Hard X-Ray Synchrotron Radiation Applications in Materials Science

Knapp, G.S.; Beno, M. A.; You, Hui

doi:10.1146/annurev.ms.26.080196.003401

Cited by 12 publications

(7 citation statements)

References 1 publication

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“…Specular X-ray reflectivity (XR) can be used to determine the electron density distribution normal to the surface of thin films at interfaces and has broad applications in the fields of biology (Ege et al, 2005;Miller et al, 2004Miller et al, , 2006, materials science (Knapp et al, 1996) and nanotechnology (Lin et al, 2007;Schultz et al, 2006;Sanyal et al, 2008). In XR, the reflectivity from an interface is measured as a function of the angle, , of the incident X-ray beam, which is related to the z component of the wavevector transfer (q z = 2k sin , where k is the wavevector).…”

Section: Introductionmentioning

confidence: 99%

Stochastic fitting of specular X-ray reflectivity data usingStochFit

et al. 2008

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Specular X‐ray reflectivity data provide detailed information on the electron density distribution at an interface. Typical modeling methods involve choosing a generic electron density distribution based on an initial speculation of the electron density profile from the physical parameters of the experimental system. This can lead to a biased set of solutions. StochFit provides stochastic model‐independent and model‐dependent methods for analyzing X‐ray reflectivities of thin films at an interface. StochFit divides an electron density profile into many small boxes and stochastically varies the electron density of these boxes to locate the best fit to a measured reflectivity. Additionally, it provides the ability to perform model‐dependent fitting with a stochastic search of the parameter space in order to locate the best possible fit. While model‐independent profile search algorithms have been described previously, they are difficult to implement because of the heavy computational requirements, and there is a dearth of software available to the general scientific public utilizing these techniques. Several cases that illustrate the usefulness of these techniques are presented, with a demonstration of how they can be used in tandem.

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Section: Introductionmentioning

confidence: 99%

Stochastic fitting of specular X-ray reflectivity data usingStochFit

et al. 2008

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“…The main obstacle for excited-state structure determination is the lack of pulsed X-ray sources that provide sufficient photons. This obstacle has been circumvented with new generation synchrotron sources that offer X-ray pulses with about 100 ps pulse duration and up to 10 4 times more photons than previous sources . In addition, notable advances in the production of ultrashort, intense X-ray pulses have recently appeared in the literature. − Here we exploit these advances and report structural studies of molecular excited states by nanosecond pump−probe XAFS in fluid solution.…”

Section: Introductionmentioning

confidence: 99%

“…This important achievement was made possible with the aid of X-ray pulses from a new generation synchrotron source with a significantly higher X-ray photon flux than was previously available. ,, A simplified time sequence of the experiment is shown in Figure . A laser pulse excites the sample, and a sextuplet X-ray pulse cluster probes the structure of the excited state at its optimal concentration.…”

Section: Introductionmentioning

confidence: 99%

Rapid Excited-State Structural Reorganization Captured by Pulsed X-rays

et al. 2002

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Visible light excitation of [Cu(I)(dmp)(2)](BArF), where dmp is 2,9-dimethyl-1,10-phenanthroline and BArF is tetrakis(3,5-bis(trifluoromethylphenyl))borate, in toluene produces a photoluminescent, metal-to-ligand charge-transfer (MLCT) excited state with a lifetime of 98 +/- 5 ns. Probing this state within 14 ns after photoexcitation with pulsed X-rays establishes that a Cu(II) center, borne in a Cu(I) geometry, binds an additional ligand to form a five-coordinate complex with increased bond lengths and a coordination geometry of distorted trigonal bipyramid. The average Cu-N bond length increases in the excited state by 0.07 A. The transiently formed five-coordinate MLCT state is photoluminescent under the condition studied, indicating that the absorptive and emissive states have distinct geometries. The data represent the first X-ray characterization of a molecular excited state in fluid solution on a nanosecond time scale.

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“…The schematic of the SAXS beam line is shown in Fig.1. This instrument views a high brilliance undulator source whose characteristics are given in Knapp et al(1996). Fig.…”

Section: Instrument Designmentioning

confidence: 99%

Design and performance of a ASAXS instrument at the Advanced Photon Source

Seifert¹,

Winans²,

Tiede³

et al. 2000

J Appl Crystallogr

121

102

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The SAXS instrument on the high brilliance undulator beam line (ID-12, BESSRC-CAT) at APS has been designed to produce highresolution scattering patterns in the millisecond time domain. This instrument is equipped with a 18 cm x 18 cm position sensitive gas detector and a 15 cm x 15 cm high-resolution position sensitive CCD mosaic detector. A photodiode detector mounted on a 3.7 mm diameter beam stop permits quick alignment of the instrument as well as precise measurement of the transmitted beam intensity. The exposure time with the CCD detector varies from 0.1 to 10 seconds depending on the scattering cross-section of the samples. Techniques to interface ancillary equipment for time-resolved studies and software for faster online analysis of the data have also been developed. We have obtained data on the unfolding of proteins in the millisecond time domain and ASAXS of metallic alloys using this instrument.

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Hard X-Ray Synchrotron Radiation Applications in Materials Science

Cited by 12 publications

References 1 publication

Stochastic fitting of specular X-ray reflectivity data usingStochFit

Stochastic fitting of specular X-ray reflectivity data usingStochFit

Rapid Excited-State Structural Reorganization Captured by Pulsed X-rays

Design and performance of a ASAXS instrument at the Advanced Photon Source

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