Measurements of integrated intensity near the absorption edge with synchrotron radiation

Fukamachi, T.; Kawamura, Takaaki; Hastings, J. B.

doi:10.1107/s0021889877013545

Cited by 26 publications

(9 citation statements)

References 7 publications

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“…Then, by the best use of an SSD (solid-state detector), it was shown that the determination of the anomalous-scattering factors as functions of energy and some applications of these factors such as polarity determination are feasible in a typical laboratory Hosoya, 1975;Fukamachi & Hosoya, 1975;Fukamachi, Hosoya & Okunuki, 1976a,b;Fukamachi, Hosoya, Kawamura & Okunuki, 1977. Concurrently, the advent of synchrotron radiation has opened great possibilities in this field (Bonse & Materlik, 1976;Phillips, Wlodawer, Yevitz & Hodgson, 1976;Phillips, Wlodawer, Goodfellow, Watenpaugh, Sieker, Jensen & Hodgson, 1977;Fukamachi, Hosoya, Kawamura & Hastings, 1977;Fukamachi, Hosoya, Kawamura, Hunter & Nakano, 1978).…”

Section: Introductionmentioning

confidence: 99%

Phase-angle determination by anomalous X-ray scattering with a four-circle SSD diffractometer

Sakamaki¹,

Hosoya²,

Fukamachi³

1980

Acta Cryst Sect A

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By the use of a four-circle diffractometer with a solidstate detector, the integrated Bragg reflexion intensities from hemimorphite [Zn4Si2Ov(OH)2.H20] have been measured by energy-dispersive diffractometry at three energy values, including the region very near the Zn K absorption edge. The anomalous difference Patterson map obtained indicated Zn-Zn peaks. By the use of the anomalous-scattering effect to the maximum extent, the phases of one hundred reflexions have been determined with a mean error of 15.4 °

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Section: Introductionmentioning

confidence: 99%

Phase-angle determination by anomalous X-ray scattering with a four-circle SSD diffractometer

Sakamaki¹,

Hosoya²,

Fukamachi³

1980

Acta Cryst Sect A

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“…The stringent requirements on the saiiiple are likely to keep the number of accessible cases limited, and the bulk of the experimental f ' will be based on calculations from the absorption coefficients. A t the moment accurate measurements extending to long wavelengths and high-resolution studies near the absorption edges are the critical points in quest of more reliable values of f', and here the tunable synchrotron radiation [15] and novel monochromator constructions [35] are opening new avenues to both directions.…”

Section: Disciissiorimentioning

confidence: 99%

Scattering of X‐rays near the K absorption edge II. Dispersion factors f′ and f″

Suortti

1979

Physica Status Solidi (b)

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BY Dispersion Factors f' and P. SUORTTIThe dispersion factors of the X-ray scattering amplitude, f' and f", are studied in the dipole approximation where they are independent of the scattering angle. The imaginary part is proportional to the absorption coefficient, and below the Kedge the observed fs is in a close agreement with the value calculated from the resonant Raman cross-section. The real part is calculated from the tabulated absorption coefficients in a number of cases where comparison with direct determinations off' can be made. The agreement is good. particularly when extensive data near the edge are available, while recent theoretical values are consistently low. Calculated values of f' are tabulated for transition elements a t several commonly used X-ray wavelengths.Die Dispersionskorrekturen f' und f" der Rontgenstreuamplitude werden in der Dipolnaherung, wo sie unabhangig voni Streuwinkel sind, untersucht. Der Irnaginarteil ist proportional zum Absorptionskocffizienten. Unterhalb der K-Absorptionskante ist der gefundene Wert von fg in guter Ubereinstimrnung mit dem theoretischen, aus dem resonanten Ramanwirkungsquerschnitt berechneten Wert. I n mehreren Fallen, in denen der Vergleich rnit direkt bestiinmten f' moglich ist, nird der Rcalteil aus den in Tabellen gegebenen Absorptionskoeffizienten berechnet. Die Ubereinstimmurig ist gut, besonders, wenn zahlreiche Werte in der Nahe der Kante vorhanderi sind, wdhrend neuere theoretische Werte systematisch zu niedrig sind. Fur die Ubergangselemente nerden die berechneten Werte von f' fur mehrere allgemein benutzte Wellenlangen tabelliert. IntroductionThe resonant response of an atom to X-rays is seen in the alniost singular changes of scattering and absorption near an absorption edge. Fluorescence and the resonant Raman scattering (RRS) is treated in the preceding paper [l]. Both phenomena are covered by a single formula for the cross-section, and there is a continuous change froin the RRS to the full fluorescence.The coherent scattering near an absorption edge is affected by the resonant phenomena as well. The drastic changes in the atomic scattering factor provide an effective tool in the crystal structure analysis; this rapidly developing field has been recently reviewed l i e

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“…The direct method has been widely used by several investigators to evaluate f ¼ and f ¼¼ . This method is based on (i) the measurement of the refractive index of the specimen of interest, (ii) the determination of intensities of Bragg reflections [23] and (iii) X-ray interferometry [24] from which f ¼ and f ¼¼ values are calculated. The principal advantage of this method is that it can yield absolute values of f ¼ and f ¼¼ .…”

Section: Introductionmentioning

confidence: 99%

Anomalous scattering factors of some rare earth elements evaluated using photon interaction cross-sections

et al. 2003

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The real and imaginary parts, f ¼´E µ and f ¼¼´E µ of the dispersion corrections to the forward Rayleigh scattering amplitude (also called anomalous scattering factors) for the elements La, Ce, Pr, Nd, Sm, Gd, Dy, Ho and Er, have been determined by a numerical evaluation of the dispersion integral that relates them through the optical theorem to the photoeffect cross-sections. The photoeffect cross-sections are derived from the total attenuation cross-section data set experimentally determined using high resolution high purity germanium detector in a narrow beam good geometry set-up for these elements in the photon energy range 5 to 1332 keV and reported earlier by the authors. Below 5 keV, Scofield's photoeffect cross-sections compiled in XCOM program have been interpolated and used. Simple formulae for f ¼¼ in terms of atomic number and energy have also been obtained. The data cover the energy region from 6 to 85 keV and atomic number Z from 57-68. The results obtained are found to agree fairly well with the other available data.

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Measurements of integrated intensity near the absorption edge with synchrotron radiation

Cited by 26 publications

References 7 publications

Phase-angle determination by anomalous X-ray scattering with a four-circle SSD diffractometer

Phase-angle determination by anomalous X-ray scattering with a four-circle SSD diffractometer

Scattering of X‐rays near the K absorption edge II. Dispersion factors f′ and f″

Anomalous scattering factors of some rare earth elements evaluated using photon interaction cross-sections

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