51
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Dell'Angela M, Anniyev T, Beye M, Coffee R, Fohlisch A, Gladh J, Katayama T, Kaya S, Krupin O, LaRue J, Mogelhoj A, Nordlund D, Norskov JK, Oberg H, Ogasawara H, Ostrom H, Pettersson LGM, Schlotter WF, Sellberg JA, Sorgenfrei F, Turner JJ, Wolf M, Wurth W, Nilsson A. Real-Time Observation of Surface Bond Breaking with an X-ray Laser. Science 2013; 339:1302-5. [DOI: 10.1126/science.1231711] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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52
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Kaya S, Schlesinger D, Yamamoto S, Newberg JT, Bluhm H, Ogasawara H, Kendelewicz T, Brown GE, Pettersson LGM, Nilsson A. Highly compressed two-dimensional form of water at ambient conditions. Sci Rep 2013; 3:1074. [PMID: 23323216 PMCID: PMC3545261 DOI: 10.1038/srep01074] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/27/2012] [Indexed: 12/31/2022] Open
Abstract
The structure of thin-film water on a BaF2(111) surface under ambient conditions was studied using x-ray absorption spectroscopy from ambient to supercooled temperatures at relative humidity up to 95%. No hexagonal ice-like structure was observed in spite of the expected templating effect of the lattice-matched (111) surface. The oxygen K-edge x-ray absorption spectrum of liquid thin-film water on BaF2 exhibits, at all temperatures, a strong resemblance to that of high-density phases for which the observed spectroscopic features correlate linearly with the density. Surprisingly, the highly compressed, high-density thin-film liquid water is found to be stable from ambient (300 K) to supercooled (259 K) temperatures, although a lower-density liquid would be expected at supercooled conditions. Molecular dynamics simulations indicate that the first layer water on BaF2(111) is indeed in a unique local structure that resembles high-density water, with a strongly collapsed second coordination shell.
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Schiros T, Nordlund D, Pálová L, Prezzi D, Zhao L, Kim KS, Wurstbauer U, Gutiérrez C, Delongchamp D, Jaye C, Fischer D, Ogasawara H, Pettersson LGM, Reichman DR, Kim P, Hybertsen MS, Pasupathy AN. Connecting dopant bond type with electronic structure in N-doped graphene. NANO LETTERS 2012; 12:4025-31. [PMID: 22746249 DOI: 10.1021/nl301409h] [Citation(s) in RCA: 207] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Robust methods to tune the unique electronic properties of graphene by chemical modification are in great demand due to the potential of the two dimensional material to impact a range of device applications. Here we show that carbon and nitrogen core-level resonant X-ray spectroscopy is a sensitive probe of chemical bonding and electronic structure of chemical dopants introduced in single-sheet graphene films. In conjunction with density functional theory based calculations, we are able to obtain a detailed picture of bond types and electronic structure in graphene doped with nitrogen at the sub-percent level. We show that different N-bond types, including graphitic, pyridinic, and nitrilic, can exist in a single, dilutely N-doped graphene sheet. We show that these various bond types have profoundly different effects on the carrier concentration, indicating that control over the dopant bond type is a crucial requirement in advancing graphene electronics.
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54
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Anniyev T, Kaya S, Rajasekaran S, Ogasawara H, Nordlund D, Nilsson A. Tuning the Metal-Adsorbate Chemical Bond through the Ligand Effect on Platinum Subsurface Alloys. Angew Chem Int Ed Engl 2012; 51:7724-8. [DOI: 10.1002/anie.201201068] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Indexed: 11/06/2022]
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55
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Anniyev T, Kaya S, Rajasekaran S, Ogasawara H, Nordlund D, Nilsson A. Tuning the Metal-Adsorbate Chemical Bond through the Ligand Effect on Platinum Subsurface Alloys. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201201068] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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56
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Friebel D, Viswanathan V, Miller DJ, Anniyev T, Ogasawara H, Larsen AH, O’Grady CP, Nørskov JK, Nilsson A. Balance of Nanostructure and Bimetallic Interactions in Pt Model Fuel Cell Catalysts: In Situ XAS and DFT Study. J Am Chem Soc 2012; 134:9664-71. [DOI: 10.1021/ja3003765] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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57
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Gladh J, Öberg H, Li J, Ljungberg MP, Matsuda A, Ogasawara H, Nilsson A, Pettersson LGM, Öström H. X-ray emission spectroscopy and density functional study of CO/Fe(100). J Chem Phys 2012; 136:034702. [DOI: 10.1063/1.3675834] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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58
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Miller DJ, Öberg H, Kaya S, Sanchez Casalongue H, Friebel D, Anniyev T, Ogasawara H, Bluhm H, Pettersson LGM, Nilsson A. Oxidation of Pt(111) under near-ambient conditions. PHYSICAL REVIEW LETTERS 2011; 107:195502. [PMID: 22181624 DOI: 10.1103/physrevlett.107.195502] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Indexed: 05/31/2023]
Abstract
The oxidation of Pt(111) at near-ambient O2 pressures has been followed in situ using x-ray photoelectron spectroscopy (XPS) and ex situ using x-ray absorption spectroscopy (XAS). Polarization-dependent XAS signatures at the O K edge reveal significant temperature- and pressure-dependent changes of the Pt-O interaction. Oxide growth commences via a PtO-like surface oxide that coexists with chemisorbed oxygen, while an ultrathin α-PtO2 trilayer is identified as the precursor to bulk oxidation. These results have important implications for understanding the chemical state of Pt in catalysis.
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59
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Friebel D, Miller DJ, Nordlund D, Ogasawara H, Nilsson A. Degradation of Bimetallic Model Electrocatalysts: An In Situ X-Ray Absorption Spectroscopy Study. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201101620] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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60
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Friebel D, Miller DJ, Nordlund D, Ogasawara H, Nilsson A. Degradation of Bimetallic Model Electrocatalysts: An In Situ X-Ray Absorption Spectroscopy Study. Angew Chem Int Ed Engl 2011; 50:10190-2. [DOI: 10.1002/anie.201101620] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2011] [Indexed: 11/11/2022]
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61
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Bhowmick R, Rajasekaran S, Friebel D, Beasley C, Jiao L, Ogasawara H, Dai H, Clemens B, Nilsson A. Hydrogen Spillover in Pt-Single-Walled Carbon Nanotube Composites: Formation of Stable C−H Bonds. J Am Chem Soc 2011; 133:5580-6. [DOI: 10.1021/ja200403m] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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62
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Miller DJ, Öberg H, Näslund LÅ, Anniyev T, Ogasawara H, Pettersson LGM, Nilsson A. Low O2 dissociation barrier on Pt(111) due to adsorbate–adsorbate interactions. J Chem Phys 2010; 133:224701. [DOI: 10.1063/1.3512618] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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63
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Friebel D, Miller DJ, O'Grady CP, Anniyev T, Bargar J, Bergmann U, Ogasawara H, Wikfeldt KT, Pettersson LGM, Nilsson A. In situ X-ray probing reveals fingerprints of surface platinum oxide. Phys Chem Chem Phys 2010; 13:262-6. [PMID: 21063617 DOI: 10.1039/c0cp01434f] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In situ X-ray absorption spectroscopy (XAS) at the Pt L(3) edge is a useful probe for Pt-O interactions at polymer electrolyte membrane fuel cell (PEMFC) cathodes. We show that XAS using the high energy resolution fluorescence detection (HERFD) mode, applied to a well-defined monolayer Pt/Rh(111) sample where the bulk penetrating hard X-rays probe only surface Pt atoms, provides a unique sensitivity to structure and chemical bonding at the Pt-electrolyte interface. Ab initio multiple-scattering calculations using the FEFF code and complementary extended X-ray absorption fine structure (EXAFS) results indicate that the commonly observed large increase of the white-line at high electrochemical potentials on PEMFC cathodes originates from platinum oxide formation, whereas previously proposed chemisorbed oxygen-containing species merely give rise to subtle spectral changes.
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64
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Tremblay NJ, Gorodetsky AA, Cox MP, Schiros T, Kim B, Steiner R, Bullard Z, Sattler A, So WY, Itoh Y, Toney MF, Ogasawara H, Ramirez AP, Kymissis I, Steigerwald ML, Nuckolls C. Photovoltaic universal joints: ball-and-socket interfaces in molecular photovoltaic cells. Chemphyschem 2010; 11:799-803. [PMID: 20157914 DOI: 10.1002/cphc.200900941] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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65
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Strasser P, Koh S, Anniyev T, Greeley J, More K, Yu C, Liu Z, Kaya S, Nordlund D, Ogasawara H, Toney MF, Nilsson A. Lattice-strain control of the activity in dealloyed core–shell fuel cell catalysts. Nat Chem 2010; 2:454-60. [DOI: 10.1038/nchem.623] [Citation(s) in RCA: 2189] [Impact Index Per Article: 156.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 03/11/2010] [Indexed: 11/09/2022]
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66
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Tremblay NJ, Gorodetsky AA, Cox MP, Schiros T, Kim B, Steiner R, Bullard Z, Sattler A, So WY, Itoh Y, Toney MF, Ogasawara H, Ramirez AP, Kymissis I, Steigerwald ML, Nuckolls C. Inside Cover: Photovoltaic Universal Joints: Ball-and-Socket Interfaces in Molecular Photovoltaic Cells (ChemPhysChem 4/2010). Chemphyschem 2010. [DOI: 10.1002/cphc.201090016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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67
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Schiros T, Takahashi O, Andersson KJ, Öström H, Pettersson LGM, Nilsson A, Ogasawara H. The role of substrate electrons in the wetting of a metal surface. J Chem Phys 2010; 132:094701. [DOI: 10.1063/1.3292681] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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68
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Anniyev T, Ogasawara H, Ljungberg MP, Wikfeldt KT, MacNaughton JB, Näslund LÅ, Bergmann U, Koh S, Strasser P, Pettersson LG, Nilsson A. Complementarity between high-energy photoelectron and L-edge spectroscopy for probing the electronic structure of 5d transition metal catalysts. Phys Chem Chem Phys 2010; 12:5694-700. [DOI: 10.1039/b926414k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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69
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MacNaughton JB, Näslund LÅ, Anniyev T, Ogasawara H, Nilsson A. Peroxide-like intermediate observed at hydrogen rich condition on Pt(111) after interaction with oxygen. Phys Chem Chem Phys 2010; 12:5712-6. [DOI: 10.1039/b926409b] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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70
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Ogasawara H, Kageyama M, Yamaji K, Takasaki Y. The possibility that autoimmune disease can be induced by a molecular mimicry mechanism between autoantigen and human endogenous retrovirus. Lupus 2009; 19:111-3. [PMID: 19884218 DOI: 10.1177/0961203309106767] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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71
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Tatarkhanov M, Fomin E, Salmeron M, Andersson K, Ogasawara H, Pettersson LGM, Nilsson A, Cerdá JI. The structure of mixed H2O-OH monolayer films on Ru(0001). J Chem Phys 2009; 129:154109. [PMID: 19045178 DOI: 10.1063/1.2988903] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Scanning tunneling microscopy (STM) and x-ray absorption spectroscopy (XAS) have been used to study the structures produced by water on Ru(0001) at temperatures above 140 K. It was found that while undissociated water layers are metastable below 140 K, heating above this temperature produces drastic transformations, whereby a fraction of the water molecules partially dissociate and form mixed H(2)O-OH structures. X-ray photoelectron spectroscopy and XAS revealed the presence of hydroxyl groups with their O-H bond essentially parallel to the surface. STM images show that the mixed H(2)O-OH structures consist of long narrow stripes aligned with the three crystallographic directions perpendicular to the close-packed atomic rows of the Ru(0001) substrate. The internal structure of the stripes is a honeycomb network of H-bonded water and hydroxyl species. We found that the metastable low temperature molecular phase can also be converted to a mixed H(2)O-OH phase through excitation by the tunneling electrons when their energy is 0.5 eV or higher above the Fermi level. Structural models based on the STM images were used for density functional theory optimizations of the stripe geometry. The optimized geometry was then utilized to calculate STM images for comparison with the experiment.
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72
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Nagai Y, Ogasawara H, Taketa Y, Aso H, Tanaka S, Kanaya T, Watanabe K, Ohwada S, Muneta Y, Yamaguchi T. Bovine anterior pituitary progenitor cell line expresses interleukin (IL)-18 and IL-18 receptor. J Neuroendocrinol 2008; 20:1233-41. [PMID: 18761716 DOI: 10.1111/j.1365-2826.2008.01779.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In the anterior pituitary gland, inflammatory mediators regulate cell function through an immuno-endocrine pathway. Recent studies have shown that undifferentiated stem cells act as immunomodulators. These studies prompted us to establish a progenitor cell line from the bovine anterior pituitary gland and to detail its function. First, we localised interleukin (IL)-18 by immunohistochemistry to the marginal cell layer of Rathke's pouch that is assumed to embody a stem/progenitor cell compartment of the postnatal pituitary gland. A cloned anterior pituitary-derived cell line from the bovine anterior pituitary gland was established from single cell clone by the limiting dilution method and was designated as bovine anterior pituitary-derived cell line (BAPC)-1. BAPC-1 cells constantly expressed mRNAs for IL-18 and IL-18 receptor, and grew steadily and rapidly in the medium containing epidermal growth factor and basic fibroblast growth factor. The cell line also expressed the mRNAs for the stem/progenitor cell- related factors such as Nanog, Oct-4, Ptch1, Nestin, Notch1, Hes1, Lrp and Fzd4, and the mRNAs for embryonic pituitary-related factors, such as Lhx3, PitX1 and Pit-1. The nuclei of BAPC-1 were immunostained positively for Pit-1, Hes1 and beta-catenin antibodies. Furthermore, BAPC-1 cells expressed mRNAs for cytokine such as IL-1alpha, IL-6, IL-7, IL-12 and IL-15. Stimulation of BAPC-1 cells with IL-18 increased expression of mRNAs for IL-1alpha, IL-6, IL-1beta and IL-8. At day 6 in culture, BAPC-1 cells also express growth hormone mRNA. These results strongly suggest that BAPC-1 is a stem/progenitor cell line and modulates the immuno-endocrine function of the anterior pituitary cells through its cytokine production.
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73
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Nordlund D, Odelius M, Bluhm H, Ogasawara H, Pettersson L, Nilsson A. Electronic structure effects in liquid water studied by photoelectron spectroscopy and density functional theory. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.04.096] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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74
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Andersson K, Ketteler G, Bluhm H, Yamamoto S, Ogasawara H, Pettersson LGM, Salmeron M, Nilsson A. Autocatalytic Water Dissociation on Cu(110) at Near Ambient Conditions. J Am Chem Soc 2008; 130:2793-7. [DOI: 10.1021/ja073727x] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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75
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Nikitin A, Li X, Zhang Z, Ogasawara H, Dai H, Nilsson A. Hydrogen storage in carbon nanotubes through the formation of stable C-H bonds. NANO LETTERS 2008; 8:162-167. [PMID: 18088150 DOI: 10.1021/nl072325k] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
To determine if carbon-based materials can be used for hydrogen storage, we have studied hydrogen chemisorption in single-walled carbon nanotubes. Using atomic hydrogen as the hydrogenation agent, we demonstrated that maximal degree of nanotube hydrogenation depends on the nanotube diameter, and for the diameter values around 2.0 nm nanotube-hydrogen complexes with close to 100% hydrogenation exist and are stable at room temperature. This means that specific carbon nanotubes can have a hydrogen storage capacity of more than 7 wt % through the formation of reversible C-H bonds.
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