Diffraction anomalous fine structure: A new x-ray structural technique

Stragier, H.; Cross, J. O.; Rehr, J. J.; Sorensen, L. B.; Bouldin, C. E.; Woicik, J. C.

doi:10.1103/physrevlett.69.3064

Cited by 229 publications

(156 citation statements)

References 9 publications

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“…However, for all of them, the information is averaged over all the orientations of atoms in crystals. In principle, non-forbidden re¯ections in the XANES region (Templeton &Templeton, 1980, 1985, andreferences therein) and in the DAFS region (Stragier et al, 1992;Proetti et al, 1999) give information about non-averaged local atomic con®gurations. However, all the atoms, affected and not affected by impurities, give their contribution to the diffraction spectra.…”

mentioning

confidence: 99%

Resonant X-ray diffraction: `forbidden' Bragg reflections induced by thermal vibrations and point defects

Дмитриенко

Овчинникова

2000

Acta Cryst Sect A

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In general, the local atomic environment becomes less symmetric owing to point defects and thermal vibrations of atoms in crystals. It is shown that, as a result of this phenomenon, an additional anisotropy of the resonant scattering factors can occur and the forbidden Bragg re¯ections can be excited near absorption edges. Examples of crystals are presented (Ge, K 2 CrO 4 , C-15 type) where such thermal-motion-induced (TMI) and point-defect-induced (PDI) re¯ections can be observed. The tensor structure factors of both types of re¯ection are computed. Owing to their resonant character, the PDI re¯ections allow both impurity atoms and host atoms of different types to be studied separately. The considered phenomena can provide a very sensitive method to study point defects because only the atoms distorted by defects produce contributions to the PDI re¯ections.

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mentioning

confidence: 99%

Resonant X-ray diffraction: `forbidden' Bragg reflections induced by thermal vibrations and point defects

Дмитриенко

Овчинникова

2000

Acta Cryst Sect A

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“…If the element in question is related to the specific Bragg peak, then the elemental absorption causes a decrease in the Bragg intensity at its absorption edge. A cusp, due to the interference between the Thomson scattering amplitude and the real part of the anomalous scattering amplitude [8], can be observed in the energy scan of the Bragg peak. This behavior was indeed observed for the Nil( and Co, 00 films.…”

Section: Resultsmentioning

confidence: 99%

Anomalous X-ray Scattering for Determination of Nanostructured Alloy Formation and Site-specific Chemistry of Bragg Peak

Chow

2002

MRS Proc.

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The properties of nanostructured films can be tailored by many factors such as composition, structure, preferred orientation, microstructure, interphase interface and grain boundaries. Compositional control of magnetic properties of recording media depends on the miscibility of constituent elements. However, for nanostructured materials with a large surfaceto-volume ratio of atoms, the miscibility at the nanoscale may not necessarily follow the prediction of conventional phase diagram that does not consider the effects of surface and interface. This limitation further complicates the prediction of phase separation at grain boundaries and interphase interface. Using anomalous x-ray scattering, the alloying and composition of a specific long range order of textured nanostructured films has been investigated. Such information may not be readily available from conventional characterization techniques.

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“…Since the intensity, I, of X-ray diffraction (XRD) is proportional to the square of the atomic scattering factor, which in turn contains the anomalous dispersion term Áf = f H + if HH , f HH being proportional to the absorption cross section, absorption-like information can be expected from precise measurements of I. Considering that the physical process behind this oscillation is the same as for XAFS, the phenomenon has been called`Bragg re¯ectivity extended ®ne structure' (BREFS) by Arcon et al (1987) and later oǹ diffraction anomalous ®ne structure' (DAFS) by Stragier et al (1992). In fact, as will be shown below, DAFS can provide the same information about the local structure of resonant atoms as XAFS does.…”

Section: Introductionmentioning

confidence: 99%

“…The XAFS signal is an average over the whole sample. Arcon et al (1987), Stragier et al (1992), Sorensen et al (1994) and Mizuki (1996) have surveyed DAFS history, theory, experimental methods, data analysis techniques and some applications in detail. The reader is referred to these publications for further study.…”

Section: Introductionmentioning

confidence: 99%

DAFS Experiments with Non-Centrosymmetric Single Crystals

Meyer¹,

Richter²,

Seidel³

et al. 1998

J Synchrotron Radiat

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Diffraction anomalous ®ne structure (DAFS) experiments were applied to an epitaxially grown (Ga,In)P layer on a [001] GaAs substrate as a single-crystalline model substance. The requirements for the reliable measurement of re¯ection intensities as a function of photon energy, as well as the quantitative DAFS analysis resulting in the complex-valued ®ne-structure function of the scattering factor, are described. In the case of single crystals, effort had to be put into performing the DAFS measurements in order to hold the position of the Bragg re¯ection exactly during the energy scan. Using the zinc-blende-type structure as an example, it is shown for the ®rst time that, similar to singlecrystal structure analysis, the lack of inversion symmetry has a signi®cant impact on the DAFS signal, so that DAFS may contribute to structure analysis as well.

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Diffraction anomalous fine structure: A new x-ray structural technique

Cited by 229 publications

References 9 publications

Resonant X-ray diffraction: `forbidden' Bragg reflections induced by thermal vibrations and point defects

Resonant X-ray diffraction: `forbidden' Bragg reflections induced by thermal vibrations and point defects

Anomalous X-ray Scattering for Determination of Nanostructured Alloy Formation and Site-specific Chemistry of Bragg Peak

DAFS Experiments with Non-Centrosymmetric Single Crystals

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