ISSN:0049-8246    

DOI:10.1002/xrs.1300090202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractWe present results of X‐ray fluorescence measurements on the Shroud of Turin. Quantitative estimates are given for the observed trace quantities of calcium, iron and strontium, and detection limits are established for other elements of potential interest. The calcium and strontium appear as uniform background distributions. Iron traces are observed in all of the data spectra but their local concentrations vary. Comparisons between image and off‐image areas reveal no differences, within the precision limits of the data, that would indicate the presence of pigments or dyes containing high‐C elements. In ‘blood’ stain regions the measurements show significantly higher concentrations of iron. However, the data do not allow a unique identification of the stain's origin. Quantitative comparisons are made between the shroud results and similar measurements on whole blood and Fe

ISSN:0049-8246    

DOI:10.1002/xrs.1300090203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe operation of a computer system for producing on‐line chemical analyses from a three‐spectrometerJEOL JXA‐5Aelectron microprobe is briefly discussed. A new method for acquiring the X‐ray data by integrating the area under the peak is discussed in greater detail. The increased reliability of the results from this new method are illustrated by considering the effect of focus error on the measured coun

ISSN:0049-8246    

DOI:10.1002/xrs.1300090204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractIn X‐ray fluorescence analysis the concept of radiometric diameter,d, is often introduced in considerations of the fluorescent intensity from a particulate sample. It represents the mean geometric path of the X‐rays through one particle and is usually simply taken to be equal to the volume‐to‐area ratio of the particle. The effective radiometric path is, however, itself dependent on geometry and absorption effects. Rigorous calculations of the fluorescent intensity from a particle in the π and π/2 geometries were carried out to evaluate the errors involved. It appears that, for π geometry, the discrepancy between these exact results and the intensity calculated via the use ofddoes not exceed 5.2%. For the π/2 geometry, the errors are much larger and can amount to 50% in realistic cases of X‐ray fluorescence analysis. These conclusions are also applicable to monolayers. The effective radiometric diameter approachesdonly when absorption effects become negligible, but is smaller i

ISSN:0049-8246    

DOI:10.1002/xrs.1300090205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractTo obtain intense linear polarized monochromatic X‐rays a single crystal where Bragg reflection occurs at an angle 2θ=90° is used. A number of suitable crystal materials is listed which fulfil the requirements of the Bragg equation for the wavelengths of standard X‐ray tubes and the angular condition. As the first result of a new construction a detection limit of 1 ng Ca was determined using a Cr anode and a Ta single crystal (002) plane as pola

ISSN:0049-8246    

DOI:10.1002/xrs.1300090206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractMethods are considered for optimizing a conventional Bragg‐‐Brentano X‐ray powder diffractometer for the identification of crystalline phases in airborne particulates deposited on membrane filters. The instrumental parameters investigated include detector stepping increment and scan range, Kβ filtration, and the incident beam divergence slit width. Sample‐related factors such as substrate material (cellulose ester, polycarbonate and polytetrafluoroethylene), off‐axis displacement of the sample and X‐ray induced specimen degradation were also studied. Scan times for sample deposits of several hundred μcm−2are in the vicinity of 24 h with an 800 W tube. These times may be reduced substantially by one or more of the following modifications: rotating anode or synchrotron radiation source, energy‐dispersive diffractometry, and Bragg‐‐Brentano diffractometry with a position

ISSN:0049-8246    

DOI:10.1002/xrs.1300090207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThis paper shows the employment of five X‐ray methods for the investigation of a thickness range of 1 Å to 0.1 mm. The well known techniques (X‐ray fluorescence and scanning electron microscopy) are treated, a new method (energy‐dispersive X‐ray diffraction) is discussed and X‐ray photoelectron spectroscopy measurements are essentially improved by a new evaluation method. Low energy electron induced X‐ray spectrometry is mentioned. As far as significance of the measured thicknesses is concerned, the range of 10‐‐50 nm deserves s

ISSN:0049-8246    

DOI:10.1002/xrs.1300090208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractA method has been investigated which allows calculations from the X‐ray fluorescence spectra of the absorption coefficients at any energy for any sample, without any additional measurement. Use is made of the ratio of the characteristic X‐ray signals from a Zr wire positioned in front of the sample and from a Pd foil placed behind the sample, both in a fixed geometry. From the experimentally measured absorption coefficient at the Pd L energy (2.9 keV), the coefficients for higher energies are calculated. By the use of an iterative computer routine in which corrections for the enhancement of the Pd foil by the sample are also included, an accuracy of 2% or better on the absorption coefficient determination can be reached for homogenous samples in one measurement. Grain‐size and heterogeneity effects induce inaccuracies on the absorption coefficient determinations which might well reach 20% for particulate samples like intermediate thickness deposits of geological materials. This approach thus has the same limitations as the classical transmission method for such heterogeneous sa

ISSN:0049-8246    

DOI:10.1002/xrs.1300090209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractThe X‐ray K absorption edges of Co in some 1,10 phenanthroline‐based complexes of cobalt have been recorded. The results have been discussed qualitatively in terms of the effective nuclear charge on the central metal atom and the nature of the lig

ISSN:0049-8246    

DOI:10.1002/xrs.1300090210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY

摘要:

AbstractOptimized multilayer X‐ray spectrometry, using lead myristate and lead stearate analyzers (2dvalues of 80 and 100 Å) has been applied to the measurement of the O‐‐Kα and the C‐‐Kα spectral bands from CO and CO2in the gas and solid phases. The LII, IIIspectra were also measured for argon in the gas and solid states under similar conditions in order to identify and to minimize any non‐molecular components in the CO and CO2spectra. These molecular orbital data have been related to those obtained with X‐ray and ultraviolet photoelectron spectroscopy and grating X‐ray spectroscopy. The consistency of the results of these complementary measurements is excellent. The ionization energies for the C and O 1s levels have been determined to be 295.4 and 542.0 eV for CO and 296.8 and 540.3 eV for CO2. The MO data have also been compared with that predicted from the symmetry, strength and binding energy of the molecular orbital spectral components as calculated using the currently available computational models, CNDO/2, MINDO/3, MNDO, extended Hückel andab initio. The molecular orbital calculated results for these organic compounds, CO and CO2, are not in as good agreement with the experimental data as previously demonstrated for molecular orbital spectra measured for C‐‐Kα and the LII, IIIbands of Cl, S and P for both organic

ISSN:0049-8246    

DOI:10.1002/xrs.1300090211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1980

数据来源: WILEY