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Precision X-ray optics for fundamental interactions in atomic physics, resolving discrepancies in the X-ray regime (1999)

Chantler, C. T. ; Barnea, Z. ; Tran, C. Q. ; [et al.]

Springer

Optical and quantum electronics 31 (1999), S. 495-505

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ISSN: 1572-817X

Keywords: accuracy ; complex form factor f ; X-ray optics

Source: Springer Online Journal Archives 1860-2000

Topics: Electrical Engineering, Measurement and Control Technology , Physics

Notes: Abstract Reliable knowledge of the complex X-ray form factor (Re(f) and f″) is required for many fields including crystallography, medical diagnosis and XAFS studies. However, there are discrepancies between theory and theory, experiment and experiment and theory and experiment of 10% and more, over central X-ray energies. Discrepancies exist for most elements, despite claimed experimental accuracies of 1%. This paper summarises the current variation between experimental and theoretical results, and outlines key issues for obtaining experimental accuracies of 1% in critical wavelength ranges for selected elements to address these issues. This paper critically surveys available experimental data for attenuation coefficients and suggests a procedure for obtaining significantly higher accuracy measurements in the future.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1006923329884

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An approach to the prediction of retention times in liquid chromatography (1981)

Hanai, T. ; Tran, C. ; Hubert, J.

Weinheim : Wiley-Blackwell

Journal of High Resolution Chromatography 4 (1981), S. 454-460

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ISSN: 0935-6304

Keywords: Reversed-phase mode liquid chromatography ; Rekker's hydrophobic fragmental constant ; Calculation of concentration of organic modifier ; Prediction of retention time ; Chemistry ; Analytical Chemistry and Spectroscopy

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology

Notes: The utility of Rekker's hydrophobic fragmental constant has been examined for optimization of reversed-phase mode liquid chromatographic separations. The chromatographic behavior of about 60 non-ionic compounds was measured in different acetonitrile/water mixtures and the logarithm of their capacity factors (log k) was correlated with their calculated hydrophobicities (log P). Linear relations were found in each case between log k and log P. The slope of the various lines was related to the percentage concentration of acetonitrile in the mobile phase. It was shown that, by using nine stand ard compounds and measuring their capacity factors in five eluents with different acetonitrile concentrations, the retention time could be predicted for 60 compounds. Calculation of the concentration of the organic modifier was also possible in a system of well coated octadecyl bonded packings with acetonitrile/water mixtures as eluent. Prediction of the capacity factor was accomplished to within 5% error.

Additional Material: 2 Ill.