Ila group metal - Zr pcrovskitc type compounds (MZrO3, M=Ba. Sr and Ca) and other oxides were studied by XPS to know the effects of M atoms to Zr atoms. And the feasibility of using XPS and high-resolution XRF for the coordination analysis of Zr atoms was examined for some kinds of stabilized zirconia. An almost linear relationship between the energy of Zr 3d peaks and the radii of Ila group metal ions was found, and, a simple model to interpret this relationship has been proposed. However, no relationship between the energy shifts of Zr 3d spectra or Zr Lα1, 2 spectra and the coordination numbers of Zr atoms in the several Zr oxide compounds was found. Thus, the coordination analysis using XPS or high-resolution XRF is not feasible.

The depth range d of x-ray photoelectron spectrometry (XPS) is determined by the inelastic mean free path λ of photoelectrons . The following considerations are dedicated to a correlation between d and λ.

This review will attempt to show how XPS now makes an important contribution to Materials Science and to highlight the developments which have brought it to this position. XPS is now a mature technique for surface analysis but it has in addition a major role as a specialised tool, being essential to studies in which derivitization methods are used to tag surface groups.

The requirements of users in this field have led to the development of X-ray sources which were not envisaged in the early development of the spectroscopy. The usual sources of aluminium Kα and magnesium Kα have limitations for those elements beyond magnesium in the periodic table which would have the Is lino as the principal peak - aluminium, silicon, oulphur and phosphorus for example. Higher energy sources such as silicon Kα or zirconium and silver Lα have made it possible to utilise the Is lines up to chlorine and have the additional advantage that a strong and well resolved series of Auger lines also becomes available. The higher energy radiations are thus particularly suited to the determination of relaxation energies in materials by use of relative shifts between the photo- and Auger lines of the spectrum. Such has been the utility of such relaxation energies that use is often made of Auger lines derived from the Bremmstrahlung component of the normal x-ray sources to make a similar measurement. This measurement is used in the study of insulating ceramics in which electrostatic charging makes measurement of binding energies uncertain.

Modern materials technology is particularly concerned with the manufacture of composites; particulate, fibre and laminate composites are all well known and the key to their success often lies within the interface between the phases. Transfer of load across the interface places particular requirements on adhesion at the phase boundary and an understanding of the locus of failure during destructive testing is crucial to the development of satisfactory bonding processes. In coated and laminated products there is no problem in the use of XPS, with its excellent chemical sensitivity but there is a problem of increasing magnitude in fibre and particulate composites as the substructures become finer. This stems, of course, from the difficulty of providing a focused source of X-rays of sufficient magnitude. Imaging XPS is slowly becoming a reality with several systems having a capability of 10μm now available, and one of the markets for such instruments is that of composite materials.

There are important areas of Materials Science in which XPS has been displaced by other techniques such as SIMS. One such area is that of polymer surface analysis. The selectivity of XPS for substituent groups in the surface region is not good. Derivitization methods have made an impact, enabling acidic or basic groups to be determined, but SIMS, which has the ability to detach molecular clusters, has obvious advantages which will become increasingly exploited aa the problems of charging become solved. Until then however XPS will continue to find a role in polymer research and development.

X-ray excited Photoelectron Spectroscopy (XPS) has become an indispensable tool for the study of metals and semiconductors. Due to the small mean free path of the photoelectrons In solids of the order of a few nanometers for energies in the keV range, it is a surface analysis technique. Its capability of quantitative analysis of all elements except hydrogen and helium and their chemical bonding states has recently been combined with small area and imaging analysis to typical spatial resolutions of about 10 μm. After a brief survey of the basic capabilities and limitations of XPS, some illustrative examples in typical metals and semiconductor research areas are presented, such as surface contamination and failure analysis in microelectronics, oxidation and corrosion, segregation at surfaces and interfaces, oxide/metal and oxide/semiconductor interfaces, and thin film analysis using angle resolved XPS and sputter depth profiling. Recent developments emphasize improved data evaluation and quantification schemes as well as instrumental capabilities with respect to both high spatial and energy resolution, and high power excitation sources such as synchrotron radiation.

For the application of TXRF in trace element analysis, two characteristic features of the total reflection of X-rays are exploited. These are the high reflectivity on flat surfaces and the low penetration depth of the primary radiation. This allows the application of TXRF for both chemical trace and ultra-trace element analysis on the one hand and surface analysis on the other. For chemical trace clement analysis, total reflection on a highly polished substrate is characterized by a high reflectivity, which leads to a drastic reduction of the spectral background. The sample to be analyzed is prepared on the substrate as a residue of small quantities by evaporation from solutions or fine-grained suspensions. Instrumental detection limits of a few pg or sub-ng/ ml−1 arc state of the art for commercially available equipment. Besides the high detection power, internal standardization is another important feature of TXRF, enabling very simple quantification of the detected elements. The small sample mass required enables especially ultra-micro analytical questions to be tackled. For trace element analysis in surfaces the low penetration depth of the primary radiation under the conditions of total reflection is exploited. The penetration depth is in the range of a few nanometers, hence, TXRF is intrinsically surface sensitive. Detection limits better than 1010 atoms/cm2 are obtained for metal impurities on silicon wafers. For the examination of layered structures elemental composition, layer thickness, and density can be derived from die angle-dependent fluorescence intensities. The present paper describes the basic features of the total reflection of X-rays and gives some representative examples of the different uses of TXRF in trace element analysis.

Improving the detection limits in TXRF by optimizing the excitation conditions is the goal of this work. The properties of the exciting radiation due to spectral distribution, polarisation, intensity and energy are investigated and compared to find best conditions. Results are given from experiments performed with synchrotron radiation, Bragg polarized monoenergetic x-rays, high energy cut-off reflector in the primary beam path of a high power x-ray tube and several geometries for the sample reflector.

This article describes the instrumentation for a total reflection fluorescent x-ray spectrometer. The reflecting intensity and the angular divergence were studied with respect to various kinds of monochromators. Using silicon wafers, the angular divergence effect of the incident beam, surface roughness influences and the smoothing of background x-ray intensity for the improvement of the lower limit of detection were investigated.

Total Reflection X-ray Fluorescence Spectrometry (TXRF) has been used for the characterisation of a 20 nm thick Ni/Fe/Cr-layer on a silicon substrate. Instrumental aspects of the technique as well as the data evaluation procedure on the basis of modelling calculations are outlined in this paper. The effect of standing waves is discussed by means of the selected example. This particular layer serves also as an illustration of the capabilities and limitations of TXRF. At least three surface parameters are covered by the technique, elemental composition, density and layer thickness.

Total Reflection X-Ray Fluorescence Analysis (TXRF) has become a powerful analytical tool for trace element analysis. Because of its advantages in excitation and background reduction TXRF has been applied for the analysis of light elements (C,O,F,Na,...). A special Ge(HP) detector offering an ultra thin window in combination with a spectrometer specially designed for the requirements of light element analysis was used. Also a new windowless X-ray tube for efficient excitation of the light elements was tested. The system was checked with standard aqueous solutions; detection limits in the ng range (7 ng for O) are obtained.

In the framework of interdisciplinary research projects TXRF has been applied for multielement analysis of rainwater, size-fractionated airborne particulates, throughfall samples and litter fall in forests, soil solutions, seepage water, river water filtrates and suspended particulate matter. Essential aspects of sample preparation techniques are briefly described. Some results are given on trace element fluxes in a forest ecosystem and on contaminant transport phenomena in estuaries in order to demonstrate the outstanding capabilities of TXRF in demanding environmental research projects.

The total reflection x-ray fluorescence (TXRF) method of analyzing elemental contents Is based on the small angle irradiation of thin samples placed on a total reflecting backing with a narrow photon beam. Two instrumental problems are to be solved here. The first is to form the narrow beam with a small angular deviation. The usual way to solve this problem is to use collimators with small solid angles. These angles must be less than the critical angle for x-ray total reflection, which, in the energy range 10 - 20 keV has an order of magnitude around 10−3 rad.

The Total Reflection X-Ray Fluorescence method was used to detect low level (ppb) uranium concentration in water.

A new procedure for indirect determination of pharmaceutical drugs is presented. The procedure consists of extracting ion pairs between organic basic compounds, that is, pharmaceutical drugs and cobalt tetrathiocyanate and of determining Co contents in the organic extraction phase using total reflection X-ray fluorescence spectrometry. Quinine, papaverine and pilocarpine are used as pharmaceutical drugs and 1,2-dichloroethane is adopted as extraction medium. Quinine cobalt tetrathiocyanate complex was isolated and was analyzed by FT-IR (Fourier Transform Infra-Red spectroscopy) suggested that approximately 4 ng of quinine could be detected by 1 μl of sampling of organic phase under ideal conditions using total reflection X-ray fluorescence spectrometry. These drugs have their own optimal pH for extraction. This technique can be applied to cocaine analysis.

Linear polarized x-rays are used as exciting radiation to reduce the background and to improve the detection limits in XRF. A combination of an x-ray tube and a measuring module realizing a compact cartesian geometry was constructed. An on-line adjustable Bragg-polarizer, a Barkla-polarizer or a secondary target can be used optionally. The anode material of the tube can be changed easily.

The intensity performance of various common XRF crystals (LiF200, Ge, PET and LSM) has been investigated under fixed experimental conditions. Measured were the raw intensities of elements particularly suitable to a given crystal, and peak-to-background ratios at different elemental concentrations. Peak profiles for each crystal type were also recorded and analysed in terms of apparent crystallite size and mosaic spread. In general the LiF crystals showed least variability in performance, whereas the PET crystals demonstrated the most.

An x-ray spectrometer has been designed for pixel by pixel analysis along lines or across selected areas of paintings and other art-objects. Characteristic technical data are: 0.8mm2 pixel size, 800mm (vert.) by 1000mm (horiz.) by 200mm (perpendicularly to object) motion distances, ±20μm precision in positioning the system, 2x3m maximum object size (mounted vertically); 2.8kW x-ray tube; Si(Li)detector. PC's are used for instrument control and new, complex data evaluation software.

It has been well established over recent years that synchrotron radiation possesses some unique features as a source of primary x-rays for x-ray fluorescence analysis. Advantage has been taken of the high intensity emanating from the bending magnets of storage rings to develop x-ray microprobes utilizing apertures or focussing optics, or both, to provide a beam spot at the specimen of the order of micrometers. The use of insertion devices wigglers and undulatora, can further increase the available intensity, especially for the high energy photons. Beam Line X-17C at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory, accepts the unmodified continuum radiation from a superconducting wiggler in the storage ring. Some initial XRF measurements have been made on this beam line using apertures in the 10 to 100 micrometer range. The fluorescent radiation was measured by an intrinsic Ge detector having an energy resolution of 300 eV at 15 kev, and located at 90° to the incident beam in the plane of the electron orbit. In samples containing many elements, detection limits of a few ppm were achieved with 100 μm beams.

With a new irradiation chamber a comparison of three excitation modes under same conditions and with the same material has been done. The results of this comparison are presented in the following manner: - Barltla scattering (graphite) versus Bragg reflection (HOPS) - Bragg reflection (Mo) versus secondary target fluorescence (Mo) - secondary target fluorescence (Sn) versus Barkla scattering (graphite) Excitation spectra and detection sensitivities of a NBS standard will be discussed for the different modes. The Barkla scattering was found to be the best excitation mode for a wide elemental range.

Two methods for improving the sensitivity of EDXRF will be presented. One method is to use a spherical geometry for the measurements. The analyzed specimen is made as a spherical layer (i.e., “orange rind”), with the exciting x-ray source and the detector being located in the inner surface of the specimen at opposite points on the diameter. The source radiation scattered into the detector is minimized by the 90° scattering angle at all points on the specimen. It has been shown that the sensitivity is improved by several times while earring out EDXRF measurements under conditions of spherical geometry as compared to the conventional flat arrangement.

The other method we have investigated makes use of polarized radiation. The source radiation is polarized by scattering from a thin, low atomic number material. Higher energy radiation from the x-ray tube passes through the polarizer, where it impinges on a secondary fluorescer. This secondary radiation is then polarized by the same scatterer as the primary radiation. A quasi-monoenergetic polarized source is produced with maximized intensity by these means. It has been shown experimentally that the use of this polarized source for excitation leads to detection limits which are several times lower in the whole range of moderate energy. It has further been shown that the use of the easily added secondary target to the standard orthogonal polarization geometry increases the polarized beam intensity by 10-15%.

X-ray micro analysis had suffered from the limited intensity of conventional X-ray sources like X-ray tubes etc. However, with the optical technique described in this paper, the so called “X-ray Capillary Optics” (XCO), it is possible to make X-Ray Fluorescence (XRF) analysis in micro-scale, down to a few μm2 still with conventional sources.