High resolution soft X-ray bending magnet beamline 9.3.2 with circularly polarized radiation capability at the Advanced Light Source

Hussain, Zahid; Huff, W.R.A.; Kellar, S. A.; Moler, Edward J.; Heimann, P. A.; McKinney, Wayne R.; Padmore, H. A.; Fadley, C. S.; Shirley, D. A.

doi:10.1016/0368-2048(96)03002-2

Cited by 60 publications

(33 citation statements)

References 3 publications

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“…The experiments were performed at beamline U49/2-PGM1 at BESSY in Berlin [21], and at beamline 9.3.2 at the Advanced Light Source in Berkeley [22]. The overall spectral resolution was 0.1 eV at the Oxygen K-edge.…”

Section: Methodsmentioning

confidence: 99%

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Bluhm¹,

Hävecker²,

et al. 2004

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The surface and near-surface region of an active catalyst and the adjacent gas-phase reactants were investigated simultaneously under reaction conditions using in situ X-ray photoelectron spectroscopy (XPS). This investigation of methanol oxidation on a copper catalyst showed that there was a linear correlation between the catalytic activity of the sample and the presence of a sub-surface oxygen species that can only be observed in situ. The concentration profile of the sub-surface oxygen species within the first few nanometers below the surface was determined using photon energy-dependent depth-profiling. The chemical composition of the surface and the near-surface region varied strongly with the oxygen-tomethanol ratio in the reactant stream. The experiments show that the pure metal is not an active catalyst for the methanol oxidation reaction, but that a certain amount of oxygen has to be present in the sub-surface region to activate the catalytic reaction. Oxide formation was found to be detrimental to formaldehyde production. Our results demonstrate also that for an understanding of heterogeneous catalysts a characterization of the surface alone may not be sufficient, and that sub-surface characterization is essential.

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Section: Methodsmentioning

confidence: 99%

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Bluhm¹,

Hävecker²,

et al. 2004

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“…The AP-XPS measurements are carried out at soft-ray beamline BL13 at Photon-Factory of High Energy Accelerator Research Organization (KEK-PF) in Tsukuba, Japan [11] and BL9.3.2 at Advanced Light Source of Lawrence Berkeley National Laboratory, USA [12]. The details of AP-XPS endstations on both synchrotron radiation facilities can be found elsewhere [13].…”

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confidence: 99%

Surface segregation and oxidation of Pt3Ni(1 1 1) alloys under oxygen environment

et al. 2016

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a b s t r a c tUtilizing ambient pressure X-ray photoelectron spectroscopy (AP-XPS), the surface segregation and oxidation of Pt 3 Ni(1 1 1) alloys are investigated as a function of temperature and oxygen pressure. The in situ AP-XPS measurements of oxygen oxidation process show that the Pt "skin" surface is not stable under the exposure of oxygen pressure of 100 mTorr at room temperature. As the temperature and pressure are elevated, the formations of Ni 2 O 3 , NiO x , and NiO are observed on surface while Pt atom starts to reduce its adsorbed oxygen, which is a clear sign of surface segregation of Ni to surface. Upon the evacuation of oxygen gas, i.e. ultrahigh vacuum condition, both of NiO x and NiO oxide get reduced and Ni 2 O 3 remains on the surface. The DFT calculation is employed to explain the formation of surface oxides under oxidation condition.

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“…The sample had a well defined uniaxial magnetic anisotropy with the easy axis in the plane of the sample. X-ray Photoemission Spectroscopy (XPS) and X-ray Magnetic Circular Dichroism (XMCD) analysis of the sample was performed on beam line 9.3.2 at the Advanced Light Source Synchrotron [12]. Right and left circular polarization was obtained by selecting the part of the synchrotron radiation emitted from a bending magnet above or below the electron orbit plane, moving vertically a slit set at the front end of the beam line.…”

Section: Methodsmentioning

confidence: 99%

Understanding the magnetic anisotropy in Fe-Si amorphous alloys

et al. 2002

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transition metal. 3d electrons in transition metals have a much weaker spin-orbit interaction compared to the Rare Earths, and they interact more strongly with the crystal field which makes their orbital moments smaller so that their magnetism is dominated by the exchange interaction. In Transition MetalMetalloid (TM-M) alloys, the Metalloid (Si, B, P..) is introduced to amorphisize the TM structure. The exchange interaction is believed to still dominate in these compounds [2]. Their ferromagnetic correlation length is longer than in the RE-TM alloys, which also implies that their spatial spinspin correlation function decays more slowly. These materials have a quasi long range magnetic order and, also due to the dominant exchange interaction, they behave as very soft ferromagnets, i.e., their coercivity and anisotropy energy are very small. The TM-M alloys prepared in the form of thin films usually have a well defined easy axis that can not come about from the pure exchange interaction which is isotropic. The anisotropy of the films should come from either the spinorbit interaction, responsible of the magneto-crystalline anisotropy at each site, or from magnetic dipolar interactions [2]. The last one can be originated at an atomic level due to structural anisotropies, or on a microscopic scale, due to defects and inhomogeneities. Identifying the factors that cause the anisotropy in these films is important from a practical point of view because it allows the control of their magnetic characteristics.Abstract-The origin of the magnetic anisotropy in a very disordered Fe-Si alloy has been investigated. The alloy containing 40% at. Si was prepared in the form of a thin film in a DC magnetron sputtering chamber. Structural disorder was obtained from Extended X-ray Absorption Fine Structure spectroscopy. The uniformity and lack of inhomogeneities at a microscopic level was checked by measuring their transverse magnetic susceptibility and hysteresis loops. The orbital component of the magnetic moment was measured by X-ray Magnetic Circular Dichroism spectroscopy. The orbital moment was extraordinary high, 0.4µ B . Such a high value contrasted with the relatively small uniaxial anisotropy energy of the thin film (2kJ/m 3 ). This suggests that the cause of the magnetic anisotropy in this alloy was a small degree of correlation in the orientation of the local orbital moments along a preferential direction.

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High resolution soft X-ray bending magnet beamline 9.3.2 with circularly polarized radiation capability at the Advanced Light Source

Cited by 60 publications

References 3 publications

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Methanol Oxidation on a Copper Catalyst Investigated Using in Situ X-ray Photoelectron Spectroscopy

Surface segregation and oxidation of Pt3Ni(1 1 1) alloys under oxygen environment

Understanding the magnetic anisotropy in Fe-Si amorphous alloys

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