| 1. |
- Nilson, K., et al.
(författare)
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Potassium-intercalated H2Pc films : Alkali-induced electronic and geometrical modifications
- 2012
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 137:4, s. 044708-
-
Tidskriftsartikel (refereegranskat)abstract
- X-ray spectroscopy studies of potassium intercalated metal-free phthalocyanine multilayers adsorbed on Al(110) have been undertaken. Photoelectron spectroscopy measurements show the presence of several charge states of the molecules upon K intercalation, due to a charge transfer from the alkali. In addition, the comparison of valence band photoemission spectra with the density functional theory calculations of the density of states of the H2Pc- anion indicates a filling of the formerly lowest unoccupied molecular orbital by charge transfer from the alkali. This is further confirmed by x-ray absorption spectroscopy (XAS) studies, which show a decreased density of unoccupied states. XAS measurements in different experimental geometries reveal that the molecules in the pristine film are standing upright on the surface or are only slightly tilted away from the surface normal but upon K intercalation, the molecular orientation is changed in that the tilt angle of the molecules increases.
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| 2. |
- Ahlund, John, et al.
(författare)
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Molecular growth determined by surface domain patterns
- 2008
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:17, s. 6887-6890
-
Tidskriftsartikel (refereegranskat)abstract
- The growth of iron phthalocyanine (FePc) on InSb(001) c(8 x 2) at submonolayer coverage has been investigated with scanning tunneling microscopy (STM). FePc adsorbs flat centered on the In rows both at 70 K and at room temperature (RT). However, the shapes of the two-dimensional molecular islands are fundamentally different; while the RT growth results in chainlike structures along the [I 10] direction, as already observed for other Pc's adsorbed on the same surface, the islands are prolonged along [110], i.e., perpendicular to the substrate rows, at 70 K. These observations are explained on the basis of a recently observed new surface phase at low temperature, resulting in structural domains on the surface. The molecular growth front follows the propagating domain boundary that freezes at low temperature.
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| 3. |
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| 4. |
- Albertsson-Wikland, Kerstin, et al.
(författare)
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Mortality Is Not Increased in Recombinant Human Growth Hormone-treated Patients When Adjusting for Birth Characteristics
- 2016
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : ENDOCRINE SOC. - 0021-972X .- 1945-7197. ; 101:5, s. 2149-2159
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed to investigate whether reported high mortality in childhood recombinant human GH (rhGH)-treated patients was related to birth-characteristics and/or rhGH treatment. Design and Setting: We sought to develop a mortality model of the Swedish general population born between 1973 and 2010, using continuous-hazard functions adjusting for birth characteristics, sex, age intervals, and calendar year to estimate standardized mortality ratio (SMR) and to apply this model to assess expected deaths in Swedish rhGH-treated patients with idiopathic isolated GH deficiency (IGHD), idiopathic short stature (155) or born small for gestational age (SGA). Participants:The general population: Swedish Medical Birth Register (1973-2010: 1 880 668 males; 1 781 131 females) and Cause of Death Register (1985-2010). Intervention Population: Three thousand eight hundred forty-seven patients starting rhGH treatment between 1985 and 2010 and followed in the National GH Register and/or in rhGH trials diagnosed with IGHD (n = 1890), ISS (n = 975), or SGA (n=982). Main Outcome Measures: Death. Results: Using conventional models adjusting for age, sex, and calendar-year, the SMR was 1.43 (95% confidence interval, 0.89-2.19), P = .14, observed/expected deaths 21/14.68. The rhGH population differed (P amp;lt; .001) from the general population regarding birth weight, birth length, and congenital malformations. Application of an Advanced Model: When applying the developed mortality model of the general population, the ratio of observed/expected deaths in rhGH-treated patients was 21/21.99; SMR = 0.955 (0.591-1.456)P = .95. Model Comparison: Expected number of deaths were 14.68 (14.35-14.96) using the conventional model, and 21.99 (21.24-22.81) using the advanced model, P amp;lt; .001, which had at all ages a higher gradient of risk per SD of the model, 24% (range, 18-42%; P amp;lt; .001). Conclusions: Compared with the general Swedish population, the ratio of observed/expected deaths (21/21.99) was not increased in childhood rhGH-treated IGHD, ISS, and SGA patients when applying an advanced sex-specific mortality model adjusting for birth characteristics.
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| 5. |
- Albertsson-Wikland, Kerstin, 1947, et al.
(författare)
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Mortality is not increased in rhGH-treated patients when adjusting for birth characteristics.
- 2016
-
Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 101:5, s. 2149-2159
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed to investigate whether reported high mortality in childhood recombinant human GH (rhGH)-treated patients was related to birth-characteristics and/or rhGH treatment. Design and Setting: We sought to develop a mortality model of the Swedish general population born between 1973 and 2010, using continuous-hazard functions adjusting for birth characteristics, sex, age intervals, and calendar year to estimate standardized mortality ratio (SMR) and to apply this model to assess expected deaths in Swedish rhGH-treated patients with idiopathic isolated GH deficiency (IGHD), idiopathic short stature (155) or born small for gestational age (SGA). Participants:The general population: Swedish Medical Birth Register (1973-2010: 1 880 668 males; 1 781 131 females) and Cause of Death Register (1985-2010). Intervention Population: Three thousand eight hundred forty-seven patients starting rhGH treatment between 1985 and 2010 and followed in the National GH Register and/or in rhGH trials diagnosed with IGHD (n = 1890), ISS (n = 975), or SGA (n=982). Main Outcome Measures: Death. Results: Using conventional models adjusting for age, sex, and calendar-year, the SMR was 1.43 (95% confidence interval, 0.89-2.19), P = .14, observed/expected deaths 21/14.68. The rhGH population differed (P < .001) from the general population regarding birth weight, birth length, and congenital malformations. Application of an Advanced Model: When applying the developed mortality model of the general population, the ratio of observed/expected deaths in rhGH-treated patients was 21/21.99; SMR = 0.955 (0.591-1.456)P = .95. Model Comparison: Expected number of deaths were 14.68 (14.35-14.96) using the conventional model, and 21.99 (21.24-22.81) using the advanced model, P < .001, which had at all ages a higher gradient of risk per SD of the model, 24% (range, 18-42%; P < .001). Conclusions: Compared with the general Swedish population, the ratio of observed/expected deaths (21/21.99) was not increased in childhood rhGH-treated IGHD, ISS, and SGA patients when applying an advanced sex-specific mortality model adjusting for birth characteristics.
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| 6. |
- Alfredsson, Ylvi, et al.
(författare)
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Electronic structure of a vapor-deposited metal-free phthalocyanine thin film
- 2005
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 122:21
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of a vapor-sublimated thin film of metal-free phthalocyanine (H2Pc) is studied experimentally and theoretically. An atom-specific picture of the occupied and unoccupied electronic states is obtained using x-ray-absorption spectroscopy (XAS), core- and valence-level x-ray photoelectron spectroscopy (XPS), and density-functional theory (DFT) calculations. The DFT calculations allow for an identification of the contributions from individual nitrogen atoms to the experimental N1s XAS and valence XPS spectra. This comprehensive study of metal-free phthalocyanine is relevant for the application of such molecules in molecular electronics and provides a solid foundation for identifying modifications in the electronic structure induced by various substituent groups.
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| 7. |
- Alfredsson, Ylfi, et al.
(författare)
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Phase and molecular orientation in H2Pc on conducting glass : characterization of two deposition methods
- 2005
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 493:1-2, s. 13-19
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Tidskriftsartikel (refereegranskat)abstract
- In this study, metal-free phthalocyanine has been deposited on a conducting glass surface by two methods: by spreading the molecular powder directly on the substrate in air and by vapor sublimation under ultra-high vacuum conditions (evaporation). The films have been characterized by means of core level X-ray Photoemission Spectroscopy, X-ray Absorption Spectroscopy (XAS) and Ultra Violet and Visible absorption spectroscopy (UV-Vis). Our results show that the two deposition methods produce molecular overlayers in different polymorphic phases; the UV-Vis measurements indicate that the film obtained by powder deposition is of x-phase type whereas sublimation leads to an α-polymorph structure. The XAS results show that in the powder deposited film the molecules are mainly oriented parallel to the surface. This is opposite to the case of the vapor deposited film, where the molecules mainly are oriented orthogonal to the surface.
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| 8. |
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| 9. |
- Andersson, Tomas, et al.
(författare)
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Photon energy influence on valence photoelectron spectra of silver clusters
- 2012
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Ingår i: Journal of Physics, Conference Series. - : IOP Publishing. - 1742-6588 .- 1742-6596. ; 388:15, s. 152028-
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Tidskriftsartikel (refereegranskat)abstract
- Silver clusters in the size range of ∼102 constituent atoms have been studied using photoelectron spec-troscopy. The 5s and 4d valence bands have been probed with 40 and 60.5 eV photon energies. Differences in the valence band spectral features have been observed and are discussed in view of earlier results on copper clusters and in terms of differences in mean free path for electrons of different energies.
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| 10. |
- Andersson, Tomas, et al.
(författare)
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Plasmon single- and multi-quantum excitation in free metal clusters as seen by photoelectron spectroscopy
- 2011
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 134:9, s. 094511-
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Tidskriftsartikel (refereegranskat)abstract
- Plasmons are investigated in free nanoscale Na, Mg, and K metal clusters using synchrotron radiation-based x-ray photoelectron spectroscopy. The core levels for which the response from bulk and surface atoms can be resolved are probed over an extended binding energy range to include the plasmon loss features. In all species the features due to fundamental plasmons are identified, and in Na and K also those due to either the first order plasmon overtones or sequential plasmon excitation are observed. These features are discussed in view of earlier results for planar macroscopic samples and free clusters of the same materials.
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| 11. |
- Andersson, Tomas, et al.
(författare)
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The electronic structure of free aluminum clusters: Metallicity and plasmons
- 2012
-
Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 136:20
-
Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of free aluminum clusters with similar to 3-4 nm radius has been investigated using synchrotron radiation-based photoelectron and Auger electron spectroscopy. A beam of free clusters has been produced using a gas-aggregation source. The 2p core level and the valence band have been probed. Photoelectron energy-loss features corresponding to both bulk and surface plasmon excitation following photoionization of the 2p level have been observed, and the excitation energies have been derived. In contrast to some expectations, the loss features have been detected at energies very close to those of the macroscopic solid. The results are discussed from the point of view of metallic properties in nanoparticles with a finite number of constituent atoms. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4718362]
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| 12. |
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| 13. |
- Bellander, Martin, et al.
(författare)
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Behavioral correlates of changes in hippocampal gray matter structure during acquisition of foreign vocabulary
- 2016
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 131, s. 205-213
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Tidskriftsartikel (refereegranskat)abstract
- Experience can affect human gray matter volume. The behavioral correlates of individual differences in such brain changes are not well understood. In a group of Swedish individuals studying Italian as a foreign language, we investigated associations among time spent studying, acquired vocabulary, baseline performance on memory tasks, and gray matter changes. As a way of studying episodic memory training, the language learning focused on acquiring foreign vocabulary and lasted for 10 weeks. T-1-weighted structural magnetic resonance imaging and cognitive testing were performed before and after the studies. Learning behavior was monitored via participants' use of a smartphone application dedicated to the study of vocabulary. A whole-brain analysis showed larger changes in gray matter structure of the right hippocampus in the experimental group (N = 33) compared to an active control group (N = 23). A first path analyses revealed that time spent studying rather than acquired knowledge significantly predicted change in gray matter structure. However, this association was not significant when adding performance on baseline memory measures into the model, instead only the participants' performance on a short-term memory task with highly similar distractors predicted the change. This measure may tap similar individual difference factors as those involved in gray matter plasticity of the hippocampus.
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| 14. |
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| 15. |
- Bidermane, Ieva, 1984-, et al.
(författare)
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Adsorption and Molecular Orientation of Lutetium bi-Phthalocyanine Adlayers on Pristine Si(100)2x1 Surface
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A combined photoelectron spectroscopy (PES), X-ray absorption spectroscopy (XAS)and scanning tunneling microscopy (STM) study has been performed to follow thechange in adsorption geometry and to characterize the adsorbate interaction with thesubstrate for dierent thicknesses of lutetium biphthalocyanine (LuPc2) adlayers onpristine Si(100)-2x1 reconstructed stepped surface. A shift to lower binding energieswith increasing thickness has been shown. The STM results showed clustering ofLuPc2 starting from submonolayer coverages and two distinct adsorption types havebeen identied. The STM and PES results have been linked together to propose twodierent adsorption types involving a stronger and weaker interaction with the Sidangling bonds. A change in average angle of molecules with respect to the normalof the surface for increasing thicknesses has been seen from the XAS measurements,leading to disordered layers for thicker films.
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| 16. |
- Bidermane, Ieva, 1984-
(författare)
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Structure and Electronic Properties of Phthalocyanine Films on Metal and Semiconductor Substrates
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The current thesis presents fundamental studies of phthalocyanines (Pcs), a group of organic macro-cycle molecules. The use of phthalocyanine molecular films in devices with a variety of possible technological applications has been the reason of the many studies dedicated to such molecules during the last decades.Core and valence photoelectron spectroscopies (PES), X-ray absorption spectroscopy (XAS) and scanning tunneling microscopy (STM) techniques are used to study phthalocyanine molecules in gas phase and adsorbed on gold (111) and silicon Si(100)-2x1 substrates. Density functional theory (DFT) is used to obtain further insights in the electronic structure of the phthalocyanines.The aim of our studies is to get a deeper understanding into the molecule-molecule and molecule-substrate interactions, a fundamental requirement for improving the devices based on such molecular materials.Gas phase PES and XAS studies and single molecule DFT calculations are performed on the valence band (VB) of iron phthalocyanine (FePc), manganese phthalocyanine (MnPc) and metal-free phthalocyanine (H2Pc). The VB simulations have shown how the metal atom of the Pc influences the inner valence states of the molecules. The HOMO of the H2Pc and FePc is formed by mostly C2p states, whereas the HOMO of MnPc has mainly Mn3d character.PES studies of H2Pc on Au(111) have revealed the influence of the surface on the adsorption of the monolayer. XAS studies indicate formation of ordered monolayer with the Pc ligands parallel to the surface and the change of the molecular tilt angle with increasing thicknesses. For LuPc2 adsorbed on Au(111), STM study demonstrates a formation of bilayer instead of a monolayer.A comparison between the results of LuPc2 adsorbed on pristine or passivated Si(100)-2x1 confirmes the different reactivities of these surfaces: LuPc2 retains many molecular-like characters, when adsorbed on the innert passivated Si. Instead, on the more reactive pristine Si surface, the spectroscopic results have indicated a more significant interaction, possible hybridization and charge redistribution between the molecules and the surface. Moreover, STM images show a modification of the geometrical shape of the molecules, which are proposed to adsorb in two different geometries on the pristine Si surface.
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| 17. |
- Björneholm, O., et al.
(författare)
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Resonant photoemission at core-level shake-up thresholds : Valence-band satellites in nickel
- 1990
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 41:15, s. 10408-10412
-
Tidskriftsartikel (refereegranskat)abstract
- Three-hole satellites (3d7 final-state configuration) in the nickel valence-band photoelectron spectrum have been identified at 13 and 18 eV binding energy with use of synchrotron radiation from the MAX storage ring. The three-hole satellites show resonances at photon energies close to the threshold for excitation of 3p53d9 core-hole shake-up states. The 13-eV satellite also shows a resonance directly at the 3p threshold. This is interpreted as an interference between the direct three-hole ionization and a shake-up transition in the Auger decay of the 3p hole. This shake-up process is also identified directly in the M2,3M4,5M4,5 Auger spectrum.
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| 18. |
- Born, Artur, et al.
(författare)
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Quantification of Ni L-2,L-3 core-hole relaxation pathways utilizing Auger photoelectron coincidence spectroscopy
- 2021
-
Ingår i: Physical Review B. - : American Physical Society. - 2469-9950 .- 2469-9969. ; 103:11
-
Tidskriftsartikel (refereegranskat)abstract
- Ni LVV Auger spectra, in coincidence with the corresponding 2p(1/2), 2p(3/2), and 6 eV satellite photoelectrons, have been used to examine electron correlation and itinerance effects in Ni. In coincidence with the 2p(3/2) core level, the Auger spectral shape is represented by localized 3d(8) and itinerant valence final states with an additional 3d(7) Auger shake-up contribution. The spectra in coincidence with the 6 eV satellite probe the decay of localized 2p(5)3d(9) double hole states, leading to 3d(7) final states. It is found that a fraction of the double hole states delocalize before the Auger decay. A similar delocalization is observed for the double hole states produced by the L2L3M45 Coster-Kronig process, and the delocalization rates have been determined.
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| 19. |
- Born, Artur, et al.
(författare)
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Separation of surface oxide from bulk Ni by selective Ni 3p photoelectron spectroscopy for chemical analysis in coincidence with Ni M-edge Auger electrons
- 2021
-
Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 11:1
-
Tidskriftsartikel (refereegranskat)abstract
- The chemical shift of core level binding energies makes electron spectroscopy for chemical analysis (ESCA) a workhorse analytical tool for science and industry. For some elements, close lying and overlapping spectral features within the natural life time broadening restrict applications. We establish how the core level binding energy chemical shift can be picked up experimentally by the additional selectivity through Auger electron photoelectron coincidence spectroscopy (APECS). Coincident measurement of Ni 3p photoemission with different MVV Auger regions from specific decay channels, narrows the 3p core-levels to a width of 1.2 eV, resolves the spin-orbit splitting of 1.6 eV and determines the chemical shift of Ni 3p levels of a Ni(111) single crystal and its oxidized surface layer to 0.6 eV.
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| 20. |
- Born, A., et al.
(författare)
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The degree of electron itinerancy and shell closing in the core-ionized state of transition metals probed by Auger-photoelectron coincidence spectroscopy
- 2022
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry (RSC). - 1463-9076 .- 1463-9084. ; 24:32, s. 19218-19222
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Tidskriftsartikel (refereegranskat)abstract
- Auger-photoelectron coincidence spectroscopy (APECS) has been used to examine the electron correlation and itinerance effects in transition metals Cu, Ni and Co. It is shown that the LVV Auger, in coincidence with 2p photoelectrons, spectra can be represented using atomic multiplet positions if the 3d-shell is localized (atomic-like) and with a self-convoluted valence band for band-like (itinerant) materials as explained using the Cini-Sawatzky model. For transition metals, the 3d band changes from band-like to localized with increasing atomic number, with the possibility of a mixed behavior. Our result shows that the LVV spectra of Cu can be represented by atomic multiplet calculations, those of Co resemble the self-convolution of the valence band and those of Ni are a mixture of both, consistent with the Cini-Sawatzky model.
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| 21. |
- Brena, Barbara, et al.
(författare)
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Equivalent core-hole time-dependent density functional theory calculations of carbon 1s shake-up states of phthalocyanine
- 2004
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:19, s. 195214-
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Tidskriftsartikel (refereegranskat)abstract
- The shake-up transition energies of the carbon 1s photoelectron spectrum of metal-free phthalocyanine (H2Pc) have been calculated by means of time-dependent density functional theory, for which an equivalent core approximation is adopted. Model calculations for the C 1s shake-up states of benzene are in excellent agreement with the latest experimental results. The complex C 1s shake-up structures associated with the aromatic and pyrrole carbons in the phthalocyanine are computed, as well as their ionization potentials. They allow us to determine the origin of the anomalous intensity ratio between the pyrrole and benzene carbons in a high resolution C 1s photoelectron spectrum measured for a H2Pc film, as due to a benzene-related shake-up contribution, hidden under the pyrrole main intensity feature.
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| 22. |
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| 23. |
- Cappel, Ute B, et al.
(författare)
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Electronic structure dynamics in a low bandgap polymer studied by time-resolved photoelectron spectroscopy.
- 2016
-
Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 18:31, s. 21921-9
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Tidskriftsartikel (refereegranskat)abstract
- Means to measure the temporal evolution following a photo-excitation in conjugated polymers are a key for the understanding and optimization of their function in applications such as organic solar cells. In this paper we study the electronic structure dynamics by direct pump-probe measurements of the excited electrons in such materials. Specifically, we carried out a time-resolved photoelectron spectroscopy (TRPES) study of the polymer PCPDTBT by combining an extreme ultraviolet (XUV) high harmonic generation source with a time-of-flight spectrometer. After excitation to either the 1st excited state or to a higher excited state, we follow how the electronic structure develops and relaxes on the electron binding energy scale. Specifically, we follow a less than 50 fs relaxation of the higher exited state and a 10 times slower relaxation of the 1st excited state. We corroborate the results using DFT calculations. Our study demonstrates the power of TRPES for studying photo-excited electron energetics and dynamics of solar cell materials.
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| 24. |
- Cappel, Ute B, et al.
(författare)
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Partially Reversible Photoinduced Chemical Changes in a Mixed-Ion Perovskite Material for Solar Cells.
- 2017
-
Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 9:40, s. 34970-34978
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Tidskriftsartikel (refereegranskat)abstract
- ) with the element specificity and chemical sensitivity of core-level photoelectron spectroscopy. By carrying out measurements at a synchrotron beamline optimized for low X-ray fluxes, we are able to avoid sample changes due to X-ray illumination and are therefore able to monitor what sample changes are induced by visible illumination only. We find that laser illumination causes partially reversible chemistry in the surface region, including enrichment of bromide at the surface, which could be related to a phase separation into bromide- and iodide-rich phases. We also observe a partially reversible formation of metallic lead in the perovskite structure. These processes occur on the time scale of minutes during illumination. The presented methodology has a large potential for understanding light-induced chemistry in photoactive materials and could specifically be extended to systematically study the impact of morphology and composition on the photostability of metal halide perovskites.
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| 25. |
- Carlsson, Nils, et al.
(författare)
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Lethal and non-lethal effects of multiple indigenous predators on the invasive golden apple snail (Pomacea canaliculata)
- 2004
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Ingår i: Freshwater Biology. - : Wiley. - 0046-5070 .- 1365-2427. ; 49:10, s. 1269-1279
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Tidskriftsartikel (refereegranskat)abstract
- 1. We investigated the individual and combined effects of two predators (the climbing perch, Anabas testudineus, and the wetland crab, Esanthelphusa nimoafi) indigenous to wetlands in Laos, on the behaviour and survival of the invasive South American golden apple snail (Pomacea canaliculata). The snail is considered a pest, consuming large amounts of rice and other aquatic vegetation in the region. 2. Snail avoidance reactions to released predator chemical cues were investigated in aquaria while the effects of predators on a mixed snail population were studied in field enclosures that contained native aquatic plants (Salvinia cucullata, Ludwigia adscendens and Ipomoea aquatica). 3. In the aquaria experiment, neonate (2-3 mm) and medium-sized snails (8-10 mm) responded to fish chemical cues by going to the surface, whereas adult snails (35-40 mm) went to the bottom. In contrast, no size class of snails reacted to chemical cues released by crabs. 4. In the field experiment, fish reduced the abundance of neonate snails, and crabs reduced the abundance of all size classes. The effect of the combined predators could not be predicted from the mortality rate observed in single predator treatments. The survival of neonate and medium-sized snails was greater and of adults less than expected. The presence of predators did not affect egg production. Snails consumed significant amounts of plants despite the presence of predators. 5. Our findings suggest that some indigenous Asian predators have lethal and sublethal effects on P. canaliculata that depend on snail size and predator type. When in the presence of several predators the response of snails to one predator may either increase or decrease the vulnerability of snails to the others.
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| 26. |
- Cavar, Elizabeta, et al.
(författare)
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A single h-BN layer on Pt(111)
- 2008
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 602:9, s. 1722-1726
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Tidskriftsartikel (refereegranskat)abstract
- The structure and formation of an ultrathin hexagonal boron nitride (h-BN) film on Pt(111) has been studied by a combination of scanning tunneling microscopy, low energy electron diffraction, low energy electron microscopy, X-ray absorption and high resolution core level spectroscopy. The study shows that a single boron nitride layer is formed on Pt(111), resulting in a coincidence structure. High resolution scanning tunneling microscopy (STM) images of the h-BN ultrathin film display only one of the atomic species in the unit cell. Probing the boron and nitrogen related local density of states by near edge X-ray absorption fine structure measurements we conclude that the nitrogen sublattice is visible in STM images. The growth of the single hexagonal boron nitride layer by vapourized borazine in the pressure range of 1 x 10(-6)-1 x 10(-8) at 800 degrees C is further studied by low energy electron microscopy, and reveals that the number of nucleation sites and the perfection of the growth is strongly pressure dependent. A model for the single, hexagonal, boron nitride layer on Pt(111) is proposed.
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| 27. |
- Dahlström, Ulf, 1946-, et al.
(författare)
-
Hjärtsvikt hos äldre
- 2001
-
Ingår i: Nordisk geriatrik. - 1403-2082. ; 1, s. 30-36
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 28. |
- Feifel, Raimund, et al.
(författare)
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From localised to delocalised electronic states in free Ar, Kr and Xe clusters
- 2004
-
Ingår i: European Physical Journal D. Atomic, Molecular, Optical and Plasma Physics. - : Springer Science and Business Media LLC. - 1434-6060 .- 1434-6079. ; 30:3, s. 343-351
-
Tidskriftsartikel (refereegranskat)abstract
- We present new results for the inner valence levels of clusters of the three inert gases Ar, Kr and Xe based on photoelectron spectroscopy studies. The inner valence levels are compared to the localised core levels and to the delocalised outer valence levels. This comparison shows a gradual change from a relatively localised behaviour for Ar inner valence 3s, over the intermediate case of Kr inner valence 4s, to a more delocalised behaviour for Xe inner valence 5s. This change correlates well with the ratio between the orbital sizes and the interatomic distances. The Kr4s intermediate case is found to exhibit characteristics of both localised and delocalised behaviour.
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| 29. |
- Forsberg, Bertil, et al.
(författare)
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Childhood asthma in four regions in Scandinavia : risk factors and avoidance effects
- 1997
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 26:3, s. 610-619
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The high and increasing prevalence of childhood asthma is a major public health issue. Various risk factors have been proposed in local studies with different designs.METHODS: We have made a questionnaire study of the prevalence of childhood asthma, potential risk factors and their relations in four regions in Scandinavia (Umeå and Malmö in Sweden, Kuopio in eastern Finland and Oslo, Norway). One urban and one less urbanized area were selected in each region, and a study group of 15962 children aged 6-12 years was recruited.RESULTS: The prevalence of symptoms suggestive of asthma varied considerably between different areas (dry cough 8-19%, asthma attacks 4-8%, physician-diagnosed asthma 4-9%), as did the potential risk factors. Urban residency was generally not a risk factor. However, dry cough was common in the most traffic polluted area. Exposure to some of the risk factors. such as smoking indoors and moisture stains or moulds at home during the first 2 years of life, resulted in an increased risk. However, current exposure was associated with odds ratios less than one.CONCLUSIONS: Our findings were probably due to a combination of early impact and later avoidance of these risk factors. The effects of some risk factors were found to differ significantly between regions. No overall pattern between air pollution and asthma was seen, but air pollution differed less than expected between the areas.
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| 30. |
- Generaloy, Alexander V., et al.
(författare)
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Evolution of CuI/Graphene/Ni(111) System during Vacuum Annealing
- 2015
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 119:22, s. 12434-12444
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Tidskriftsartikel (refereegranskat)abstract
- We present a combined core-level spectroscopy and low-energy electron diffraction study of the evolution of thin CuI layers on graphene/Ni(111) during annealing. It has been found that the annealing of the CuI/graphene/Ni(111) system up to 160 degrees C results in the formation of an ordered CuI overlayer with a (root 3 x root 3) R30 degrees structure on top of the graphene surface. At annealing temperatures of about 180 degrees C or higher, the CuI overlayer decomposes with a simultaneous intercalation of Cu and I atoms underneath the graphene monolayer on Ni(111). Nearly complete intercalation of graphene by Cu and I atoms can be achieved by deposition of about 20 angstrom of CuI, followed by annealing at 200 degrees C. The intercalated graphene layer is p-doped due to interfacial iodine atoms.
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| 31. |
- Giangrisostomi, Erika, et al.
(författare)
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Low Dose Photoelectron Spectroscopy at BESSY II : Electronic structure of matter in its native state
- 2018
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 224:SI, s. 68-78
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Tidskriftsartikel (refereegranskat)abstract
- The implementation of a high-transmission, angular-resolved time-of-Right electron spectrometer with a 1.25 MHz pulse selector at the PM4 soft X-ray dipole beamline of the synchrotron BESSY II creates unique capabilities to inquire electronic structure via photoelectron spectroscopy with a minimum of radiation dose. Solid-state samples can be prepared and characterized with standard UHV techniques and rapidly transferred from various preparation chambers to a 4-axis temperature-controlled measurement stage. A synchronized MHz laser system enables excited-state characterization and dynamical studies starting from the picosecond timescale. This article introduces the principal characteristics of the PM4 beamline and LowDosePES end-station. Recent results from graphene, an organic hole transport material for solar cells and the transition metal dichalcogenide MoS2 are presented to demonstrate the instrument performances. (C) 2017 The Authors. Published by Elsevier B.V.
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| 32. |
- Gladh, Jörgen, 1964-
(författare)
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Ultrafast Probing of CO Reactions on Metal Surfaces : Changes in the molecular orbitals during the catalysis process
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis presents experimental studies of three different chemical reaction steps relevant for heterogeneous catalysis: dissociation, desorption, and oxidation. CO on single-crystal metal surfaces was chosen as the model systems.X-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) provide information about the electronic structure, and were performed on CO/Fe to measure both a non-dissociative, and a pre-dissociative state. The measurement on the pre-dissociative state showed a π → π* excitation, which implies a partly broken internal π bond in the molecule.Ultrafast laser-induced reactions were used to examine the dynamic properties of desorption and oxidation. Here CO/Ru and CO/O/Ru were used as model systems. Desorption of CO from a Ru surface involve both hot electrons and phonons. In the case of CO oxidation from CO/O/Ru a pronounced wavelength dependence of the branching ratio between desorption and oxidation was observed. Excitation with 400 nm showed a factor of 3-4 higher selectivity towards oxidation than 800 nm. This was attributed to coupling to transiently excited, non-thermalized electrons.Finally, by performing optical pump/x-ray probe XAS and XES changes in the electronic structure during the reaction could be followed, both for desorption and oxidation. In the CO/Ru experiment, two different transient excitation paths were observed, one leading to a precursor state, and one where CO moves into a more highly coordinated site. Using selective excitation in XES, these were shown to coexist on the surface. In the oxidation experiment, probing the reacting species located near the transition state region in an associative catalytic surface reaction was demonstrated for the very first time.
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| 33. |
- Glover, C. J., et al.
(författare)
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Stationary and dispersive features in resonant inelastic soft X-ray scattering at the Ge 3p resonances
- 2009
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 173:2-3, s. 103-107
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Tidskriftsartikel (refereegranskat)abstract
- Resonant inelastic soft X-ray scattering at the 3p resonances in crystalline Ge is presented. Both stationary and dispersive features are observed in a wide energy range above as well as below the ionization limits. These observations are in agreement with theoretical predictions based on a two-step model where the initially excited electron has no influence on the emission step. Excess population of states in the conduction band is found, and discussed in terms of attosecond electron dynamics. (c) 2009 Elsevier B.V. All rights reserved.
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| 34. |
- Gorgoi, Mihaela, et al.
(författare)
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HAXPES studies of solid materials for applications in energy and information technology using the HIKE facility at HZB-BESSY II
- 2015
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - Elsevier : Elsevier BV. - 0368-2048 .- 1873-2526. ; 200, s. 40-48
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Tidskriftsartikel (refereegranskat)abstract
- In the present work we review a number of research directions addressed at the HIKE end-station at the BESSY II storage ring at the Helmholtz-Zentrum Berlin, HZB, using hard X-ray photoelectron spectroscopy (HAXPES). The emphasis of this review is on the specific properties of the technique, which are required in order to address different scientific questions at the HIKE beamline.
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| 35. |
- Gorgoi, M., et al.
(författare)
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Relative sub-shell photoionization cross-sections of nickel metal determined by hard X-ray high kinetic energy photoemission
- 2013
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 190, s. 153-158
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Tidskriftsartikel (refereegranskat)abstract
- Recently, hard X-ray high kinetic energy photoelectron spectroscopy has lead to a break-through due to its non destructive way of investigating the bulk electronic properties of materials. However, due to the relatively new development of this technique there is a lack of information concerning the photoionization cross sections at high energies. Whenever compound materials are investigated or when estimating signal levels and the feasibility of an electron spectroscopy experiment the knowledge of cross sections is essential. In the present work the experimentally determined relative sub-shell photoionization cross sections of shallow levels of nickel metal in the energy range of 2-9 keV will be shown. The data are compared with calculated sub-shell photoionization cross sections.
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| 36. |
- Granroth, Sari, et al.
(författare)
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Investigation of interface properties of Ni/Cu multilayers by high kinetic energy photoelectron spectroscopy
- 2009
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121 .- 1550-235X. ; 80:9
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Tidskriftsartikel (refereegranskat)abstract
- High kinetic-energy photoelectron spectroscopy (HIKE) or hard x-ray photoelectron spectroscopy has been used to investigate the alloying of Ni/Cu (100) multilayers. Relative intensities of the corelevels and their chemical shifts derived from binding energy changes are shown to give precise information on physicochemical properties and quality of the buried layers. Interface roughening, including kinetic properties such as the rate of alloying, and temperature effects on the processes can be analyzed quantitatively. Using HIKE, we have been able to precisely follow the deterioration of the multilayer structure at the atomic scale and observe the diffusion of the capping layer into the multilayer structure which in turn is found to lead to a segregation in the ternary system. This is of great importance for future research on multilayered systems of this kind. Our experimental data are supplemented by first-principles theoretical calculations of the core-level shifts for a ternary alloy to allow for modeling of the influence of capping materials on the chemical shifts.
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| 37. |
- Guimaraes, Tor, et al.
(författare)
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Empirically testing the impact of manufacturing system complexity on performance
- 1999
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Ingår i: International Journal of Operations and Production Management. - : Emerald. - 1758-6593 .- 0144-3577. ; 19:12, s. 1254-1269
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Tidskriftsartikel (refereegranskat)abstract
- As the increase in manufacturing competitiveness forces organizations to use more sophisticated and complex software, system performance depends on clever systems design, efficient planning and scheduling of the related processes. For these advanced manufacturing systems the dependence on human competence is greater. However, previous studies indicate that the human aspects for successfully implementing such systems have been neglected. The objective here is to test the hypotheses that system complexity is inversely related to performance, and that training of system operators, and the quality of the man/machine interface reduces the negative impact of system complexity. A sample of discreet manufacturing systems from 128 organizations was used to test these hypotheses empirically. Moderated multivariate regression indicates that man/machine interfaces are significant contributors to reducing the negative effect of systems complexity. With a lower level of significance, operator training has a similar impact. For complex manufacturing systems software, it behoves managers to insure that the man/machine interface provides the desirable features outlined in this study.
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| 38. |
- Holldack, K., et al.
(författare)
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Single bunch X-ray pulses on demand from a multi-bunch synchrotron radiation source
- 2014
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Synchrotron radiation facilities routinely operate in a multi-bunch regime, but applications relying on time-of-flight schemes require single bunch operation. Here we show that pulse picking by resonant excitation in a storage ring creates in addition to the multi-bunch operation a distinct and separable single bunch soft X-ray source. It has variable polarization, a photon flux of up to 10(7)-10(9) ph s(-1)/0.1%BW at purity values of 10(4)-10(2) and a repetition rate of 1.25 MHz. The quasi-resonant excitation of incoherent betatron oscillations of electrons allows horizontal pulse separation at variable (also circular) polarization accessible for both, regular 30 ps pulses and ultrashort pulses of 2-3 ps duration. Combined with a new generation of angularly resolving electron spectrometers this creates unique opportunities for time-resolved photoemission studies as confirmed by time-of-flight spectra. Our pulse picking scheme is particularly suited for surface physics at diffraction-limited light sources promising ultimate spectral resolution.
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| 39. |
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| 40. |
- Isvoranu, Cristina, et al.
(författare)
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Electron spectroscopy study of the initial stages of iron phthalocyanine growth on highly oriented pyrolitic graphite.
- 2009
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 131:21
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Tidskriftsartikel (refereegranskat)abstract
- The nature of the intermolecular and substrate bonds of iron phthalocyanine adsorbed on highly oriented pyrolitic graphite has been investigated by x-ray photoelectron spectroscopy and x-ray absorption spectroscopy. We find that the molecules grow in a highly ordered fashion with the molecules essentially plane-parallel to the surface in both the mono- and multilayers. The spectra obtained on both types of film are virtually identical, which shows that the bonds both between the adsorbate and substrate and between the molecular layers have a pure van der Waals nature. Supporting density functional theory results indicate that the layers are stabilized by weak hydrogen bonds within the molecular layers.
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| 41. |
- Jacobse, Peter H., et al.
(författare)
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One Precursor but Two Types of Graphene Nanoribbons : On-Surface Transformations of 10,10'-Dichloro-9,9'-bianthryl on Ag(111)
- 2019
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 123:14, s. 8892-8901
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Tidskriftsartikel (refereegranskat)abstract
- On-surface synthesis has emerged in the last decade as a method to create graphene nanoribbons (GNRs) with atomic precision. The underlying premise of this bottom-up strategy is that precursor molecules undergo a well-defined sequence of inter- and intramolecular reactions, leading to the formation of a single product. As such, the structure of the GNR is encoded in the precursors. However, recent examples have shown that not only the molecule, but also the coinage metal surface on which the reaction takes place, plays a decisive role in dictating the nanoribbon structure. In this work, we use scanning probe microscopy and X-ray photoelectron spectroscopy to investigate the behavior of 10,10'-dichloro-9,9'-bianthryl (DCBA) on Ag(111). Our study shows that Ag(111) can induce the formation of both seven-atom wide armchair GNRs (7-acGNRs) and 3,1-chiral GNRs (3,1-cGNRs), demonstrating that a single molecule on a single surface can react to different nanoribbon products. We additionally show that coadsorbed dibromoperylene can promote surface-assisted dehydrogenative coupling in DCBA, leading to the exclusive formation of 3,1-cGNRs.
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| 42. |
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| 43. |
- Johansson, Christer, et al.
(författare)
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Robots in Flexible Assembly
- 1987
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Ingår i: Robotics. - 0167-8493. ; 3:1, s. 41-46
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Tidskriftsartikel (refereegranskat)
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| 44. |
- Johansson, Fredrik, et al.
(författare)
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Auger- and Photoelectron Coincidences of Molecular O2 Adsorbed on Ag(111)
- 2022
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 256
-
Tidskriftsartikel (refereegranskat)abstract
- The oxygen on Ag(111) system has been investigated with Auger electron–photoelectron coincidence spectroscopy (APECS). The coincidence spectra between O 1s core level photoelectrons and O KLL Auger electrons have been studied together with Ag3d/AgM4,5NN coincidences. We also describe the electron–electron coincidence spectrometer setup, CoESCA, consisting of two angle resolved time-of-flight spectrometers at a synchrotron light source. Contributions from molecular oxygen and chemisorbed oxygen are assigned using the coincidence data, conclusions are drawn primarily from the O 1s/O KLL data. The data acquisition and treatment procedure are also outlined. The chemisorbed oxygen species observed are relevant for the catalytic ethylene oxidation.
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| 45. |
- Karis, O., et al.
(författare)
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High-kinetic-energy photoemission spectroscopy of Ni at 1s: 6-eV satellite at 4 eV
- 2008
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121 .- 1550-235X. ; 78:23, s. 3-3
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Tidskriftsartikel (refereegranskat)abstract
- Electron correlations are responsible for many profound phenomena in solid-state physics. A classical example is the 6-eV satellite in the photoelectron spectrum of Ni. Until now the satellite structure has only been investigated at the L shell and more shallow levels. Here we report a high-kinetic-energy photoemission spectroscopy (HIKE) investigation of Ni metal. We present 1s and 2p photoelectron spectra, obtained using excitation energies up to 12.6 keV. Our investigation demonstrates that the energy position of the satellite relative to the main line is different for the 1s and the 2p levels. In combination with electronic structure calculations, we show that this energy shift is attributed to unique differences in the core-valence coupling for the K and L-2,L-3 shells in 3d transition metals, resulting in different screening of the core holes.
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| 46. |
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| 47. |
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| 48. |
- Kjeldgaard, Lisbeth, et al.
(författare)
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Intramolecular vibronic dynamics in molecular solids: C60
- 2005
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 72:20
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Tidskriftsartikel (refereegranskat)abstract
- Vibronic coupling in solid C60 has been investigated with a combination of resonant photoemission spectroscopy (RPES) and resonant inelastic x-ray scattering (RIXS). Excitation as a function of energy within the lowest unoccupied molecular orbital resonance yielded strong oscillations in intensity and dispersion in RPES, and a strong inelastic component in RIXS. Reconciling these two observations establishes that vibronic coupling in this core hole excitation leads to predominantly inelastic scattering and localization of the excited vibrations on the molecule on a femtosecond time scale. The coupling extends throughout the widths of the frontier valence bands.
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| 49. |
- Kuehn, Danilo, et al.
(författare)
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Directional sub-femtosecond charge transfer dynamics and the dimensionality of 1T-TaS2
- 2019
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- For the layered transition metal dichalcogenide 1T-TaS2, we establish through a unique experimental approach and density functional theory, how ultrafast charge transfer in 1T-TaS2 takes on isotropic three-dimensional character or anisotropic two-dimensional character, depending on the commensurability of the charge density wave phases of 1T-TaS2. The X-ray spectroscopic core-hole-clock method prepares selectively in-and out-of-plane polarized sulfur 3p orbital occupation with respect to the 1T-TaS2 planes and monitors sub-femtosecond wave packet delocalization. Despite being a prototypical two-dimensional material, isotropic three-dimensional charge transfer is found in the commensurate charge density wave phase (CCDW), indicating strong coupling between layers. In contrast, anisotropic two-dimensional charge transfer occurs for the nearly commensurate phase (NCDW). In direct comparison, theory shows that interlayer interaction in the CCDW phase - not layer stacking variations - causes isotropic three-dimensional charge transfer. This is presumably a general mechanism for phase transitions and tailored properties of dichalcogenides with charge density waves.
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| 50. |
- Kühn, Danilo, et al.
(författare)
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Capabilities of Angle Resolved Time of Flight electron spectroscopy with the 60 degrees wide angle acceptance lens
- 2018
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier. - 0368-2048 .- 1873-2526. ; 224, s. 45-50
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Tidskriftsartikel (refereegranskat)abstract
- The simultaneous detection of energy, momentum and temporal information in electron spectroscopy is the key aspect to enhance the detection efficiency in order to broaden the range of scientific applications. Employing a novel 60 degrees wide angle acceptance lens system, based on an additional accelerating electron optical element, leads to a significant enhancement in transmission over the previously employed 30 degrees electron lenses. Due to the performance gain, optimized capabilities for time resolved electron spectroscopy and other high transmission applications with pulsed ionizing radiation have been obtained. The energy resolution and transmission have been determined experimentally utilizing BESSY II as a photon source. Four different and complementary lens modes have been characterized. (C) 2017 The Authors. Published by Elsevier B.V.
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