The XRF11 program by John Criss and the EXACT program are two commercially available fundamental parameters programs for energy dispersive x-ray fluorescence spectrometry (EDXRF). These programs are both based on the same underlying equations but use different approaches to the calculations. The EXACT program assumes monochromatic excitation, and the XEF11 program models polychromatic excitation sources. There are also great differences in how the two programs approach the iterations in the calculations and in how the data from standards are used in the two programs for calibration.

To produce the monochromatic excitation neeiled by the EXACT program, secondary targets have been the preferred method. But it is also possible to approximate monochromatic excitation by using filtered direct excitation. The purpose of this study is to compare the data obtained from both secondary targets and direct filtered excitation as processed through both XRF11 and EXACT.

In order to reduce the error of quantitative electron probe microanalysis, error sources in the preparation and measurement of specimens and standards must be minimized. These sources of error are described, and literature references for detailed study are given. A critical analysis is made of 150 analytical measurements of binary specimens previously discussed by Poole and Thomas. It is shown that the cases of serious errors reported by these authors are mainly due to poorly characterized or measured specimens and, in. some cases, to the omission of characteristic fluorescence corrections. If these sources of error are eliminated, a much more favorable error distribution can be obtained through relatively simple correction calculations. Further progress in quantitative micro probe analysis is dependent upon measurements under well-controlled conditions and standard materials of experimentally proven microhomogeneity and reliably determined composition.

The x-ray fluorescence (XRF) method is well known for its capability to perform fast and accurate quantitative analysis for all elements with atomic numbers greater than ten. Energy dispersive x-ray fluorescence (EDXRF) adds to this capability the benefit of quick qualitative analysis, due to its simultaneous sensitivity to all the elements. The method has the potential for rapid and complete chemical analysis of any sample which arrives on the analytical chemist's doorstep. Although the method has been a productive tool for fast and accurate repetitive analysis of similar samples, its applicability to unique unknowns has been rather limited. The limitation arises from the usual need to calibrate the instrument's response with a set of 6 to 12 standards, whose compositions must be similar to the unknown sample. Anyone who has struggled to develop and maintain such a suite of accurately certified standards knows that a great deal of effort and expense is involved. This effort is well justified when the analyst expects to analyze the same type of material frequently over an extended tine period. However, for a unique sample analysis, the task of developing a suite of similar standards simply makes the analysis impractical. What is needed is a method that requires minimal standards, or uses no standards at all.

Photoelectron spectrometry is shown to be an excellent technique for the analysis of x rays in the ultrasoft and soft x-ray regions. X rays are converted into photoelectrons which are ejected from a suitable atomic level, and the photoelectrons are analyzed with an electron spectrometer. The method is energy dispersive, provides a resolution ranging from 0.1 eV at 20 eV to 1.1 eV at 3 keV, and gives well-defined intensity characteristics throughout the range. The energy range can be extended into the 10 keV decade. Properties of the new technique are discussed, compared with conventional techniques, and exemplified by a series of measurements which include determination of the emission spectra of M x rays of yttrium to rhodium, L x rays of zirconium, and the band structures of molybdenum and holmium.

Three novel methods of x-ray spectrometry have been developed in recent years at Texas Tech University. These are:

• 1. Three crystal spectrometer

• 2. Two curved crystal spectrometer

• 3. Spherically bent crystal spectrometer.

In this paper the new design features, and experimental results will be discussed to indicate the usefulness of the new instruments. The three crystal spectrometer is a modified two crystal instrument. A third crystal is used to analyze the output of the two crystal spectrometer. The first two crystals are operated as a standard two crystal spectrometer. The third crystal is swept through the spectrum transmitted by the first two crystals for each setting of the first two crystals. The peak intensity of the third crystal sweep corresponds to the energy setting of the two crystal spectrometer, and is the intensity used to plot the spectral lines. The two curved crystal spectrometer utilizes two transmission spectrographs with radii having a 2:1 ratio in series, the crystal with the smaller radius being set so that its focal point falls on the Rowland circle of the larger radius crystal, This instrument has a very low background intensity and is suitable for precision scattering and diffraetion work. The spherically bent crystal spectrometer makes use of high light gathering power and high orders of reflection to allow high resolution studies of weak spectral lines. It also has the advantage of ease of alignment and operation.

Traditionally, clinical studies of lead's effect on health have relied on blood lead levels to indicate lead exposure. However, this is unsatisfactory because blood lead levels have a half-life of approximately 5 weeks (Rabinowitz et al., 1976), and thus reflect recent exposure. Over 90% of the lead body burden is in bone, and it is thought to have a long residence time, thus implying that measurements of bone lead reflect cumulative exposure (Barry, 1975). So, measurements of bone lead are useful m understanding the long-term health effects of lead.

X-Ray diffraction measurements of MnO confirm the hypothesis that the structural temperature and the magnetic transition temperature, or Néel temperature) are the same. The usefulness of X-ray diffraction intensity data of MnO, with respect to an atomic structural refinement problem involving α-Mn powders, is discussed. Lattice constant values of MnO are listed between 100 and 310°K

Considering all fields of analysis by X-ray fluorescence spectrometry geochemical analysis is probably the most complex. The geochemical analyst is often requested to analyse samples of unknown composition and origin. While these samples need to be analysed for a number of elements of economic or geochemical significance it is often impossible or uneconomic to analyse for all elements that could possibly be present in the sample.

Machine parts made of ceramics are usually finished by grinding. Residual stresses as well as defects introduced by grinding will influence the fracture strength and the function of the ceramic parts. Although several investigators measured the grinding residual stresses by the X-ray diffraction method, their grinding conditions were rather limited.

Atomic energy levels, which represent the energy necessary to remove an electron in a given level from the atom, are used for a variety of purposes-from predicting possible interfering x-ray lines in analysis to serving as experimental values with which to compare the results of complicated computer calculations. X-ray wavelength data is essential to determine energy level differences but cannot be used to place the resulting level scheme on an absolute energy basis , X-ray absorption data can be so used but the results of photoelectron energy measurements are superior. Since there are a very large number of possible x-ray lines from a typical element, one can readily obtain many more energy differences than there are energy levels ; hence, to make the best use of the data available, a least squares fitting procedure is used to obtain the most probable value for each energy level,

Recently variable sample exit-angle x-ray fluorescence spectrometry (VEA-XRF) has been shorn to be a useful analytical tool for monitoring the oxidation of the surfaces of bulk Cu, Ni as well as that of Fe. In these studies advantage was taken of the well known phenomenon that for each transition metal oxide (MO) Lβ/Lα intensity ratio value is higher than for the transition metal (M), itself. Within the limits of the photon-escape depth de, which for these photons are generally below 5000 Å, varying the sample exit-angle θ offers an opportunity for seeing whether or not the oxidation of the surfaces of bulk M belongs to one of the following two classes: (I) uniform oxidation throughout the entire observable sample-depth, (II) preferential oxidation of the top surface layer, i.e. depth dependent oxidation.

A set of experimentally obtained “d” values is subject to a variety of random and systematic errors, some of which are inherent to a given diffractometer configuration and some of which may result from incorrect alignment of the diffractometer or technique in establishing peak positions and subsequent calculation of “d” values. In a previous paper (1) we have discussed the problems involved in the identification and control of errors in the computer controlled diffractometer and in that paper we indicated that it is useful to differentiate between different types of two-theta values. Firstly the Theoretical 20 values are those values which are dependant only on the size and distribution of atoms in the unit cell of the phase. The Practical 20 values on the other hand result when aberrations inherent in a given diffractometer geometry are convoluted with the Theoretical 20 values. In terms of their typical magnitudes the most important of these aberrations in decreasing order are: Specimen Displacement, Axial Divergence, Flat Specimen and Transparency Errors. Other inherent errors include refraction and the effects of focal line and receiving slit widths etc., but these latter effects are generally considered small. At the second level, Experimental 20 values also depend on misalignment errors. The third level errors accrue in the conversion of the experimental 20 value to “d” spacing. These errors may arise simply from round-off errors or from more fundamental reasons arising from the polychromatic nature of the source and uncertainties in the wavelength of the diffracted radiation.

Austempered ductile cast iron (ADI) lias microstructures that consist of martensite and of retained austenite. ADI has very toughness compared with cast iron heat-treated differently. The retained austenite near fracture surfaces transforms to martensite when fracture occurs.

In the present study, X-ray fraetography is applied to fatigue fracture surfaces of ADI. The fatigue tests were carried out on compact tension (CT) specimens. The volume fraction of retained austenite was measured quantitatively and the line broadening of X-ray diffraction profiles was measured on and beneath fatigue fracture surfaces. The depth of the plastic zone left on fracture surfaces was evaluated from line broadening. The results are discussed on the basis of fracture mechanics.

The back reflection x-ray divergent beam technique is examined as a tool for studying elastic strains. In particular, a method of calculating interplanar spacings using a least squares fit of experimental "conic" coordinates to Newman's general equation for back reflection (J. Appl. Cryst. 3 (1970) 191) is described. Using this technique, interplanar spacings can be obtained from partial conies. To determine the precision of this method an unstrained silicon single crystal is studied, and the errors associated with determining its interplanar spacings are discussed. The technique is then applied to elastically strained silicon and the results compared to theoretical predictions. It is shown that strains down to 2 × 10−5 are readily measured on high angle planes in silicon.

A protocol for semi-quantitative XRD analysis of fly ash has been applied to 178 ashes in studies of the typical mineralogy of high-calcium and iow-calcium fly ash, the consistency of fly ash mineralogy from a typical power station, the partitioning of chemical constituents into crystalline phases, and the crystalline phases relevant to the use of fly ash in concrete.

The present study concerns residual stresses analysis in porycrystalhtie solar silicon material, which is continuously cast in a cold crucible. The observation of cracks and a modeling of thermal stresses suggest us that stresses in the center region are tensile and the ones in the peripheral region are compressive. X-ray measurement of stresses would be an experimental proof of the observations and an evaluation of the stresses levels. Unfortunately, the obtained material exhibits coarse grains with the size of up to one millimeter. In this case, where only a few crystals are irradiated by the incident X-ray beam, the classical sin2Ψ method is no longer valid. A specific analysis must be carried out. The results are of good accuracy comparing the low stress levels observed. The measured stress distribution on a radius of the billet is not always in good agreement with the analytical calculus.

The location of x-ray diffractometer line profiles is of fundamental importance in x-ray stress analysis. Objective estimates of the line profile position may be derived from diffractometer measurements at a number of equally-spaced points in the region of maximum intensity. These estimates are generally based upon the corresponding turning-point of a polynomial fitted to step-scanning data. Techniques are described which simplify the computation involved. A least-squares fitting of a quadratic is satisfactory for most routine applications provided that a reasonable number of points is involved. The three-point parabola method is less satisfactory. Expressions are presented, derived using the maximum-likelihood approach, for peak location and counting variance using both quadratic and cubic equations.