Small-Angle X-Ray Scattering of Carbon-Supported Metal Catalysts

1987 ◽  
Vol 111 ◽  
Author(s):  
J Goodtsman ◽  
M. G. Phillips ◽  
H. Brumberger
Keyword(s):  
Small Angle ◽  
Metal Catalysts ◽  
Supported Metal Catalysts ◽  
Carbon Phase ◽  
X Ray ◽  
Density Correlation ◽  
X Ray Scattering ◽  
Three Phase ◽  
Supported Metal ◽  
Ray Scattering

AbstractThe slit-smeared intensity of X-radiation scattered from carbon-supported metal catalysts behaves as clh−1 + c2h−3 for higher h-values in the small-angle region (h+4πλ−1 sinθ, λ + X-ray wavelength,θ + half of scattering angle, c1, c2 are constants). For three-phase systems with sharp phase boundaries, uniform electron-densities in the metal and void phases, and lamellar electrondensity fluctuations in the carbon phase, the small-angle X-ray scattering (SAXS) can be described in terms of inter- and intraphase electron-density correlation functions, and can be shown to yield the observed behavior. Further assumptions are required to separate these contributions and calculate interfacial specific surfaces. SAXS measurements on Pt, Ru, Pd, and Rh/C are presented.

scholarly journals In situanomalous small-angle X-ray scattering from metal particles in supported-metal catalysts. II. Results

2005 ◽  
Vol 38 (2) ◽  
pp. 324-332 ◽  
Author(s):  
H. Brumberger ◽  
D. Hagrman ◽  
J. Goodisman ◽  
K. D. Finkelstein
Keyword(s):  
Small Angle ◽  
Platinum Metal ◽  
Metal Particles ◽  
Metal Catalyst ◽  
Supported Metal Catalysts ◽  
X Ray ◽  
Average Value ◽  
X Ray Scattering ◽  
Supported Metal ◽  
Ray Scattering

Information about the metal phase in a supported-metal catalyst can be obtained using anomalous small-angle X-ray scattering (ASAXS). The difference between the scattering profiles for SAXS at two different wavelengths near the metal's absorption edge is essentially the scattering of the metal alone. Novelin situASAXS measurements are made on mordenite impregnated with platinum metal while the temperature and composition of gas in the sample cell are changed. Measurements are made 62 times during treatment of the catalyst. The metal particles are assumed to be randomly distributed spheres withN(R)dR= number of spheres with radii betweenRandR+ dR. It is found thatN(R) is always a monotonically decreasing function ofR, and that the average value ofR, obtained fromN(R), decreases by a factor of two over the time (approximately 6 h) for which the system is observed.

scholarly journals In situanomalous small-angle X-ray scattering from metal particles in supported-metal catalysts. I. Theory

2005 ◽  
Vol 38 (1) ◽  
pp. 147-151 ◽  
Author(s):  
H. Brumberger ◽  
D. Hagrman ◽  
J. Goodisman ◽  
K. D. Finkelstein
Keyword(s):  
Small Angle ◽  
Platinum Metal ◽  
Metal Particles ◽  
Metal Catalyst ◽  
Supported Metal Catalysts ◽  
X Ray ◽  
Average Value ◽  
X Ray Scattering ◽  
Supported Metal ◽  
Ray Scattering

A supported-metal catalyst can be considered as a mixture of three homogeneous phases: support, void and metal. Information about the metal phase alone can be obtained using anomalous small-angle X-ray scattering (ASAXS), which requires measuring the SAXS for two different wavelengths near the metal's absorption edge. Herein, the conditions that must be obtained so that the difference between the two scattering profiles gives the scattering of the metal alone are presented. In a following contribution, the analysis will be applied toin situASAXS measurements made on mordenite impregnated with platinum metal while the temperature and composition of gas in the sample cell are changed. The metal particles are assumed to be randomly distributed spheres withN(R)dRbeing the number of spheres with radii betweenRandR+ dR. FromN(R) one can obtain the average value ofR.

Synchrotron Small Angle X-ray Scattering Study of Melt Crystallized Polymers

1999 ◽  
Vol 590 ◽  
Author(s):  
Georgi Georgiev ◽  
Patrick Shuanghua Dai ◽  
Elizabeth Oyebode ◽  
Peggy Cebe ◽  
Malcolm Capel
Keyword(s):  
Small Angle ◽  
Structural Model ◽  
Structural Parameters ◽  
Lamellar Thickness ◽  
Melt Crystallization ◽  
Two Phase ◽  
X Ray ◽  
Density Correlation ◽  
X Ray Scattering ◽  
Ray Scattering

ABSTRACTIn this paper we report a synchrotron small angle x-ray scattering (SAXS) study of development of structure in semicrystalline Poly(Ether Ether Ketone), (PEEK) and an 80/20 blend with amorphous Poly(Ether Imide) (PEEK/PEI). Samples were treated to dual stage melt crystallization scheme involving initial isothermal crystallization at T1 followed by a second isothermal period at T2 (T1 < T2). Intensity of small angle scattering was measured in real-time. Structural parameters characterizing the lamellar thickness, 1c, long period, L, and SAXS invariant were deduced from the one-dimensional electron density correlation function assuming an ideal, two-phase structural model.

Anomalous small-angle x-ray scattering from mesoporous noble metal catalysts

2013 ◽  
Vol 291 (9) ◽  
pp. 2163-2171 ◽  
Author(s):  
Karsten Vogtt ◽  
Guenter Goerigk ◽  
Matthias Ballauff ◽  
Roger Gläser ◽  
Nico Dingenouts
Keyword(s):  
Noble Metal ◽  
Small Angle ◽  
Metal Catalysts ◽  
X Ray ◽  
Noble Metal Catalysts ◽  
X Ray Scattering ◽  
Ray Scattering

A Revised O2 Reduction Model in Li-O2 Batteries as Revealed by in Situ Small Angle X-Ray Scattering

2019 ◽  
Author(s):  
Christian Prehal ◽  
Aleksej Samojlov ◽  
Manfred Nachtnebel ◽  
Manfred Kriechbaum ◽  
Heinz Amenitsch ◽  
...  
Keyword(s):  
Small Angle ◽  
Wide Angle ◽  
Reduction Mechanism ◽  
Reduction Model ◽  
X Ray ◽  
X Ray Scattering ◽  
O2 Reduction ◽  
Ray Scattering

<b>Here we use in situ small and wide angle X-ray scattering to elucidate unexpected mechanistic insights of the O2 reduction mechanism in Li-O2 batteries.<br></b>

In situ Time-Resolved Small-Angle X-ray Scattering Reveals the Formation Kinetics of Polyelectrolyte Complex Micelles

2019 ◽  
Author(s):  
Hao Wu ◽  
Jeffrey Ting ◽  
Siqi Meng ◽  
Matthew Tirrell
Keyword(s):  
Small Angle ◽  
Self Assembly ◽  
Electrostatic Interactions ◽  
Polyelectrolyte Complex ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Ray Scattering

We have directly observed the <i>in situ</i> self-assembly kinetics of polyelectrolyte complex (PEC) micelles by synchrotron time-resolved small-angle X-ray scattering, equipped with a stopped-flow device that provides millisecond temporal resolution. This work has elucidated one general kinetic pathway for the process of PEC micelle formation, which provides useful physical insights for increasing our fundamental understanding of complexation and self-assembly dynamics driven by electrostatic interactions that occur on ultrafast timescales.

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