet photoelectron spectroscopy and within the density functional theory. In order to determine effects of heteroatom substitution in the chelate ligand, a comparative analysis was carried out for the electronic structure of three model compounds. In a range of model compounds, the HOMO's nature was revealed to be the same. The HOMO-1 orbital of nitrogen containing compounds is determined by the presence of lone electron pairs of nitrogen. In a range of the complexes under study, the influence of aromatic substituents on the electronic structure was defined. In the imidoylamidinate complex, in contrast to formazanates and β-diketonates, it was found the absence of any noticeable mixing of π-orbitals of the chelate and benzene rings. It was shown that within energy range to 11 eV, the calculated results reproduce well the energy differences between the ionized states of complexes.

Long-Range Coulomb Effect in Intense Laser-Driven Photoelectron Dynamics.

Science.gov (United States)

Quan, Wei; Hao, XiaoLei; Chen, YongJu; Yu, ShaoGang; Xu, SongPo; Wang, YanLan; Sun, RenPing; Lai, XuanYang; Wu, ChengYin; Gong, QiHuang; He, XianTu; Liu, XiaoJun; Chen, Jing

2016-06-03

In strong field atomic physics community, long-range Coulomb interaction has for a long time been overlooked and its significant role in intense laser-driven photoelectron dynamics eluded experimental observations. Here we report an experimental investigation of the effect of long-range Coulomb potential on the dynamics of near-zero-momentum photoelectrons produced in photo-ionization process of noble gas atoms in intense midinfrared laser pulses. By exploring the dependence of photoelectron distributions near zero momentum on laser intensity and wavelength, we unambiguously demonstrate that the long-range tail of the Coulomb potential (i.e., up to several hundreds atomic units) plays an important role in determining the photoelectron dynamics after the pulse ends.

ac impedance, X-ray photoelectron spectroscopy and density functional theory studies of 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles as efficient corrosion inhibitors for carbon steel surface in hydrochloric acid solution

Energy Technology Data Exchange (ETDEWEB)

Outirite, Moha; Lagrenee, Michel; Lebrini, Mounim [Unite de Catalyse et de Chimie du Solide, UMR-CNRS 8181, ENSCL, B.P. 90108, F-59652 Villeneuve d' Ascq Cedex (France); Traisnel, Michel; Jama, Charafeddine [Laboratoire des Procedes d' Elaboration des Revetements Fonctionnels, PERF UMR-CNRS 8008, ENSCL, B.P. 90108, F-59652 Villeneuve d' Ascq Cedex (France); Vezin, Herve [Laboratoire de Chimie Organique et Macromoleculaire, UMR-CNRS 8009, USTL Bat C4, F-59655 Villeneuve d' Ascq Cedex (France); Bentiss, Fouad, E-mail: fbentiss@enscl.f [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco)

2010-02-01

The corrosion inhibition properties of a new class of oxadiazole derivatives, namely 3,5-bis(n-pyridyl)-1,2,4-oxadiazoles (n-DPOX) for C38 carbon steel corrosion in 1 M HCl medium were analysed by electrochemical impedance spectroscopy (EIS). An adequate structural model of the interface was used and the values of the corresponding parameters were calculated and discussed. The experimental results showed that these compounds are excellent inhibitors for the C38 steel corrosion in acid solution and that the protection efficiency increased with increasing the inhibitors concentration. Electrochemical impedance data demonstrate that the addition of the n-DPOX derivatives in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Adsorption of these inhibitors on the steel surface obeys to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) and the thermodynamic data of adsorption showed that inhibition of steel corrosion in normal hydrochloric solution by n-DPOX is due to the formation of a chemisorbed film on the steel surface. Quantum chemical calculations using the Density Functional Theory (DFT) and the Quantitative Structure Activity Relationship (QSAR) approach were performed on n-DPOX derivatives to determine the relationship between molecular structure and their inhibition efficiencies. The results of the quantum chemical calculations and experimental inhibition efficiency were subjected to correlation analysis and indicate that their inhibition effect is closely related to E{sub HOMO}, E{sub LUMO}, and dipole moment (mu).

Photoelectron Emission Studies in CsBr at 257 nm

International Nuclear Information System (INIS)

Maldonado, Juan R.; Liu, Zhi; Sun, Yun; Pianetta, Piero A.; Pease, Fabian W.

2006-01-01

CsBr/Cr photocathodes were found [1,2] to meet the requirements of a multi-electron beam lithography system operating with a light energy of 4.8 eV (257nm). The fact that photoemission was observed with a light energy below the reported 7.3 eV band gap for CsBr was not understood. This paper presents experimental results on the presence of intra-band gap absorption sites (IBAS) in CsBr thin film photo electron emitters, and presents a model based on IBAS to explain the observed photoelectron emission behavior at energies below band gap. A fluorescence band centered at 330 nm with a FWHM of about 0.34 eV was observed in CsBr/Cr samples under 257 nm laser illumination which can be attributed to IBAS and agrees well with previously obtained synchrotron photoelectron spectra[1] from the valence band of CsBr films

Dealloying of Cu{sub x}Au studied by hard X-ray photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Rajput, Parasmani, E-mail: parasmani.rajput@northwestern.edu [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Gupta, Ajay [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India); Detlefs, Blanka [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Kolb, Dieter M. [Institute for Electrochemistry, University of Ulm, D-89069 Ulm (Germany); Potdar, Satish [UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 (India); Zegenhagen, Jörg [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France)

2013-10-15

Highlights: ► The shift in binding energy of Cu and Au lines in CuAu alloys is opposite to expected from the nobility of the elements. ► The magnitude of the chemical shifts of the metal lines in CuAu alloys is strongly influenced by finite size effects and disorder. ► Cu 3s and/or Au 4f cross-sections are not well described by theory (Scofield). The Cu 3s photoabsorption cross-section seems to be strongly overestimated. ► We find/confirm that (CuAu) dealloying proceeds into depth like a spinodal decomposition. -- Abstract: We studied pristine and leached ultra-thin Cu{sub x}Au (x ≈ 4) films by hard X-ray photoelectron spectroscopy. The Au 4f and Cu 3s core levels show a shift in binding energy which is opposite to expected from the nobility of the elements, which is explained by charge transfer involving differently screening s and d valence levels of the elements [W. Eberhardt, S.C. Wu, R. Garrett, D. Sondericker, F. Jona, Phys. Rev. B 31 (1985) 8285]. The magnitude of the chemical shifts of the metal lines is strongly influenced by the finite size and disorder of the films. Angular dependent photoelectron emission allowed to assess the alloy composition as a function of depth larger than 5 nm. The potential controlled dealloying proceeds into depth like a spinodal decomposition with Cu going into solution and the remaining Au accumulating in the surface region. The compositional gradient did not lead to a significant broadening of the metal photoelectron lines suggesting a non-local screening mechanism.

Photoelectronic characterization of heterointerfaces.

Energy Technology Data Exchange (ETDEWEB)

Brumbach, Michael Todd

2012-02-01

In many devices such as solar cells, light emitting diodes, transistors, etc., the performance relies on the electronic structure at interfaces between materials within the device. The objective of this work was to perform robust characterization of hybrid (organic/inorganic) interfaces by tailoring the interfacial region for photoelectron spectroscopy. Self-assembled monolayers (SAM) were utilized to induce dipoles of various magnitudes at the interface. Additionally, SAMs of molecules with varying dipolar characteristics were mixed into spatially organized structures to systematically vary the apparent work function. Polymer thin films were characterized by depositing films of varying thicknesses on numerous substrates with and without interfacial modifications. Hard X-ray photoelectron spectroscopy (HAXPES) was performed to evaluate a buried interface between indium tin oxide (ITO), treated under various conditions, and poly(3-hexylthiophene) (P3HT). Conducting polymer films were found to be sufficiently conducting such that no significant charge redistribution in the polymer films was observed. Consequently, a further departure from uniform substrates was taken whereby electrically disconnected regions of the substrate presented ideally insulating interfacial contacts. In order to accomplish this novel strategy, interdigitated electrodes were used as the substrate. Conducting fingers of one half of the electrodes were electrically grounded while the other set of electrodes were electronically floating. This allowed for the evaluation of substrate charging on photoelectron spectra (SCOPES) in the presence of overlying semiconducting thin films. Such an experiment has never before been reported. This concept was developed out of the previous experiments on interfacial modification and thin film depositions and presents new opportunities for understanding chemical and electronic changes in a multitude of materials and interfaces.

Biomass carbon composited FeS2 as cathode materials for high-rate rechargeable lithium-ion battery

Science.gov (United States)

Xu, Xin; Meng, Zhen; Zhu, Xueling; Zhang, Shunlong; Han, Wei-Qiang

2018-03-01

Pyrite FeS2 has long been used as commercial primary lithium batteries at room temperature. To achieve rechargeable FeS2 battery, biomass-carbon@FeS2 composites are prepared using green and renewable auricularia auricula as carbon source through the process of carbonization and sulfuration. The auricularia auricula has strong swelling characteristics to absorb aqueous solution which can effectively absorb Fe ions into its body. FeS2 homogeneously distributed in biomass carbon matrix performs high electronic and ionic conductivity. The specific capacity of biomass-carbon@FeS2 composites remains 850 mAh g-1 after 80 cycles at 0.5C and 700 mAh g-1 at the rate of 2C after 150 cycles. Biomass-carbon@FeS2 composites exhibit high-rate capacity in lithium-ion battery.

Evaluation of residual iron in carbon nanotubes purified by acid treatments

Energy Technology Data Exchange (ETDEWEB)

Edwards, E.R., E-mail: eliltonedwards@hotmail.com [Sao Paulo State University - UNESP, Av. Dr. Ariberto Pereira da Cunha, 333, CEP: 12.516-410 CP:20, Guaratingueta, SP (Brazil); Antunes, E.F. [National Institute for Space Research - INPE, Av. dos Astronautas, 1758, CEP: 12.254-97, Sao Jose dos Campos-SP (Brazil); Aeronautical Institute of Technology - ITA, Praca Marechal Eduardo Gomes, 50, CEP: 12.228-900, Sao Jose dos Campos-SP (Brazil); Botelho, E.C. [Sao Paulo State University - UNESP, Av. Dr. Ariberto Pereira da Cunha, 333, CEP: 12.516-410 CP:20, Guaratingueta, SP (Brazil); Baldan, M.R.; Corat, E.J. [National Institute for Space Research - INPE, Av. dos Astronautas, 1758, CEP: 12.254-97, Sao Jose dos Campos-SP (Brazil)

2011-11-01

A detailed analysis by X-ray photoelectron spectroscopy was carried out on multi-walled carbon nanotube (MWCNT) surfaces after non-oxidative and oxidative purification treatments in liquid-phase. The MWCNT were produced by pyrolysis of camphor and ferrocene, that provides a high yield but with high iron contamination ({approx}15% wt). The elimination and/or oxidation of iron nanoparticles were monitored by Fe2p and O1s core level. Oxygen-based functional groups attachment was also investigated by C1s fitting. The effectiveness of each treatment in iron removal was evaluated by thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS). The integrity of the MWCNT structure was verified by Raman spectroscopy (RS) and transmission electron microscopy (TEM). A purity degree higher than 98% was achieved only with non-oxidative treatments using sonification process.

Theory of photoelectron counting statistics

International Nuclear Information System (INIS)

Blake, J.

1980-01-01

The purpose of the present essay is to provide a detailed analysis of those theoretical aspects of photoelectron counting which are capable of experimental verification. Most of our interest is in the physical phenomena themselves, while part is in the mathematical techniques. Many of the mathematical methods used in the analysis of the photoelectron counting problem are generally unfamiliar to physicists interested in the subject. For this reason we have developed the essay in such a fashion that, although primary interest is focused on the physical phenomena, we have also taken pains to carry out enough of the analysis so that the reader can follow the main details. We have chosen to present a consistently quantum mechanical version of the subject, in that we follow the Glauber theory throughout. (orig./WL)

Properties of the chalcogenide–carbon nano tubes and graphene composite materials

International Nuclear Information System (INIS)

Singh, Abhay Kumar; Kim, JunHo; Park, Jong Tae; Sangunni, K.S.

2015-01-01

Highlights: • Chalcogenides. • Melt quenched. • Composite materials. • Multi walled carbon nano tubes. • Bilayer graphene. - Abstract: Composite can deliver more than the individual elemental property of the material. Specifically chalcogenide- multi walled carbon nano tubes and chalcogenide- bilayer graphene composite materials could be interesting for the investigation, which have been less covered by the investigators. We describe micro structural properties of Se 55 Te 25 Ge 20, Se 55 Te 25 Ge 20 + 0.025% multi walled carbon nano tubes and Se 55 Te 25 Ge 20 + 0.025% bilayer graphene materials. This gives realization of the alloying constituents inclusion/or diffusion inside the multi walled carbon nano tubes and bilayer graphene under the homogeneous parent alloy configuration. Raman spectroscopy, X-ray photoelectron spectroscopy, UV/Visible spectroscopy and Fourier transmission infrared spectroscopy have also been carried out under the discussion. A considerable core energy levels peak shifts have been noticed for the composite materials by the X-ray photoelectron spectroscopy. The optical energy band gaps are measured to be varied in between 1.2 and 1.3 eV. In comparison to parent (Se 55 Te 25 Ge 20 ) alloy a higher infrared transmission has been observed for the composite materials. Subsequently, variation in physical properties has been explained on the basis of bond formation in solids

MoS{sub 2}/cotton-derived carbon fibers with enhanced cyclic performance for sodium-ion batteries

Energy Technology Data Exchange (ETDEWEB)

Li, Xiang [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Yang, Yan [School of Electrical Engineering, Southwest Jiaotong University, Chengdu, 610031 (China); Liu, Jiangwen; Ouyang, Liuzhang; Liu, Jun; Hu, Renzong [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Yang, Lichun, E-mail: mslcyang@scut.edu.cn [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China); Zhu, Min [School of Materials Science and Engineering, Guangdong Provincial Key Laboratory of Advanced Energy Storage Materials, South China University of Technology, Guangzhou, 510641 (China)

2017-08-15

Highlights: • MoS{sub 2} nanosheets vertically grow on cotton-derived carbon microfibers. • The carbon fibers facilitate charge transfer and structure stabilization. • The MoS{sub 2}/CDCFs exhibit enhanced cyclic performance for reversible Na{sup +} storage. - Abstract: Carbon fibers derived from bio-template are low cost and environmental benign, therefore have attracted much attention in energy storage materials. In this work, we successfully fabricated MoS{sub 2}/cotton-derived carbon fibers (MoS{sub 2}/CDCFs) via hydrothermal route followed by carbonization process. In the composite of MoS{sub 2}/CDCFs, MoS{sub 2} nanosheets vertically grow on the carbon fibers which offer fast ways for electron transfer and at the same time act as robust support to buffer the volume changes of MoS{sub 2} nanosheets during discharge/charge cycles. As anode materials for sodium-ion batteries, MoS{sub 2}/CDCFs exhibit good rate performance and markedly enhanced cyclic stability due to the conductive support of CDCFs. At a current density of 0.1 A g{sup −1}, the MoS{sub 2}/CDCFs-1 shows an initial reversible capacity of 504.9 mAh g{sup −1}, and maintains 444.5 mAh g{sup −1} after 50 cycles. Even when the current density increases to 0.5 A g{sup −1}, it maintains 323.1 mAh g{sup −1} after 150 cycles, which is much higher than the capacity retention of 149.6 mAh g{sup −1} for the bare MoS{sub 2} nanosheets. The improved electrochemical performance verifies the effective strategy of using cotton as carbon source to construct hierarchical composites for sodium-ion batteries.

A novel activated carbon for supercapacitors

Energy Technology Data Exchange (ETDEWEB)

Shen, Haijie [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Liu, Enhui, E-mail: liuenhui99@sina.com.cn [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China); Xiang, Xiaoxia; Huang, Zhengzheng; Tian, Yingying; Wu, Yuhu; Wu, Zhilian; Xie, Hui [Key Laboratory of Environmentally Friendly Chemistry and Applications of Ministry of Education, College of Chemistry, Xiangtan University, Hunan 411105 (China)

2012-03-15

Highlights: Black-Right-Pointing-Pointer A novel activated carbon was prepared from phenol-melamine-formaldehyde resin. Black-Right-Pointing-Pointer The carbon has large surface area with microporous, and high heteroatom content. Black-Right-Pointing-Pointer Heteroatom-containing functional groups can improve the pseudo-capacitance. Black-Right-Pointing-Pointer Physical and chemical properties lead to the good electrochemical properties. -- Abstract: A novel activated carbon has been prepared by simple carbonization and activation of phenol-melamine-formaldehyde resin which is synthesized by the condensation polymerization method. The morphology, thermal stability, surface area, elemental composition and surface chemical composition of samples have been investigated by scanning electron microscope, thermogravimetry and differential thermal analysis, Brunauer-Emmett-Teller measurement, elemental analysis and X-ray photoelectron spectroscopy, respectively. Electrochemical properties have been studied by cyclic voltammograms, galvanostatic charge/discharge, and electrochemical impedance spectroscopy measurements in 6 mol L{sup -1} potassium hydroxide. The activated carbon shows good capacitive behavior and the specific capacitance is up to 210 F g{sup -1}, which indicates that it may be a promising candidate for supercapacitors.

Single walled carbon nanotube network—Tetrahedral amorphous carbon composite film

Energy Technology Data Exchange (ETDEWEB)

Iyer, Ajai, E-mail: ajai.iyer@aalto.fi; Liu, Xuwen; Koskinen, Jari [Department of Materials Science and Engineering, School of Chemical Technology, Aalto University, POB 16200, 00076 Espoo (Finland); Kaskela, Antti; Kauppinen, Esko I. [NanoMaterials Group, Department of Applied Physics, School of Science, Aalto University, POB 15100, 00076 Espoo (Finland); Johansson, Leena-Sisko [Department of Forest Products Technology, School of Chemical Technology, Aalto University, POB 16400, 00076 Espoo (Finland)

2015-06-14

Single walled carbon nanotube network (SWCNTN) was coated by tetrahedral amorphous carbon (ta-C) using a pulsed Filtered Cathodic Vacuum Arc system to form a SWCNTN—ta-C composite film. The effects of SWCNTN areal coverage density and ta-C coating thickness on the composite film properties were investigated. X-Ray photoelectron spectroscopy measurements prove the presence of high quality sp{sup 3} bonded ta-C coating on the SWCNTN. Raman spectroscopy suggests that the single wall carbon nanotubes (SWCNTs) forming the network survived encapsulation in the ta-C coating. Nano-mechanical testing suggests that the ta-C coated SWCNTN has superior wear performance compared to uncoated SWCNTN.

N/S Co-doped Carbon Derived From Cotton as High Performance Anode Materials for Lithium Ion Batteries

Directory of Open Access Journals (Sweden)

Jiawen Xiong

2018-04-01

Full Text Available Highly porous carbon with large surface areas is prepared using cotton as carbon sources which derived from discard cotton balls. Subsequently, the sulfur-nitrogen co-doped carbon was obtained by heat treatment the carbon in presence of thiourea and evaluated as Lithium-ion batteries anode. Benefiting from the S, N co-doping, the obtained S, N co-doped carbon exhibits excellent electrochemical performance. As a result, the as-prepared S, N co-doped carbon can deliver a high reversible capacity of 1,101.1 mA h g−1 after 150 cycles at 0.2 A g−1, and a high capacity of 531.2 mA h g−1 can be observed even after 5,000 cycles at 10.0 A g−1. Moreover, excellently rate capability also can be observed, a high capacity of 689 mA h g−1 can be obtained at 5.0 A g−1. This superior lithium storage performance of S, N co-doped carbon make it as a promising low-cost and sustainable anode for high performance lithium ion batteries.

Ar 3p photoelectron sideband spectra in two-color XUV + NIR laser fields

Science.gov (United States)

Minemoto, Shinichirou; Shimada, Hiroyuki; Komatsu, Kazma; Komatsubara, Wataru; Majima, Takuya; Mizuno, Tomoya; Owada, Shigeki; Sakai, Hirofumi; Togashi, Tadashi; Yoshida, Shintaro; Yabashi, Makina; Yagishita, Akira

2018-04-01

We performed photoelectron spectroscopy using femtosecond XUV pulses from a free-electron laser and femtosecond near-infrared pulses from a synchronized laser, and succeeded in measuring Ar 3p photoelectron sideband spectra due to the two-color above-threshold ionization. In our calculations of the first-order time-dependent perturbation theoretical model based on the strong field approximation, the photoelectron sideband spectra and their angular distributions are well reproduced by considering the timing jitter between the XUV and the NIR pulses, showing that the timing jitter in our experiments was distributed over the width of {1.0}+0.4-0.2 ps. The present approach can be used as a method to evaluate the timing jitter inevitable in FEL experiments.

Hydrogen spillover in Pt-single-walled carbon nanotube composites: formation of stable C-H bonds.

Science.gov (United States)

Bhowmick, Ranadeep; Rajasekaran, Srivats; Friebel, Daniel; Beasley, Cara; Jiao, Liying; Ogasawara, Hirohito; Dai, Hongjie; Clemens, Bruce; Nilsson, Anders

2011-04-13

Using in situ electrical conductivity and ex situ X-ray photoelectron spectroscopy (XPS) measurements, we have examined how the hydrogen uptake of single-walled carbon nanotubes (SWNTs) is influenced by the addition of Pt nanoparticles. The conductivity of platinum-sputtered single-walled carbon nanotubes (Pt-SWNTs) during molecular hydrogen exposure decreased more rapidly than that of the corresponding pure SWNTs, which supports a hydrogenation mechanism facilitated by "spillover" of dissociated hydrogen from the Pt nanoparticles. C 1s XPS spectra indicate that the Pt-SWNTs store hydrogen by means of chemisorption, that is, covalent C-H bond formation: molecular hydrogen charging at elevated pressure (8.27 bar) and room temperature yielded Pt-SWNTs with up to 16 ± 1.5 at. % sp(3)-hybridized carbon atoms, which corresponds to a hydrogen-storage capacity of 1.2 wt % (excluding the weight of Pt nanoparticles). Pt-SWNTs prepared by the Langmuir-Blodgett (LB) technique exhibited the highest Pt/SWNT ratio and also the best hydrogen uptake. © 2011 American Chemical Society

Electronic structure of the misfit-layer compound (SnS)1.17NbS2 deduced from band-structure calculations and photoelectron spectra

NARCIS (Netherlands)

Fang, C.M.; Ettema, A.R.H.F.; Haas, C.; Wiegers, G.A.; Leuken, H. van; Groot, R.A. de

1995-01-01

In order to understand the electronic structure of the misfit-layer compound (SnS)1.17NbS2 we carried out an ab initio band-structure calculation of the closely related commensurate compound (SnS)1.20NbS2. The band structure is compared with calculations for NbS2 and for hypothetical SnS with

X-ray photoelectron spectroscopic study of catalyst based zinc oxide thin films

International Nuclear Information System (INIS)

Shinde, S.S.; Rajpure, K.Y.

2011-01-01

Research highlights: → The two step approach for quantitative XPS analysis of ZnO films has been reported. → Surface composition and chemical states of F and In/ZnO catalysts have been studied. → The chemical shifts and Auger parameter have been investigated. - Abstract: X-ray photoelectron spectroscopy (XPS) is a powerful tool for surface and interface analysis, providing an elemental composition of surfaces and the local chemical environment of adsorbed species. The surface composition and chemical states of the F/ZnO and In/ZnO catalysts deposited using spray technique have been studied by high resolution and high sensitivity X-ray photoelectron spectroscopy. A hybrid multiline method is proposed for quantitative XPS analysis that combines the first principles approach with the experimental determination of overall response function. The chemical shifts of XPS core lines for Zn (2P 3/2 , F 1s and In 3d) and Auger parameter for zinc (β Zn = 2012.6, 2011.48 eV for F/ZnO and In/ZnO, respectively) have been calculated. The results have been used to determine the bond iconicity (0.55).

Carbon coated CoS_2 thermal battery electrode material with enhanced discharge performances and air stability

International Nuclear Information System (INIS)

Xie, Song; Deng, Yafeng; Mei, Jun; Yang, Zhaotang; Lau, Woon-Ming; Liu, Hao

2017-01-01

Graphical abstract: A novel carbon coated CoS_2 composite is prepared and investigated as a cathode material for thermal batteries. - Highlights: • A novel C@CoS_2 composite is successfully prepared by hydrothermal method. • The growth of CoS_2 in the glucose solution results in a smaller grain size. • The coating of carbon favors electron transfer and buffers polysulfides formation. • The in situ coated carbon layer effectively prevents the oxidation of CoS_2. • The C@CoS_2 composite shows competitive thermal stability and discharge property. - Abstract: Cobalt disulfide (CoS_2) is a promising thermal battery electrode material for its superior thermal stability and discharge performance. However, the low natural resource and poor air stability restrict its application in thermal battery fabrication. In this work, carbon coated CoS_2 composite was prepared by a facile one-pot hydrothermal method with glucose as carbon source. During the growth of CoS_2, the glucose molecules were in situ adsorbed and carbonized on the surface of the as-synthesized CoS_2, and the resultant carbon coating provided improved electrical conductivity and discharge performances to the composite. The thermal battery cell, which was fabricated with such a composite cathode and with a Li-Si anode, can output a capacity of 235.8 mAh g"−"1 and an energy density of 416.9 Wh kg"−"1 at a cut-off voltage of 1.7 V. This carbon coated CoS_2 composite also presented enhanced air stability. After being stored in dry air for 3 months, the composite can still provide a capacity of 232.4 mAh g"−"1 to 1.7 V, whereas the capacity of bare CoS_2 stored with the same condition dropped from 202.4 mAh g"−"1 to 189.7 mAh g"−"1.

The origin of narrowing of the Si 2p coincidence photoelectron spectroscopy main line of Si(1 0 0) surface

International Nuclear Information System (INIS)

Ohno, Masahide

2011-01-01

Highlights: → The Si 2p coincidence photoelectron spectroscopy (PES) main line of Si(1 0 0) is calculated. → The PES main line shows an asymmetric line shape change compared to the singles one. → The narrowing of the coincidence Si 2p PES main line is well reproduced. → The inherent mechanism of APECS is explained by a many-body theory. - Abstract: The Si 2p photoelectron spectroscopy (PES) main line of Si(1 0 0) surface measured in coincidence with the singles (noncoincidence) Si L 2,3 -VV Auger-electron spectroscopy (AES) elastic peak is calculated. The agreement with the experiment is good. The present work is the first many-body calculation of the experimental coincidence PES spectrum of solid surface. The narrowing of the coincidence Si 2p PES main line compared to the singles one is due to the mechanism inherent in the coincidence PES. The inherent mechanism is explained by a many-body theory by which photoemission and Auger-electron emission are treated on the same footing.

Functionalized carbon nanotubes containing isocyanate groups

International Nuclear Information System (INIS)

Zhao Chungui; Ji Lijun; Liu Huiju; Hu Guangjun; Zhang Shimin; Yang Mingshu; Yang Zhenzhong

2004-01-01

Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

A temperature-programmed X-ray photoelectron spectroscopy (TPXPS) study of chlorine adsorption and diffusion on Ag(1 1 1)

Science.gov (United States)

Piao, H.; Adib, K.; Barteau, Mark A.

2004-05-01

Synchrotron-based temperature programmed X-ray photoelectron spectroscopy (TPXPS) has been used to investigate the surface chloridation of Ag(1 1 1) to monolayer coverages. At 100 K both atomic and molecular chlorine species are present on the surface; adsorption at 300 K or annealing the adlayer at 100 K to this temperature generates adsorbed Cl atoms. As the surface is heated from 300 to 600 K, chlorine atoms diffuse below the surface, as demonstrated by attenuation of the Cl2p signals in TPXPS experiments. Quantitative analysis of the extent of attenuation is consistent with chlorine diffusion below the topmost silver layer. For coverages in the monolayer and sub-monolayer regime, chlorine diffusion to and from the bulk appears not to be significant, in contrast to previous results obtained at higher chlorine loadings. Chlorine is removed from the surface at 650-780 K by desorption as AgCl. These results demonstrate that chlorine diffusion beneath the surface does occur at coverages and temperatures relevant to olefin epoxidation processes carried out on silver catalysts with chlorine promoters. The surface sensitivity advantages of synchrotron-based XPS experiments were critical to observing Cl diffusion to the sub-surface at low coverages.

Amperometric biosensor for bisphenol A based on a glassy carbon electrode modified with a nanocomposite made from polylysine, single walled carbon nanotubes and tyrosinase

International Nuclear Information System (INIS)

Han, Miao; Qu, Ying; Chen, Shiqin; Wang, Yali; Zhang, Zhi; Zhan, Guoqing; Li, Chunya; Ma, Ming; Wang, Zhengguo

2013-01-01

We have prepared a nanocomposite consisting of single-walled carbon nanotubes and polylysine. It was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and by UV/vis and FTIR spectroscopy. Tyrosinase was covalently immobilized on the nanocomposite, and the resulting bioconjugate deposited on a glassy carbon electrode to form a biosensor for bisphenol A. The biosensor was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Under optimized experimental conditions, the biosensor gives a linear response to bisphenol A in the 4.00 nM to 11.5 μM concentration range. Its sensitivity is 788 mA M −1 cm −2 , and the lower detection limit is 0.97 nM (at an S/N of 3). The biosensor shows good repeatability, reproducibility and long-term stability. In a preliminary practical application, it was successfully applied to the determination of bisphenol A in leachates of plastic spoons. (author)

Correlation of sp{sup 3} and sp{sup 2} fraction of carbon with electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon films

Energy Technology Data Exchange (ETDEWEB)

Dwivedi, Neeraj [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi (India); Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Kumar, Sushil, E-mail: skumar@nplindia.org [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi (India); Malik, H.K. [Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India); Govind [Surface Physics and Nano Structures Group, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi 110012 (India); Rauthan, C.M.S.; Panwar, O.S. [Physics of Energy Harvesting Division, National Physical Laboratory (CSIR), Dr. K.S. Krishnan Road, New Delhi (India)

2011-05-15

In the present work the correlation of electrical, optical and nano-mechanical properties of argon-diluted diamond-like carbon (Ar-DLC) thin films with sp{sup 3} and sp{sup 2} fractions of carbon have been explored. These Ar-DLC thin films have been deposited, under varying C{sub 2}H{sub 2} gas pressures from 25 to 75 mTorr, by radio frequency-plasma enhanced chemical vapor deposition technique. X-ray photoelectron spectroscopy studies are performed to estimate the sp{sup 3} and sp{sup 2} fractions of carbon by deconvoluting C 1s core level spectra. Various electrical, optical and nano-mechanical parameters such as conductivity, I-V characteristics, optical band gap, stress, hardness, elastic modulus, plastic resistance parameter, elastic recovery and plastic deformation energy have been estimated and then correlated with calculated sp{sup 3} and sp{sup 2} fractions of carbon and sp{sup 3}/sp{sup 2} ratios. Observed tremendous electrical, optical and nano-mechanical properties in Ar-DLC films deposited under high base pressure conditions made it a cost effective material for not only hard and protective coating applications but also for electronic and optoelectronic applications.

Analysis of Charge Transfer for in Situ Li Intercalated Carbon Nanotubes

KAUST Repository

Rana, Kuldeep

2012-05-24

Vertically aligned carbon nanotube (VA-CNT) arrays have been synthesized with lithium (Li) intercalation through an alcohol-catalyzed chemical vapor deposition technique by using a Li-containing catalyst. Scanning electron microscopy images display that synthesized carbon nanotubes (CNTs) are dense and vertically aligned. The effect of the Li-containing catalyst on VA-CNTs has been studied by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). XPS results show the change in binding energy of Li 1s and C 1s peaks, which indicates that Li is inserted in VA-CNTs during growth. Analysis of Raman spectra reveals that the G-band profile of CNTs synthesized with the Li-containing catalyst is shifted, suggesting an electronic interaction between Li and neighboring C atoms of the CNTs. The EELS spectra of the C K edge and Li K edge from CNTs also confirmed that Li is inserted into CNTs during synthesis. We have performed ab inito calculations based on density functional theory for a further understanding of the structural and electronic properties of Li intercalated CNTs, especially addressing the controversial charge-transfer state between Li and C. © 2012 American Chemical Society.

Analysis of Charge Transfer for in Situ Li Intercalated Carbon Nanotubes

KAUST Repository

Rana, Kuldeep; Kucukayan-Dogu, Gokce; Sen, H. Sener; Boothroyd, Chris; Gulseren, Oguz; Bengu, Erman

2012-01-01

Vertically aligned carbon nanotube (VA-CNT) arrays have been synthesized with lithium (Li) intercalation through an alcohol-catalyzed chemical vapor deposition technique by using a Li-containing catalyst. Scanning electron microscopy images display that synthesized carbon nanotubes (CNTs) are dense and vertically aligned. The effect of the Li-containing catalyst on VA-CNTs has been studied by using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electron energy loss spectroscopy (EELS). XPS results show the change in binding energy of Li 1s and C 1s peaks, which indicates that Li is inserted in VA-CNTs during growth. Analysis of Raman spectra reveals that the G-band profile of CNTs synthesized with the Li-containing catalyst is shifted, suggesting an electronic interaction between Li and neighboring C atoms of the CNTs. The EELS spectra of the C K edge and Li K edge from CNTs also confirmed that Li is inserted into CNTs during synthesis. We have performed ab inito calculations based on density functional theory for a further understanding of the structural and electronic properties of Li intercalated CNTs, especially addressing the controversial charge-transfer state between Li and C. © 2012 American Chemical Society.

Facile synthesis of NiS anchored carbon nanofibers for high-performance supercapacitors

Science.gov (United States)

Xu, Jinling; Zhang, Li; Xu, Guancheng; Sun, Zhipeng; Zhang, Chi; Ma, Xin; Qi, Chunling; Zhang, Lu; Jia, Dianzeng

2018-03-01

Transition metal sulfide compounds with carbon materials are promising for high-performance supercapacitors. Carbon nanofibers (CNFs) wrapped with NiS nanoparticles were herein obtained through electrospinning and calcination. NiS nanoparticles in composite nanofibers are covered by a layer of graphitic carbon, which not only increase the conductivity but also provide active regions for nanoparticle growth to prevent aggregation. The CNFs-NiS electrode has high specific capacity of 177.1 mAh g-1 at 1 A g-1 (0.41 mAh cm-2 at a current density of 2.3 mA cm-2) and long-term cycling stability, with 88.7% capacitance retention after 5000 cycles. The excellent electrochemical activity may be attributed to the accessible specific surface, unique porous structure of CNFs and high specific capacitance of NiS. In addition, the asymmetric supercapacitor has an enhanced volumetric energy density of 13.32 mWh cm-3 at a volumetric power density of 180 mW cm-3 and high cycling stability, with 89.5% capacitance retention after 5000 cycles. It also successfully lights up a light-emitting diode. The CNFs-NiS composite has significant potential applications in supercapacitor.

Electrochemical study of nitrobenzene reduction using novel Pt nanoparticles/macroporous carbon hybrid nanocomposites

International Nuclear Information System (INIS)

Zhang Yufan; Zeng Lijun; Bo Xiangjie; Wang Huan; Guo Liping

2012-01-01

Graphical abstract: A one-step microwave-assisted route for rapidly synthesizing Pt nanoparticles ensemble on macroporous carbon hybrid nanocomposites (PNMPC) has been reported. As a novel electrode material, the excellent electrochemical behavior of nitrobenzene was investigated thoroughly at the PNMPC modified glassy carbon electrode. And moreover, the modified electrode was successfully applied to the determination of nitrobenzene in real samples. Highlights: ► One-step microwave-assisted heating synthesis Pt nanoparticles/macroporous carbon hybrid nanocomposites (PNMPC). ► Catalytic rate constant being 3.14 × 10 4 M −1 s −1 for NB in pH 7.0. ► Sensitive electrochemical detection of NB at the PNMPC/Nafion/GC electrode. ► The electrode showing excellent anti-interference ability and good stability for NB. - Abstract: Novel Pt nanoparticles (PN) ensemble on macroporous carbon (MPC) hybrid nanocomposites (PNMPC) were prepared through a rapidly and simple one-step microwave-assisted heating procedure. The obtained PNMPC was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and electrochemical methods. The electrochemical reduction of nitrobenzene (NB) was thoroughly investigated at the PNMPC modified glassy carbon (GC) electrode, and the catalytic rate constant was calculated to be 3.14 × 10 4 M −1 s −1 for NB. A sensitive NB sensor was developed based on the PNMPC/GC electrode, which showed a wide linear range (1–200 μM), low detection limit (50 nM), high sensitivity (6.93 μA μM −1 ), excellent anti-interference ability and good stability. And moreover, the electrode was successfully applied to the determination of NB in real samples.

Effect of Additional Sulfide and Thiosulfate on Corrosion of Q235 Carbon Steel in Alkaline Solutions

Directory of Open Access Journals (Sweden)

Bian Li Quan

2016-01-01

Full Text Available This paper investigated the effect of additional sulfide and thiosulfate on Q235 carbon steel corrosion in alkaline solutions. Weight loss method, scanning electron microscopy (SEM equipped with EDS, X-ray photoelectron spectroscopy (XPS, and electrochemical measurements were used in this study to show the corrosion behavior and electrochemistry of Q235 carbon steel. Results indicate that the synergistic corrosion rate of Q235 carbon steel in alkaline solution containing sulfide and thiosulfate is larger than that of sulfide and thiosulfate alone, which could be due to redox reaction of sulfide and thiosulfate. The surface cracks and pitting characteristics of the specimens after corrosion were carefully examined and the corrosion products film is flake grains and defective. The main corrosion products of specimen induced by S2− and S2O32- are FeS, FeS2, Fe3O4, and FeOOH. The present study shows that the corrosion mechanism of S2− and S2O32- is different for the corrosion of Q235 carbon steel.

Synchrotron radiation photoelectron spectroscopy study of dextran-coated Fe3O4 magnetic nanoparticles

International Nuclear Information System (INIS)

Li Shaoxia; Meng Qiang; Wang Bing; Feng Weiyue; Wang Zhuo; Kui Rexi; Qian Haijie; Wang Jia'o

2009-01-01

Dextran-coated Fe 3 O 4 nanoparticles were prepared by untrasonification of Fe 3 O 4 nanoparticles with dextran at 85 degree C in sodium citrate medium. The surface chemical component, structure and bond of uncoated and dextran-coated nanoparticles were measured by synchrotron radiation XPS(X-ray photoelectron spectroscopy). Qualitative and quantitative analysis of C1s and O1s of Fe 3 O 4 and dextran-Fe 3 O 4 showed that the Fe 3 O 4 nanoparticles were successively coated by sodium citrate via Fe-O-C bond, and dextrans, which can be linked with their carboxylate moiety via hydrogen bond. Sodium citrate could enhance the disperse stability of reaction system and hydrophilicity of dextran-Fe 3 O 4 . (authors)

Hydroxyapatite-diamondlike carbon nanocomposite films

International Nuclear Information System (INIS)

Narayan, Roger J.

2005-01-01

Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Conventional plasma-sprayed hydroxyapatite coatings demonstrate poor adhesion and poor mechanical integrity. We have developed hydroxyapatite-diamondlike carbon bilayer film. The diamondlike carbon interlayer serves to prevent metal ion release and improve adhesion of the hydroxyapatite film. These films were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, nanoindentation, and microscratch adhesion testing. Based on the results of this study, hydroxyapatite-diamondlike carbon bilayers demonstrate promise for use in several orthopedic implants

Hydroxyapatite-diamondlike carbon nanocomposite films

Energy Technology Data Exchange (ETDEWEB)

Narayan, Roger J. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)]. E-mail: roger.narayan@mse.gatech.edu

2005-05-15

Hydroxyapatite is a bioactive ceramic that mimics the mineral composition of natural bone. Conventional plasma-sprayed hydroxyapatite coatings demonstrate poor adhesion and poor mechanical integrity. We have developed hydroxyapatite-diamondlike carbon bilayer film. The diamondlike carbon interlayer serves to prevent metal ion release and improve adhesion of the hydroxyapatite film. These films were characterized using X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Raman spectroscopy, nanoindentation, and microscratch adhesion testing. Based on the results of this study, hydroxyapatite-diamondlike carbon bilayers demonstrate promise for use in several orthopedic implants.

Photoelectron Spectroscopy and Density Functional Theory Studies of Iron Sulfur (FeS)m- (m = 2-8) Cluster Anions: Coexisting Multiple Spin States.

Science.gov (United States)

Yin, Shi; Bernstein, Elliot R

2017-10-05

Iron sulfur cluster anions (FeS) m - (m = 2-8) are studied by photoelectron spectroscopy (PES) at 3.492 eV (355 nm) and 4.661 eV (266 nm) photon energies, and by density functional theory (DFT) calculations. The most probable structures and ground state spin multiplicities for (FeS) m - (m = 2-8) clusters are tentatively assigned through a comparison of their theoretical and experiment first vertical detachment energy (VDE) values. Many spin states lie within 0.5 eV of the ground spin state for the larger (FeS) m - (m ≥ 4) clusters. Theoretical VDEs of these low lying spin states are in good agreement with the experimental VDE values. Therefore, multiple spin states of each of these iron sulfur cluster anions probably coexist under the current experimental conditions. Such available multiple spin states must be considered when evaluating the properties and behavior of these iron sulfur clusters in real chemical and biological systems. The experimental first VDEs of (FeS) m - (m = 1-8) clusters are observed to change with the cluster size (number m). The first VDE trends noted can be related to the different properties of the highest singly occupied molecular orbitals (NBO, HSOMOs) of each cluster anion. The changing nature of the NBO/HSOMO of these (FeS) m - (m = 1-8) clusters from a p orbital on S, to a d orbital on Fe, and to an Fe-Fe bonding orbital is probably responsible for the observed increasing trend for their first VDEs with respect to m.

Photoelectron spectroscopic studies of some transition metals and alloys

International Nuclear Information System (INIS)

McLachlan, A.D.

1974-01-01

Photoelectron spectra of polycrystalline samples of Cu, Ag and Au at photon energies of 21.22, 40.81 eV and 1487 eV were measured. The corrected 40.81 eV results were compared to theoretical band structure calculations and monochromatized x-ray photoelectron results. Correlation of hitherto unresolved peaks in the 40.81 eV spectra was observed. Comparison of the relative intensities of the spectral d bands and the theoretical calculations revealed discrepancies which were assigned to matrix element modulation effects in the photoelectron emission process. Experimental measurements and theories of the electronic structure of disordered alloy systems were reviewed. The 21.22 eV and 40.81 eV photoelectron spectra of some AgPd and AgAu alloys were measured. The spectra were compared with previous x-ray photon results, and with theoretical calculations based on the Coherent Potential Approximation (CPA) model of disordered alloy systems. The present results were found to give more clearly defined spectral details, with differences in the comparison reflecting the simplifying assumptions of the CPA calculation. (author)

Photoelectron diffraction and holography: Present status and future prospects

Energy Technology Data Exchange (ETDEWEB)

Fadley, C.S. [California Univ., Davis, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States); Thevuthasan, S. [California Univ., Davis, CA (United States). Dept. of Physics; Kaduwela, A.P. [Lawrence Berkeley Lab., CA (United States)] [and others

1993-07-01

Photoelectron diffraction and photoelectron holography, a newly developed variant of it, can provide a rich range of information concerning surface structure. These methods are sensitive to atomic type, chemical state, and spin state. The theoretical prediction of diffraction patterns is also well developed at both the single scattering and multiple scattering levels, and quantitative fits of experiment to theory can lead to structures with accuracies in the {plus_minus}0.03 {Angstrom} range. Direct structural information can also be derived from forward scattering in scanned-angle measurements at higher energies, path length differences contained in scanned-energy data at lower energies, and holographic inversions of data sets spanning some region in angle and energy space. Diffraction can also affect average photoelectron emission depths. Circular dichroism in core-level emission can be fruitfully interpreted in terms of photoelectron diffraction theory, as can measurements with spin-resolved core-spectra, and studies of surface magnetic structures and phase transitions should be possible with these methods. Synchrotron radiation is a key element of fully utilizing these techniques.

Alternative mannosylation method for nanomaterials: application to oxidized debris-free multiwalled carbon nanotubes

International Nuclear Information System (INIS)

Sousa, Marcelo de; Martinez, Diego Stéfani Teodoro; Alves, Oswaldo Luiz

2016-01-01

Mannosylation is a method commonly used to deliver nanomaterials to specific organs and tissues via cellular macrophage uptake. In this work, for the first time, we proposed a method that involves the binding of d-mannose to ethylenediamine to form mannosylated ethylenediamine, which is then coupled to oxidized and purified multiwalled carbon nanotubes. The advantage of this approach is that mannosylated ethylenediamine precipitates in methanol, which greatly facilitates the separation of this product in the synthesis process. Carbon nanotubes were oxidized using concentrated H_2SO_4 and HNO_3 by conventional reflux method. However, during this oxidation process, carbon nanotubes generated carboxylated carbonaceous fragments (oxidation debris). These by-products were removed from the oxidized carbon nanotubes to ensure that the functionalization would occur only on the carbon nanotube surface. The coupling of mannosylated ethylenediamine to debris-free carbon nanotubes was accomplished using n-(3-dimethylaminopropyl)-n-ethylcarbodiimide and n-hydroxysuccinimide. Deconvoluted N1s spectra obtained from X-ray photoelectron spectroscopy gave binding energies of 399.8 and 401.7 eV, which we attributed to the amide and amine groups, respectively, of carbon nanotubes functionalized with mannosylated ethylenediamine. Deconvoluted O1s spectra showed a binding energy of 532.4 eV, which we suggest is caused by an overlap in the binding energies of the aliphatic CO groups of d-mannose and the O=C group of the amide bond. The functionalization degree was approximately 3.4 %, according to the thermogravimetric analysis. Scanning electron microscopy demonstrated that an extended carbon nanotube morphology was preserved following the oxidation, purification, and functionalization steps.

Alternative mannosylation method for nanomaterials: application to oxidized debris-free multiwalled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Sousa, Marcelo de, E-mail: marcelosousap2@yahoo.com.br [University of Campinas (Unicamp), Solid State Chemistry Laboratory (LQES) and NanoBioss Laboratory, Institute of Chemistry (Brazil); Martinez, Diego Stéfani Teodoro, E-mail: diego.martinez@lnnano.cnpem.br [Brazilian Center for Research in Energy and Materials (CNPEM), Brazilian Nanotechnology National Laboratory (LNNano) (Brazil); Alves, Oswaldo Luiz, E-mail: oalves@iqm.unicamp.br [University of Campinas (Unicamp), Solid State Chemistry Laboratory (LQES) and NanoBioss Laboratory, Institute of Chemistry (Brazil)

2016-06-15

Mannosylation is a method commonly used to deliver nanomaterials to specific organs and tissues via cellular macrophage uptake. In this work, for the first time, we proposed a method that involves the binding of d-mannose to ethylenediamine to form mannosylated ethylenediamine, which is then coupled to oxidized and purified multiwalled carbon nanotubes. The advantage of this approach is that mannosylated ethylenediamine precipitates in methanol, which greatly facilitates the separation of this product in the synthesis process. Carbon nanotubes were oxidized using concentrated H{sub 2}SO{sub 4} and HNO{sub 3} by conventional reflux method. However, during this oxidation process, carbon nanotubes generated carboxylated carbonaceous fragments (oxidation debris). These by-products were removed from the oxidized carbon nanotubes to ensure that the functionalization would occur only on the carbon nanotube surface. The coupling of mannosylated ethylenediamine to debris-free carbon nanotubes was accomplished using n-(3-dimethylaminopropyl)-n-ethylcarbodiimide and n-hydroxysuccinimide. Deconvoluted N1s spectra obtained from X-ray photoelectron spectroscopy gave binding energies of 399.8 and 401.7 eV, which we attributed to the amide and amine groups, respectively, of carbon nanotubes functionalized with mannosylated ethylenediamine. Deconvoluted O1s spectra showed a binding energy of 532.4 eV, which we suggest is caused by an overlap in the binding energies of the aliphatic CO groups of d-mannose and the O=C group of the amide bond. The functionalization degree was approximately 3.4 %, according to the thermogravimetric analysis. Scanning electron microscopy demonstrated that an extended carbon nanotube morphology was preserved following the oxidation, purification, and functionalization steps.

Band alignment of HfO{sub 2}/multilayer MoS{sub 2} interface determined by x-ray photoelectron spectroscopy: Effect of CHF{sub 3} treatment

Energy Technology Data Exchange (ETDEWEB)

Liu, Xinke; He, Jiazhu; Tang, Dan; Jia, Fang; Lu, Youming, E-mail: ymlu@szu.edu.cn; Zhu, Deliang; Liu, Wenjun; Cao, Peijiang; Han, Sun [College of Materials Science and Engineering, Shenzhen Engineering Laboratory for Advanced Technology of Ceramics, Nanshan District Key Lab for Biopolymer and Safety Evaluation, Shenzhen University, 3688 Nanhai Ave, Shenzhen 518060 (China); Liu, Qiang; Wen, Jiao; Yu, Wenjie, E-mail: casan@mail.sim.ac.cn [State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, CAS,865 Chang Ning Road, Shanghai 200050 (China); Pan, Jisheng [Institute of Materials Research and Engineering, Agency for Science Technology and Research, Singapore 117602 (Singapore); He, Zhubing [Department of Materials Science and Engineering, South University of Science and Technology of China, 1088 Xueyuan Road, Shenzhen 518055 (China); Ang, Kah-Wee [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117583 (Singapore)

2015-09-07

The energy band alignment between HfO{sub 2}/multilayer (ML)-MoS{sub 2} was characterized using high-resolution x-ray photoelectron spectroscopy. The HfO{sub 2} was deposited using an atomic layer deposition tool, and ML-MoS{sub 2} was grown by chemical vapor deposition. A valence band offset (VBO) of 1.98 eV and a conduction band offset (CBO) of 2.72 eV were obtained for the HfO{sub 2}/ML-MoS{sub 2} interface without any treatment. With CHF{sub 3} plasma treatment, a VBO and a CBO across the HfO{sub 2}/ML-MoS{sub 2} interface were found to be 2.47 eV and 2.23 eV, respectively. The band alignment difference is believed to be dominated by the down-shift in the core level of Hf 4d and up-shift in the core level of Mo 3d, or the interface dipoles, which caused by the interfacial layer in rich of F.

Photoelectron and electron momentum spectroscopy of 1-butene at benchmark theoretical levels

International Nuclear Information System (INIS)

Shojaei, S H Reza; Morini, Filippo; Hajgató, Bálazs; Deleuze, Michael S

2011-01-01

The results of experimental studies of the valence electronic structure of 1-butene employing photoelectron spectroscopy as well as electron momentum spectroscopy are interpreted on the ground of quantitative calculations of one-electron and shake-up ionization energies and of the related Dyson orbitals, using one-particle Green's function theory in conjunction with the third-order algebraic diagrammatic construction scheme (ADC(3)). Comparison is made with simulations of (e, 2e) electron momentum distributions obtained from standard (B3LYP) Kohn-Sham orbitals. Our analysis is based on highly quantitative determinations of the energy difference between the cis and gauche (C 1 ) conformers, within ∼0.02 kcal mol -1 accuracy, and a thermostatistical evaluation thereby of conformer weights beyond the level of the rigid rotor harmonic oscillator approximation. Relative entropies are found to be particularly sensitive to hindered rotations. The shake-up onset is located at 15.9 eV, and the orbital picture of ionization breaks down completely at electron binding energies above 19 eV. If the available experimental momentum profiles demonstrate the dominance of the C 1 conformer, they are in this case clearly not sensitive enough to the molecular conformation for evaluating conformer abundances with accuracies better than 10% due to the limited energy and momentum resolutions and likely physical complications.

In-situ observation of oxidation of Ti(0001) surface by real-time photoelectron spectroscopy using synchrotron radiation

CERN Document Server

Takakuwa, Y; Yoshigoe, A; Teraoka, Y; Mizuno, Y; Tonda, H; Homma, T

2003-01-01

Temperature dependence of the initial oxidation kinetics of Ti(0001) surface was investigated by low energy electron diffraction (LEED) and real-time photoelectron spectroscopy using synchrotron radiation of surface- and bulk-sensitive photon energies. LEED observation revealed that oxide layers grow epitaxially with different surface structures depending on temperature: 1x1 at 200degC and sq root 3 x sq root 3 at 400degC. From the oxygen uptake curve measured by O 1s photo-electron intensity, it was clarified that oxygen diffusion through the epitaxially grown oxide layer is significantly enhanced with raising temperature, making the oxide layer thicker than 70A at 400degC. The chemical shift components observed for Ti 2p showed that TiO sub 2 becomes predominant at the subsurface with O sub 2 dose, while the stoichiometry of oxide near the interface is maintained as TiO and Ti sub 2 O sub 3 , for both cases at 200degC and 400degC. Thus it is concluded that the epitaxial growth of a very thin oxide on the Ti...

Honeycomb-like Nitrogen and Sulfur Dual-Doped Hierarchical Porous Biomass-Derived Carbon for Lithium-Sulfur Batteries.

Science.gov (United States)

Chen, Manfang; Jiang, Shouxin; Huang, Cheng; Wang, Xianyou; Cai, Siyu; Xiang, Kaixiong; Zhang, Yapeng; Xue, Jiaxi

2017-04-22

Honeycomb-like nitrogen and sulfur dual-doped hierarchical porous biomass-derived carbon/sulfur composites (NSHPC/S) are successfully fabricated for high energy density lithium-sulfur batteries. The effects of nitrogen, sulfur dual-doping on the structures and properties of the NSHPC/S composites are investigated in detail by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and charge/discharge tests. The results show that N, S dual-doping not only introduces strong chemical adsorption and provides more active sites but also significantly enhances the electronic conductivity and hydrophilic properties of hierarchical porous biomass-derived carbon, thereby significantly enhancing the utilization of sulfur and immobilizing the notorious polysulfide shuttle effect. Especially, the as-synthesized NSHPC-7/S exhibits high initial discharge capacity of 1204 mA h g -1 at 1.0 C and large reversible capacity of 952 mA h g -1 after 300 cycles at 0.5 C with an ultralow capacity fading rate of 0.08 % per cycle even at high sulfur content (85 wt %) and high active material areal mass loading (2.8 mg cm -2 ) for the application of high energy density Li-S batteries. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

International Oil Price’s Impacts on Carbon Emission in China’s Transportation Industry

Directory of Open Access Journals (Sweden)

Guoxing Zhang

2014-09-01

Full Text Available Purpose: This paper analyses the impact mechanism of international oil price on the industrial carbon emission, and uses the partial least squares regression model to study international oil price’s impact on carbon emissions in China’s transportation industry.Design/methodology/approach: This paper chooses five independent variables of GDP, international oil price, private car population, passenger and freight transportation volume as impact factors to investigate industrial carbon emissions, the paper also analyses the impact mechanism of international oil price on the industrial carbon emission, and finally the paper uses the partial least squares regression model to study international oil price’s impact on carbon emissions in China’s transportation industry. With the independent variables’ historical data from 1994 to 2009 as a sample, the fitting of the industry carbon emissions is satisfying. And based on the data of 2011, the paper maintains the private car owning, passenger and freight transportation volume to study international oil prices’ impact on the industry carbon emissions at different levels of GDP.Findings: The results show that: with the same GDP growth, the industry carbon emissions increase with the rise in international oil prices, and vice versa, the industry carbon emissions decrease; and lastly when GDP increases to a certain extent, in both cases of international oil prices’ rise or fall, the industry carbon emissions will go up, and the industry carbon emissions increase even faster while the energy prices are rising.Practical implications: Limit the growth in private-vehicle ownership, change China's transport sector within the next short-term in the structure of energy consumption and put forward China's new energy, alternative energy sources and renewable energy application so as to weaken the dependence on international oil, and indirectly slowdown China's GDP growth rate, which are all possible

X-Ray and UV Photoelectron Spectroscopy | Materials Science | NREL

Science.gov (United States)

backsheet material, showing excellent quantitative agreement between measured and predicted peak area ratios XPS spectra of carbon 1s from polyethylene terephthalate backsheet material, showing excellent

Pattern and change of soil organic carbon storage in China: 1960s-1980s

International Nuclear Information System (INIS)

Shaoqiang Wang; Hanqin Tian; Jiyuan Liu; Shufen Pan

2003-01-01

Soils, an important component of the global carbon cycle, can be either net sources or net sinks of atmospheric carbon dioxide (CO 2 ). In this study, we use the first and second national soil surveys of China to investigate patterns and changes in soil organic carbon storage (SOC) during the period from the 1960s to the 1980s. Our results show that there is a large amount of variability in SOC density among different soil types and land uses in the 1980s. The SOC density in the wetlands of Southwest China was the highest (45 kg/m 2 ), followed by meadow soils in the South (26 kg/m 2 ), forest and woodlands in the Northwest (19 kg/m 2 ), steppe and grassland in the Northwest (15 kg/m 2 ), shrubs in the Northwest (12 kg/m 2 ), paddy lands in the Northwest (13 kg/m 2 ), and drylands in the Northwest (11 kg/m 2 ). The desert soils of the Western region ranked the lowest (1 kg/m 2 ). The density of SOC was generally higher in the west than other regions. Eastern China had the lowest SOC density, which was associated with a long history of extensive land use in the region. The estimation of SOC storage for the entire nation was 93 Pg C in the 1960s and 92 Pg C in the 1980s. SOC storage decreased about 1 Pg C during the 1960s-1980s. This amount of decrease in SOC for the entire nation is small and statistically insignificant. To adequately characterize spatial variations in SOC, larger sampling sizes of soil profiles will be required in the future analyses

Coaxial MoS2@Carbon Hybrid Fibers: A Low-Cost Anode Material for High-Performance Li-Ion Batteries

Directory of Open Access Journals (Sweden)

Rui Zhou

2017-02-01

Full Text Available A low-cost bio-mass-derived carbon substrate has been employed to synthesize MoS2@carbon composites through a hydrothermal method. Carbon fibers derived from natural cotton provide a three-dimensional and open framework for the uniform growth of MoS2 nanosheets, thus hierarchically constructing coaxial architecture. The unique structure could synergistically benefit fast Li-ion and electron transport from the conductive carbon scaffold and porous MoS2 nanostructures. As a result, the MoS2@carbon composites—when serving as anodes for Li-ion batteries—exhibit a high reversible specific capacity of 820 mAh·g−1, high-rate capability (457 mAh·g−1 at 2 A·g−1, and excellent cycling stability. The use of bio-mass-derived carbon makes the MoS2@carbon composites low-cost and promising anode materials for high-performance Li-ion batteries.

The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy

Czech Academy of Sciences Publication Activity Database

Ottosson, N.; Wernersson, Erik; Söderström, J.; Pokapanich, W.; Kaufmann, S.; Svensson, S.; Persson, I.; Öhrwall, G.; Björneholm, O.

2011-01-01

Roč. 13, č. 26 (2011), s. 12261-12267 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z40550506 Keywords : water surface * carboxylic acids * photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

Scaling laws for photoelectron holography in the midinfrared wavelength regime

NARCIS (Netherlands)

Huismans, Y.; Gijsbertsen, A.; Smolkowska, A S; Jungmann, J H; Rouz??e, A.; Logman, P. S W M; L??pine, F.; Cauchy, C.; Zamith, S; Marchenko, T; Bakker, Joost M.; Berden, G.; Redlich, B; Van Der Meer, A. F G; Ivanov, M Yu; Yan, T. M.; Bauer, D.; Smirnova, O; Vrakking, M. J J

2012-01-01

Midinfrared strong-field laser ionization offers the promise of measuring holograms of atoms and molecules, which contain both spatial and temporal information of the ion and the photoelectron with subfemtosecond temporal and angstrom spatial resolution. We report on the scaling of photoelectron

Scaling Laws for Photoelectron Holography in the Midinfrared Wavelength Regime

NARCIS (Netherlands)

Huismans, Y.; Gijsbertsen, A.; Smolkowska, A. S.; Jungmann, J. H.; Rouzee, A.; Logman, Pswm; Lepine, F.; Cauchy, C.; Zamith, S.; Marchenko, T.; Bakker, J. M.; G. Berden,; Redlich, B.; van der Meer, A. F. G.; Ivanov, M. Y.; Yan, T. M.; Bauer, D.; Smirnova, O.; Vrakking, M. J. J.

2012-01-01

Midinfrared strong-field laser ionization offers the promise of measuring holograms of atoms and molecules, which contain both spatial and temporal information of the ion and the photoelectron with subfemtosecond temporal and angstrom spatial resolution. We report on the scaling of photoelectron

Photoelectron spectroscopy and Auger electron spectroscopy of solids and surfaces

International Nuclear Information System (INIS)

Kowalczyk, S.P.

1976-01-01

The use of photoelectron spectroscopy, primarily x-ray photoelectron spectroscopy, to obtain information on the electronic structure of a wide variety of solids (especially the bulk electronic structure of solids) is covered. Both valence band and core-level spectra, as well as a few cases of photon excited Auger electron spectroscopy, are employed in the investigations to derive information on N(E). The effect of several modulations inherent in the measured I(E)'s, such as final state band structure, cross section, and relaxation, is discussed. Examples of many-electron interactions in PES are given. Some experimental aspects of PES and AES studies are given with emphasis on sample preparation techniques. Multiple splitting of core levels is examined using the Mn levels in MnF 2 as a detailed case study. Core level splittings in transition metals, rare earth metals, transition metal halides and several alloys are also reported. The application of PES to the study of the chemical bond in some crystalline semiconductors and insulators, A/sup N/B/sup 8-N/ and A/sup N/B/sup 10-N/ compounds is treated, and a spectroscopic scale of ionicity for these compounds is developed from the measured ''s-band'' splitting in the valence band density of states

Study of organic radicals through anion photoelectron velocity-map imaging spectroscopy

Science.gov (United States)

Dixon, Andrew Robert

We report preliminary results on the photoelectron imaging of phenylcarbene, cyanophenylcarbene, and chlorophenylcarbene anions. Triplet phenylcarbene is observed to have an EA of ≤ 0.83 eV, considerably lower than the previously indirectly-determined value. Transitions to the singlet and triplet ground state of both cyanophenylcarbene and chlorophenylcarbene are observable, though unidentified bands make full assignment difficult. Cyanophenylcarbene is found to have a triplet ground-state, with a tentative EA of 2.04 eV. Chlorophenylcarbene is found to have a singlet ground-state. The phenyl-group is found to favor the singlet state slightly. The cyanofluoromethyl radical, FC(H)CN, was estimated to have an EA of 1.53 +/- 0.08 eV, by a combination of experimental and theoretical results.. With similar methodology, we report the adiabatic electron affinity of the cyanobenzyl radical, EA(PhCHCN) = 1.90 +/- 0.01 eV, and assign an upper limit of the EA for the chlorobenzyl radical, EA(PhCHCl) ≤ 1.12 eV. These values were used to estimate the C-H bond dissociation energy (BDE)s for these substituted methanes. Fluoroacetonitrile was found to have a BDE of D H198 = 90.7 +/- 2.8 kcal mol□1. The C-H bond dissociation energies at the benzyl-alpha sites of the phenylmethanes are determined as 80.9 +/- 2.3 kcal mol-1 for benzyl nitrile and an upper limit of 84.2 kcal mol-1 for benzyl chloride. These results are discussed in terms of substituent interactions in a simple MO framework and in relation to other similar molecules, including recently reported results for chloroacetonitrile. The 532 nm photoelectron spectrum of glyoxal provides the first direct spectroscopic determination of the adiabatic electron affinity, EA = 1.10(2) eV. This assignment is supported by a Franck-Condon simulation of the experimental spectrum that successfully reproduces the observed spectral features. The vertical detachment energy (VDE) of the glyoxal radical anion is determined as VDE = 1

Chalcogenide oxygen reduction reaction catalysis: X-ray photoelectron spectroscopy with Ru, Ru/Se and Ru/S samples emersed from aqueous media

Energy Technology Data Exchange (ETDEWEB)

Lewera, A. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Department of Chemistry, Warsaw University, Pasteura 1, 02-093 Warsaw (Poland); Inukai, J. [Clean Energy Research Center, University of Yamanashi, 7-32 Miyamae-cho, Kofu 400-0006 (Japan); Zhou, W.P. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Cao, D. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Duong, H.T. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Alonso-Vante, N. [Laboratory of Electrocatalysis, UMR-CNRS 6503, University of Poitiers, F-86022 Poitiers (France)]. E-mail: Nicolas.Alonso.Vante@univ-poitiers.fr; Wieckowski, A. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States)]. E-mail: andrzej@scs.uiuc.edu

2007-05-10

Oxygen reduction Ru/Se and Ru/S fuel cell surface chalcogenide catalysts were prepared via chemical reaction of reduced Ru nanoparticles with selenium and sulfur in xylenes [D. Cao, A. Wieckowski, J. Inukai, N. Alonso-Vante, J. Electrochem. Soc. 153 (2006) A869]. The chalcogenide samples - as well as the starting chalcogens-free Ru nanoparticle material - were immobilized on a gold disk for X-ray Photoelectron Spectroscopy (XPS) characterization. While we found oxygen in most of the samples, predominantly from Ru oxides, we conclude that the oxygen on Ru/S may be located in subsurface sites: the subsurface oxygen. We also found that the transformation of the oxidized Ru black to metallic Ru required intensive electrochemical treatment, including hydrogen evolution. In contrast, five cyclic voltammetric scans in the potential range from 0.00 and 0.75 V versus RHE were sufficient to remove the oxygen forms from Ru/Se and, to a large extent, from Ru/S. We therefore conclude that Ru metal is protected against oxidation to Ru oxides by the chalcogens additives. The voltammetric treatment in the 0.00 and 0.75 V range also removed the SeO{sub 2} or SO {sub x} forms leaving anionic/elemental Se or S on the surface. Upon larger amplitude voltammetric cycling, from 0.00 to 1.20 V versus RHE, both Se and S were dissolved and the dissolution process was coincidental with the oxygen growth in/on the Ru samples.

Chalcogenide oxygen reduction reaction catalysis: X-ray photoelectron spectroscopy with Ru, Ru/Se and Ru/S samples emersed from aqueous media

International Nuclear Information System (INIS)

Lewera, A.; Inukai, J.; Zhou, W.P.; Cao, D.; Duong, H.T.; Alonso-Vante, N.; Wieckowski, A.

2007-01-01

Oxygen reduction Ru/Se and Ru/S fuel cell surface chalcogenide catalysts were prepared via chemical reaction of reduced Ru nanoparticles with selenium and sulfur in xylenes [D. Cao, A. Wieckowski, J. Inukai, N. Alonso-Vante, J. Electrochem. Soc. 153 (2006) A869]. The chalcogenide samples - as well as the starting chalcogens-free Ru nanoparticle material - were immobilized on a gold disk for X-ray Photoelectron Spectroscopy (XPS) characterization. While we found oxygen in most of the samples, predominantly from Ru oxides, we conclude that the oxygen on Ru/S may be located in subsurface sites: the subsurface oxygen. We also found that the transformation of the oxidized Ru black to metallic Ru required intensive electrochemical treatment, including hydrogen evolution. In contrast, five cyclic voltammetric scans in the potential range from 0.00 and 0.75 V versus RHE were sufficient to remove the oxygen forms from Ru/Se and, to a large extent, from Ru/S. We therefore conclude that Ru metal is protected against oxidation to Ru oxides by the chalcogens additives. The voltammetric treatment in the 0.00 and 0.75 V range also removed the SeO 2 or SO x forms leaving anionic/elemental Se or S on the surface. Upon larger amplitude voltammetric cycling, from 0.00 to 1.20 V versus RHE, both Se and S were dissolved and the dissolution process was coincidental with the oxygen growth in/on the Ru samples

Analysis of the laser photoelectron spectrum of CH-2

International Nuclear Information System (INIS)

Bunker, P.R.; Sears, T.J.

1985-01-01

We have simulated the photoelectron spectrum of CH - 2 using the model described previously [Sears and Bunker, J. Chem. Phys. 79, 5265 (1983)]. The optimization of the fit of the simulated spectrum to the recently observed spectrum of Lineberger and co-workers [J. Chem. Phys. 81, 1048 (1984) and preceding paper] has enabled us to determine the rotation-bending energy levels of triplet CH 2 over an energy range of more than 1 eV. It has also enabled us to determine that the rotational temperature of the CH - 2 in the experiment is 220 K and that, for v 2 = 1, the vibrational temperature is 680 K. For CH - 2 we determine that a/sub e/ = 103 0 and that ν 2 = 1230 cm -1 . The singlet--triplet splitting in methylene is determined to be 3150 +- 30 cm -1 (0.3905 +- 0.004 eV, 9.01 +- 0.09 kcal/mol) from the photoelectron spectrum, in excellent agreement with the more accurate value previously obtained from LMR spectroscopy [McKellar et al., J. Chem. Phys. 79, 5251 (1983)] of 3165 +- 20 cm -1 (0.3924 +- 0.0025 eV, 9.05 +- 0.06 kcal/mol), and the electron affinity of triplet CH 2 is determined to be 0.652 +- 0.006 eV

Carbon nitride films synthesized by NH3-ion-beam-assisted deposition

International Nuclear Information System (INIS)

Song, H.W.; Cui, F.Z.; He, X.M.; Li, W.Z.; Li, H.D.

1994-01-01

Carbon nitride thin film films have been prepared by NH 3 -ion-beam-assisted deposition with bombardment energies of 200-800 eV at room temperature. These films have been characterized by transmission electron microscopy. Auger electron spectroscopy and x-ray photoelectron spectroscopy for chemical analysis. It was found that the structure of the films varied with the bombardment energy. In the case of 400 eV bombardment, the tiny crystallites immersed on an amorphous matrix were identified to be β-C 3 N 4 . X-ray photoelectron spectroscopy indicated that some carbon atoms and nitrogen atoms form unpolarized covalent bonds in these films. (Author)

Simulated photoelectron intensities at the aqueous solution–air interface for flat and cylindrical (microjet) geometries

Science.gov (United States)

Olivieri, Giorgia; Parry, Krista M.; Powell, Cedric J.; Tobias, Douglas J.

2017-01-01

Ion spatial distributions at the aqueous-air/vacuum interface are accessible by energy-dependent X-ray photoelectron spectroscopy (XPS). Here we quantify the difference between a flat surface and a cylindrical shaped microjet on the energy-dependent information depth of the XPS experiment and on the simulated photoelectron intensities using solutions of pure water and of 1 mol/L NaI as examples. PMID:28203664

Photoelectron Spectroscopy of Substituted Phenylnitrenes

Science.gov (United States)

Wijeratne, Neloni R.; Da Fonte, Maria; Wenthold, Paul G.

2009-06-01

Nitrenes are unusual molecular structures with unfilled electronic valences that are isoelectronic with carbenes. Although, both can be generated by either thermal or photochemical decomposition of appropriate precursors they usually exhibit different reactivities. In this work, we carry out spectroscopic studies of substituted phenylnitrene to determine how the introduction of substituents will affect the reactivity and its thermochemical properties. All studies were carried out by using the newly constructed time-of-flight negative ion photoelectron spectrometer (NIPES) at Purdue University. The 355 nm photoelectron spectra of the o-, m-, and p-chlorophenyl nitrene anions are fairly similar to that measured for phenylnitrene anion. All spectra show low energy triplet state and a high energy singlet state. The singlet state for the meta isomer is well-resolved, with a well defined origin and observable vibrational structure. Whereas the singlet states for the ortho and para isomers have lower energy onsets and no resolved structure. The isomeric dependence suggests that the geometry differences result from the resonance interaction between the nitrogen and the substituent. Quinoidal resonance structures are possible for the open-shell singlet states of the o- and p-chlorinated phenyl nitrenes. The advantages of this type of electronic structures for the open-shell singlet states is that the unpaired electrons can be more localized on separate atoms in the molecules, minimizing the repulsion between. Because the meta position is not in resonance with the nitrenes, substitution at that position should not affect the structure of the open-shell singlet state. The measured electron affinities (EA) of the triplet phenylnitrenes are in excellent agreement with the values predicted by electronic structure calculations. The largest EA, 1.82 eV is found for the meta isomer, with para being the smallest, 1.70 eV.

The surface of 1-euro coins studied by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Gou, F.; Gleeson, M.A.; Villette, J.; Kleyn, S.E.F.; Kleyn, A.W.

2004-01-01

The two alloy surfaces (pill and ring) that are present on 1-euro coins have been studied by X-ray photoelectron spectroscopy (XPS). Comparison is made between coins from general circulation and coin surfaces that have been subjected to a variety of cleaning and oxidation treatments. The concentrations and possible oxidation states of the metals (nickel, copper and zinc) at the surface were derived from analysis of the 2p 3/2 core levels. The surface atomic ratios measured for the pill and the ring parts of the euro coins were compared to the official bulk ratios. This study shows a clear nickel enrichment of both pill and ring surfaces. Nickel at surface seems to be present mainly in hydroxide form although the chloride form cannot be excluded. A small concentration of zinc was present on the surface of the pill, even though it is not present in the bulk alloy. Evidence of both nickel and zinc surface enrichment is observed for the ring. No surface enrichment is observed for the atomically clean or oxidized alloy surfaces over a 60-h time scale

Pulse plating of Pt on n-GaAs (1 0 0) wafer surfaces: Synchrotron induced photoelectron spectroscopy and XPS of wet fabrication processes

International Nuclear Information System (INIS)

Ensling, D.; Hunger, R.; Kraft, D.; Mayer, Th.; Jaegermann, W.; Rodriguez-Girones, M.; Ichizli, V.; Hartnagel, H.L.

2003-01-01

Preparation steps of Pt/n-GaAs Schottky contacts as applied in the fabrication process of varactor diode arrays for THz applications are analysed by photoelectron spectroscopy. Pulsed cathodic deposition of Pt onto GaAs (1 0 0) wafer surfaces from acidic solution has been studied by core level photoelectron spectroscopy using different excitation energies. A laboratory AlKα source as well as synchrotron radiation of hν=130 and 645 eV at BESSY was used. Chemical analyses and semiquantitative estimates of layer thickness are given for the natural oxide of an untreated wafer surface, a surface conditioning NH 3 etching step, and stepwise pulse plating of Pt. The structural arrangement of the detected species and interface potentials are considered

Polyaniline-deposited porous carbon electrode for supercapacitor

International Nuclear Information System (INIS)

Chen, W.-C.; Wen, T.-C.; Teng, H.

2003-01-01

Electrodes for supercapacitors were fabricated by depositing polyaniline (PANI) on high surface area carbons. The chemical composition of the PANI-deposited carbon electrode was determined by X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of electrodes. An equivalent circuit was proposed to successfully fit the EIS data, and the significant contribution of pseudocapacitance from PANI was thus identified. A comparative analysis on the electrochemical properties of bare-carbon electrodes was also conducted under similar conditions. The performance of the capacitors equipped with the resulting electrodes in 1 M H 2 SO 4 was evaluated by constant current charge-discharge cycling within a potential range from 0 to 0.6 V. The PANI-deposited electrode exhibits high specific capacitance of 180 F/g, in comparison with a value of 92 F/g for the bare-carbon electrode

Tautomerism in 5-aminotetrazole investigated by core-level photoelectron spectroscopy and {Delta}SCF calculations

Energy Technology Data Exchange (ETDEWEB)

Pinto, R.M., E-mail: ruipinto@fct.unl.pt [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Dias, A.A. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Coreno, M. [CNR-IMIP, Montelibretti, Rome I-00016 (Italy); Simone, M. de [CNR-IOM, Laboratorio TASC, 34149 Trieste (Italy); Giuliano, B.M. [Departamento de Quimica da Universidade de Coimbra, 3004-535 Coimbra (Portugal); Santos, J.P.; Costa, M.L. [CFA, Centro de Fisica Atomica, Departamento de Fisica, Faculdade de Ciencias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal)

2012-03-15

Highlights: Black-Right-Pointing-Pointer High-resolution XPS of 5-aminotetrazole reveals different tautomers. Black-Right-Pointing-Pointer 5ATZ exists mainly in the 2H-form. Black-Right-Pointing-Pointer Results obtained with DSCF are in good agreement with the observed binding energies. - Abstract: The C 1s and N 1s photoelectron spectra of gas-phase 5-aminotetrazole (5ATZ) were recorded using synchrotron radiation, with the aim of evaluating 1H/2H tautomer population ratios. The core-electron binding energies (CEBEs) were estimated from computational results, using the delta self-consistent-field ({Delta}SCF) approach. Simulated spectra were generated using these CEBEs and the results from GAUSSIAN-n (Gn, n = 1, 2 and 3) and Complete Basis Set (CBS-4M and CBS-Q) methods. Results reveal the almost exclusive predominance of the 2H-tautomer, with a 1H/2H ratio of ca. 0.12/0.88, taken from a gross analysis of the XPS C 1s spectrum, recorded at 365 K.

Numerical solution of the kinetic equation for photoelectrons in the plasmasphere with account for free and trapped zones

International Nuclear Information System (INIS)

Khazanov, G.V.; Koen, M.A.; Burenkov, S.I.

1979-01-01

Considered is the dinamics of photoelectron fluxes formation in the Earth plasmasphere with account of zone interaction of free and trapped photoelectrons. An algorithm and the results of numerical solution of the equation are presented. The problem of boundary condition choice is discussed. The angular distribution of 10 eV energy photoelectrons at different altitudes of plasmasphere is presented as an example. It is shown that the changes of photoelectron distribution function from bottom of plasmasphere to the top of a force line of the geomagnetic field are within the 1.6 limits. Presented is the estimate of plasmasphere transmittance value and its comparison with the experiment for Mc Ilwain parameter L=2

Efficient and tunable high-order harmonic light sources for photoelectron spectroscopy at surfaces

International Nuclear Information System (INIS)

Chiang, Cheng-Tien; Huth, Michael; Trützschler, Andreas; Schumann, Frank O.; Kirschner, Jürgen; Widdra, Wolf

2015-01-01

Highlights: • An overview of photoelectron spectroscopy using high-order harmonics is presented. • Photoemission spectra on Ag(0 0 1) using megahertz harmonics are shown. • A gas recycling system for harmonic generation is presented. • Non-stop operation of megahertz harmonics up to 76 h is demonstrated. • The bandwidth and pulse duration of the harmonics are discussed. - Abstract: With the recent progress in high-order harmonic generation (HHG) using femtosecond lasers, laboratory photoelectron spectroscopy with an ultrafast, widely tunable vacuum-ultraviolet light source has become available. Despite the well-established technique of HHG-based photoemission experiments at kilohertz repetition rates, the efficiency of these setups can be intrinsically limited by the space-charge effects. Here we present recent developments of compact HHG light sources for photoelectron spectroscopy at high repetition rates up to megahertz, and examples for angle-resolved photoemission experiments are demonstrated.

Synchrotron radiation photoelectron spectroscopy studies of self-organization in As.sub.40./sub.Se.sub.60./sub. nanolayers stored under ambient conditions and after laser irradiation

Czech Academy of Sciences Publication Activity Database

Kondrat, O.; Popovich, N.; Holomb, R.; Mitsa, V.; Lyamayev, V.; Tsud, N.; Cháb, Vladimír; Matolín, V.; Prince, K. C.

2012-01-01

Roč. 358, č. 21 (2012), s. 2910-2916 ISSN 0022-3093 Institutional support: RVO:68378271 Keywords : chalcogenide glass * photostructural changes * photoelectron spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.597, year: 2012

Photoelectron angular distributions for states of any mixed character: An experiment-friendly model for atomic, molecular, and cluster anions

International Nuclear Information System (INIS)

Khuseynov, Dmitry; Blackstone, Christopher C.; Culberson, Lori M.; Sanov, Andrei

2014-01-01

We present a model for laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to anionic states of any mixed character. In the limit of atomic-anion photodetachment, the model reproduces the Cooper-Zare formula. In the case of an initial orbital described as a superposition of s and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, whereas the relative scaling of the partial-wave cross-sections is assumed to follow the Wigner threshold law. The resulting model describes the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions, usually without requiring a direct calculation of the transition dipole matrix elements. As a benchmark case, we apply the p-d variant of the model to the experimental results for NO − photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters. Overall, the presented formalism delivers insight into the photodetachment process and affords a new quantitative strategy for analyzing the photoelectron angular distributions and characterizing mixed-character molecular orbitals using photoelectron imaging spectroscopy of negative ions

Photoelectron angular distributions for states of any mixed character: An experiment-friendly model for atomic, molecular, and cluster anions

Science.gov (United States)

Khuseynov, Dmitry; Blackstone, Christopher C.; Culberson, Lori M.; Sanov, Andrei

2014-09-01

We present a model for laboratory-frame photoelectron angular distributions in direct photodetachment from (in principle) any molecular orbital using linearly polarized light. A transparent mathematical approach is used to generalize the Cooper-Zare central-potential model to anionic states of any mixed character. In the limit of atomic-anion photodetachment, the model reproduces the Cooper-Zare formula. In the case of an initial orbital described as a superposition of s and p-type functions, the model yields the previously obtained s-p mixing formula. The formalism is further advanced using the Hanstorp approximation, whereas the relative scaling of the partial-wave cross-sections is assumed to follow the Wigner threshold law. The resulting model describes the energy dependence of photoelectron anisotropy for any atomic, molecular, or cluster anions, usually without requiring a direct calculation of the transition dipole matrix elements. As a benchmark case, we apply the p-d variant of the model to the experimental results for NO- photodetachment and show that the observed anisotropy trend is described well using physically meaningful values of the model parameters. Overall, the presented formalism delivers insight into the photodetachment process and affords a new quantitative strategy for analyzing the photoelectron angular distributions and characterizing mixed-character molecular orbitals using photoelectron imaging spectroscopy of negative ions.

Nanodiamond infiltration into porous silicon through etching of solid carbon produced at different graphitization temperatures

Energy Technology Data Exchange (ETDEWEB)

Miranda, C. R. B., E-mail: claudia_rbm@yahoo.com.br [Instituto Nacional de Pesquisas Espaciais-INPE, Centro de Ciencias do Sistema Terrestre-CCST, Centro de Ciencias do Sistema Terrestre-CCST (Brazil); Baldan, M. R.; Beloto, A. F.; Ferreira, N. G. [CTE/INPE, Centro de Tecnologias Espaciais (Brazil)

2011-09-15

Nanocrystalline diamond (NCD) was grown on the porous silicon (PS) substrate using Reticulated Vitreous Carbon (RVC) as an additional solid carbon source. RVC was produced at different heat treatment temperatures of 1300, 1500, and 2000 Degree-Sign C, resulting in samples with different turbostratic carbon organizations. The PS substrate was produced by an electrochemical method. NCD film was obtained by the chemical vapor infiltration/deposition process where a RVC piece was positioned just below the PS substrate. The PS and NCD samples were characterized by Field Emission Gun-Scanning Electron Microscopy (FEG-SEM). NCD films presented faceted nanograins with uniform surface texture covering all the pores resulting in an apparent micro honeycomb structure. Raman's spectra showed the D and G bands, as well as, the typical two shoulders at 1,150 and 1,490 cm{sup -1} attributed to NCD. X-ray diffraction analyses showed the predominant (111) diamond orientation as well as the (220) and (311) peaks. The structural organization and the heteroatom presence on the RVC surface, analyzed from X-ray photoelectron spectroscopy, showed their significant influence on the NCD growth process. The hydrogen etching released, from RVC surface, associated to carbon and/or oxygen/nitrogen amounts led to different contributions for NCD growth.

Electronic structure and photoelectron spectra of boron beta-diketonates

International Nuclear Information System (INIS)

Borisenko, A.V.; Vovna, V.I.

1990-01-01

Photoelectron spectra and data of semiempirical (MNDO, CNDO/2, CNDO/S, INDO) and nonempirical (with STO-3G basis) methods of calculation were obtained to analyse the electronic structure of boron-containing diketonate cycle and the influence of substitution effect (aromatic substituents in particular) on it. The sequence and the character of upper occupied MO were determined; the nature of bond of the fragment X 2 B + and AA was established; charges of six-membered ion and influence of substituents on their values were determined. 13 refs.; 5 figs.; 4 tabs

Monochromatization of synchrotron radiation for studies in photoelectron spectroscopy

International Nuclear Information System (INIS)

Murty, P.S.

1981-01-01

Synchrotron radiation provides a tunable photon source which bridges the wavelength gap between HeI and AlKsub(α) radiation sources in photoelectron spectroscopy. The essential component for using synchrotron radiation is a monochromator. Some design features of the monochromators fabricated at Stanford, U.S.A., and Orsay, France, are described. The Stanford monochromator is a silicon crystal monochromator yielding 8 keV X-ray beam and is used with SPEAR storage ring facility, while the Orsay monochromator is a grazing incidence grating monochromator used for UPS studies. (M.G.B.)

Photoelectron angular distribution parameters for elements Z=55 to Z=100 in the photoelectron energy range 100-5000 eV

CERN Document Server

Trzhaskovskaya, M B; Yarzhemsky, V G

2002-01-01

Presented here are parameters of the angular distribution of photoelectrons along with the subshell photoionization cross sections for all atoms with 55<=Z<=100 and for atomic shells with binding energies lower than 2000 eV. The parameters are given for nine photoelectron energies in the range 100-5000 eV. Relativistic calculations have been carried out within the quadrupole approximation by the use of the central Dirac-Fock-Slater potential. The effect of the hole resulting in the atomic subshell after photoionization has been taken into account in the framework of the frozen orbital approximation.

Carbon nanotubes/cobalt sulfide composites as potential high-rate and high-efficiency supercapacitors

Science.gov (United States)

Chen, Chia-Ying; Shih, Zih-Yu; Yang, Zusing; Chang, Huan-Tsung

2012-10-01

We have prepared carbon nanotube (CNT)/cobalt sulfide (CoS) composites from cobalt nitrate, thioacetamide, and CNTs in the presence of poly(vinylpyrrolidone). CNT/CoS composites are deposited onto fluorine-doped tin oxide glass substrates and then subjected to simple annealing at 300 °C for 0.5 h to fabricate CNT/CoS electrodes. Data collected from Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and d-spacing reveal the changes in the CoS structures and crystalline lattices after annealing. Cyclic voltammetry results reveal that the annealed CNT/CoS composite electrodes yield values of 2140 ± 90 and 1370 ± 50 F g-1 for specific capacitance at scan rates of 10 and 100 mV s-1, respectively. To the best of our knowledge, the annealed CNT/CoS composite electrodes provide higher specific capacitance relative to other reported ones at a scan rate of 100 mV s-1. CNT/CoS composite electrodes yield a power density of 62.4 kW kg-1 at a constant discharge current density of 217.4 A g-1. With such a high-rate capacity and power density, CNT/CoS composite supercapacitors demonstrate great potential as efficient energy storage devices.

Quantitative in-depth state analysis by means of x-ray photoelectron spectroscopy and its application to surface Layer of SiC coatings

International Nuclear Information System (INIS)

Yabe, Katsumasa; Yamashina, Toshiro.

1980-01-01

An attempt of quantitative state analysis was made on the surface and the depth profile of inorganic compounds by X-ray photoelectron spectroscopy (XPS) which was combined by the sputter-etching with argon ions. A masking attachment was designed for an area of sample which is exposed to the non-uniform portion of the ion beam. Uniform sputter-etching could be attained, with the advantages on XPS observation of low background level and less impurity spectra from other origins than the sample. The photoelectron yields were examined for the quantitative analysis by XPS. The method established here was applied to analyze the surface and in-depth composition of SiC coatings onto carbon and molybdenum which are promising candidate materials as the first wall in a controlled thermonuclear reactor. (author)

Thorium effect on the oxidation of uranium: Photoelectron spectroscopy (XPS/UPS) and cyclic voltammetry (CV) investigation on (U1 − xThx)O2 (x = 0 to 1) thin films

NARCIS (Netherlands)

Cakir, P.; Eloirdi, R; Huber, F.; Konings, R.J.M.; Gouder, T

2017-01-01

Thin films of U_1− xTh_xO₂ (x = 0 to 1) have been deposited via reactive DC sputter technique and characterized by X-ray/Ultra-violet Photoelectron Spectroscopy (XPS/UPS), X-ray Powder Diffractometer (XRD) and Cyclic Voltammetry (CV) in order to understand the

Mechanisms of tryptophan adsorption onto single-walled carbon nanotubes

International Nuclear Information System (INIS)

Zhou Jieping; Tan Jun; Xu Pengshou; Sheng Liusi; Pan Guoqiang

2011-01-01

Near edge X-ray absorption fine structure spectroscopy (NEXAFS) and synchrotron radiation photoelectron spectroscopy (SRPES) were employed to investigate the adsorption mechanism of tryptophan (Trp) onto single-walled carbon nanotubes (SWCNTs). The difference of the carbon K-edge NEXAFS spectra between Trp molecules and Trp-adsorbed SWCNTs shows that a significant interaction occurs among the SWCNTs and Trp molecules adsorbed. However, negligible changes in the peak profiles and energy positions of nitrogen K-edge imply that neither of the two nitrogen atoms in Trp molecule is involved in the interface interaction. A change of the shape of the main absorption peak at the oxygen K-edge reveals that O atoms of the C=O or C-O or both are likely involved in the interface interaction. The fact that the peak at about 529 eV at the O K-edge become sharper and stronger demonstrates that the O atom in the C=O participates in the interface interaction, which was confirmed by O1s SRPES spectrum. (authors)

X-ray photoelectron and x-ray-induced Auger electron spectroscopic data, 1

International Nuclear Information System (INIS)

Baba, Yuji; Sasaki, T.A.

1984-02-01

The intrinsic data of the X-ray photoelectron spectra (XPS) and X-ray-induced Auger electron spectra (XAES) for 3d transition-metals and related oxides were presented. The clean surfaces of the metals were obtained by two different methods ; mechanical filings and Ar + ion etchings. The oxides examined are typical compounds such as Sc 2 O 3 , TiO 2 , V 2 O 5 and NiO. The report consists of 4 wide scans, 26 core-line spectra, 10 valence-band spectra and 20 XAES spectra. The peak positions of the core-lines and the Auger lines were summarized in 8 tables together with their chemical shifts. (author)

Threshold photoelectron spectroscopy and photoionization total ion yield spectroscopy of simple organic acids, aldehydes, ketones and amines

International Nuclear Information System (INIS)

Yencha, Andrew J; Malins, Andrew E R; Siggel-King, Michele R F; Eypper, Marie; King, George C

2009-01-01

We have initiated a research program to investigate the ionization behavior of some simple organic molecules containing the carboxyl group (R 2 C=O), where R could be H, OH, NH 2 , or CH 3 or other aliphatic or aromatic carbon groups, using threshold photoelectron spectroscopy and photoionization total ion yield spectroscopy. We report here on the simplest organic acid, formic acid, and two simple aldehydes: acetaldehyde and the simplest unsaturated aldehyde, 2-propenal (acrolein). The objective of this study was to characterize the valence cationic states of these molecules with vibrational structural resolution.

The Pr 2O 3/Si(0 0 1) interface studied by synchrotron radiation photo-electron spectroscopy

Science.gov (United States)

Schmeißer, D.; Müssig, H.-J.

2003-10-01

Pr 2O 3 is currently under consideration as a potential replacement for SiO 2 as the gate-dielectric material for sub-0.1 μm complementary metal-oxide-semiconductor (CMOS) technology. We studied the Pr 2O 3/Si(0 0 1) interface by a non-destructive depth profiling using synchrotron radiation photoelectron spectroscopy. Our data suggests that there is no silicide formation at the interface. Based on reported results, a chemical reactive interface exists, consisting of a mixed Si-Pr oxide such as (Pr 2O 3) x(SiO 2) 1- x, i.e. as a silicate phase with variable silicon content. This pseudo-binary alloy at the interface offers large flexibility toward successful integration of Pr 2O 3 into future CMOS technologies.

Electrophoretic deposition of carbon nanotubes on a carbon fiber surface with different index graphitization

International Nuclear Information System (INIS)

Almeida, E.C.; Baldan, M.R.; Ferreira, N.G.; Edwards, E.R.

2009-01-01

Full text: The purpose of this work is to examine the electrophoretic deposition of carbon nanotubes powder on carbon fibers, produced at different heat treatments temperatures. Besides, a systematic study of the effects of graphitization index from substrate on the structure and morphology of CNTs has been available. Carbon fibers were produced from polyacrylonitrile at three different heat treatments temperatures, 1000, 1500 and 2000 deg C. The carbon fibers microstructure or its graphitization index may be controlled by the heat treatments temperatures. The electrophoretic deposition of carbon nanotubes was obtained with the powder of carbon nanotubes dispersed in water by ultrasonication to obtain dispersions of 0.05 mg/mL. The carbon fibers were immersed in the nanotube dispersion, and a positive potential of 10 V/cm was applied. Morphology and microstructure of carbon nanotubes on carbon fibers were obtained by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. (author)

Oxygen-rich hierarchical porous carbon made from pomelo peel fiber as electrode material for supercapacitor

Science.gov (United States)

Li, Jing; Liu, Wenlong; Xiao, Dan; Wang, Xinhui

2017-09-01

Oxygen-rich hierarchical porous carbon has been fabricated using pomelo peel fiber as a carbon source via an improved KOH activation method. The morphology and chemical composition of the obtained carbon materials were characterized by X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), electron microscopy (EM), Raman spectra and elemental analysis. The unique porous structure with abundant oxygen functional groups is favorable to capacitive behavior, and the as-prepared carbon material exhibits high specific capacitance of 222.6 F g-1 at 0.5 A g-1 in 6 M KOH and superior stability over 5000 cycles. This work not only describes a simple way to prepare high-performance carbon material from the discarded pomelo peel, but also provides a strategy for its disposal issue and contributes to the environmental improvement.

A simple model for determining photoelectron-generated radiation scaling laws

International Nuclear Information System (INIS)

Dipp, T.M.

1993-12-01

The generation of radiation via photoelectrons induced off of a conducting surface was explored using a simple model to determine fundamental scaling laws. The model is one-dimensional (small-spot) and uses monoenergetic, nonrelativistic photoelectrons emitted normal to the illuminated conducting surface. Simple steady-state radiation, frequency, and maximum orbital distance equations were derived using small-spot radiation equations, a sin 2 type modulation function, and simple photoelectron dynamics. The result is a system of equations for various scaling laws, which, along with model and user constraints, are simultaneously solved using techniques similar to linear programming. Typical conductors illuminated by low-power sources producing photons with energies less than 5.0 eV are readily modeled by this small-spot, steady-state analysis, which shows they generally produce low efficiency (η rsL -10.5 ) pure photoelectron-induced radiation. However, the small-spot theory predicts that the total conversion efficiency for incident photon power to photoelectron-induced radiated power can go higher than 10 -5.5 for typical real conductors if photons having energies of 15 eV and higher are used, and should go even higher still if the small-spot limit of this theory is exceeded as well. Overall, the simple theory equations, model constraint equations, and solution techniques presented provide a foundation for understanding, predicting, and optimizing the generated radiation, and the simple theory equations provide scaling laws to compare with computational and laboratory experimental data

Measurement of core level and band offsets at the interface of ITO/Hg{sub 3}In{sub 2}Te{sub 6}(1 1 0) heterojunction by synchrotron radiation photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Li, Yapeng [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Fu, Li, E-mail: fuli@nwpu.edu.cn [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Sun, Jie [State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072 (China); Ibrahim, Kurash; Wang, Jia-ou [Laboratory of Synchrotron Radiation, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100039 (China)

2016-02-15

Highlights: • The valence band maximum of ITO film and MIT were measured to be 1.6 eV and 0.6 eV, respectively. • The concentration of In element presented a trend of increasing first and then decreasing from MIT to ITO. • The valence band offsets of the ITO/MIT(1 1 0) heterojunction was confirmed to be a type-II band alignment phenomenon. - Abstract: The Indium Tin Oxide (ITO) film was deposited on the surface of Hg{sub 3}In{sub 2}Te{sub 6} (short for MIT) (1 1 0) for the fabrication of ITO/MIT(1 1 0) heterojunction by using the pulsed laser deposition method. In situ X-ray photoelectron spectroscopy was utilized to examine the band offsets and core level of ITO/MIT(1 1 0) heterojunctions. The result showed that the valence band maximum of ITO films and MIT(1 1 0) were 1.6 eV and 0.6 eV, respectively. Meanwhile, it was found that the binding energy of Te 3d, Sn 3d and Hg 4f remained unchanged during the ITO deposition process. However, the binding energy of O 1s and In 3d{sub 5/2} increased about 0.3 eV and 0.2 eV, respectively, with the thickness increasing of ITO film from 3.5 nm to 5 nm. This may due to the elements diffusion at the interface region during the film growing process. According to the core level spectrum, it can be speculated that no significant chemical reaction occurred at the interface of ITO/MIT(1 1 0). In addition, the valence band offset of the ITO/MIT(1 1 0) heterojunction can be calculated to be −1 ± 0.15 eV by the means of the photoelectron spectroscopy methods. The conduction band offset is deduced to be −3.96 ± 0.15 eV from the known valence band offset value, indicating that the band offsets of ITO/MIT(1 1 0) heterojunction is a type-II band alignment.

EDTA modified glassy carbon electrode: Preparation and characterization

International Nuclear Information System (INIS)

Ustuendag, Zafer; Solak, Ali Osman

2009-01-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){2-[bis(carboxymethyl)amino]-ethyl}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb 2+ ions was investigated if this electrode could be used as a metal sensor.

Renner-Teller effects in the photoelectron spectra of CNC, CCN, and HCCN.

Science.gov (United States)

Coudert, Laurent H; Gans, Bérenger; Garcia, Gustavo A; Loison, Jean-Christophe

2018-02-07

The line intensity of photoelectron spectra when either the neutral or cationic species display a Renner-Teller coupling is derived and applied to the modeling of the photoelectron spectra of CNC, CCN, and HCCN. The rovibronic energy levels of these three radicals and of their cations are investigated starting from ab initio results. A model treating simultaneously the bending mode and the overall rotation is developed to deal with the quasilinearity problem in CNC + , CCN + , and HCCN and accounts for the large amplitude nature of their bending mode. This model is extended to treat the Renner-Teller coupling in CNC, CCN, and HCCN + . Based on the derived photoelectron line intensity, the photoelectron spectra of all three molecules are calculated and compared to the experimental ones.

Population of the 3P2,1,0 fine-structure states in the 3s and 3p photoionization of atomic chlorine

International Nuclear Information System (INIS)

Krause, M.O.; Caldwell, C.D.; Whitfield, S.B.; de Lange, C.A.; van der Meulen, P.

1993-01-01

In a high-resolution photoelectron-spectrometry study of the photoionization of chlorine atoms in both the 3s and 3p subshells, we were able to resolve contributions from ionic states with specific J values and measure the relative populations of these fine-structure components. Our photoelectron spectra, recorded at hν=29.2 eV, give ratios of 3 P 2 : 3 P 1 : 3 P 0 =100:40.59.5 for 3p photoionization and 3 P 2 : 3 P 1 =100:31 for 3s photoionization. While the results for 3p ionization are in accord with predictions based on a simple geometric analysis, the contribution of the 3 P 1 state in 3s photoionization is larger than that predicted by this simple model. The geometric predictions are also compared with results from a similar measurement of the population of the 4p -1 ( 3 P J ) states produced in the 4p ionization of Br and with earlier work on the production of 3 D 2,1,0 states in d-shell photoionization of Cu and Ag

The PhotoElectron Boundary as observed by MAVEN instruments

Science.gov (United States)

Garnier, P.; Steckiewicz, M.; Mazelle, C. X.; Xu, S.; Mitchell, D. L.; Holmberg, M.; Halekas, J. S.; Andersson, L.; Brain, D.; Connerney, J. E. P.; Espley, J. R.; Lillis, R. J.; Luhmann, J. G.; Savaud, J. A.; Jakosky, B. M.

2017-12-01

Photoelectron peaks in the 20-30 eV energy range are commonly observed in planetary atmospheres (Earth, Mars, Titan...), produced by the intense photoionization from solar 30.4 nm photons. At Mars, these photoelectrons result from the ionization of CO2 and O atmospheric neutrals, and are known to escape the planet down its tail, making them tracers for the atmospheric escape (Frahm et al., 2006). Furthermore, their presence or absence allows us to define the so-called PhotoElectron Boundary (PEB), that separates the sunlit photoelectron-dominated ionosphere from the solar wind controlled environment, as initially observed by the Mars Global Surveyor (MGS) MAG/ER instrument (Mitchell et al. (2000, 2001). We provide here a detailed statistical analysis of the location and properties of the PEB based on the Mars Atmosphere and Volatile Evolution (MAVEN) mission electron and magnetic field data. Our dataset includes 1696 dayside PEB crossings obtained from September 2014 until May 2016 (the observations of escaping photoelectrons in the wake being not included). The PEB appears as mostly sensitive to the solar wind dynamic and crustal magnetic fields pressures, for which a quantitative dependance is derived and compared with two other important boundaries : the bow shock and magnetic pileup boundary. The PEB altitude is highly variable, leading to a variable wake cross section for escape (up to +- 50%), which is important for deriving global escape rates from in situ photoelectron escape rates. The PEB is not always sharp, and is, despite a strong variability, characterized on average by : a magnetic field topology typical for the edge of the Magnetic Pile Up Region above it, more field aligned fluxes above than below, and a clear change of the altitude dependence of both electron fluxes and total density (that appears different from the ionopause). The PEB thus appears as a transition region between two plasma and field configurations which is determined by the

A high pressure x-ray photoelectron spectroscopy experimental method for characterization of solid-liquid interfaces demonstrated with a Li-ion battery system

Energy Technology Data Exchange (ETDEWEB)

Maibach, Julia; Xu, Chao; Gustafsson, Torbjörn; Edström, Kristina [Department of Chemistry–Ångström Laboratory, Uppsala University, Box 538, SE-751 21 Uppsala (Sweden); Eriksson, Susanna K. [Department of Chemistry–Ångström Laboratory, Uppsala University, Box 523, SE-751 20 Uppsala (Sweden); Åhlund, John [VG Scienta AB, Box 15120, SE-750 15 Uppsala (Sweden); Siegbahn, Hans; Rensmo, Håkan; Hahlin, Maria, E-mail: maria.hahlin@physics.uu.se [Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala (Sweden)

2015-04-15

We report a methodology for a direct investigation of the solid/liquid interface using high pressure x-ray photoelectron spectroscopy (HPXPS). The technique was demonstrated with an electrochemical system represented by a Li-ion battery using a silicon electrode and a liquid electrolyte of LiClO{sub 4} in propylene carbonate (PC) cycled versus metallic lithium. For the first time the presence of a liquid electrolyte was realized using a transfer procedure where the sample was introduced into a 2 mbar N{sub 2} environment in the analysis chamber without an intermediate ultrahigh vacuum (UHV) step in the load lock. The procedure was characterized in detail concerning lateral drop gradients as well as stability of measurement conditions over time. The X-ray photoelectron spectroscopy (XPS) measurements demonstrate that the solid substrate and the liquid electrolyte can be observed simultaneously. The results show that the solid electrolyte interphase (SEI) composition for the wet electrode is stable within the probing time and generally agrees well with traditional UHV studies. Since the methodology can easily be adjusted to various high pressure photoelectron spectroscopy systems, extending the approach towards operando solid/liquid interface studies using liquid electrolytes seems now feasible.

Assessing net ecosystem carbon exchange of U S terrestrial ecosystems by integrating eddy covariance flux measurements and satellite observations

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Qianlai [Purdue University; Law, Beverly E. [Oregon State University; Baldocchi, Dennis [University of California, Berkeley; Ma, Siyan [University of California, Berkeley; Chen, Jiquan [University of Toledo, Toledo, OH; Richardson, Andrew [Harvard University; Melillo, Jerry [Marine Biological Laboratory; Davis, Ken J. [Pennsylvania State University; Hollinger, D. [USDA Forest Service; Wharton, Sonia [University of California, Davis; Falk, Matthias [University of California, Davis; Paw, U. Kyaw Tha [University of California, Davis; Oren, Ram [Duke University; Katulk, Gabriel G. [Duke University; Noormets, Asko [North Carolina State University; Fischer, Marc [Lawrence Berkeley National Laboratory (LBNL); Verma, Shashi [University of Nebraska; Suyker, A. E. [University of Nebraska, Lincoln; Cook, David R. [Argonne National Laboratory (ANL); Sun, G. [USDA Forest Service; McNulty, Steven G. [USDA Forest Service; Wofsy, Steve [Harvard University; Bolstad, Paul V [University of Minnesota; Burns, Sean [University of Colorado, Boulder; Monson, Russell K. [University of Colorado, Boulder; Curtis, Peter [Ohio State University, The, Columbus; Drake, Bert G. [Smithsonian Environmental Research Center, Edgewater, MD; Foster, David R. [Harvard University; Gu, Lianhong [ORNL; Hadley, Julian L. [Harvard University; Litvak, Marcy [University of New Mexico, Albuquerque; Martin, Timothy A. [University of Florida, Gainesville; Matamala, Roser [Argonne National Laboratory (ANL); Meyers, Tilden [NOAA, Oak Ridge, TN; Oechel, Walter C. [San Diego State University; Schmid, H. P. [Indiana University; Scott, Russell L. [USDA ARS; Torn, Margaret S. [Lawrence Berkeley National Laboratory (LBNL)

2011-01-01

More accurate projections of future carbon dioxide concentrations in the atmosphere and associated climate change depend on improved scientific understanding of the terrestrial carbon cycle. Despite the consensus that U.S. terrestrial ecosystems provide a carbon sink, the size, distribution, and interannual variability of this sink remain uncertain. Here we report a terrestrial carbon sink in the conterminous U.S. at 0.63 pg C yr 1 with the majority of the sink in regions dominated by evergreen and deciduous forests and savannas. This estimate is based on our continuous estimates of net ecosystem carbon exchange (NEE) with high spatial (1 km) and temporal (8-day) resolutions derived from NEE measurements from eddy covariance flux towers and wall-to-wall satellite observations from Moderate Resolution Imaging Spectroradiometer (MODIS). We find that the U.S. terrestrial ecosystems could offset a maximum of 40% of the fossil-fuel carbon emissions. Our results show that the U.S. terrestrial carbon sink varied between 0.51 and 0.70 pg C yr 1 over the period 2001 2006. The dominant sources of interannual variation of the carbon sink included extreme climate events and disturbances. Droughts in 2002 and 2006 reduced the U.S. carbon sink by 20% relative to a normal year. Disturbances including wildfires and hurricanes reduced carbon uptake or resulted in carbon release at regional scales. Our results provide an alternative, independent, and novel constraint to the U.S. terrestrial carbon sink.

Photoelectron Imaging Spectroscopy as a Window to Unexpected Molecules

Science.gov (United States)

Blackstone, Christopher C.

2017-06-01

Targeting an anion with the formula CH_{3}O_{3} for exploration with photoelectron imaging spectroscopy, we determine its identity to be dihydroxymethanolate, an anion largely absent in the literature, and the conjugate base of the hypothetical species orthoformic acid. Comparing the observed photoelectron spectrum to CCSD-EOM-IP and CCSD-EOM-SF calculations completed in QChem and Franck-Condon overlap simulations in PESCAL, we are able to determine with confidence the connectivity of the atoms in this molecule.

Photoelectron spectroscopy study of the X-ray-induced decomposition of some gold(III) dithiocarbamates

International Nuclear Information System (INIS)

Attekum, P.M.Th.M. van; Trooster, J.M.

1980-01-01

The factors influencing the decomposition rate of two gold(III) complexes, [AuMe 2 (S 2 CNMe 2 )] and [AuBr 2 (S 2 CNPr 2 sup(n))]; in an X-ray photoelectron spectroscopy experiment have been studied. It is shown that the decomposition rate can be slowed down by using graphite as substrate and by lowering the sample temperature. From the Au(4f) spectrum a direct measure has been made of the shift in the binding energy between Ausup(III) and Ausup(I) and this shift is shown to be dependent on the electronegativity of the ligands. The valence bands of the complexes show a narrow Au(5d) band with a spin-orbit splitting of ca. 1.6 eV. (author)

Mechanism of the adsorption of gold cyanide on activated carbon

Energy Technology Data Exchange (ETDEWEB)

McDougall, G. (University of the Witwatersrand, Johannesburg (South Africa). Dept. of Chemistry); Hancock, R.D. (Klipfontein Organic Products, Kempton Park (South Africa)); Wellington, O.L.; Nicol, M.J. (National Inst. for Metallurgy, Johannesburg (South Africa)); Copperthwaite, R.G. (Council for Scientific and Industrial Research, Pretoria (South Africa). National Chemical Research Lab.)

1981-12-01

X-ray photoelectron spectroscopy showed that the adsorption of gold cyanide on carbon in the presence or absence of electrolytes and acids proceeds by the same mechanism. The first detailed investigation of the fundamentals of the adsorption and elution of gold and silver cyanide on carbon, theories to state the results and the experimental method are discussed.

Carbon dots decorated vertical SnS_2 nanosheets for efficient photocatalytic oxygen evolution

International Nuclear Information System (INIS)

Cheng, Zhongzhou; Wang, Fengmei; Shifa, Tofik Ahmed; Liu, Kaili; Huang, Yun; Jiang, Chao; He, Jun; Liu, Quanlin

2016-01-01

Metal sulfides are highly desirable materials for photocatalytic water splitting because of their appropriate energy bands. However, the poor stability under light illumination in water hinders their wide applications. Here, two-dimensional SnS_2 nanosheets, along with carbon dots of the size around 10 nm, are uniformly grown on fluorine doped tin oxide glasses with a layer of nickel nanoparticles. Significantly, strong light absorption and enhanced photocurrent density are achieved after integration of SnS_2 nanosheets with carbon dots. Notably, the rate of oxygen evolution reached up to 1.1 mmol g"−"1 h"−"1 under simulated sunlight irradiation featuring a good stability.

A green and efficient method to produce graphene for electrochemical capacitors from graphene oxide using sodium carbonate as a reducing agent

Science.gov (United States)

Jin, Yuhong; Huang, Shuo; Zhang, Mei; Jia, Mengqiu; Hu, Dong

2013-03-01

The green and efficient synthesis of graphene using sodium carbonate (Na2CO3) as a chemical reducing agent was studied. Extensive characterization confirmed the formation of graphene from graphene oxide using a Na2CO3 solution. The C/O atomic ratio of the as-prepared graphene has increased from 2.48 to 8.15 after reduction as determined by X-ray photoelectron spectroscopy. The conductivity of as-prepared graphene sheets is as high as 10 S m-1. After electrochemical measurements, gravimetric capacitances of 228 and 166 F g-1 at current densities of 5 and 25 mA cm-2, respectively, were obtained with KOH electrolyte.

Alkaloids extract of Retama monosperma (L.) Boiss. seeds used as novel eco-friendly inhibitor for carbon steel corrosion in 1 M HCl solution: Electrochemical and surface studies

Energy Technology Data Exchange (ETDEWEB)

El Hamdani, Naoual; Fdil, Rabiaa [Laboratoire de Chimie Bioorganique, Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Tourabi, Mustapha [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Jama, Charafeddine [UMET-PSI, CNRS UMR 8207, ENSCL, Université Lille 1, CS 90108, F-59652 Villeneuve d’Ascq Cedex (France); Bentiss, Fouad, E-mail: fbentiss@enscl.fr [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); UMET-PSI, CNRS UMR 8207, ENSCL, Université Lille 1, CS 90108, F-59652 Villeneuve d’Ascq Cedex (France)

2015-12-01

Graphical abstract: - Highlights: • AERS is good eco-friendly corrosion inhibitor for carbon steel in 1 M HCl. • AERS acts as mixed-type inhibitor in 1 M HCl medium. • AERS adsorption is well described by Langmuir isotherm. • Surface analyses were used to explain the AERS mechanism of carbon steel corrosion inhibition. - Abstract: Current research efforts now focus on the development of non-toxic, inexpensive and environmentally friendly corrosion inhibitors as alternatives to different organic and non-organic compounds. In this field, alkaloids extract of Retama monosperma (L.) Boiss. seeds (AERS) was tested for the first time as corrosion inhibitor for carbon steel in 1 M HCl medium using electrochemical and surface characterization techniques. The obtained results showed that this plant extract's acts as an efficient corrosion inhibitor for carbon steel in 1 M HCl and an inhibition efficiency of 94.4% was reached with 400 mg/L of AERS at 30 °C. Ac impedance experimental data revealed a frequency distribution of the capacitance, simulated as constant phase element. Impedance results demonstrated that the addition of the AERS in the corrosive solution decreases the charge capacitance and simultaneously increases the function of the charge/discharge of the interface, facilitating the formation of an adsorbed layer over the steel surface. Polarization curves indicated that AERS is a mixed inhibitor. Adsorption of such alkaloid extract on the steel surface obeyed to the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy (XPS) showed that the inhibition of steel corrosion in normal hydrochloric solution by AERS is mainly controlled by a physisorption process and the inhibitive layer is composed of an iron oxide/hydroxide mixture where AERS molecules are incorporated.

Effect of CO on surface oxidation of uranium metal

International Nuclear Information System (INIS)

Wang, X.; Fu, Y.; Xie, R.

1997-01-01

The surface reactions of uranium metal with carbon monoxide at 25 and 200 deg C have been studied by X-ray photoelectron spectroscopy (XPS);respectively. Adsorption of carbon monoxide on the surface layer of uranium metal leads to partial reduction of surface oxide and results in U4f photoelectron peak shifting to the lower binding energy. The content of oxygen in the surface oxide is decreased and O1s/O4f ratio decreases with increasing the exposure of carbon monoxide. The investigation indicates the surface layer of uranium metal has resistance to further oxidation in the atmosphere of carbon monoxide. (author)

Photoelectron spectroscopy of liquid water and aqueous solution: Electron effective attenuation lengths and emission-angle anisotropy

Energy Technology Data Exchange (ETDEWEB)

Ottosson, Niklas [Department of Physics, Uppsala University, SE-75121 Uppsala (Sweden); Faubel, Manfred [Max-Planck-Institut fuer Dynamik und Selbstorganisation, Bunsenstrasse 10, D-37073 Goettingen (Germany); Bradforth, Stephen E. [Department of Chemistry, University of Southern California, Los Angeles, CA 90089 (United States); Jungwirth, Pavel [Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, and Center for Biomolecules and Complex Molecular Systems, Flemingovo nam. 2, 16610 Prague 6 (Czech Republic); Winter, Bernd, E-mail: winter@bessy.d [Helmholtz-Zentrum Berlin fuer Materialien und Energie, and BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin (Germany); Max-Born-Institut, Max-Born-Strasse 2A, D-12489 Berlin (Germany)

2010-03-15

Photoelectron (PE) spectroscopy measurements from liquid water and from a 4 m NaI aqueous solution are performed using a liquid microjet in combination with soft X-ray synchrotron radiation. From the oxygen 1s PE signal intensity from liquid water, measured as a function of photon energy (up to 1500 eV), we quantitatively determine relative electron inelastic effective attenuation lengths (EAL) for (photo)electron kinetic energies in the 70-900 eV range. In order to determine the absolute electron escape depths a calibration point is needed, which is not directly accessible by experiment. This information can instead be indirectly derived by comparing PE experiments and molecular dynamics (MD) simulations of an aqueous solution interface where density profiles of water, anions, and cations are distinctively different. We have chosen sodium iodide in water because iodide has a considerable propensity for the solution surface, whereas the sodium cation is repelled from the surface. By measuring the intensities of photoelectrons emitted from different orbitals of different symmetries from each aqueous ion we also evaluate whether gas-phase ionization cross sections and asymmetry parameters can describe the photoemission from ions at and near the aqueous solution/vapor interface. We show that gas-phase data reproduce surprisingly well the experimental observations for hydrated ions as long as the photon energy is sufficiently far above the ionization threshold. Electrons detected at the higher photon energies originate predominantly from deeper layers, suggesting that bulk-solution electron elastic scattering is relatively weak.

X-ray photoelectron spectroscopy applied to the characterization of surfaces at pressures of up to 0.1 mbar

International Nuclear Information System (INIS)

Kong, C.W.

1987-01-01

The thesis describes the design principles, operation and an X-Ray Photoelectron Spectrometer capable of analyzing surfaces under in situ conditions in the pressure range of 10 -11 to 1 mbar. Measurements at pressures exceeding 10 -5 mbar are carried out by placing a differentially pumped aperture system between sample surface and the hemispherical electron energy analyzer. The reduction of signal intensity due to the aperture is, depending on the operating mode and resolution of the analyzer, between a factor of 5-12. Measurements at pressures as high as 6 x 10 -1 mbar show that the sensitivity of the apparatus is sufficient to detect coverages as low as ∼.1 monolayers. The experimental work described in this thesis relates to the interaction of sulfur dioxide with metallic copper and CuO and Cu 2 O surfaces. Adsorption and reaction of SO 2 with these surfaces comprise one of the elemental steps in the flue gas cleanup process from a duct stream using copper oxide particles. The adsorption and reaction of SO 2 with copper and copper oxide surfaces was studied by in situ x-ray photoelectron spectroscopy between 173 K-473 K and pressures ranging from UHV to 10 -1 mbar. It was found that a Cu 2 SO 3 species acts as an intermediate in the formation of CuSO 4 at T 300 K, in the formation of copper sulfide. The presence of gas phase oxygen was found to accelerate the surface reaction between SO 2 and the substrates. Contrary to previous suggestions, the author finds that a copper sulfate is found only under conditions which are far removed form the conditions in a duct-pipe. Under temperature and partial pressure conditions resembling the industrial process, a copper sulfide is formed

Effect of epoxy coatings on carbon fibers during manufacture of carbon fiber reinforced resin matrix composites

International Nuclear Information System (INIS)

Guo, Hui; Huang, Yudong; Liu, Li; Shi, Xiaohua

2010-01-01

The changes in oxygen and nitrogen during manufacture of the carbon fiber reinforced resin matrix composites were measured using the X-ray photoelectron spectroscopy method. The effects of the change in oxygen and nitrogen on the strength of the carbon fibers were investigated and the results revealed that the change of the tensile strength with increasing heat curing temperature was attributed to the change in the surface flaws of the carbon fibers because the carbon fibers are sensitive to the surface flaws. The effect of the surface energy that was calculated using Kaelble's method on the strength of the carbon fibers was investigated. Furthermore, the surface roughness of the carbon fibers was measured using atom force microscopy. The change trend of roughness was reverse to that of the strength, which was because of the brittle fracture of the carbon fibers.

Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

Energy Technology Data Exchange (ETDEWEB)

Hassan, S., E-mail: suhaimihas@uthm.edu.my; Yusof, M. S., E-mail: mdsalleh@uthm.edu.my; Maksud, M. I., E-mail: midris1973@gmail.com [Faculty of Mechanical and Manufacturing Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia); Embong, Z., E-mail: zaidi@uthm.edu.my [Faculty of Science, Technology and Human Development, Universiti Tun Hussein Onn Malaysia, 86400 Batu Pahat, Johor (Malaysia)

2016-01-22

Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La{sub 2}O{sub 3}) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La{sub 2}O{sub 3} deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La{sub 2}O{sub 3} and La(OH){sub 3}. The information of oxygen species, O{sup 2-} component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O{sup 2−}), two chemisorb component (La{sub 2}O{sub 3}) and La(OH){sub 3} and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

Angle resolved x-ray photoelectron spectroscopy (ARXPS) analysis of lanthanum oxide for micro-flexography printing

Science.gov (United States)

Hassan, S.; Yusof, M. S.; Embong, Z.; Maksud, M. I.

2016-01-01

Micro-flexography printing was developed in patterning technique from micron to nano scale range to be used for graphic, electronic and bio-medical device on variable substrates. In this work, lanthanum oxide (La2O3) has been used as a rare earth metal candidate as depositing agent. This metal deposit was embedded on Carbon (C) and Silica (Si) wafer substrate using Magnetron Sputtering technique. The choose of Lanthanum as a target is due to its wide application in producing electronic devices such as thin film battery and printed circuit board. The La2O3 deposited on the surface of Si wafer substrate was then analyzed using Angle Resolve X-Ray Photoelectron Spectroscopy (ARXPS). The position for each synthetic component in the narrow scan of Lanthanum (La) 3d and O 1s are referred to the electron binding energy (eV). The La 3d narrow scan revealed that the oxide species of this particular metal is mainly contributed by La2O3 and La(OH)3. The information of oxygen species, O2- component from O 1s narrow scan indicated that there are four types of species which are contributed from the bulk (O2-), two chemisorb component (La2O3) and La(OH)3 and physisorp component (OH). Here, it is proposed that from the adhesive and surface chemical properties of La, it is suitable as an alternative medium for micro-flexography printing technique in printing multiple fine solid lines at nano scale. Hence, this paper will describe the capability of this particular metal as rare earth metal for use in of micro-flexography printing practice. The review of other parameters contributing to print fine lines will also be described later.

Enhanced cyclic stability of SnS microplates with conformal carbon coating derived from ethanol vapor deposition for sodium-ion batteries

Science.gov (United States)

Li, Xiang; Liu, Jiangwen; Ouyang, Liuzhang; Yuan, Bin; Yang, Lichun; Zhu, Min

2018-04-01

Carbon coated SnS microplates (SnS@C MPs) were prepared via a facile chemical vapor deposition method using SnS2 nanoflakes as precursor and ethanol vapor as carbon source. The carbon coating restrains the growth of SnS during the heat treatment. Furthermore, it improves the electronic conductivity as well as accommodates volume variations of SnS during the sodiation and desodiation processes. Therefore, the rate capability and cycle performance of the SnS@C MPs as anode materials for sodium-ion batteries are remarkably enhanced compared with the bare SnS and the SnS2 precursor. At current densities of 0.1, 0.2, 0.5, 1 and 2 A g-1, the optimized SnS@C MPs exhibit stable capacities of 602.9, 532.1, 512.2, 465.9 and 427.2 mAh g-1, respectively. At 1 A g-1, they show a reversible capacity of 528.8 mAh g-1 in the first cycle, and maintain 444.7 mAh g-1 after 50 cycles, with capacity retention of 84.1%. The carbon coating through chemical vapor deposition using ethanol vapor as carbon sources is green, simple and cost-effective, which shows great promise to improve the reversible Na+ storage of electrode materials.

Development of X-ray photoelectron microscope with a compact X-ray source generated by line-focused laser irradiation

International Nuclear Information System (INIS)

Yamaguchi, N.; Takahashi, Z.; Nishimura, Y.; Watanabe, K.; Okamoto, Y.; Sakata, A.; Azuma, H.; Hara, T.

2005-01-01

A laboratory-sized X-ray photoelectron microscope was constructed using a compact X-ray source produced by line-focused laser irradiation. The system is a scanning type photoelectron microscope where X-ray beam is micro-focused via Schwarzschild optics. A compact laser-plasma X-ray source has been developed with a YAG laser, a line-focus lens assembly, an Al tape-target driver and a debris prevention system. The 13.1 nm X-ray was delivered along line plasma whose length was 0.6 or 11 mm with higher intensity than that from a point-focused source. The Schwarzschild optics having the designed demagnification of 224, which was coated with Mo/Si multilayers for 13.1 nm X-ray, was set on the beamline 1 m distant from the source. The electron energy analyser was a spherical capacitor analyser with the photoelectron image detection system that was suited for detection of vast photoelectrons excited by an X-ray pulse of ns-order duration. The spatial resolution less than 5 μm has been confirmed from the variation of As 3d electron intensity along the position of the GaAs sample coated with a photo-resist test pattern

Electron-diffraction and spectroscopical characterisation of ultrathin ZnS films grown by molecular beam epitaxy on GaP(0 0 1)

International Nuclear Information System (INIS)

Zhang, L.; Szargan, R.; Chasse, T.

2004-01-01

ZnS films were grown by molecular beam epitaxy employing a single compound effusion cell on GaP(0 0 1) substrate at different temperatures, and characterised by means of low energy electron diffraction, X-ray and ultra-violet photoelectron spectroscopy, angle-resolved ultra-violet photoelectron spectroscopy and X-ray emission spectroscopy. The GaP(0 0 1) substrate exhibits a (4x2) reconstruction after Ar ion sputtering and annealing at 370 deg. C. Crystal quality of the ZnS films depends on both film thickness and growth temperature. Thinner films grown at higher temperatures and thicker films grown at lower temperatures have better crystal quality. The layer-by-layer growth mode of the ZnS films at lower (25, 80 and 100 deg. C) temperatures changes to layer-by-layer-plus-island mode at higher temperatures (120, 150 and 180 deg. C). A chemical reaction takes place and is confined to the interface. The valence band offset of the ZnS-GaP heterojunction was determined to be 0.8±0.1 eV. Sulphur L 2,3 emission spectra of ZnS powder raw material and the epitaxial ZnS films display the same features, regardless of the existence of the Ga-S bonding in the film samples

Valence photoelectron spectrum of KBr: Effects of electron correlation

International Nuclear Information System (INIS)

Calo, A.; Huttula, M.; Patanen, M.; Aksela, H.; Aksela, S.

2008-01-01

The valence photoelectron spectrum has been measured for molecular KBr. Experimental energies of the main and satellite structures have been compared with the results of ab initio calculations based on molecular orbital theory including configuration and multiconfiguration interaction approaches. Comparison between the experimental KBr spectrum and previously reported Kr valence photoelectron spectrum has also been performed in order to find out if electron correlation is of the same importance in the valence ionized state of KBr as in the corresponding state of Kr

The effect of different order of purification treatments on the purity of multiwalled carbon nanotubes

Energy Technology Data Exchange (ETDEWEB)

Ling, Xinlong [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Department of Biological and Chemical Engineering, Guangxi University of Technology, 268 Donghuan Road, Liuzhou 545006 (China); Wei, Yizhe [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Zou, Liming, E-mail: lmzou@dhu.edu.cn [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China); Xu, Su [College of Materials Science and Engineering, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Donghua University, 2999 North People Road, Shanghai 201620 (China)

2013-07-01

The multiwalled carbon nanotubes were purified with different order treatments of gas phase and liquid phase. Amorphous carbon and iron catalysts were removed and some oxygen-containing groups were attached to the surface of multiwalled carbon nanotubes after purification. The multiwalled carbon nanotubes were determined and characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Boehm's neutralizing titration method and weighing method. The morphology of multiwalled carbon nanotubes was verified using scanning electron microscopy and transmission electron microscopy. The results indicated amorphous carbon and iron catalysts were removed completely while the structure of multiwalled carbon nanotubes was slightly destructed by two treatment methods. Three principal oxygen-containing groups on the surface of multiwalled carbon nanotubes were carboxyl, lactone and phenolic hydroxyl in descending order of their concentrations. The method I including gas phase treatment firstly and then liquid phase treatment, is more effective to purify multiwalled carbon nanotubes and to protect the structure of multiwalled carbon nanotubes than method II including liquid phase treatment firstly and then gas phase treatment.

Increased photoelectron transmission in High-pressure photoelectron spectrometers using “swift acceleration”

Energy Technology Data Exchange (ETDEWEB)

Edwards, Mårten O.M.; Karlsson, Patrik G. [VG Scienta AB, Box 15120, 750 15 Uppsala (Sweden); Eriksson, Susanna K. [Department of Chemistry-Ångström, Uppsala University, Box 523, 751 20 Uppsala (Sweden); Hahlin, Maria; Siegbahn, Hans; Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala (Sweden); Kahk, Juhan M.; Villar-Garcia, Ignacio J.; Payne, David J. [Department of Materials, Imperial College London, Exhibition Road, London SW7 2AZ (United Kingdom); Åhlund, John, E-mail: john.ahlund@vgscienta.com [VG Scienta AB, Box 15120, 750 15 Uppsala (Sweden)

2015-06-11

A new operation mode of a HPXPS (high-pressure X-ray photoelectron spectroscopy) analyzer is evaluated on a HPXPS system fitted with an Al Kα X-ray source. A variety of metal foil samples (gold, silver and copper) were measured in different sample gas environments (N{sub 2} and H{sub 2}O), and a front aperture diameter of 0.8 mm. The new design concept is based upon “swiftly” accelerating the photoelectrons to kinetic energies of several keV after they pass the analyzer front aperture. Compared to the standard mode, in which the front section between the two first apertures is field-free, this gives a wider angular collection and a lower tendency for electron losses in collisions with gas molecules within the analyzer. With the swift-acceleration mode we attain, depending on the experimental conditions, up to about 3 times higher peak intensities in vacuum and about 10 to 20 times higher peak intensities in the 6–9 mbar regime, depending on kinetic energy. These experimental findings agree well with simulated transmission functions for the analyzer. The new mode of operation enables faster data acquisition than the standard mode of operation, particularly valuable in a home laboratory environment. Further demonstrations of performance are highlighted by measurements of the valence band structure in dye-sensitized solar cell photoelectrodes under a 2 mbar H{sub 2}O atmosphere, a molecularly modified surface of interest in photoelectrochemical devices.

Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF6 electrolyte

International Nuclear Information System (INIS)

Azam, M.A.; Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A.; Kudin, T.I.T.; Yahya, M.Z.A.

2015-01-01

Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF 6 non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g −1 . - Abstract: Carbon nanotubes have been extensively studied because of their wide range of potential application such as in nanoscale electric circuits, textiles, transportation, health, and the environment. Carbon nanotubes feature extraordinary properties, such as electrical conductivities higher than those of copper, hardness and thermal conductivity higher than those of diamond, and strength surpassing that of steel, among others. This research focuses on the fabrication of an energy storage device, namely, an electrochemical capacitor, by using carbon materials, i.e., activated carbon and single-walled carbon nanotubes, of a specific weight ratio as electrode materials. The electrolyte functioning as an ion carrier is 1 M lithium hexafluorophosphate. Variations in the electrochemical performance of the device, including its capacitance, charge/discharge characteristics, and impedance, are reported in this paper. The electrode proposed in this work exhibits a maximum capacitance of 60.97 F g −1 at a scan rate of 1 mV s −1

Convenient hydrothermal decomposition process for preparation of nanocrystalline mineral Cu3BiS3 and Pb1-xBi2x/3S

International Nuclear Information System (INIS)

Hu Junqing; Deng Bin; Wang Chunrui; Tang Kaibin; Qian Yitai

2003-01-01

Mineral nanocrystalline Cu 3 BiS 3 and Pb 1-x Bi 2x/3 S (or Bi 0.22 Pb 0.89 S 1.22 ) have been prepared at low synthetic temperature of 100-150 deg. C by convenient hydrothermal decomposition process. X-ray powder diffraction, transmission electron microscopy, X-ray photoelectron spectra, and element analysis were used to characterize and measure the samples. The as-prepared Cu 3 BiS 3 sample consisted of whisker-like particles with an average size of 50x10 nm 2 and the Pb 1-x Bi 2x/3 S sample displayed aggregative particles with size in the range of 30-50 nm. Preliminary results showed that the prepared precursors, reaction temperature and time played a role in the formation of the final products. A possible reaction mechanism was also discussed briefly

Assessment of the Quality of Newly Formed Bone around Titanium Alloy Implants by Using X-Ray Photoelectron Spectroscopy

Directory of Open Access Journals (Sweden)

Hiroshi Nakada

2012-01-01

Full Text Available The aim of this study was to evaluate differences in bones quality between newly formed bone and cortical bone formed around titanium alloy implants by using X-ray photoelectron spectroscopy. As a result of narrow scan measurement at 4 weeks, the newly formed bone of C1s, P2p, O1s, and Ca2p were observed at a different peak range and strength compared with a cortical bone. At 8 weeks, the peak range and strength of newly formed bone were similar to those of cortical bone at C1s, P2p, and Ca2p, but not O1s. The results from this analysis indicate that the peaks and quantities of each element of newly formed bone were similar to those of cortical bone at 8 weeks, suggestive of a strong physicochemical resemblance.

DESIGN OF A DC/RF PHOTOELECTRON GUN

International Nuclear Information System (INIS)

YU, D.; NEWSHAM, Y.; SMIRONOV, A.; YU, J.; SMEDLEY, J.; SRINIVASAN RAU, T.; LEWELLEN, J.; ZHOLENTS, A.

2003-01-01

An integrated dc/rf photoelectron gun produces a low-emittance beam by first rapidly accelerating electrons at a high gradient during a short (∼1 ns), high-voltage pulse, and then injecting the electrons into an rf cavity for subsequent acceleration. Simulations show that significant improvement of the emittance appears when a high field (∼ 0.5-1 GV/m) is applied to the cathode surface. An adjustable dc gap ((le) 1 mm) which can be integrated with an rf cavity is designed for initial testing at the Injector Test Stand at Argonne National Laboratory using an existing 70-kV pulse generator. Plans for additional experiments of an integrated dc/rf gun with a 250-kV pulse generator are being made

Controlled interface between carbon fiber and epoxy by molecular self-assembly method

International Nuclear Information System (INIS)

He Jinmei; Huang Yudong; Liu Li; Cao Hailin

2006-01-01

In this paper, a new treatment method based on molecular self-assembly on carbon fiber surface was proposed for obtaining a controlled interface between carbon fiber and epoxy matrix in composite system. To form the controlled interfacial region, the surfaces of carbon fibers were first metallized by electroless Ag plating, then were reacted with a series of thiols (different chain lengths and terminally functional groups) to form self-assembly monolayers (SAMs), which further reacted with epoxy resin to generate a strong adhesion interface. The morphology, structure and composition of untreated and treated carbon fiber surface were investigated by atomic force microscope (AFM), surface-enhanced Raman scattering spectroscopy (SERS) and X-ray photoelectron spectroscopy (XPS), respectively. SERS study showed that thiols chemisorbed on Ag/carbon fiber in the form of thiolate species via the strong S-Ag coordinative bond. XPS study further confirmed the chemisorption by an S 2p 3/2 component observed at 162.2 eV. The binding energy was characteristic of silver thiolate. The interfacial shear strength of the carbon fiber/epoxy microcomposites was evaluated by the microbond technique. The results showed that there was a direct effect of the interfacial parameters changes such as chain lengths and surface functional groups on the fiber/matrix adhesion

Investigating Low-Carbon Agriculture: Case Study of China’s Henan Province

Directory of Open Access Journals (Sweden)

Min Su

2017-12-01

Full Text Available Developing low-carbon agriculture requires investigating the trajectory, decoupling statuses, and driving forces of agricultural carbon emissions. This study explored the evolution of agricultural carbon emissions based on 18 kinds of major carbon emission sources in Henan Province of China, which produces approximately one-tenth of China’s total grain output. We then analyzed the relationship between carbon emissions and economic growth using the decoupling elasticity model, and identified the factors driving the decoupling status. This analysis was done with a decoupling elasticity model, using the Logarithmic Mean Divisia Index technique. There were three key results: (1 Agricultural carbon emissions totaled 16.61 million tons in 1999, and increased by 7.99% to 17.93 million tons in 2014, with an average growth rate of approximately 0.65%; (2 The decoupling relationship between agricultural carbon emissions and economic output was dominated by weak decoupling during the study period; (3 Agricultural labor productivity was the leading contributor to changes in agricultural carbon emissions, followed by farming-animal husbandry carbon intensity, labor, and agricultural structure.

Adsorption of H{sub 2}S or SO{sub 2} on an activated carbon cloth modified by ammonia treatment

Energy Technology Data Exchange (ETDEWEB)

Boudou, J.P.; Chehimi, M.; Broniek, E.; Siemieniewska, T.; Bimer, J. [University of Paris, Paris (France)

2003-07-01

The aim of this research is to investigate how ammonia treatment of the surface can influence the activity of a viscose-based activated carbon cloth (ACC) for the oxidative retention of H{sub 2}S and SO{sub 2} in humid air at 25{sup o}C. Surface basic nitrogen groups were introduced either by treatment with ammonia/air at 300{sup o}C or with ammonia/steam at 800{sup o}C. The pore structure of the samples so prepared was examined by adsorption measurements. Changes in the surface chemistry were assessed by X-ray photoelectron spectroscopy, X-ray absorption spectroscopy and temperature programmed desorption (TPD). The change of ACC activity could not be merely attributed to surface nitrogen groups but to other changes in the support. Ammonia/steam treatment improved ACC performance the most, not only by introducing nitrogen surface groups, but also by extending the microporosity and by modifying the distribution of surface oxygen groups. Successive adsorption-regeneration cycles showed important differences between oxidative retention of H{sub 2}S and SO{sub 2} and the subsequent catalyst/support regeneration process.

Effect of Al Hot-Dipping on High-Temperature Corrosion of Carbon Steel in N2/0.1% H2S Gas

Directory of Open Access Journals (Sweden)

Muhammad Ali Abro

2016-02-01

Full Text Available High-temperature corrosion of carbon steel in N2/0.1% H2S mixed gas at 600–800 °C for 50–100 h was studied after hot-dipping in the aluminum molten bath. Hot-dipping resulted in the formation of the Al topcoat and the Al-Fe alloy layer firmly adhered on the substrate. The Al-Fe alloy layer consisted primarily of a wide, tongue-like Al5Fe2 layer and narrow Al3Fe layer. When corroded at 800 °C for 100 h, the Al topcoat partially oxidized to the protective but non-adherent α-Al2O3 layer, and the interdiffusion converted the Al-Fe alloy layer to an (Al13Fe4, AlFe3-mixed layer. The interdiffusion also lowered the microhardness of the hot-dipped steel. The α-Al2O3 layer formed on the hot-dipped steel protected the carbon steel against corrosion. Without the Al hot-dipping, the carbon steel failed by forming a thick, fragile, and non-protective FeS scale.

Electrochemically modified sulfisoxazole nanofilm on glassy carbon for determination of cadmium(II) in water samples

International Nuclear Information System (INIS)

Gupta, Vinod Kumar; Yola, Mehmet Lütfi; Atar, Necip; Solak, Ali Osman; Uzun, Lokman; Üstündağ, Zafer

2013-01-01

Highlights: • Sulfisoxazole was grafted onto glassy carbon electrode. • The electrode was characterized by spectroscopic and electrochemical methods. • It has been used for the determination of Cd(II) ions in real samples in very low concentrations. -- Abstract: Sulfisoxazole (SO) was grafted to glassy carbon electrode (GCE) via the electrochemical oxidation of SO in acetonitrile solution containing 0.1 M tetrabutylammoniumtetra-fluoroborate (TBATFB). The prepared electrode was characterized by using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), reflection–absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS). The ellipsometric thickness of SO nanofilm at the glassy carbon surface was obtained as 14.48 ± 0.11 nm. The stability of the SO modified GCE was studied. The SO modified GCE was also utilized for the determination of Cd(II) ions in water samples in the presence of Pb(II) and Fe(II) by adsorptive stripping voltammetry. The linearity range and the detection limit of Cd(II) ions were 1.0 × 10 −10 to 5.0 × 10 −8 M and 3.3 × 10 −11 M (S/N = 3), respectively

An improved pyrolysis route to synthesize carbon-coated CdS quantum dots with fluorescence enhancement effect

International Nuclear Information System (INIS)

Zhang Kejie; Liu Xiaoheng

2011-01-01

Well-dispersed carbon-coated CdS (CdS-C) quantum dots were successfully prepared via the improved pyrolysis of bis(1-dodecanethiol)-cadmium(II) under nitrogen atmosphere. This simple method effectively solved the sintered problem resulted from conventional pyrolysis process. The experimental results indicated that most of the as-prepared nanoparticles displayed well-defined core-shell structures. The CdS cores with diameter of ∼5 nm exhibited hexagonal crystal phase, the carbon shells with thickness of ∼2 nm acted as a good dispersion medium to prevent CdS particles from aggregation, and together with CdS effectively formed a monodisperse CdS-Carbon nanocomposite. This composite presented a remarkable fluorescence enhancement effect, which indicated that the prepared nanoparticles might be a promising photoresponsive material or biosensor. This improved pyrolysis method might also offer a facile way to prepare other carbon-coated semiconductor nanostructures. - Graphical abstract: We demonstrated a facile approach to synthesize well-dispersed carbon-coated CdS quantum dots. The as-prepared nanoparticles presented remarkable fluorescence enhancement effect. Highlights: → Carbon-coated CdS quantum dots were synthesized by an one-step pyrolysis method. → Well-dispersed CdS-carbon nanoparticles were obtained by an acid treatment process. → As-prepared nanoparticles presented remarkable fluorescence enhancement effect.

Poly(urethane–carbonate)s from Carbon Dioxide

KAUST Repository

Chen, Zuliang; Hadjichristidis, Nikolaos; Feng, Xiaoshuang; Gnanou, Yves

2017-01-01

A one-pot, two-step protocol for the direct synthesis of polyurethanes containing few carbonate linkages through polycondensation of diamines, dihalides, and CO2 in the presence of Cs2CO3 and tetrabutylammonium bromide is described. The conditions were optimized by studying the polycondensation of CO2 with 1,6-hexanediamine and 1,4-dibromobutane as model monomers. Then, various diamines and dihalides were tested under optimal conditions. Miscellaneous samples of such carbonate-containing polyurethanes exhibiting molar masses from 6000 to 22 000 g/mol (GPC) and yields higher than 85% were obtained. The thermal properties of such polyurethanes were unveiled by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA): they were found very similar to those of traditional polyurethanes obtained by diisocyanates + diols polycondensation.

Poly(urethane–carbonate)s from Carbon Dioxide

KAUST Repository

Chen, Zuliang

2017-03-09

A one-pot, two-step protocol for the direct synthesis of polyurethanes containing few carbonate linkages through polycondensation of diamines, dihalides, and CO2 in the presence of Cs2CO3 and tetrabutylammonium bromide is described. The conditions were optimized by studying the polycondensation of CO2 with 1,6-hexanediamine and 1,4-dibromobutane as model monomers. Then, various diamines and dihalides were tested under optimal conditions. Miscellaneous samples of such carbonate-containing polyurethanes exhibiting molar masses from 6000 to 22 000 g/mol (GPC) and yields higher than 85% were obtained. The thermal properties of such polyurethanes were unveiled by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA): they were found very similar to those of traditional polyurethanes obtained by diisocyanates + diols polycondensation.

Solid-State Spun Fibers from 1 mm Long Carbon Nanotube Forests Synthesized by Water-Assisted Chemical Vapor Deposition

Science.gov (United States)

Zhang, Shanju; Zhu, Lingbo; Minus, Marilyn L.; Chae, han Gi; Jagannathan, Sudhakar; Wong, Ching-Ping; Kowalik, Janusz; Roberson, Luke B.; Kumar, Satish

2007-01-01

In this work, we report continuous carbon nanotube fibers dry-drawn directly from water-assisted CVD grown forests with millimeter scale length. As-drawn nanotube fibers exist as aerogel and can be transformed into more compact fibers through twisting or densification with a volatile liquid. Nanotube fibers are characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman microscopy and wide-angle X-ray diffraction (WAXD). Mechanical behavior and electrical conductivity of the post-treated nanotube fibers are investigated.

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

International Nuclear Information System (INIS)

Borgatti, F.; Torelli, P.; Panaccione, G.

2016-01-01

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Hard X-ray PhotoElectron Spectroscopy of transition metal oxides: Bulk compounds and device-ready metal-oxide interfaces

Energy Technology Data Exchange (ETDEWEB)

Borgatti, F., E-mail: francesco.borgatti@cnr.it [Istituto per lo Studio dei Materiali Nanostrutturati (ISMN), Consiglio Nazionale delle Ricerche (CNR), via P. Gobetti 101, Bologna I-40129 (Italy); Torelli, P.; Panaccione, G. [Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, Trieste I-34149 (Italy)

2016-04-15

Highlights: • Hard X-ray PhotoElectron Spectroscopy (HAXPES) applied to buried interfaces of systems involving Transition Metal Oxides. • Enhanced contribution of the s states at high kinetic energies both for valence and core level spectra. • Sensitivity to chemical changes promoted by electric field across metal-oxide interfaces in resistive switching devices. - Abstract: Photoelectron spectroscopy is one of the most powerful tool to unravel the electronic structure of strongly correlated materials also thanks to the extremely large dynamic range in energy, coupled to high energy resolution that this form of spectroscopy covers. The kinetic energy range typically used for photoelectron experiments corresponds often to a strong surface sensitivity, and this turns out to be a disadvantage for the study of transition metal oxides, systems where structural and electronic reconstruction, different oxidation state, and electronic correlation may significantly vary at the surface. We report here selected Hard X-ray PhotoElectron Spectroscopy (HAXPES) results from transition metal oxides, and from buried interfaces, where we highlight some of the important features that such bulk sensitive technique brings in the analysis of electronic properties of the solids.

Metal/Carbon Hybrid Nanostructures Produced from Plasma-Enhanced Chemical Vapor Deposition over Nafion-Supported Electrochemically Deposited Cobalt Nanoparticles

Directory of Open Access Journals (Sweden)

Mohammad Islam

2018-04-01

Full Text Available In this work, we report development of hybrid nanostructures of metal nanoparticles (NP and carbon nanostructures with strong potential for catalysis, sensing, and energy applications. First, the etched silicon wafer substrates were passivated for subsequent electrochemical (EC processing through grafting of nitro phenyl groups using para-nitrobenzene diazonium (PNBT. The X-ray photoelectron spectroscope (XPS and atomic force microscope (AFM studies confirmed presence of few layers. Cobalt-based nanoparticles were produced over dip or spin coated Nafion films under different EC reduction conditions, namely CoSO4 salt concentration (0.1 M, 1 mM, reduction time (5, 20 s, and indirect or direct EC reduction route. Extensive AFM examination revealed NP formation with different attributes (size, distribution depending on electrochemistry conditions. While relatively large NP with >100 nm size and bimodal distribution were obtained after 20 s EC reduction in H3BO3 following Co2+ ion uptake, ultrafine NP (<10 nm could be produced from EC reduction in CoSO4 and H3BO3 mixed solution with some tendency to form oxides. Different carbon nanostructures including few-walled or multiwalled carbon nanotubes (CNT and carbon nanosheets were grown in a C2H2/NH3 plasma using the plasma-enhanced chemical vapor deposition technique. The devised processing routes enable size controlled synthesis of cobalt nanoparticles and metal/carbon hybrid nanostructures with unique microstructural features.

Real-time visualization of the vibrational wavepacket dynamics in electronically excited pyrimidine via femtosecond time-resolved photoelectron imaging

Science.gov (United States)

Li, Shuai; Long, Jinyou; Ling, Fengzi; Wang, Yanmei; Song, Xinli; Zhang, Song; Zhang, Bing

2017-07-01

The vibrational wavepacket dynamics at the very early stages of the S1-T1 intersystem crossing in photoexcited pyrimidine is visualized in real time by femtosecond time-resolved photoelectron imaging and time-resolved mass spectroscopy. A coherent superposition of the vibrational states is prepared by the femtosecond pump pulse at 315.3 nm, resulting in a vibrational wavepacket. The composition of the prepared wavepacket is directly identified by a sustained quantum beat superimposed on the parent-ion transient, possessing a frequency in accord with the energy separation between the 6a1 and 6b2 states. The dephasing time of the vibrational wavepacket is determined to be 82 ps. More importantly, the variable Franck-Condon factors between the wavepacket components and the dispersed cation vibrational levels are experimentally illustrated to identify the dark state and follow the energy-flow dynamics on the femtosecond time scale. The time-dependent intensities of the photoelectron peaks originated from the 6a1 vibrational state exhibit a clear quantum beating pattern with similar periodicity but a phase shift of π rad with respect to those from the 6b2 state, offering an unambiguous picture of the restricted intramolecular vibrational energy redistribution dynamics in the 6a1/6b2 Fermi resonance.

Subcycle interference dynamics of time-resolved photoelectron holography with midinfrared laser pulses

International Nuclear Information System (INIS)

Bian Xuebin; Yuan, Kai-Jun; Bandrauk, Andre D.; Huismans, Y.; Smirnova, O.; Vrakking, M. J. J.

2011-01-01

Time-resolved photoelectron holography from atoms using midinfrared laser pulses is investigated by solving the corresponding time-dependent Schroedinger equation (TDSE) and a classical model, respectively. The numerical simulation of the photoelectron angular distribution of Xe irradiated with a low-frequency free-electron laser source agrees well with the experimental results. Different types of subcycle interferometric structures are predicted by the classical model. Furthermore with the TDSE model it is demonstrated that the holographic pattern is sensitive to the shape of the atomic orbitals. This is a step toward imaging by means of photoelectron holography.

EDTA modified glassy carbon electrode: Preparation and characterization

Energy Technology Data Exchange (ETDEWEB)

Ustuendag, Zafer [Dumlupinar University, Faculty of Arts and Sciences, Department of Chemistry, Kuetahya (Turkey); Solak, Ali Osman [Ankara University, Faculty of Science, Department of Chemistry, Degol Street, Tandogan, 06100 Ankara (Turkey)], E-mail: osolak@science.ankara.edu.tr

2009-11-01

EDTA-phenoxyamide modified glassy carbon electrode (EDTA-GC) was prepared at a glassy carbon electrode by surface synthesis. In the first step, nitrophenyl was grafted to the glassy carbon (GC) surface via the electrochemical reduction of its tetraflouroborate diazonium salt. In the second step, nitrophenyl-modified electrode (NP-GC) was subjected to the cathodic potential scan to reduce the nitro to amine group. p-Aminophenyl modified glassy carbon electrode (AP-GC) was dipped into a EDTA solution containing 1-ethyl-3(3-(dimethlyamino)propyl)-carbodiimide (EDC) as an activating agent. Thus formed ((2-anilino-2-oxoethyl){l_brace}2-[bis(carboxymethyl)amino]-ethyl{r_brace}amino)acetic acid modified GC electrode was denoted as EDTA-GC and characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), ellipsometry and X-ray photoelectron spectroscopy (XPS). Complexation of the EDTA-GC surface with Pb{sup 2+} ions was investigated if this electrode could be used as a metal sensor.

Voltammetric sensing of bisphenol A based on a single-walled carbon nanotubes/poly{3-butyl-1-[3-(N-pyrrolyl)propyl] imidazolium ionic liquid} composite film modified electrode

International Nuclear Information System (INIS)

Chen, Xuemin; Ren, Tongqing; Ma, Ming; Wang, Zhengguo; Zhan, Guoqing; Li, Chunya

2013-01-01

Highlights: • Single-walled carbon nanotubes (SWCNTs)-ionic liquid (IL) nanocomposite fabrication. • SWCNTs-Poly-IL film modified electrode was prepared and characterized. • Voltammetric behaviors of bisphenol A were investigated thoroughly. • Sensitive voltammetric method for bisphenol A determination was developed. -- Abstract: Using carboxylic acid-functionalized single walled carbon nanotubes (SWCNTs-COO − ) as an anion and 3-butyl-1-[3-(N-pyrrolyl)propyl]imidazolium as a cation, a novel SWCNTs-COO-ionic liquid (SWCNTs-COO-IL) nanocomposite was fabricated successfully. The as-prepared SWCNTs-COO-IL nanocomposite was confirmed with transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis, FTIR and Raman spectroscopy. The SWCNTs-COO-IL nanocomposite was coated onto a glassy carbon electrode surface followed by cyclic voltammetric scanning to fabricate a SWCNTs/poly{3-butyl-1-[3-(N-pyrrolyl)propyl] imidazolium ionic liquid} composite film modified electrode (SWCNTs/Poly-IL/GCE). Scanning electron microscope and electrochemical impedance spectroscopy were used to characterize SWCNTs/Poly-IL/GCE. Electrochemical behaviors of bisphenol A (BPA) at the SWCNTs/Poly-IL/GCE were investigated thoroughly. It was found that an obvious oxidation peak appeared without reduction peak in the reverse scanning, indicating an irreversible electrochemical process. The oxidation peak currents of BPA were linearly related to scan rate in the range of 20–300 mV s −1 , suggesting an adsorption controlled process rather than a diffusion controlled process. Differential pulse voltammetry was employed for the voltammetric sensing of BPA. Experimental conditions such as film thickness, pH value, accumulation potential and time that influence the analytical performance of the SWCNTs/Poly-IL/GCE were optimized. Under optimal conditions, the oxidation peak current was linearly related to BPA concentration in the range of 5.0 × 10 −9 to 3.0 × 10 −5 mol L

Effect of heat treatment on carbon fiber surface properties and fibers/epoxy interfacial adhesion

International Nuclear Information System (INIS)

Dai Zhishuang; Zhang Baoyan; Shi Fenghui; Li Min; Zhang Zuoguang; Gu Yizhuo

2011-01-01

Carbon fiber surface properties are likely to change during the molding process of carbon fiber reinforced matrix composite, and these changes could affect the infiltration and adhesion between carbon fiber and resin. T300B fiber was heat treated referring to the curing process of high-performance carbon fiber reinforced epoxy matrix composites. By means of X-ray photoelectron spectroscopy (XPS), activated carbon atoms can be detected, which are defined as the carbon atoms conjunction with oxygen and nitrogen. Surface chemistry analysis shows that the content of activated carbon atoms on treated carbon fiber surface, especially those connect with the hydroxyl decreases with the increasing heat treatment temperature. Inverse gas chromatography (IGC) analysis reveals that the dispersive surface energy γ S d increases and the polar surface energy γ S sp decreases as the heat treatment temperature increases to 200. Contact angle between carbon fiber and epoxy E51 resin, which is studied by dynamic contact angle test (DCAT) increases with the increasing heat treatment temperature, indicating the worse wettability comparing with the untreated fiber. Moreover, micro-droplet test shows that the interfacial shear strength (IFSS) of the treated carbon fiber/epoxy is lower than that of the untreated T300B fiber which is attributed to the decrement of the content of reactive functional groups including hydrogen group and epoxy group.

S L Sharma

Indian Academy of Sciences (India)

Home; Journals; Bulletin of Materials Science. S L Sharma. Articles written in Bulletin of Materials Science. Volume 25 Issue 2 April 2002 pp 85-93 Materials Synthesis. Photoelectronic properties of HgI2 crystals for nuclear radiation detection · S L Sharma H N Acharya · More Details Abstract Fulltext PDF. Photoelectronic ...

Adsorption/desorption of low concentration of carbonyl sulfide by impregnated activated carbon under micro-oxygen conditions

Energy Technology Data Exchange (ETDEWEB)

Wang, Xueqian, E-mail: wxqian3000@yahoo.com.cn [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Qiu, Juan; Ning, Ping; Ren, Xiaoguang; Li, Ziyan; Yin, Zaifei; Chen, Wei; Liu, Wei [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

2012-08-30

Highlights: Black-Right-Pointing-Pointer Carbonyl sulfide can be catalytic oxidized by micro-oxygen in the off-gas. Black-Right-Pointing-Pointer How to use the trace oxygen for the oxidation of carbonyl sulfide was a challenge. Black-Right-Pointing-Pointer The SO{sub 4}{sup 2-} species in the adsorbent sample were generated by a catalytic oxidation process. - Abstract: Activated carbon modified with different impregnants has been studied for COS removal efficiency under micro-oxygen conditions. Activated carbon modified with Cu(NO{sub 3}){sub 2}-CoPcS-KOH (denoted as Cu-Co-KW) is found to have markedly enhanced adsorption purification ability. In the adsorption purification process, the reaction temperature, oxygen concentration, and relative humidity of the gas are determined to be three crucial factors. A breakthrough of 43.34 mg COS/g adsorbent at 60 Degree-Sign S and 30% relative humidity with 1.0% oxygen is shown in Cu-Co-KW for removing COS. The structures of the activated carbon samples are characterized using nitrogen adsorption, and their surface chemical structures are analyzed with X-ray photoelectron spectroscopy (XPS). Modification of Cu(NO{sub 3}){sub 2}-CoPcS-KOH appears to improve the COS removal capacity significantly, during which, SO{sub 4}{sup 2-} is presumably formed, strongly adsorbed, and present in the micropores ranging from 0.7 to 1.5 nm. TPD is used to identify the products containing sulfur species on the carbon surface, where SO{sub 2} and COS are detected in the effluent gas generated from exhausted Cu-Co-KW (denoted Cu-Co-KWE). According to the current study results, the activated carbon impregnated with Cu(NO{sub 3}){sub 2}-CoPcS-KOH promises a good candidate for COS adsorbent, with the purified gas meeting requirements for desirable chemical feed stocks.

Accuracy of single photoelectron time spread measurement of fast photomultipliers

International Nuclear Information System (INIS)

Leskovar, B.

1975-01-01

The accuracy of time spread measurements of fast photomultipliers was investigated, using single photoelectrons. The effect of the finite light pulse width on the measurement accuracy was determined and discussed. Experimental data were obtained on a special measuring system for light pulse widths ranging from 200 psec to 10 nsec, using fast photomultipliers 8850 and C31024 with optimized operating conditions for minimum transit time spread. A modified exponential function expression and curve-fitting parameters are given, which fit closely the experimentally obtained data over a wide dynamic range of light pulse widths. (U.S.)

Reference binding energies of transition metal carbides by core-level x-ray photoelectron spectroscopy free from Ar+ etching artefacts

Science.gov (United States)

Greczynski, G.; Primetzhofer, D.; Hultman, L.

2018-04-01

We report x-ray photoelectron spectroscopy (XPS) core level binding energies (BE's) for the widely-applicable groups IVb-VIb transition metal carbides (TMCs) TiC, VC, CrC, ZrC, NbC, MoC, HfC, TaC, and WC. Thin film samples are grown in the same deposition system, by dc magnetron co-sputtering from graphite and respective elemental metal targets in Ar atmosphere. To remove surface contaminations resulting from exposure to air during sample transfer from the growth chamber into the XPS system, layers are either (i) Ar+ ion-etched or (ii) UHV-annealed in situ prior to XPS analyses. High resolution XPS spectra reveal that even gentle etching affects the shape of core level signals, as well as BE values, which are systematically offset by 0.2-0.5 eV towards lower BE. These destructive effects of Ar+ ion etch become more pronounced with increasing the metal atom mass due to an increasing carbon-to-metal sputter yield ratio. Systematic analysis reveals that for each row in the periodic table (3d, 4d, and 5d) C 1s BE increases from left to right indicative of a decreased charge transfer from TM to C atoms, hence bond weakening. Moreover, C 1s BE decreases linearly with increasing carbide/metal melting point ratio. Spectra reported here, acquired from a consistent set of samples in the same instrument, should serve as a reference for true deconvolution of complex XPS cases, including multinary carbides, nitrides, and carbonitrides.

Low temperature synthesis and characterization of carbonated hydroxyapatite nanocrystals

Science.gov (United States)

Anwar, Aneela; Asghar, Muhammad Nadeem; Kanwal, Qudsia; Kazmi, Mohsin; Sadiqa, Ayesha

2016-08-01

Carbonate substituted hydroxyapatite (CHA) nanorods were synthesized via coprecipitation method from aqueous solution of calcium nitrate tetrahydrate and diammonium hydrogen phosphate (with urea as carbonate ion source) in the presence of ammonium hydroxide solution at 70 °C at the conditions of pH 11. The obtained powders were physically characterized using transmission electron microscopy (TEM), X-ray powder diffraction analysis (XRD), and FTIR and Raman spectroscopy. The particle size was evaluated by Dynamic light scattering (DLS). The chemical structural analysis of as prepared sample was performed using X-ray photoelectron spectroscopy (XPS). After ageing for 12 h, and heat treatment at 1000 °C for 1 h, the product was obtained as highly crystalline nanorods of CHA.

Photoelectron spectroscopy of phosphites and phosphates

Energy Technology Data Exchange (ETDEWEB)

Chattopadhyay, S.; Findley, G.L.; McGlynn, S.P.

1981-01-01

The ultraviolet photoelectron spectra (UPS) of trimethyl and triethyl phosphite, trimethyl and triethyl phosphate and four substituted phosphates are presented. Assignments are based on analogies to the UPS of phosphorus trichloride and phosphoryl trichloride and are substantiated by CNDO/2 computations. The mechanisms of P-O (axial) bond formation is discussed.

Angular Correlation between Photoelectrons and Auger Electrons from K-Shell Ionization of Neon

International Nuclear Information System (INIS)

Landers, A. L.; Robicheaux, F.; Bhandary, A.; Jahnke, T.; Schoeffler, M.; Titze, J.; Akoury, D.; Doerner, R.; Osipov, T.; Lee, S. Y.; Adaniya, H.; Hertlein, M.; Weber, Th.; Prior, M. H.; Belkacem, A.; Ranitovic, P.; Bocharova, I.; Cocke, C. L.

2009-01-01

We have used cold target recoil ion momentum spectroscopy to study the continuum correlation between the photoelectron of core-photoionized neon and the subsequent Auger electron. We observe a strong angular correlation between the two electrons. Classical trajectory Monte Carlo calculations agree quite well with the photoelectron energy distribution that is shifted due to the potential change associated with Auger decay. However, a striking discrepancy results in the distribution of the relative angle between Auger and photoelectron. The classical model predicts a shift in photoelectron flux away from the Auger emission direction, and the data strikingly reveal that the flux is lost rather than diverted, indicating that the two-step interpretation of photoionization followed by Auger emission is insufficient to fully describe the core-photoionization process.

Structural, nanomechanical and variable range hopping conduction behavior of nanocrystalline carbon thin films deposited by the ambient environment assisted filtered cathodic jet carbon arc technique

Energy Technology Data Exchange (ETDEWEB)

Panwar, O.S., E-mail: ospanwar@mail.nplindia.ernet.in [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Rawal, Ishpal; Tripathi, R.K. [Polymorphic Carbon Thin Films Group, Physics of Energy Harvesting Division, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Srivastava, A.K. [Electron and Ion Microscopy, Sophisticated and Analytical Instruments, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India); Kumar, Mahesh [Ultrafast Opto-Electronics and Tetrahertz Photonics Group, CSIR-National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi - 110 012 (India)

2015-04-15

Highlights: • Nanocrystalline carbon thin films are grown by filtered cathodic jet carbon arc process. • Effect of gaseous environment on the properties of carbon films has been studied. • The structural and nanomechanical properties of carbon thin films have been studied. • The VRH conduction behavior in nanocrystalline carbon thin films has been studied. - Abstract: This paper reports the deposition and characterization of nanocrystalline carbon thin films by filtered cathodic jet carbon arc technique assisted with three different gaseous environments of helium, nitrogen and hydrogen. All the films are nanocrystalline in nature as observed from the high resolution transmission electron microscopic (HRTEM) measurements, which suggests that the nanocrystallites of size ∼10–50 nm are embedded though out the amorphous matrix. X-ray photoelectron spectroscopic studies suggest that the film deposited under the nitrogen gaseous environment has the highest sp{sup 3}/sp{sup 2} ratio accompanied with the highest hardness of ∼18.34 GPa observed from the nanoindentation technique. The film deposited under the helium gaseous environment has the highest ratio of the area under the Raman D peak to G peak (A{sub D}/A{sub G}) and the highest conductivity (∼2.23 S/cm) at room temperature, whereas, the film deposited under the hydrogen environment has the lowest conductivity value (2.27 × 10{sup −7} S/cm). The temperature dependent dc conduction behavior of all the nanocrystalline carbon thin films has been analyzed in the light of Mott’s variable range hopping (VRH) conduction mechanism and observed that all the films obey three dimension VRH conduction mechanism for the charge transport.

Accurate quasiparticle calculation of x-ray photoelectron spectra of solids.

Science.gov (United States)

Aoki, Tsubasa; Ohno, Kaoru

2018-05-31

It has been highly desired to provide an accurate and reliable method to calculate core electron binding energies (CEBEs) of crystals and to understand the final state screening effect on a core hole in high resolution x-ray photoelectron spectroscopy (XPS), because the ΔSCF method cannot be simply used for bulk systems. We propose to use the quasiparticle calculation based on many-body perturbation theory for this problem. In this study, CEBEs of band-gapped crystals, silicon, diamond, β-SiC, BN, and AlP, are investigated by means of the GW approximation (GWA) using the full ω integration and compared with the preexisting XPS data. The screening effect on a deep core hole is also investigated in detail by evaluating the relaxation energy (RE) from the core and valence contributions separately. Calculated results show that not only the valence electrons but also the core electrons have an important contribution to the RE, and the GWA have a tendency to underestimate CEBEs due to the excess RE. This underestimation can be improved by introducing the self-screening correction to the GWA. The resulting C1s, B1s, N1s, Si2p, and Al2p CEBEs are in excellent agreement with the experiments within 1 eV absolute error range. The present self-screening corrected GW approach has the capability to achieve the highly accurate prediction of CEBEs without any empirical parameter for band-gapped crystals, and provide a more reliable theoretical approach than the conventional ΔSCF-DFT method.

Accurate quasiparticle calculation of x-ray photoelectron spectra of solids

Science.gov (United States)

Aoki, Tsubasa; Ohno, Kaoru

2018-05-01

It has been highly desired to provide an accurate and reliable method to calculate core electron binding energies (CEBEs) of crystals and to understand the final state screening effect on a core hole in high resolution x-ray photoelectron spectroscopy (XPS), because the ΔSCF method cannot be simply used for bulk systems. We propose to use the quasiparticle calculation based on many-body perturbation theory for this problem. In this study, CEBEs of band-gapped crystals, silicon, diamond, β-SiC, BN, and AlP, are investigated by means of the GW approximation (GWA) using the full ω integration and compared with the preexisting XPS data. The screening effect on a deep core hole is also investigated in detail by evaluating the relaxation energy (RE) from the core and valence contributions separately. Calculated results show that not only the valence electrons but also the core electrons have an important contribution to the RE, and the GWA have a tendency to underestimate CEBEs due to the excess RE. This underestimation can be improved by introducing the self-screening correction to the GWA. The resulting C1s, B1s, N1s, Si2p, and Al2p CEBEs are in excellent agreement with the experiments within 1 eV absolute error range. The present self-screening corrected GW approach has the capability to achieve the highly accurate prediction of CEBEs without any empirical parameter for band-gapped crystals, and provide a more reliable theoretical approach than the conventional ΔSCF-DFT method.

Activated carbon and single-walled carbon nanotube based electrochemical capacitor in 1 M LiPF{sub 6} electrolyte

Energy Technology Data Exchange (ETDEWEB)

Azam, M.A., E-mail: asyadi@utem.edu.my [Carbon Research Technology Research Group, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Jantan, N.H.; Dorah, N.; Seman, R.N.A.R.; Manaf, N.S.A. [Carbon Research Technology Research Group, Faculty of Manufacturing Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka (Malaysia); Kudin, T.I.T. [Ionics Materials & Devices Research Laboratory, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor (Malaysia); Yahya, M.Z.A. [Ionics Materials & Devices Research Laboratory, Faculty of Applied Sciences, Universiti Teknologi MARA, Shah Alam, Selangor (Malaysia); National Defence University of Malaysia, Kem Sungai Besi, 57000 Kuala Lumpur (Malaysia)

2015-09-15

Highlights: • Activated carbon and single-walled CNT based electrochemical capacitor. • Electrochemical analysis by means of CV, charge/discharge and impedance. • 1 M LiPF{sub 6} non-aqueous solution as an electrolyte. • AC/SWCNT electrode exhibits a maximum capacitance of 60.97 F g{sup −1}. - Abstract: Carbon nanotubes have been extensively studied because of their wide range of potential application such as in nanoscale electric circuits, textiles, transportation, health, and the environment. Carbon nanotubes feature extraordinary properties, such as electrical conductivities higher than those of copper, hardness and thermal conductivity higher than those of diamond, and strength surpassing that of steel, among others. This research focuses on the fabrication of an energy storage device, namely, an electrochemical capacitor, by using carbon materials, i.e., activated carbon and single-walled carbon nanotubes, of a specific weight ratio as electrode materials. The electrolyte functioning as an ion carrier is 1 M lithium hexafluorophosphate. Variations in the electrochemical performance of the device, including its capacitance, charge/discharge characteristics, and impedance, are reported in this paper. The electrode proposed in this work exhibits a maximum capacitance of 60.97 F g{sup −1} at a scan rate of 1 mV s{sup −1}.

Angular distribution of Xe 5s→epsilonp photoelectrons: Disagreement between experiment and theory

International Nuclear Information System (INIS)

Fahlman, A.; Carlson, T.A.; Krause, M.O.

1983-01-01

The angular asymmetry parameter β for the Xe 5s→epsilonp photoelectrons has been studied with use of synchrotron radiation (hν = 28--65 eV). The present results show that the relativistic random-phase approximation theory does not satisfactorily describe the Xe 5s photoionization process close to the Cooper minimum and thus require a renewed theoretical approach. The 5s partial photoionization cross section was obtained over the same photon region and the results agree with experimental values found in the literature

Liquid microjet for photoelectron spectroscopy

International Nuclear Information System (INIS)

Winter, Bernd

2009-01-01

Photoelectron spectroscopy from highly volatile liquids, especially from water and aqueous solutions, has recently become possible due to the development of the vacuum liquid microjet in combination of high-brilliance synchrotron radiation. The present status of this rapidly growing field is reported here, with an emphasize on the method's sensitivity for detecting local electronic structure, and for monitoring ultrafast dynamical processes in aqueous solution exploiting core-level resonant excitation.

Introduction to x-ray photoelectron spectroscopy (XPS)

International Nuclear Information System (INIS)

Liesegang, J.; Pigram, P.J.

1999-01-01

Full text: XPS is one of several important surface analytical tools. Developed in Sweden in the 1960s, it was originally named by Kai Siegbahn as Electron Spectroscopy for Chemical Analysis or ESCA; and although it is the best method for non-invasively determining the elemental composition of the first 10 nm of any surface, modern XPS systems are capable of much more than elemental chemical analysis. High resolution photoelectron energy analysis (c. 0.2 eV) now permits easy identification of chemical state as well as concentration; angular variation of detection and depth profiling allow quantitative analysis as a function of depth below a sample surface; energy loss mechanisms may be studied; Auger peaks can be measured in an XPS system; and developments in the area of photoelectron imaging allow high resolution (c. 7 μm) mapping of the distribution of elements and their chemical states to be determined spatially on non-homogeneous surfaces. The workshop sessions will outline the link between the physics and chemistry of surfaces and the process of photoemission. The presentation will illustrate the features and capabilities of a newly acquired Kratos (UK) Axis Ultra XPS and Imaging System recently installed in the Centre for Materials and Surface Science at La Trobe University, and its capabilities regarding the foregoing issues. The first part of the presentation will outline the basics of XPS and the second part will illustrate its usefulness, and in particular, will illustrate the power of the instrumentation through the presentation of several applications of both fundamental and industrial significance. Copyright (1999) Australian X-ray Analytical Association Inc

Recent trends in spin-resolved photoelectron spectroscopy

Science.gov (United States)

Okuda, Taichi

2017-12-01

Since the discovery of the Rashba effect on crystal surfaces and also the discovery of topological insulators, spin- and angle-resolved photoelectron spectroscopy (SARPES) has become more and more important, as the technique can measure directly the electronic band structure of materials with spin resolution. In the same way that the discovery of high-Tc superconductors promoted the development of high-resolution angle-resolved photoelectron spectroscopy, the discovery of this new class of materials has stimulated the development of new SARPES apparatus with new functions and higher resolution, such as spin vector analysis, ten times higher energy and angular resolution than conventional SARPES, multichannel spin detection, and so on. In addition, the utilization of vacuum ultra violet lasers also opens a pathway to the realization of novel SARPES measurements. In this review, such recent trends in SARPES techniques and measurements will be overviewed.

Investigation of corrosion behavior of nitrogen doped and platinum/ruthenium doped diamond-like carbon thin films in Hank's solution

Energy Technology Data Exchange (ETDEWEB)

Khun, N.W.; Liu, E., E-mail: MEJLiu@ntu.edu.sg

2011-10-10

Undoped (DLC), nitrogen-doped (N-DLC) and platinum/ruthenium doped diamond-like carbon (PtRu-DLC) thin films were deposited on p-Si (100) substrates using a DC magnetron sputtering deposition system. The chemical composition, bonding structure, surface morphology and adhesion strength of the films were characterized using X-ray photoelectron spectroscopy (XPS), micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch test, respectively. The corrosion behavior of the films in a Hank's solution was investigated using potentiodynamic polarization test. The corrosion results revealed that the PtRu-DLC film had the highest corrosion potential among the films used in this study. Highlights: {yields} DLC thin films were deposited on Si substrates via dc magnetron sputtering. {yields} Some DLC films were doped with N and/or Pt/Ru. {yields} The film corrosion behavior was studied in a Hank solution with polarization test. {yields} The PtRu-DLC film showed the highest corrosion potential among the films studied.

A photoelectron imaging and quantum chemistry study of the deprotonated indole anion.

Science.gov (United States)

Parkes, Michael A; Crellin, Jonathan; Henley, Alice; Fielding, Helen H

2018-05-29

Indole is an important molecular motif in many biological molecules and exists in its deprotonated anionic form in the cyan fluorescent protein, an analogue of green fluorescent protein. However, the electronic structure of the deprotonated indole anion has been relatively unexplored. Here, we use a combination of anion photoelectron velocity-map imaging measurements and quantum chemistry calculations to probe the electronic structure of the deprotonated indole anion. We report vertical detachment energies (VDEs) of 2.45 ± 0.05 eV and 3.20 ± 0.05 eV, respectively. The value for D0 is in agreement with recent high-resolution measurements whereas the value for D1 is a new measurement. We find that the first electronically excited singlet state of the anion, S1(ππ*), lies above the VDE and has shape resonance character with respect to the D0 detachment continuum and Feshbach resonance character with respect to the D1 continuum.

Atomic and molecular photoelectron and Auger-electron-spectroscopy studies using synchrotron radiation

International Nuclear Information System (INIS)

Southworth, S.H.

1982-01-01

Electron spectroscopy, combined with synchrotron radiation, was used to measure the angular distributions of photoelectrons and Auger electrons from atoms and molecules as functions of photon energy. The branching ratios and partial cross sections were also measured in certain cases. By comparison with theoretical calculations, the experimental results are interpreted in terms of the characteristic electronic structure and ionization dynamics of the atomic or molecular sample. The time structure of the synchrotron radiation source was used to record time-of-flight (TOF) spectra of the ejected electrons. The double-angle-TOF method for the measurement of photoelectron angular distributions is discussed. This technique offers the advantages of increased electron collection efficiency and the elimination of certain systematic errors. An electron spectroscopy study of inner-shell photoexcitation and ionization of Xe, photoelectron angular distributions from H 2 and D 2 , and photoionization cross sections and photoelectron asymmetries of the valence orbitals of NO are reported

Photoelectron spectroscopy study on Li substituted NiO using PES beamline installed on Indus-1

Science.gov (United States)

Banerjee, A.; Chaudhari, S. M.; Phase, D. M.; Dasannacharya, B. A.

2003-01-01

Photoelectron spectroscopy beamline based on a toroidal grating monochromator (TGM) is recently commissioned on Indus-1 storage ring. It has been used to carry out valence band photoemission study of Li substituted NiO. In this paper initially a brief description of the beamline components and the experimental station for angle integrated photoemission experiment is presented. The later part of this paper is devoted to studies carried out on Li xNi 1- xO with x=0.0, 0.35 and 0.5 samples. Thin pellets of polycrystalline samples were used for the measurements reported here. Valence band spectra recorded on polycrystalline Li xNi 1- xO samples show drastic changes in various features as compared to that of pure NiO. The prominent changes are: (i) change in the relative contributions of Ni-3d and O-2p emissions, (ii) change in the peak position of Ni-3d from the top of the valance band of NiO and (iii) no noticeable change in the Ni satellite peak. These results are evaluated in terms of earlier findings in pure and low Li doped NiO.

Photoelectron spectroscopy study on Li substituted NiO using PES beamline installed on Indus-1

CERN Document Server

Banerjee, A; Phase, D M; Dasannacharya, B A

2003-01-01

Photoelectron spectroscopy beamline based on a toroidal grating monochromator (TGM) is recently commissioned on Indus-1 storage ring. It has been used to carry out valence band photoemission study of Li substituted NiO. In this paper initially a brief description of the beamline components and the experimental station for angle integrated photoemission experiment is presented. The later part of this paper is devoted to studies carried out on Li sub x Ni sub 1 sub - sub x O with x=0.0, 0.35 and 0.5 samples. Thin pellets of polycrystalline samples were used for the measurements reported here. Valence band spectra recorded on polycrystalline Li sub x Ni sub 1 sub - sub x O samples show drastic changes in various features as compared to that of pure NiO. The prominent changes are: (i) change in the relative contributions of Ni-3d and O-2p emissions, (ii) change in the peak position of Ni-3d from the top of the valance band of NiO and (iii) no noticeable change in the Ni satellite peak. These results are evaluated...

a near ambient pressure UV photoelectron spectroscopy

Indian Academy of Sciences (India)

Manoj Kumar Ghosalya

2018-03-02

Mar 2, 2018 ... UV photoelectron spectroscopy (NAP-UPS) investigations. MANOJ KUMAR ... gations led to various models of Ag-O2 interaction to explain its role in the .... charge lamp (for He I and He II excitations) are available as photon ...

Corrosion inhibition performance of 2,5-bis(4-dimethylaminophenyl)-1,3,4-oxadiazole for carbon steel in HCl solution: Gravimetric, electrochemical and XPS studies

Energy Technology Data Exchange (ETDEWEB)

Bouanis, M.; Tourabi, M.; Nyassi, A. [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Zarrouk, A. [LCAE-URAC 18, Faculty of Science, First Mohammed University, PO Box 717, M-60 000 Oujda (Morocco); Jama, C. [UMET-ISP, CNRS UMR 8207, ENSCL, Université Lille Nord de France, CS 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F., E-mail: fbentiss@gmail.com [Laboratoire de Catalyse et de Corrosion des Matériaux (LCCM), Faculté des Sciences, Université Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); UMET-ISP, CNRS UMR 8207, ENSCL, Université Lille Nord de France, CS 90108, F-59652 Villeneuve d' Ascq Cedex (France)

2016-12-15

Highlights: • 2,5-Bis(4-dimethylaminophenyl)-1,3,4-oxadiazole is good corrosion inhibitor for carbon steel in 1 M HCl. • XPS analysis has provided the composition of adsorbed protective layer on the steel surface. • The adsorption of the investigated 1,3,4-oxadiazole is mainly due to chemisorption. - Abstract: Corrosion inhibition of carbon steel in normal hydrochloric acid solution at 30 °C by 2,5-bis(4-dimethylaminophenyl)-1,3,4-oxadiazole (DAPO) has been studied by weight loss measurements and electrochemical techniques (polarization and AC impedance). The experimental results showed that DAPO acted as an efficient inhibitor against the carbon steel corrosion in 1 M HCl, and its inhibition efficiency increased with the inhibitor concentration reaching a value up to 93% at 1 mM. Polarization studies showed that the DAPO was a mixed-type inhibitor. The adsorption of this 1,3,4-oxadiazole derivative on the carbon steel surface in 1 M HCl solution followed the Langmuir adsorption isotherm and the corresponding value of the standard Gibbs free energy of adsorption (ΔG°{sub ads}) is associated to a chemisorption mechanism. Scanning Electron Microscopy (SEM) and X-Ray Photoelectron Spectroscopy (XPS) analyses were carried out to characterize the chemical composition of the inhibitive film formed on the steel surface. The surfaces studies showed that the inhibitive layer is composed of an iron oxide/hydroxide mixture where DAPO molecules are incorporated. The cytotoxicity of DAPO was also determined using cell culture system.

Photoelectron spectroscopy of supersonic molecular beams

International Nuclear Information System (INIS)

Pollard, J.E.; Trevor, D.J.; Lee, Y.T.; Shirley, D.A.

1981-01-01

A high-resolution photoelectron spectrometer which uses molecular beam sampling is described. Photons from a rare-gas resonance lamp or UV laser are crossed with the beam from a differentially pumped supersonic nozzle source. The resulting photoelectrons are collected by an electrostatic analyzer of a unique design consisting of a 90 0 spherical sector preanalyzer, a system of lenses, and a 180 0 hemispherical deflector. A multichannel detection system based on dual microchannel plates with a resistive anode position encoder provides an increase in counting efficiency by a factor of 12 over the equivalent single channel detector. The apparatus has demonstrated an instrumental resolution of better than 10 meV FWHM, limited largely by the photon source linewidth. A quadrupole mass spectrometer is used to characterize the composition of the molecular beam. Extensive differential pumping is provided to protect the critical surfaces of the analyzer and mass spectrometer from contamination. Because of the near elimination of Doppler and rotational broadenings, the practical resolution is the highest yet obtained in molecular PES

An analytical investigation: Effect of solar wind on lunar photoelectron sheath

Science.gov (United States)

Mishra, S. K.; Misra, Shikha

2018-02-01

The formation of a photoelectron sheath over the lunar surface and subsequent dust levitation, under the influence of solar wind plasma and continuous solar radiation, has been analytically investigated. The photoelectron sheath characteristics have been evaluated using the Poisson equation configured with population density contributions from half Fermi-Dirac distribution of the photoemitted electrons and simplified Maxwellian statistics of solar wind plasma; as a consequence, altitude profiles for electric potential, electric field, and population density within the photoelectron sheath have been derived. The expression for the accretion rate of sheath electrons over the levitated spherical particles using anisotropic photoelectron flux has been derived, which has been further utilized to characterize the charging of levitating fine particles in the lunar sheath along with other constituent photoemission and solar wind fluxes. This estimate of particle charge has been further manifested with lunar sheath characteristics to evaluate the altitude profile of the particle size exhibiting levitation. The inclusion of solar wind flux into analysis is noticed to reduce the sheath span and altitude of the particle levitation; the dependence of the sheath structure and particle levitation on the solar wind plasma parameters has been discussed and graphically presented.

Many-body effect in the partial singles N2,3 photoelectron spectroscopy spectrum of atomic Cd

International Nuclear Information System (INIS)

Ohno, Masahide

2008-01-01

We can extract out the photoelectron kinetic energy (KE) dependent imaginary part of the core-hole self-energy by employing Auger-photoelectron coincidence spectroscopy (APECS). The variation with photoelectron KE in the Auger electron spectroscopy (AES) spectral peak intensity of a selected decay channel measured in coincidence with photoelectrons of a selected KE is the partial singles (non-coincidence) photoelectron spectroscopy (PES) spectrum, i.e., the product of the singles PES one and the branching ratio of the partial Auger decay width of a selected decay channel to the imaginary part of the core-hole self-energy. When a decay channel the partial Auger decay width of which is photoelectron KE independent is selected, we can extract out spectroscopically the imaginary part of the core-hole self-energy because the variation with photoelectron KE in the relative spectral intensity of the partial singles PES spectrum to the singles one is that in the branching ratio of the partial Auger decay width of a selected decay channel. As an example we discussed the N 2,3 -hole self-energy of atomic Cd

Analysis of the Interphase on Carbon Black Formed in High Voltage Batteries

DEFF Research Database (Denmark)

Younesi, Reza; Christiansen, Ane Sælland; Scipioni, Roberto

2015-01-01

Carbon black (CB) additives commonly used to increase the electrical conductivity of electrodes in Li-ion batteries are generally believed to be electrochemically inert additives in cathodes. Decomposition of electrolyte in the surface region of CB in Li-ion cells at high voltages up to 4.9 V...... is here studied using electrochemical measurements as well as structural and surface characterizations. LiPF6 and LiClO4 dissolved in ethylene carbonate:diethylene carbonate (1:1) were used as the electrolyte to study irreversible charge capacity of CB cathodes when cycled between 4.9 V and 2.5 V....... Synchrotron-based soft X-ray photoelectron spectroscopy (SOXPES) results revealed spontaneous partial decomposition of the electrolytes on the CB electrode, without applying external current or voltage. Depth profile analysis of the electrolyte/cathode interphase indicated that the concentration of decomposed...

Coupling of carbon monoxide molecules over oxygen-defected UO2(111) single crystal and thin film surfaces.

Science.gov (United States)

Senanayake, S D; Waterhouse, G I N; Idriss, H; Madey, Theodore E

2005-11-22

While coupling reactions of carbon-containing compounds are numerous in organometallic chemistry, they are very rare on well-defined solid surfaces. In this work we show that the reductive coupling of two molecules of carbon monoxide to C2 compounds (acetylene and ethylene) could be achieved on oxygen-defected UO2(111) single crystal and thin film surfaces. This result allows in situ electron spectroscopic investigation of a typical organometallic reaction such as carbon coupling and extends it to heterogeneous catalysis and solids. By using high-resolution photoelectron spectroscopy (HRXPS) it was possible to track the changes in surface states of the U and O atoms as well as identify the intermediate of the reaction. Upon CO adsorption U cations in low oxidation states are oxidized to U4+ ions; this was accompanied by an increase of the O-to-U surface ratios. The HRXPS C 1s lines show the presence of adsorbed species assigned to diolate species (-OCH=CHO-) that are most likely the reaction intermediate in the coupling of two CO molecules to acetylene and ethylene.

Coupling of Carbon Monoxide Molecules over Oxygen Defected UO2 (111) Single Crystal and Thin Film Surfaces

International Nuclear Information System (INIS)

Senanayake, S.; Waterhouse, G.; Idriss, H.; Madey, T.

2005-01-01

While coupling reactions of carbon-containing compounds are numerous in organometallic chemistry, they are very rare on well-defined solid surfaces. In this work we show that the reductive coupling of two molecules of carbon monoxide to C 2 compounds (acetylene and ethylene) could be achieved on oxygen-defected UO 2 (111) single crystal and thin film surfaces. This result allows in situ electron spectroscopic investigation of a typical organometallic reaction such as carbon coupling and extends it to heterogeneous catalysis and solids. By using high-resolution photoelectron spectroscopy (HRXPS) it was possible to track the changes in surface states of the U and O atoms as well as identify the intermediate of the reaction. Upon CO adsorption U cations in low oxidation states are oxidized to U 4+ ions; this was accompanied by an increase of the O-to-U surface ratios. The HRXPS C 1s lines show the presence of adsorbed species assigned to diolate species (-OCH=CHO-) that are most likely the reaction intermediate in the coupling of two CO molecules to acetylene and ethylene

Thickness measurement of SiO2 films thinner than 1 nm by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Joong Kim, Kyung; Park, Ki Tae; Lee, Jong Wan

2006-01-01

The thickness measurement of ultra-thin SiO 2 films thinner than 1 nm was studied by X-ray photoelectron spectroscopy (XPS). Amorphous SiO 2 thin films were grown on amorphous Si films to avoid the thickness difference due to the crystalline structure of a substrate. SiO 2 thin films were grown by ion beam sputter deposition under oxygen gas flow and the thickness was measured by in situ XPS. The attenuation length was determined experimentally by a SiO 2 film with a known thickness. The straight line fit between the measured thickness using XPS and the nominal thickness showed a good linear relation with a gradient of 0.969 and a small offset of 0.126 nm. The gradient measured at the range of 3.4-0.28 nm was very close to that measured at sub-nanometer range of 1.13-0.28 nm. This result means that the reliable measurement of SiO 2 film thickness below 1 nm is possible by XPS

Catalytic and peroxidase-like activity of carbon based-AuPd bimetallic nanocomposite produced using carbon dots as the reductant

International Nuclear Information System (INIS)

Yang, Liuqing; Liu, Xiaoying; Lu, Qiujun; Huang, Na; Liu, Meiling; Zhang, Youyu; Yao, Shouzhuo

2016-01-01

In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H 2 O 2 ) has been designed using 3,3′,5,5′-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H 2 O 2 in wide linear range of 5 μM–500 μM and 500 μM–4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas. - Highlights: • Carbon-based AuPd bimetallic nanocomposite was synthesized using carbon dots. • The green sequential reduction strategy synthesis method is simple, green, convenient and effective. • The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like activity. • The AuPd/C NC exhibits noticeably higher catalytic activity in reduction of 4-nitrophenol. • A new colorimetric detection method for hydrogen peroxide based on AuPd/C NC was proposed.

Catalytic and peroxidase-like activity of carbon based-AuPd bimetallic nanocomposite produced using carbon dots as the reductant

Energy Technology Data Exchange (ETDEWEB)

Yang, Liuqing [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Liu, Xiaoying [College of Science, Science and Technological Innovation Platform, Hunan Agricultural University, Hunan, Changsha 410128 (China); Lu, Qiujun; Huang, Na [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Liu, Meiling, E-mail: liumeilingww@126.com [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Zhang, Youyu; Yao, Shouzhuo [Key Laboratory of Chemical Biology & Traditional Chinese Medicine Research (Ministry of Education, China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China)

2016-08-03

In this report, carbon-based AuPd bimetallic nanocomposite (AuPd/C NC) was synthesized using carbon dots (C-dots) as the reducing agent and stabilizer by a simple green sequential reduction strategy, without adding other agents. The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like property. The structure and morphology of these nanoparticles were clearly characterized by UV–Vis spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The AuPd/C NC catalyst exhibits noticeably higher catalytic activity than Pd and Au nanoparticles in catalysis reduction of 4-nitrophenol (4-NP). Moreover, based on the high peroxidase-like property of AuPd/C NC, a new colorimetric detection method for hydrogen peroxide (H{sub 2}O{sub 2}) has been designed using 3,3′,5,5′-tetramethyl-benzidine (TMB) as the substrate, which provides a simple and sensitive means to detect H{sub 2}O{sub 2} in wide linear range of 5 μM–500 μM and 500 μM–4 mM with low detection limit of 1.6 μM (S/N = 3). Therefore, the facile synthesis strategy for bimetallic nanoparticles by the mild reductant of carbon dot will provide some new thoughts for preparing of carbon-based metal nanomaterials and expand their application in catalysis and analytical chemistry areas. - Highlights: • Carbon-based AuPd bimetallic nanocomposite was synthesized using carbon dots. • The green sequential reduction strategy synthesis method is simple, green, convenient and effective. • The as synthesized AuPd/C NC showed good catalytic activity and peroxidase-like activity. • The AuPd/C NC exhibits noticeably higher catalytic activity in reduction of 4-nitrophenol. • A new colorimetric detection method for hydrogen peroxide based on AuPd/C NC was proposed.

Mechanical desorption of immobilized proteins using carbon dioxide aerosols for reusable biosensors

International Nuclear Information System (INIS)

Singh, Renu; Hong, Seongkyeol; Jang, Jaesung

2015-01-01

Highlights: • Immobilized proteins were removed using carbon dioxide aerosols. • We observed high removal efficiencies due to the aerosol treatment. • We confirmed the removal with FTIR and X-ray photoelectron spectroscopy. • This CO 2 aerosol treatment did not undermine re-functionalization. • This technique is a fast and damage-free method to reuse a sensor surface. - Abstract: Reusability of a biosensor has recently received considerable attention, and it is closely related with the effective desorption of probe molecules. We present a novel mechanical desorption technique to reuse biosensors by using periodic jets of carbon dioxide (CO 2 ) aerosols (a mixture of solid and gaseous CO 2 ), and demonstrate its feasibility by removing physically adsorbed and covalently bonded fluorescent proteins i.e., Escherichia coli fluorescein isothiocyanate antibody and bovine serum albumin (E. coli FITC–Ab and FITC–BSA) from silicon chips. The proteins on the chip surfaces were measured by fluorescent images before and after applying the aerosols. The removal efficiency of the aerosol treatment was measured for various concentrations (1–20 μg mL −1 ) of E. coli FITC–Ab and FITC–BSA with two different removal cycles (5 and 11 cycles; each cycle: 8 s). We observed high removal efficiencies (>93.5% for physically adsorbed Ab and >84.6% for covalently bonded Ab) at 11 cycle aerosol treatment. This CO 2 aerosol treatment did not undermine re-functionalization, which was confirmed by the fluorescent images of FITC–Abs for fresh and reused chips. Desorption of the immobilized layers was validated by Fourier transform infrared and X-ray photoelectron spectroscopic analyses. We also conducted an experiment on the regeneration of E. coli sensing chips using this aerosol treatment, and the chips were re-used 5 times successfully. This mechanical desorption technique is a highly effective and novel strategy for reusable biosensors

High performance thiol-ene thermosets based on fully bio-based poly(limonene carbonate)s

NARCIS (Netherlands)

Li, C.; Johansson, M.; Sablong, R.J.; Koning, C.E.

2017-01-01

High glass transition temperature (Tg) thiol-ene networks (TENs) based on poly(limonene carbonate)s (PLCs), derived from orange oils and of potential degradability are described here. PLCs with moderate molecular weight were prepared by copolymerization of limonene oxide with CO2 and subsequent

Negative ion photoelectron spectroscopy of SeO-

International Nuclear Information System (INIS)

Coe, J.V.; Snodgrass, J.T.; Freidhoff, C.B.; McHugh, K.M.; Bowen, K.H.

1985-01-01

Negative ion photoelectron spectroscopy (NIPES) involves a kinetic energy analysis of electrons which are photodetached when a mass selected beam of negative ions is crossed with a fixed frequency laser beam. The photodetachment spectra of SeO - displays transitions from the X 2 PI state of SeO - to both the X 3 Σ - and a 1 Δ states of SeO. The singlet-triplet splitting of SeO is readily observable since selection rules regarding spin do not apply in the bound to free state process of photodetachment. The electron affinity of SeO and the negative ion potential parameters of SeO - have been determined

Geometry Optimization of DC/RF Photoelectron Gun

CERN Document Server

Chen Ping; Yu, David

2005-01-01

Pre-acceleration of photoelectrons in a pulsed, high voltage, short, dc gap and its subsequent injection into an rf gun is a promising method to improve electron beam emittance in rf accelerators. Simulation work has been performed in order to optimize the geometric shapes of a dc/rf gun and improve electron beam properties. Variations were made on cathode and anode shapes, dc gap distance, and inlet shape of the rf cavity. Simulations showed that significant improvement on the normalized emittance (< 1 mm-mrad), compared to a dc gun with flat cathode, could be obtained after the geometric shapes of the gun were optimized.

Photoelectron Spectroscopy in Advanced Placement Chemistry

Science.gov (United States)

Benigna, James

2014-01-01

Photoelectron spectroscopy (PES) is a new addition to the Advanced Placement (AP) Chemistry curriculum. This article explains the rationale for its inclusion, an overview of how the PES instrument records data, how the data can be analyzed, and how to include PES data in the course. Sample assessment items and analysis are included, as well as…

High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

Energy Technology Data Exchange (ETDEWEB)

Knut, Ronny; Lindblad, Rebecka [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Gorgoi, Mihaela [Helmholtz Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Str. 15, 12489 Berlin (Germany); Rensmo, Håkan [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden); Karis, Olof, E-mail: olof.karis@physics.uu.se [Department of Physics and Astronomy, Uppsala University, SE-751 21 Uppsala (Sweden)

2013-10-15

Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems.

High energy photoelectron spectroscopy in basic and applied science: Bulk and interface electronic structure

International Nuclear Information System (INIS)

Knut, Ronny; Lindblad, Rebecka; Gorgoi, Mihaela; Rensmo, Håkan; Karis, Olof

2013-01-01

Highlights: •We demonstrate how hard X-ray photoelectron spectroscopy can be used to investigate interface properties of multilayers. •By combining HAXPES and statistical methods we are able to provide quantitative analysis of the interface diffusion process. •We show how photoionization cross sections can be used to map partial density of states contributions to valence states. •We use HAXPES to provide insight into the valence electronic structure of e.g. multiferroics and dye-sensitized solar cells. -- Abstract: With the access of new high-performance electron spectrometers capable of analyzing electron energies up to the order of 10 keV, the interest for photoelectron spectroscopy has grown and many new applications of the technique in areas where electron spectroscopies were considered to have limited use have been demonstrated over the last few decades. The technique, often denoted hard X-ray photoelectron spectroscopy (HX-PES or HAXPES), to distinguish the experiment from X-ray photoelectron spectroscopy performed at lower energies, has resulted in an increasing interest in photoelectron spectroscopy in many areas. The much increased mean free path at higher kinetic energies, in combination with the elemental selectivity of the core level spectroscopies in general has led to this fact. It is thus now possible to investigate the electronic structure of materials with a substantially enhanced bulk sensitivity. In this review we provide examples from our own research using HAXPES which to date has been performed mainly at the HIKE facility at the KMC-1 beamline at HZB, Berlin. The review exemplifies the new opportunities using HAXPES to address both bulk and interface electronic properties in systems relevant for applications in magnetic storage, energy related research, but also in purely curiosity driven problems

X‐ray Photoelectron Spectroscopy of Pyridinium‐Based Ionic Liquids: Comparison to Imidazolium‐ and Pyrrolidinium‐Based Analogues

Science.gov (United States)

Mitchell, Daniel S.; Lovelock, Kevin R. J.

2015-01-01

Abstract We investigate eight 1‐alkylpyridinium‐based ionic liquids of the form [CnPy][A] by using X‐ray photoelectron spectroscopy (XPS). The electronic environment of each element of the ionic liquids is analyzed. In particular, a reliable fitting model is developed for the C 1s region that applies to each of the ionic liquids. This model allows the accurate charge correction of binding energies and the determination of reliable and reproducible binding energies for each ionic liquid. Shake‐up/off phenomena are determinedfor both C 1s and N 1s spectra. The electronic interaction between cations and anions is investigated for both simple ionic liquids and an example of an ionic‐liquid mixture; the effect of the anion on the electronic environment of the cation is also explored. Throughout the study, a detailed comparison is made between [C8Py][A] and analogues including 1‐octyl‐1‐methylpyrrolidinium‐ ([C8C1Pyrr][A]), and 1‐octyl‐3‐methylimidazolium‐ ([C8C1Im][A]) based samples, where X is common to all ionic liquids. PMID:25952131

Mixed resin and carbon fibres surface treatment for preparation of carbon fibres composites with good interfacial bonding strength

International Nuclear Information System (INIS)

He, Hongwei; Wang, Jianlong; Li, Kaixi; Wang, Jian; Gu, Jianyu

2010-01-01

The objective of this work is to improve the interlaminar shear strength of composites by mixing epoxy resin and modifying carbon fibres. The effect of mixed resin matrix's structure on carbon fibres composites was studied. Anodic oxidation treatment was used to modify the surface of carbon fibres. The tensile strength of multifilament and interlaminar shear strength of composites were investigated respectively. The morphologies of untreated and treated carbon fibres were characterized by scanning electron microscope and X-ray photoelectron spectroscopy. Surface analysis indicates that the amount of carbon fibres chemisorbed oxygen-containing groups, active carbon atom, the surface roughness, and wetting ability increases after treatment. The tensile strength of carbon fibres decreased little after treatment by anodic oxidation. The results show that the treated carbon fibres composites could possess excellent interfacial properties with mixed resins, and interlaminar shear strength of the composites is up to 85.41 MPa. The mechanism of mixed resins and treated carbon fibres to improve the interfacial property of composites is obtained.

X-ray photoelectron spectroscopy study of pyrolytically coated graphite platforms submitted to simulated electrothermal atomic absorption spectrometry conditions

International Nuclear Information System (INIS)

Ruiz, Frine; Benzo, Zully; Quintal, Manuelita; Garaboto, Angel; Albornoz, Alberto; Brito, Joaquin L.

2006-01-01

The present work is part of an ongoing project aiming to a better understanding of the mechanisms of atomization on graphite furnace platforms used for electrothermal atomic absorption spectrometry (ETAAS). It reports the study of unused pyrolytic graphite coated platforms of commercial origin, as well as platforms thermally or thermo-chemically treated under simulated ETAAS analysis conditions. X-ray photoelectron spectroscopy (XPS) was employed to study the elements present at the surfaces of the platforms. New, unused platforms showed the presence of molybdenum, of unknown origin, in concentrations up to 1 at.%. Species in two different oxidations states (Mo 6+ and Mo 2+ ) were detected by analyzing the Mo 3d spectral region with high resolution XPS. The analysis of the C 1s region demonstrated the presence of several signals, one of these at 283.3 eV related to the presence of Mo carbide. The O 1s region showed also various peaks, including a signal that can be attributed to the presence of MoO 3 . Some carbon and oxygen signals were consistent with the presence of C=O and C-O- (probably C-OH) groups on the platforms surfaces. Upon thermal treatment up to 2900 deg. C, the intensity of the Mo signal decreased, but peaks due to Mo oxides (Mo 6+ and Mo 5+ ) and carbide (Mo 2+ ) were still apparent. Thermo-chemical treatment with 3 vol.% HCl solutions and heating up to 2900 deg. C resulted in further diminution of the Mo signal, with complete disappearance of Mo carbide species. Depth profiling of unused platforms by Ar + ion etching at increasing time periods demonstrated that, upon removal of several layers of carbonaceous material, the Mo signal disappears suggesting that this contamination is present only at the surface of the pyrolytic graphite platform

Carbon dots decorated vertical SnS{sub 2} nanosheets for efficient photocatalytic oxygen evolution

Energy Technology Data Exchange (ETDEWEB)

Cheng, Zhongzhou [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); Wang, Fengmei; Shifa, Tofik Ahmed; Liu, Kaili; Huang, Yun; Jiang, Chao; He, Jun, E-mail: hej@nanoctr.cn [CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing 100190 (China); CAS Center for Excellence in Nanoscience, National Center for Nanoscience and Technology, Beijing 100190 (China); Liu, Quanlin [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2016-08-01

Metal sulfides are highly desirable materials for photocatalytic water splitting because of their appropriate energy bands. However, the poor stability under light illumination in water hinders their wide applications. Here, two-dimensional SnS{sub 2} nanosheets, along with carbon dots of the size around 10 nm, are uniformly grown on fluorine doped tin oxide glasses with a layer of nickel nanoparticles. Significantly, strong light absorption and enhanced photocurrent density are achieved after integration of SnS{sub 2} nanosheets with carbon dots. Notably, the rate of oxygen evolution reached up to 1.1 mmol g{sup −1} h{sup −1} under simulated sunlight irradiation featuring a good stability.

Preparation and investigation of diamond-like carbon stripper foils by filtered cathodic vacuum arc

International Nuclear Information System (INIS)

Fan, Qiwen; Du, Yinghui; Zhang, Rong; Xu, Guoji

2013-01-01

Thin diamond-like carbon (DLC) stripper foils ∼5μg/cm 2 in thickness were produced and evaluated as heavy-ion strippers for the Beijing HI-13 Tandem Accelerator. The DLC layers ∼4μg/cm 2 in thickness were produced by the filtered cathodic vacuum arc technology onto glass slides coated with betaine–saccharose as releasing agent, which were previously covered with evaporated carbon layers ∼1μg/cm 2 in thickness by the controlled ac arc-discharge method. Irradiation lifetimes of the DLC stripper foils were tested using the heavy-ion beams at the terminal of the Beijing HI-13 Tandem Accelerator, and compared with those of the standard carbon stripper foils made by the combined dc and ac arc-discharge method. The measurements indicate that the DLC stripper foils outlast the standard combined dc and ac arc-discharge carbon stripper foils by a factor of at least 13 and 4 for the 197 Au − (∼9MeV, ∼1μA) and 63 Cu − (∼9MeV, ∼1μA) ion beams, respectively. The structure and properties of the DLC foils deposited onto silicon substrates by the filtered cathodic vacuum arc technology were also evaluated and analyzed by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy images show that the DLC foils contain hardly droplets through the double 90° filters. The X-ray photoelectron spectrum indicates that sp 3 bonds of the DLC foils exceed 70%. The integral intensity ratio of the D peak to the G peak (I D /I G ) measured by the Raman spectroscopy is 0.78

Plasma-activated multi-walled carbon nanotube-polystyrene composite substrates for biosensing

Energy Technology Data Exchange (ETDEWEB)

Fernandez-Sanchez, Cesar; Orozco, Jahir; Jimenez-Jorquera, Cecilia [Instituto de Microelectronica de Barcelona, IMB-CNM (CSIC), Campus UAB, E-08193 Bellaterra, Barcelona (Spain); Pellicer, Eva; Lechuga, Laura M; Mendoza, Ernest, E-mail: cesar.fernandez@imb-cnm.csic.e [Nanobiosensors and Molecular Nanobiophysics Group, Research Center on Nanoscience and Nanotechnology (CIN2) CSIC-ICN, ETSE, Campus UAB-Edificio Q, E-08193 Bellaterra, Barcelona (Spain)

2009-08-19

Carbon nanotube-polymer composites have shown to be suitable materials for the fabrication of electrochemical transducers. The exposed surface of these materials is commonly passivated by a very thin layer of the polymer component that buries the conductive carbon particles. Working with multi-walled carbon nanotube-polystyrene (MWCNT-PS) composite structures, it was previously described how a simple low power oxygen plasma process produced an effective etching of the composite surface, thereby exposing the conductive surface of CNTs. This work shows how this plasma process not only gave rise to a suitable composite conductive surface for electrochemical sensing but simultaneously exposed and created a high density of oxygen-containing functional groups at both the CNT and the PS components, without affecting the material's mechanical stability. These chemical groups could be effectively modified for the stable immobilization of biological receptors. A detailed chemical characterization of the plasma-activated composite surface was possible using x-ray photoelectron spectroscopy. The material reactivity towards the tethering of a protein was studied and protein-protein interactions were then evaluated on the modified composite transducers by scanning electron microscopy. Finally, an amperometric immunosensor approach for the detection of rabbit Immunoglobulin G target analyte was described and a minimum concentration of 3 ng ml{sup -1} was easily measured.

A preliminary study of thermo-mechanical stability of carbon S-phase formed in austenitic stainless steel

Energy Technology Data Exchange (ETDEWEB)

Li, Wei; Chiu, Yu Long; Dong, Hanshan, E-mail: wsgddf@hotmail.com [School of Metallurgy and Materials, College of Physical and Engineering Sciences, The University of Birmingham, Birmingham (United Kingdom)

2010-07-01

Carbon S-phase was generated in the surface of AISI316 austenitic stainless steel by plasma carburising at 500°C for 10h in a gas mixture of 1.5%CH4 and 98.5%H{sub 2}. The thermo-mechanical stability of the carbon S-phase was studied by stressing the 'dog-bone' tensile specimens in the range of 0-200MPa at temperatures ranging from 400 to 500°C for 100-150h. Post-test characterisation was conducted using XRD, SEM, TEM and micro-indentation. The experimental results demonstrate that when tested at a fix temperature the thickness of the carbon S-phase layer increased with the stress applied to the tensile specimens during the thermo-mechanical stability tests. This indicates that tensile stress promotes the diffusion of carbon in the carbon-S-phase. When stressed at 400°C the microstructure of the carbon S-phase was not affected by the stress level; however, when stressed at 450 and 500°C for 100MPa or above, the corrosion resistance of the carbon S-phase slightly deteriorated. The application of a tensile stress during annealing of S-phase layer can retard the deduction of its hardness. This is believed to be related to the early stage precipitation of carbides in the S-phase, which could be facilitated by the applied tensile stress during thermal annealing. (author)

Resonant photoelectron spectroscopy at the Mo 4p→4d absorption edge in MoS2

International Nuclear Information System (INIS)

Lince, J.R.; Didziulis, S.V.; Yarmoff, J.A.

1991-01-01

A systematic study has been conducted of the resonant behavior of the valence-band photoelectron spectrum of MoS 2 for hν=26--70 eV, spanning the Mo 4p→4d transition region. A broad Fano-like resonance appears at ∼42 eV in the constant-initial-state (CIS) intensity plot of the d z 2 peak near the valence-band maximum [∼2 eV binding energy (BE)], confirming its predominantly Mo 4d character. A second shoulder on the higher-hν side of the maximum in the d z 2 CIS intensity plot is suggested to result from transitions to unoccupied states in the 5sp band ∼10 eV above E F , by comparison with a partial-yield spectrum and previous inverse-photoemission data. The region of the valence band in the range 3--4.5-eV BE also exhibits resonant behavior, indicating Mo 4d character, although somewhat less than for the d z 2 peak. The 5--7-eV BE range does not exhibit resonance behavior at the Mo 4p edge and, therefore, contains negligible Mo 4d character. A feature at ∼30 eV in the CIS intensity plot for the 5--7-eV BE range could not be definitively assigned in this study, but may be due to a resonance between direct photoemission and a process involving absorption and autoionization of electronic states that contain Mo 5s and 5p character

Modification of carbon fiber surfaces via grafting with Meldrum's acid

Science.gov (United States)

Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

2015-11-01

The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

A simple and sensitive fluorescent sensor for methyl parathion based on L-tyrosine methyl ester functionalized carbon dots.

Science.gov (United States)

Hou, Juying; Dong, Jing; Zhu, Haishuang; Teng, Xue; Ai, Shiyun; Mang, Minglin

2015-06-15