An absolute intensity standard for small-angle X-ray scattering measured with position-sensitive detectors

Russell, Thomas

doi:10.1107/s0021889883010857

Cited by 19 publications

(19 citation statements)

References 23 publications

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“…These include the relatively weak scattering of readily available primary standards coupled with the lower sensitivity of the bench-top instrument, difficulties in obtaining stable precalibrated secondary standards, and the practical difficulties, e.g. removing and realigning of the beam-stop, when calibrating on a routine basis (Russell, 1983;Orthaber et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

On the absolute calibration of bench-top small-angle X-ray scattering instruments: a comparison of different standard methods

2006

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Absolute calibration relates the measured (arbitrary) intensity to the differential scattering cross section of the sample, which contains all of the quantitative information specific to the material. The importance of absolute calibration in small-angle scattering experiments has long been recognized. This work details the absolute calibration procedure of a small-angle X-ray scattering instrument from Bruker AXS. The absolute calibration presented here was achieved by using a number of different types of primary and secondary standards. The samples were: a glassy carbon specimen, which had been independently calibrated from neutron radiation; a range of pure liquids, which can be used as primary standards as their differential scattering cross section is directly related to their isothermal compressibility; and a suspension of monodisperse silica particles for which the differential scattering cross section is obtained from Porod's law. Good agreement was obtained between the different standard samples, provided that care was taken to obtain significant signal averaging and all sources of background scattering were accounted for. The specimen best suited for routine calibration was the glassy carbon sample, due to its relatively intense scattering and stability over time; however, initial calibration from a primary source is necessary. Pure liquids can be used as primary calibration standards, but the measurements take significantly longer and are, therefore, less suited for frequent use.

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Section: Introductionmentioning

confidence: 99%

On the absolute calibration of bench-top small-angle X-ray scattering instruments: a comparison of different standard methods

2006

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“…However, calibration of foils is dif®cult and strong attenuation of the incident beam can distort the energy distribution of the radiation. The scattering of a gas at low angles can also be used to determine P 0 , but the design of the sample cell and the inherent weak scattering are problematic (Russell, 1983). Another problem which is worth mentioning is the smearing effect when using a slit collimation for the measurements.…”

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confidence: 99%

“…The ®rst one is the direct method, consisting of the mechanical attenuation of the primary beam by a rotating disc (Kratky & Wawra, 1963) or a moving slit (Stabinger & Kratky, 1978). However, this mechanical attenuation is not well suited to use with position-sensitive detectors (PSDs) (Russell, 1983).…”

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confidence: 99%

SAXS experiments on absolute scale with Kratky systems using water as a secondary standard

2000

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For small-angle scattering, of X-rays (SAXS) and neutrons (SANS), the importance of absolute calibration has been recognized since the inception of the technique. The work reported here focuses on SAXS measurements using Kratky slit systems. In former days, only molecular weights or scattering per particle were determined, but today absolute calibration implies the use of the unit of cm À1 for the scattering curve. It is necessary to measure the so-called absolute intensity, which is the ratio of the scattering intensity to the primary intensity P 0 . Basically there are two possible ways to determine the absolute intensity. The ®rst one is the direct method, which involves the mechanical attenuation of the primary beam by a rotating disc or a moving slit. The second is the indirect method, using secondary standards. Water is well suited as a calibration standard because of the angle-independent scattering. The essential advantage is that the scattering of water only depends on the physical property of isothermal compressibility. Before presenting an example of the practical performance of this method, the most important theoretical equations for an SAS experiment on the absolute scale are summarized. With the slit collimation system, the scattering curve of water can be measured with high enough statistical accuracy. As a ®rst example, the scattering curve of the protein lysozyme on the absolute scale is presented. The second example is the determination of the aggregation number of a triblock copolymer P94 (EO 17 ± PO 42 ±EO 17 ). Taking into account that at least 10% of the polymer sample consists of diblocks, the accuracy of around 10% for the determined aggregation number is rather good. The data of P94 are also considered on the particle scale in order to obtain the radial scattering-length density distribution.

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“…The importance of the absolute calibration of SAS intensity has been recognized since the very early stages of its technical development, for both X-rays [6][7][8] and neutrons. [3,9] Despite the acknowledged advantage of placing data on the absolute scale, the use of suitable calibration techniques is by no means straightforward in the field of SAS.…”

mentioning

confidence: 99%

“…While these are usually appropriate standards for biosciences, their X-ray scattering cross sections are too low to be adopted as a general SAXS standard, especially in the areas of materials science, polymer science, ceramics, chemistry, etc. Monodisperse colloidal suspensions have also been used as primary intensity calibration standards, [8] for which the differential cross section is obtained from their well-defined internal surface area according to Porod's law. Unfortunately, the metastable nature of these colloidal systems leaves their long-term use in question.…”

mentioning

confidence: 99%

Glassy Carbon as an Absolute Intensity Calibration Standard for Small-Angle Scattering

Zhang

Ilavský

Long

et al. 2009

Metall Mater Trans A

376

297

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An absolute intensity standard for small-angle X-ray scattering measured with position-sensitive detectors

Cited by 19 publications

References 23 publications

On the absolute calibration of bench-top small-angle X-ray scattering instruments: a comparison of different standard methods

On the absolute calibration of bench-top small-angle X-ray scattering instruments: a comparison of different standard methods

SAXS experiments on absolute scale with Kratky systems using water as a secondary standard

Glassy Carbon as an Absolute Intensity Calibration Standard for Small-Angle Scattering

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