First commissioning results for the elliptically polarizing undulator beamline at the Advanced Light Source

Young, A. T.; Feng, Jun; Arenholz, Elke; Padmore, H. A.; Henderson, T. F.; Marks, S.; Hoyer, E.; Schlueter, R.; Kortright, J. B.; Мартынов, В. В.; Steier, C.; Portmann, G.

doi:10.1016/s0168-9002(01)00409-0

Cited by 40 publications

(18 citation statements)

References 8 publications

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“…Examples include conductive polymers for organic electronics and structural anisotropy in membrane materials for gas separation. Beamline 4.0.2 is optimized for magnetic spectroscopy 32 and provides a high flux of nearly 10 12 photons/second. It is equipped with an Apple-II Elliptical Polarizing undulator 33 for various X-ray polarizations including linear s and p and provides a free beam port that can accommodate mobile user instruments such as the UHV scattering chamber developed and operated by J.…”

Section: Discussionmentioning

confidence: 99%

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

et al. 2011

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We present a technique to study depth profiles of molecular orientation in soft matter thin films with nanometer resolution. The method is based on dichroism in resonant soft X-ray reflectivity using linear s-and p-polarization. It combines the chemical sensitivity of Near-Edge X-ray Absorption Fine Structure spectroscopy to specific molecular bonds and their orientation relative to the polarization of the incident beam with the precise depth profiling capability of X-ray reflectivity. We demonstrate these capabilities on side chain liquid crystalline polymer thin films with soft X-ray reflectivity data at the carbon K edge. Optical constants of the anisotropic refractive index ellipsoid were obtained from a quantitative analysis using the Berreman formalism. For films up to 50 nm thickness we find that the degree of orientation of the long axis exhibits no depth variation and is independent of the film thickness.

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Section: Discussionmentioning

confidence: 99%

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

et al. 2011

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“…The experiment was performed at Bl 4.0 [10] of the Advanced Light Source using the COLTRIMS technique (Cold Target Recoil Ion Momentum Spectroscopy) [11]. The photon beam intersected a supersonic molecular gas jet.…”

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confidence: 99%

“…polarization vector of the linearly polarized light was rotated in steps of 10 deg from parallel to perpendicular to the spectrometer axis [10] has been performed. By this rotation of the polarization vector we collected a data set which covers all directions of the molecular axis and the Auger electron with respect to the polarization and to each other.…”

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confidence: 99%

Auger Electron Emission from Fixed-in-Space CO

et al. 2003

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We have measured the angular distribution of Carbon K-Auger electrons from fixed in space, core-ionized, CO molecules in coincidence with the kinetic energy release of the C + and O + fragments . We find a very narrow ejection of Auger electrons in the direction of the oxygen and an oscillatory diffraction pattern. Even for similar electron energies, the angular distribution strongly depends on the symmetry of the final state. Our results do not support an earlier study (Guillemin et al [1]) which claimed observation of a breakdown of the two-step model of Auger and photoelectron emission.The study of Auger decay from molecules still pursues many open questions. One of the challenges results from the number and complexity of the final states. The many very broad overlapping structures in the Auger energy distribution often do not allow for a clear assignment of the decay channel [2]. A second challenge results from the interaction of the Auger electron with the molecular potential. Similar to photoelectrons [3,4] the Auger electron will be multiply scattered in the molecule hence modifying Auger rates and angular distributions. A third challenge was posed recently by the claim [1] that even off-resonance the creation of a core hole by photo-ionization and its subsequent Auger decay cannot be treated as two independent steps (two-step model), as has been commonly assumed [3,5].In the present letter we address these three challenges by reporting an experiment on the Auger decay of carbon K-shell ionized CO + . We have measured the Auger electron energy and angle in coincidence with the energy and angle of both fragment ions of the CO 2+ . Such complete monitoring of the process results in a qualitatively new level of insight into the molecular Auger decay. First the high resolution in electron energy and kinetic energy release (KER) allows determination of the final electronic states of the C + and O + fragments which in turn helps to identify the molecular decay channel. Second and more importantly, the measurement of the direction of fragmentation often, a posteriori, determines the molecular axis at the instant of Auger emission. We therefore obtain Auger electron angular distributions in * Electronic address: doerner@hsb.uni-frankfurt.de the molecular frame. These have, as we show below, a very rich structure. It has been emphasized from the theory side that the angular distributions from fixed in space molecules are a key to deeper understanding of the molecular Auger process [3,7,8]. Zähringer et al. have shown that the Auger electron angular distribution can be understood as resulting from two processes acting together. The symmetry of the molecular states involved and their nonspherical electron density lead to a coarse structure. On top of this a diffraction pattern from the interaction of the Auger electron wave with the molecular potential has been seen in the calculations. None of these effects have been observed experimentally until now [1,9].The experiment was performed at Bl 4.0 [10] of the Advanc...

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“…Near edge X-ray absorption fine structure (NEXAFS) spectroscopy measurements at Ce M 4,5 and C K absorption edges on weathered CePO 4 ÁH 2 O samples in the absence or presence of catechol and dissolved oxygen were conducted on beamline 4.0.2 at the Advanced Light Source, Lawrence Berkeley National Laboratory (Young et al, 2001). The spectroscopic data were obtained by scanning the X-ray energy through the Ce M 4,5 edges with an approximate energy resolution of 0.2 eV and measuring the absorption signal through the total electron yield (TEY) with a channeltron electron-multiplier.…”

Section: X-ray Spectroscopy and Spectromicroscopymentioning

confidence: 99%

Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral

Cervini-Silva

Gilbert

Fakra

et al. 2008

Geochimica et Cosmochimica Acta

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First commissioning results for the elliptically polarizing undulator beamline at the Advanced Light Source

Cited by 40 publications

References 8 publications

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

Molecular orientation in soft matter thin films studied by resonant soft x-ray reflectivity

Auger Electron Emission from Fixed-in-Space CO

Coupled redox transformations of catechol and cerium at the surface of a cerium(III) phosphate mineral

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