X-ray fluorescence (XRF) has become a well established technique for the measurement of trace levels of toxic heavy metals in vivo, including cadmium, platinum, mercury and lead (Mattsson et al.. 1987). The clinical motivation for the measurement of platinum (Pt) is the need to investigate the kinetics of Pt-based cancer chemotherapy drugs such as cisplatin and paraplatin. Currently the main research interest in Swansea lies in the study of the uptake and distribution of Pt administered during chemotherapy of patients with tumours in the head and neck region.

Calculations carried out to investigate the van Cittert iterative deconvolution method and the effects of random noise and truncation errors on its convergence behavior are presented. Gaussian functions are used for "both the true function W and the system, response function A. The model "observed" function S is generated from W and A. Both rms differences between the result of n iterations Wn and the true function, and between Wn*A and S are used to measure convergence. The effects of introducing errors can be measured against standards set by the convergence without such errors. These "no-error" calculations make use of true functions with widths from 2.0 to 0.67 times the response function width. The effects of random noise are investigated by adding noise to W*A before deconvolution. A small amount of random noise initially added builds up rapidly in amplitude during the iterative process and eventually dominates the rms difference calculations. To suppress the effects of random noise build-up; smoothing techniques are applied, the best of which involved smoothing both the noisy observed function, S, and the system response function, A, before deconvolution. The smoothing operation is thus taken as part of the measurement and. the divergence resulting from, the noise build-up is avoided. The results depend strongly upon, the -width of the smoothing function. Uhsymmetric system response functions, similar' to those encountered in soft x-ray appearance potential spectroscopy and in x-ray continuum, isochromat measurements, are used in investigations of truncation errors. Abrupt cut-offs of the model S and A functions before deconvolution result in the build-up of large fluctuations in W . These truncation errors become increasingly localized with continued iterations and make only minor contributions to the errors in Wn in the vicinity of the real peak if the truncations are made sufficiently far from the peak location. Alternatively, the truncation errors can be avoided by analytical continuation.

An unexplained anomalous sin2ψ split in x-ray stress measurements has consistently resulted from the use of Cr Kα radiation with nickel and austenitic stainless steels. Both, materials have diffraction peaks at low back-reflection angles for this radiation (nickel: 20 ⋍ 134°, austenitic stainless steel: 20 ⋍ 128°). The anomalous split is not evident when the measurements are made using Cr Kβ radiation, In an attempt to explain the errors produced by the Cr Kα radiation, focusing circle effects were analyzed and compared to experimental measurements made with both Cr Kα and Cr Kβ radiation on nickel-based samples,

A simple method for high-resolution measurement of surface misorientation in electronic materials is introduced. The technique combines laser optical alignment with double-crystal x-ray diffraction to yield a typical sensitivity of better than 1-2 arc sec. The technique can also be used to make corrections in spectrometric measurements in which commonly ignored rocking - curve errors may be significant.

Automated powder diffractometers are beginning to come into general use. The principal reason for automating or purchasing an automated powder diffractometer is to increase the speed and accuracy of the analysis. Three principal methods are used. The first is that a multisample changer increases the through-put on the instrument since the unit can be operated unattended during the evening. The second is the diffractometer can be scanned at faster rates when digital data are collected, as opposed to the analog method of using a strip chart recorder. The third is the elimination of reading the peak positions and intensities from the strip charts. These readings would typically have to be tabulated manually for later interpretation. Another reason for having an automated powder diffractometer is for experiments where digital data are necessary to make the analysis practical. These experiments include routine quantitative analysis, radial distribution functions, Fourier profile analysis, and signal averaging to bring out very weak diffraction peaks.

The excitation efficiencies for K- and L- x-ray fluorescence by a Mo transmission tube operated at 30 kV have been measured. K x-ray excitation efficiencies for 14 elements ranging from A1 to Y and L x-ray excitation efficiencies for 12 elements ranging from Br to U are presented. The K x-ray excitation efficiencies are compared to those predicted from theoretical photoionization cross sections and empirical fluorescence yields, and the L x-ray excitation efficiencies are used in conjunction with theoretical photoionization cross sections to derive average L-shell fluorescence yields.

A single function for the elimination of errors in precision lattice parameter determination has not been developed for the Bragg-Brentano x-ray diffractometer method, because of the different angular dependencies of the systematic errors. A review of the error functions shows that all but one can be calculated from the instrumental settings and known properties of a sample under investigation. The residual sample displacement error can be then be eliminated by using extrapolation plots or computer methods to correct the data to cosθcotθ plots. The slopes of cosθcotθ plots can also be used to align high temperature furnaces and low temperature cryostats mounted on x-ray diffractometers.

The behavior of charged dislocations in alkali-halide crystals has been drawing attention in connection with the charge transfer which occurs during plastic deformation.1-9 Recently, Itagaki proposed a charged dislocation mechanism to account for the dielectric properties of ice.10 His theory is in part supported by the dielectric measurements o f strained ice made by Ackley and Itagaki.11 Brantley and Bauer12 derived similar equations for the dielectric constant based on charged dislocation motion. They also proposed a new mechanism for apparent piezoelectricity based on moving charged dislocations in an electric field .

Because the cost of the large number of standards required for quantitative X-ray fluorescence analysis is prohibitive, a mathematical procedure, the “fundamental parameters method” is gaining popularity. A major problem in using the method is the limited knowledge of the spectral distribution of the primary radiation from the X-ray tube, the need for a large computer memory which makes it difficult to use with minicomputers and uncertainties in the basic parameters. A monochromatic X-ray source was developed to avoid the problem of the spectral distribution. This permitted simple calculations for the calibration and a simple algorithm to transform the intensities to mass fraction or coating thickness. The calculations were made with a slide rule calculator.

Empirical algorithms for the treatment of interelement effects in x-ray fluorescence spectrometry are reviewed. It is recommended that the effects of tertiary x-ray emission be treated separately from those of x-ray absorption, and that standard reference materials of composition close to that of the specimen be used.

We have recently described an automated powder diffractometer, the APD-3500, in which a small (4K x 18 bit) minicomputer is utilized for hardware control and data processing. Among the software programs developed for this system is a “Peak Search“ routine which is designed to record a diffraction pattern with optimum, use of scanning time and to give output directly in J.C.P.D.S. Powder Data File Format. Optimum use of scanning time is achieved by a double-pass System in which a first (rapid) pass is made to establish significant data.

A second routine is a “Line Profile” routine which gives the choice of rapid slewing or slow Step scanning of the goniometer between selected angular ranges. The routine thus allows the controlled stepping of the goniometer between selected angular ranges giving incremental and integral, background corrected counts. An automatic internal and/or external calibration capability makes this particular mode ideal for quantitative analysis.

Use of Chelex-100 impregnated filter membranes for preconcentration of uranium in ground-water samples for XRF analysis leads to lower processing time, sample size, and detection limit than achieved in a batch extraction process. Data is presented, for potential effects of iron and organic matter in natural waters upon the recovery of uranium when using Chelex-100.

This is a review of Total reflection X-Ray Fluorescence (TXRF) applications for semiconductors. This review is limited to surface analysis of contamination for semiconductors and does not include chemical analysis in semiconductor processing. TXRF for surface analysis is a relatively new technology. One of the first publications occurred in 1986 using synchrotron radiation. Publications using commercially available TXRF instruments for semiconductor applications began in 1988. Today there are on the order of 100 TXRF instruments worldwide in the semiconductor industry. Since 1988 there have been about 100 publications in this field, but this number does not include numerous abstracts and publications in Japan where the majority of the commercial instruments are found today. The commercial instruments were developed for the primary application of characterizing the cleaning of planar silicon wafers, however, numerous unforeseen applications were developed by users and many of those applications are reported here. In essence TXRF has much broader application today in the semiconductor industry than supporting the cleaning of silicon wafers.

Polarized x-rays are used to excite samples of any kind and shape to emit characteristic radiation. In the appropriate geometry, where source-sample-ED detector are in any orthogonal position to each other, the exciting poLarized x-rays will be practically not scattered from sample and substrate into the detector. This reduces the background considerably and hence improves the lower limits of detection. The production of intensive polarized x-rays is done by using a single crystal-where Bragg reflection occurs at an angle 2 θ = 90° instead of amorphous low Z scatterers. The result is a linear polarized and monochromatic beam. The use of curved crystals instead of plane single crystals further increases the intensity of the exciting radiation. The lower limits of detection attainable with the recently constructed compact polarizer device are in the sub ppm range or in absolute amounts around 150 pg for medium Z elements.

Two years ago a paper on a new method of X-ray fluorescence analysis was presented. This method uses a variable take-off geometry and permits a quantitative analysis without calibration curves or the knowledge of the primary X-ray spectrum. As references either chemically analysed samples or pure elements are used. In case that only primary excitation exists, under the aspect, mentioned above, the method is to be regarded as “absolute”. For secondary excitation a simple parabolic approximation has been introduced, which requires a calibration. This paper gives an outline on the progress obtained during the last two years.

The majority of sulfide mineral patterns in the International Centre for Diffraction Data Mineral Powder Diffraction File have historically been of low quality (e.g., FN < 10 and qualitative intensities). A five-year study has resulted in upgrading approximately 20% of the poorer quality patterns and will triple the number of “star quality” patterns. This paper describes the experimental methods used to obtain these upgraded patterns. The essential role of diffraction pattern calculations and diffractogram simulations is stressed.

Thin film technology is rapidly evolving today, and the characterization of the thin film and its surface have become very important issue not only from scientific but also technological viewpoints. Although x-ray diffraction measurements have been used as suitable evaluation methods in crystallography studies, its application to the structural evaluation of the thin films, especially organic one having the low electron densities, is not easy due to the small amounts of scattering volume and the high obstructive scattering noise from the substrate. However, the x-ray diffraction measurements under grazing incidence will aid not only in overcoming the such problems but also in analyzing in-plane structure of the thin films. Therefore, so-called grazing incidence x-ray diffraction (GIXD) has been recognized as one of the most powerful tools for the surface and thin film studies.

The fundamental-parameter technique is an important tool for quantitative x-ray chemical analysis and is routinely applied for the quantification of bulk specimens and single layer films. A method extending it to multiple film layers has recently been introduced by Mantler and results from such applications have been reported by Huang and Parrish. In addition, fundamental-parameter methods can be employed to predict intensity ratios of fluorescent lines as well as the spectral distribution of radiation scattered by the specimen (shape of the background in the vicinity of emission, lines). This is useful for accurate quantitative analysis in the case of a poor peak-to-background ratio, where the precise determination of net intensities is difficult.

This paper deals with soft X-ray spectra of compounds which have one or more spectator hole(s) in the valence orbitals. The aim is to give a simple picture of the complicated chemical effects and to describe implications of the chemical effects to know the chemical state from the complicated spectra of materials. The first example of the system which has a spectator hole in the valence orbital is the intensity modifications of the shake-off satellites (KM-→LM) in chlorine Kα spectra. The second example of the system which has spectator holes in the valence orbitals is the multiplet structure of Lα spectra of the transition-metal compounds. It is described that the chemical effects of these two systems are clearly interpreted by the avoided crossing [1] of the molecular orbitals, one of which has a localized hole. We also describe the systems which have no spectator holes. The interpretation of the X-ray spectra of these systems are easy by a molecular-orbital calculation at the ground state.

The following study is an evaluation of several different types of instrumentation available for use in powder x-ray diffraction work. The particular units used are those at the Dow Chemical Company x-ray diffraction lab. The variety of instrumentation allows analyses from routine phase identification to more specialized work such as low-angle x-ray diffraction of polymers and high-resolution analysis for cell parameter refinements.

The purpose of this work is to compare the relative capabilities of these different instruments under typical day-to-day operating conditions. While not a comprehensive study, the conclusions drawn should be applicable to powder x-ray diffraction in general.