Musings about the development of XAFS

Stern, Edward A.

doi:10.1107/s0909049500014138

Cited by 34 publications

(13 citation statements)

References 30 publications

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“…The limited k-range of the EXAFS spectra prevents the direct analysis of the shell separation on the basis of the beat pattern in the χ(k) function according to the relation 76,77 : ∆R≈π/(2∆k). For ∆R=0.1Å the necessary k-range is calculated to ∆k=15.7Å −1 , which is considerably larger than ∆k ≈9Å −1 available in this experiment.…”

Section: Iii: B2 Analysis Of Co/cu(001)in E⊥ Geometrymentioning

confidence: 99%

Direct proof of mesoscopic misfit in nanoscale islands by x-ray absorption spectroscopy

et al. 2012

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Polarization-dependent extended x-ray absorption fine structure (EXAFS) measurements above the Co-K absorption edge were carried out to experimentally prove the theoretically predicted contraction of interatomic distances in nanoscale Co islands (⊘≈ 1nm) on Cu(001). Within the one monolayer (ML) thick Co islands which were deposited at 160 K substrate temperature, we find an in-plane Co-Co distance of 2.45±0.02Å , significantly shorter than in bulk Co (2.51Å) and in close agreement with theoretical predictions. The effective in plane coordination number (N * Co ( )) is equals to 3.2±0.5 and 5.0±0.7 (N*=6 for an infinite island) for samples covered by 0.3 and 0.7 monolayers (ML) of Co, respectively. The low value for the 0.3 ML sample is related to the finite island size and to about 20% of intermixing between adsorbate and substrate atoms. The experimental results are supported by ab-initio and molecular dynamics calculations.

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Section: Iii: B2 Analysis Of Co/cu(001)in E⊥ Geometrymentioning

confidence: 99%

Direct proof of mesoscopic misfit in nanoscale islands by x-ray absorption spectroscopy

et al. 2012

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“…EXAFS is an important probe for materials, since knowledge of local atomic structure, i.e., the species of atoms present and their locations, essential to progress in many scientific fields, whether for biology, chemistry, electronics, geophysics, metallurgy, or materials science. (Lytle 1999;Stern 2001;Tournus et al 2002;Hricovini et al 2003;Ascone et al 2003).…”

Section: Introductionmentioning

confidence: 98%

On the method of calibration of the energy dispersive EXAFS beamline at Indus-2 and fitting theoretical model to the EXAFS spectrum

Gaur

Johari

Shrivastava

et al. 2011

Sadhana

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A procedure for calibration of the recently developed energy dispersive EXAFS beamline at the Indus-2 synchrotron source at RRCAT, Indore, India has been described. The procedure involves recording of absorption spectra of two standard samples, whose absorption edge energies are well-established. Two methods have been considered for calibration. In the first method, the position of the first maximum of the derivative of absorption curve is taken as the position of the edge energy. In the second method, the position of the point at half edge step in the absorption curve is taken as the position of the edge energy. It has been shown that only the first method gives same values of dispersion even when the beam current is varied and should be used for calibrating the experimental spectra. Further, it is recommended that the performance of the beamline for a particular setting should be checked by recording and analysing EXAFS of a standard. Hence, the procedure for analysis and extracting information about the various parameters that can be determined by fitting the EXAFS data with a theoretical model has also been described, by taking the example of K-absorption spectra of copper metal foil recorded on this beamline.

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“…For a detailed review on the early investigations of adsorption and the development of adsorption isotherms from the mid-1800s to early 1900s, see the reviews by Giles (1971a,b, 1972). Discussions on these terms and physical descriptions of what was occurring has continued for decades (Sposito, 1984;Sparks, 2003). Today we know that a species at the solid-liquid interface can be either inner or outer sphere adsorbed.…”

Section: The Early Yearsmentioning

confidence: 99%

“…If the model assumes that adsorption occurs on a specifi c surface site, then it is implicitly also describing the adsorption reaction as surface complexation. Inner sphere adsorption involves strong ionic or covalent bonds, while outer sphere adsorption involves a weaker electrostatic attraction (Sposito, 1984).…”

Section: Langmuir Modelmentioning

confidence: 99%

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Historical Perspective on the Tools That Helped Shape Soil Chemistry

Schulthess

2011

Soil Science Society of America Journal

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SSSA 75 th Anniversary Paper T he tools of soil chemistry include instruments, mathematics, models, and software. Th ere is also the mind and imagination. Th roughout the history of our science, we have been shift ing away from a very labor-intensive laboratory environment, where long hours of concentration on tedious tasks was the norm. Th is change in the way we work has been accelerating, particularly since the 1950s. We are accomplishing more work but with less eff ort and more time to contemplate what the data are trying to tell us. Th e essence of our research activity has changed dramatically.Numerous laboratory tools have been used in soil chemistry during the last 200 yr, and the major changes that have occurred are highlighted here. It is hoped that the picture presented will help us decide how to better train our students for the future. By knowing how we have changed in the past and how we appear to be changing in the present, we can perhaps trace the path that we are taking, at least in the near future.Eight major themes are addressed here:1. Th e early years reviews the research environment of the 1800s up to the early 1900s. It marks the beginning years of soil chemistry that shaped many of our ideas for the decades that followed.2. Th e age of electronics covers the early part of the 1900s and the origins of the fi rst portable meters on the market.3. Spectroscopy is at the core of most of our modern methods of analysis. While the development of only a few tools are described here, the impact of spectroscopy on our current research activity cannot be understated.

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Musings about the development of XAFS

Cited by 34 publications

References 30 publications

Direct proof of mesoscopic misfit in nanoscale islands by x-ray absorption spectroscopy

Direct proof of mesoscopic misfit in nanoscale islands by x-ray absorption spectroscopy

On the method of calibration of the energy dispersive EXAFS beamline at Indus-2 and fitting theoretical model to the EXAFS spectrum

Historical Perspective on the Tools That Helped Shape Soil Chemistry

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