| 1. |
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| 2. |
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| 3. |
- Rohringer, N., et al.
(författare)
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Stimulated X-Ray Raman Scattering with Free-Electron Laser Sources
- 2016
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Ingår i: X-Ray Lasers 2014. - Cham : Springer. - 0930-8989. - 9783319195216 - 9783319195209 ; , s. 201-207
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Bokkapitel (refereegranskat)abstract
- Stimulated electronic x-ray Raman scattering is the building block for several proposed x-ray pump probe techniques, that would allow the study of electron dynamics at unprecedented timescales.We present high spectral resolution data on stimulated electronic x-ray Raman scattering in a gas sample of neon using a self-amplified spontaneous emission x-ray free-electron laser. Despite the limited spectral coherence and broad bandwidth of these sources, high-resolution spectra can be obtained by statistical methods, opening the path to coherent stimulated x-ray Raman spectroscopy. An extension of these ideas to molecules and the results of a recent experiment in CO are discussed.
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| 4. |
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| 5. |
- Bergqvist, Jenny, et al.
(författare)
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Quantitative real-time PCR analysis and microarray-based RNA expression of HER2 in relation to outcome
- 2007
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Ingår i: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 18:5, s. 845-850
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Our aim was to use quantitative real-time PCR (Q-PCR) and RNA expression profiles (RNA-EPs) to investigate HER2 status in relation to outcome. PATIENTS AND METHODS: Cut-off levels for Q-PCR and RNA-EP were established in relation to immunohistochemistry (IHC) validated by FISH in a test set of frozen tissue samples from 40 primary breast cancers. The HER2 status was subsequently studied in another validation set of 306 tumors, where Q-PCR and RNA-EP results were compared with previously carried out IHC that we had validated by chromogenic in situ hybridization (CISH). RESULTS: Q-PCR and RNA-EP offered similar sensitivity (90% versus 77%), specificity (93% versus 95%), and negative (99% versus 98%) and positive (63% versus 61%) predictive values for HER2 determinations. Analyses of relapse-free survival (RFS) and overall survival on the basis of 5 and 10 years of follow-up indicated equivalent hazard ratios for all three techniques. In contrast to IHC/CISH, both Q-PCR and RNA-EP analyses of HER2 also gave statistically significant results regarding RFS and breast cancer-corrected survival after 10 years of follow-up. CONCLUSION: The use of RNA-EP and Q-PCR to analyze HER2 in frozen and formalin-fixed breast cancer samples may be an alternate approach to IHC in combination with FISH/CISH.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Söderström, J., et al.
(författare)
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X-ray yield and selectively excited X-ray emission spectra of atenolol and nadolol
- 2005
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 144, s. 283-285
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Tidskriftsartikel (refereegranskat)abstract
- A pre-study in a project aimed at increasing the understanding of drug solubility by applying X-ray spectroscopy to substances in solid phases, in aqueous solution, and in gas-phase is presented. Influence of the molecular surrounding on the local electronic structure is reflected in X-ray yield fine structure, and in site-selectively excited X-ray emission spectra. Results for atenolol and nadolol in solid form are discussed.
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| 13. |
- de Graaf, M., et al.
(författare)
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Emergence of a novel GII.17 norovirus - End of the GII.4 era?
- 2015
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Ingår i: Eurosurveillance. - : EUR CENTRE DIS PREVENTION and CONTROL. - 1025-496X .- 1560-7917. ; 20:26, s. 21178-
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Tidskriftsartikel (refereegranskat)abstract
- In the winter of 2014/15 a novel GII.P17-GII.17 norovirus strain (GII.17 Kawasaki 2014) emerged, as a major cause of gastroenteritis outbreaks in China and Japan. Since their emergence these novel GII.P17-GII.17 viruses have replaced the previously dominant GII.4 genotype Sydney 2012 variant in some areas in Asia but were only detected in a limited number of cases on other continents. This perspective provides an overview of the available information on GII.17 viruses in order to gain insight in the viral and host characteristics of this norovirus genotype. We further discuss the emergence of this novel GII.P17-GII.17 norovirus in context of current knowledge on the epidemiology of noroviruses. It remains to be seen if the currently dominant norovirus strain GII.4 Sydney 2012 will be replaced in other parts of the world. Nevertheless, the public health community and surveillance systems need to be prepared in case of a potential increase of norovirus activity in the next seasons caused by this novel GII.P17-GII.17 norovirus.
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| 14. |
- Guo, J. -H, et al.
(författare)
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Electronic structure study of the bases in DNA duplexes by in situ photon-in/photon-out soft X-ray spectroscopy
- 2010
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 181:2-3, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- Understanding protein functionality is of fundamental importance in biochemistry. Soft X-ray transitions, where the core-level vacancies are filled by the valence-orbital electrons, give direct information about the chemical bonding. Soft X-ray absorption and emission study of poly(dG) -poly(dC) in aqueous solutions can elucidate the relation between the structure and functionality of proteins. We report the N K-edge soft X-ray absorption (XAS) and resonant soft X-ray emission spectroscopy (XES) to characterize the electronic structure near the Fermi level of DNA duplexes to specify the charge migration mechanism. Since N atoms are included in only bases in DNA duplexes, the XES spectra excited from N Is to unoccupied states purely extract the electronic orbital features of the bases in DNA. The fact that N atoms in different bonding environments form well-defined structure has been determined. The experimental findings provide the evidence for the charge-hopping and/or charge-transfer effects in understanding of electric conduction in DNA duplexes when electrons pass through the pi* states of DNA bases.
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| 15. |
- Käämbre, T, et al.
(författare)
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Study of oxygen-C compound formation by NEXAFS and RIXS
- 2001
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Ingår i: The European Physical Journal D. ; 16:1-3, s. 357-360
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Tidskriftsartikel (refereegranskat)abstract
- The interaction of oxygen with C60 molecules was studied on a C60 film which had been exposed simultaneously to oxygen and UV-light for 190 hours, producing an approximately C60O1 stoichiometry in the bulk of the sample. C K-edge and O K-edge NEXAFS (using total fluorescence yield detection) and resonant X-ray inelastic scattering (RIXS) spectra from the sample film were measured and the C K-edge data were compared to the spectra from pristine C60 as reference. The C K-edge absorption and emission spectral profiles of the oxygen-doped sample are similar to those of the C60 reference, suggesting that cage breaking of C60 under these conditions, if any, is negligible. However, the redistribution of intensities in the spectra indicates changes in the occupancies of different molecular orbitals, possibly due to changes in electron density upon reaction. Similarities of the O K-edge soft X-ray emission (SXES) spectra to several small oxygen-containing molecules is being discussed in terms of bonding models.
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| 16. |
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| 17. |
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| 18. |
- Modin, A., et al.
(författare)
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Closed source experimental system for soft x-ray spectroscopy of radioactive materials
- 2008
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Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 79:9, s. 093103-
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Tidskriftsartikel (refereegranskat)abstract
- An instrumental and experimental setup for soft x-ray spectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample, mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO2 confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.
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| 19. |
- Nilsson, P. O., et al.
(författare)
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Electronic structure of buried Si layers in GaAs(001) as studied by soft-x-ray emission
- 1995
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 52, s. R8643-
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Tidskriftsartikel (refereegranskat)abstract
- It is demonstrated that it is possible to investigate details of the electronic structure of an internal atomic monolayer using soft-x-ray-emission spectroscopy. The local and partial density of states of one monolayer and three monolayers of Si, embedded deep below a GaAs(001) surface, was extracted. Clear differences to the density of states for bulk Si were observed.
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| 20. |
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| 21. |
- Agui, A., et al.
(författare)
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Direct observation of interface effects of thin AlAs(100) layers buried in GaAs
- 2000
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Ingår i: Applied Surface Science. - : Elsevier. - 0169-4332 .- 1873-5584. ; 166:1-4, s. 309-312
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Tidskriftsartikel (refereegranskat)abstract
- A study of the electronic structure of ultrathin AlAs layers buried in GaAs(100) and their interfaces is presented. Al L2,3 soft-X-ray-emission (SXE) spectra from the AlAs layers were measured. The spectra show distinct thickness-dependent features, which are reproduced using ab initio calculations.
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| 22. |
- Agåker, Marcus, et al.
(författare)
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Novel instruments for ultra-soft X-ray emission spectroscopy
- 2009
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 601:1-2, s. 213-219
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Tidskriftsartikel (refereegranskat)abstract
- Two alternative instrument designs to the traditional Rowland grating spectrometer for high resolution ultra-soft X-ray spectroscopy are presented. The first instrument is a plane grating spectrometer using off-axis parabolic mirrors for collection and refocusing, and with a spatially resolving multichannel detector with delay line read-out. The instrument offers substantially higher performance in terms of resolution and sensitivity than traditional instruments. The second instrument is a Fourier transform spectrometer based on a grazing incidence Mach-Zehnder interferometer using wavefront dividing beamsplitters. The path length difference can be scanned over 0.1 mm, which corresponds to a resolution of 12 meV. (C) 2009 Elsevier B.V. All rights reserved.
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| 23. |
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| 24. |
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| 25. |
- Bolte, S., et al.
(författare)
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The Roots of Autism and ADHD Twin Study in Sweden (RATSS)
- 2014
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Ingår i: Twin Research and Human Genetics. - Stockholm : Cambridge University Press (CUP). - 1832-4274 .- 1839-2628. ; 17:3, s. 164-176
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Tidskriftsartikel (refereegranskat)abstract
- Neurodevelopmental disorders affect a substantial minority of the general population. Their origins are still largely unknown, but a complex interplay of genetic and environmental factors causing disturbances of the central nervous system's maturation and a variety of higher cognitive skills is presumed. Only limited research of rather small sample size and narrow scope has been conducted in neurodevelopmental disorders using a twin-differences design. The Roots of Autism and ADHD Twin Study in Sweden (RATSS) is an ongoing project targeting monozygotic twins discordant for categorical or dimensional autistic and inattentive/hyperactive-impulsive phenotypes as well as other neurodevelopmental disorders, and typically developing twin controls. Included pairs are 9 years of age or older, and comprehensively assessed for psychopathology, medical history, neuropsychology, and dysmorphology, as well as structural, functional, and molecular brain imaging. Specimens are collected for induced pluripotent (iPS) and neuroepithelial stem cells, genetic, gut bacteria, protein-/monoamine, and electron microscopy analyses. RATSS's objective is to generate a launch pad for novel surveys to understand the complexity of genotype-environment-phenotype interactions in autism spectrum disorder and attention-deficit hyperactivity disorder (ADHD). By October 2013, RATSS had collected data from 55 twin pairs, among them 10 monozygotic pairs discordant for autism spectrum disorder, seven for ADHD, and four for other neurodevelopmental disorders. This article describes the design, recruitment, data collection, measures, collected pairs' characteristics, as well as ongoing and planned analyses in RATSS. Potential gains of the study comprise the identification of environmentally mediated biomarkers, the emergence of candidates for drug development, translational modeling, and new leads for prevention of incapacitating outcomes.
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| 26. |
- Butorin, S.M, et al.
(författare)
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Tunable excitation x-ray-fluorescence spectroscopy in phase-analysis of high-Tc superconductors
- 1994
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Ingår i: Journal of physics-condensed matter. - 0953-8984. ; 6:43, s. 9267-9274
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Tidskriftsartikel (refereegranskat)abstract
- O Kalpha x-ray fluorescence of YBa2Cu3O7-delta and Sr0.85Nd0.15CuO2 samples containing CO3(2-) impurities, as well as pure BaCO3, have been studied using tunable monochromatic synchrotron radiation excitation. When the excitation energy is set to the most intense features in the O 1s absorption edge of cuprates and to bound states above this edge the O Kalpha spectra recorded are very similar to those of pure BaCO3 even if the admixture of CO3(2-) is small. The observed changes in the O Kalpha profiles of multi-phase YBa2Cu3O7-delta and Sr0.85Nd0.15CuO2 samples are discussed in terms of different x-ray absorption cross sections for O in the main phase and in the CO3(2-) fraction.
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| 27. |
- 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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| 28. |
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| 29. |
- Guo, J.-H., et al.
(författare)
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How the phenyle rings (benzene) act as building blocks in pi conjugated polymers
- 1998
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Ingår i: Advanced Light Source. - Berkeley : Ernest Orlando Lawrence Berkeley National Laboratory, University of California Berkeley, California, USA. ; , s. 129-132
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Organic conjugated polymers have the electronic structure of semiconductors and can be doped to become good conductors (1). Conjugated polymers are now used as active materials in a wide variety of prototype applications such as light emitting diodes [2] and organic transistors [3,4]. Most of the interesting chemistry and physics of conjugated polymers is associated with the details of the electronic structure at the valence and conduction band edges and, in this connection, various electron spectroscopies can be used as tools for diagnosis of the relevant electronic and geometric properties....
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| 30. |
- Guo, J.-H., et al.
(författare)
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Molecular structure of alcohol-water mixtures
- 2003
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 91:15
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Tidskriftsartikel (refereegranskat)abstract
- We use x-ray emission spectroscopy to elucidate the molecular structure of liquid methanol, water, and methanol-water solutions. We find that molecules in the pure liquid methanol predominantly persist as hydrogen-bonded chains and rings with six and/or eight molecules of equal abundance. For water-methanol solutions we find evidence of incomplete mixing at the microscopic level. Our results provide a new explanation for a smaller entropy increase in the solution due to water molecules bridging methanol chains to form rings.
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| 31. |
- Guo, J.-H., et al.
(författare)
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Resonant and nonresonant x-ray scattering spectra of some poly(phenylenevinylene)s
- 1998
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 108:14, s. 5990-5996
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of some poly(phenylenevinylene)s have been investigated by resonant and nonresonant x-ray inelastic scattering spectroscopies. The nonresonant as well as all resonant spectra for each polymer demonstrate benzene-like features, indicating a local character of the x-ray emission in which the phenyl ring acts as a building block. Theoretical simulations of x-ray energies and intensities taking the repeat unit as a model molecule of the polymer agree with the experimental spectra fairly well. The edges of the occupied bands have been identified in the nonresonant spectra of each polymer. By subtracting the emission energy of the highest occupied molecular orbital in the nonresonant spectrum from the core excitation energy in the resonant spectrum an alternative way to determine the optical band gap is obtained. As for free benzene the outer π band in the polymer spectra show a depletion of the emission going from the nonresonant to the resonant x-ray emission spectra. It is demonstrated that this transition, which is strictly symmetry forbidden for free benzene, becomes effectively forbidden in the polymer case as a result of strong interference effects, and it is argued that this is the general case for resonant x-ray emission of conjugated polymers as far as the frozen orbital approximation holds.
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| 32. |
- Guo, J.H., et al.
(författare)
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Resonant excitation x-ray-fluorescence from C-60
- 1995
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 52, s. 10681-
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Tidskriftsartikel (refereegranskat)abstract
- X-ray fluorescence of condensed C-60 has been recorded in high resolution using monochromatic synchrotron radiation excitation. Strong intensity modulation of constituent spectral features is observed with varying excitation energy up to 10 eV above threshold. The energy dependence is interpreted as due to resonant inelastic x-ray scattering, leading to symmetry selection rules governing the two-photon process in the fully symmetric molecule.
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| 33. |
- Guo, J. H., et al.
(författare)
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X-ray emission spectroscopy of hydrogen bonding and electronic structure of liquid water
- 2002
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 89:13
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Tidskriftsartikel (refereegranskat)abstract
- We use x-ray emission spectroscopy to examine the influence of the intermolecular interaction on the local electronic structure of liquid water. By comparing x-ray emission spectra of the water molecule and liquid water, we find a strong involvement of the a(1)-symmetry valence-orbital in the hydrogen bonding. The local electronic structure of water molecules, where one hydrogen bond is broken at the hydrogen site, is separately determined. Our results provide an illustration of the important potential of x-ray emission spectroscopy for elucidating basic features of liquids.
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Hellgren, N., et al.
(författare)
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Nitrogen bonding structure in carbon nitride thin films studied by soft x-ray spectroscopy
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:26, s. 4348-4350
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray absorption (SXAS) and emission (SXES) spectroscopies were applied to study the nitrogen bonding structure in magnetron sputtered CNx thin films. By comparing with calculated spectra of N in different model systems, N in three main bonding environments can be identified: (i) C equivalent toN bonds, with a sharp SXAS peak at 399.5 eV, (ii) pyridine-like N (i.e., N bonded to two C atoms), with an x-ray absorption resonance at similar to 398.5 eV, and (iii) N substituted in graphite, possibly with one sp(3) carbon as a neighbor (SXAS energy similar to 401 eV). These bondings are present in all CNx films analyzed; however, as shown earlier, the relative intensities between the peaks may vary with the growth conditions. Differences in the coordination of the nearest or second nearest C neighbors only cause slight changes in the peak positions and spectrum shape.
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| 38. |
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| 39. |
- Kashtanov, Stepan, et al.
(författare)
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Local structures of liquid water studied by x-ray emission spectroscopy
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 69:2
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Tidskriftsartikel (refereegranskat)abstract
- The O Kalpha x-ray emission spectra of water clusters with different sizes and conformations embedded in a continuum medium are simulated. The calculations have successfully explained the experimental spectra of water in both gas and liquid phases. It is shown that the x-ray emission spectra are very sensitive to the local hydrogen bonding structures. Strong electron sharing between different water molecules is observed and its possible connection to the covalency of hydrogen bonding is discussed. The experimentally observed strong excitation energy dependence of the spectra has been interpreted in terms of the polarization and angular dependence for the gas phase, and in terms of variations of local hydrogen bonding structures for the liquid phase.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Mankefors, S., et al.
(författare)
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Theoretical investigation of the thickness dependence of soft-x-ray emission from thin AlAs(100) layers buried in GaAs
- 2000
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Ingår i: Physical Review B Condensed Matter. - : American Physical Society. - 0163-1829 .- 1095-3795. ; 61:8, s. 5540-5545
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Tidskriftsartikel (refereegranskat)abstract
- Ultrathin AlAs(100) layers of 1-, 2-, and 5-ML thickness buried in GaAs are investigated by ab initio calculations. Unique experimental soft-x-ray emission spectra are explained in terms of interface effects and changes with layer thickness are found in the density of states. Only the central layer in the 5-ML geometry is bulklike. A valence-band offset of 0.53 eV is also found for this structure, while no offset exists in the 1- and 2-ML cases. Very good agreement is achieved between theory and experiment.
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| 44. |
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| 45. |
- Nyberg, M., et al.
(författare)
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Bond formation in titanium fulleride compounds studied through x-ray emission spectroscopy
- 2001
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 63:11, s. art. no.-115117
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Tidskriftsartikel (refereegranskat)abstract
- The geometric and electronic structures of titanium fulleride complexes have been studied at the gradient corrected density-functional theory level by using various C60Tix (x=1,2) clusters. The cluster with the Ti atom binding on the six-ring site (eta (6)) Of the fullerene is shown to be lower in energy than those with Ti atom adsorbed on either five-ring (eta (5)) Or bridge(eta (2)) sites. The bond formation for titanium fulleride has further been examined by calculated nonresonant, resonant, and off-resonant . x-ray emission spectra of the clusters, and a comparison to the experimental counterpart. The examination shows that only the theoretical spectra of clusters with a six-ring adsorption site are in close agreement with the experimental x-ray emission spectra of titanium fulleride films. Our results indicate that off-resonant x-ray emission spectra provide an excellent basis for the probing of the bonding between metals and organic molecules.
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Rubensson, J. E., et al.
(författare)
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Resonant behavior in soft x-ray fluorescence excited by monochromatized synchrotron radiation
- 1988
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Ingår i: Physical Review Letters. - 0031-9007. ; 60:17, s. 1759-1762
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Tidskriftsartikel (refereegranskat)abstract
- Soft x-ray emission spectra of TiN, excited by monochromatized synchrotron radiation, have been recorded in a grazing-incidence spectrometer. The tunability of the excitation energy has allowed the pure N K and Ti LIII emission spectra to be isolated for the first time. A new type of resonance is observed in the Ti L emission spectrum, and interpreted as due to the decay of a quasiatomic intermediate state. The results call for a reinterpretation of Ti L spectra and a revision of the interpretation of 3d-metal L-emission spectra in general.
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| 50. |
- Schiessling, J, et al.
(författare)
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Bulk and surface charge states of K3C60
- 2005
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Ingår i: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 71:16
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Tidskriftsartikel (refereegranskat)abstract
- We detect a significant angle-dependence in the core level and valence line shapes of photoelectron spectra of single crystal K3C60. This allows the identification of bulk and surface components in the data, and allows us to explain the anomalous line shapes observed for this system. The states near the Fermi level are associated with the bulk of the sample. There is strong evidence of an insulating surface layer, which we ascribe to intermolecular electron correlations. These results simplify the interpretation of previous, apparently conflicting observations.
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