In XRF wavelength dispersive sequential spectrometers, two general types of X-ray tubes are employed: end-window and side-window. In the side-window design, anode and window are grounded. This allows a large portion of high energy electrons, scattered from the target, to fall on and heat the window. The heating, which results in the loss of window strength, requires increased window thickness and shortens an X-ray tube's life cycle.

In end-window tubes, potential is reversed: cathode and window are grounded while the anode operates at a high potential. Scattered electrons are attracted back to the anode with very few striking the window. The window does not suffer from heating, and its thickness can be decreased to 125 microns. Such a window is transparent to soft radiation, which is beneficial when exciting light elements.

It has been recognized that more nearly perfect crystal surfaces have a low intensity of X-ray reflection as a result of extinction effects. Therefore, it has been common practice to abrade analyzer crystals used in X-ray fluorescence analysis so that they approximate so-called mosaic crystals.

While investigating the intensity of reflection from various ADP crystals about 10 years ago, one of the authors (A) and his colleague discovered that wavelength dependence of the intensity of reflection widely varied among crystals. in other words, crystals that had a high reflection intensity for short wavelengths displayed a low reflection intensity for long wavelengths, and crystals effective for long wavelengths were not effective for short wavelengths. Also, they discovered that this phenomenon was related to the perfect quality of the crystal surfaces. As-grown crystals were more effective for longer wavelengths than commercially available crystals into which a certain amount of imperfection presumably had been introduced.

A high vacuum soft x-ray source has been coupled to a large volume experimental chamber to provide a versatile facility for x-ray investigations in the energy range of 0.1 to 10 kev. The source chamber presently contains a modified Herike tube, but can employ any of a variety of source designs. The large experimental chamber is equipped with a kinematic mount to position a number of x-ray optical instruments. The source and experimental chambers are connected through a high vacuum valve/shutter, and are pumped separately with provision for a thin window to isolate one from the other, single and double crystal spectrometers have been used in the experimental chamber. A variable chord diffractometer/reflectometer using double crystal monnotiromatization has been designed, in addition, the facility has been used to expose photoresists in x-ray lithography tests.

Spectrographic analysis of light elements by soft and ultrasoft fluorescent x-rays has become a useful technique for many applications of elemental analysis, using single crystals, soap multilayers and a combination of total reflection and filtering.

Instead of the wavelength dispersive method based on Bragg reflection which provides high resolution combined with low reflecting intensity, monochromatization combining total reflection by a selected mirror and an appropriate filter offered an alternative approach in order to increase measurable intensity with reasonable spectral resolution.

Recently, the use of synthetic multilayers, which are prepared by sputter/evaporation techniques, has been introduced for the detection of soft and ultrasoft x-rays. Studies on the use of these new wavelength dispersing devices have been conducted and it has been found that the reflectivity of these devices is very high compared with single crystals and soap multilayers and that their resolving power is fairly good.

There has recently been growing interest in various atomic and nuclear techniques for the measurement of elements in the body. This has arisen through the realisation that (a) clinically-important amounts of toxic elements can be absorbed as a result of low-level environmental exposure, and (b) important information about the nutritional status of a patient can be obtained from measurements of major body elements. Where such information can be obtained by taking samples, a very wide range of analytical techniques is available, some capable of a sensitivity measured in parts-per-billion. Sampling is not possible, however, when the whole-body content (e.g. of nitrogen) is required, and is clinically undesirable when the element in question is concentrated in particular organs, for example as lead accumulates in the bones, and cadmium and many other toxic elements accumulate in the kidneys. It is in such cases that the various in vivo techniques are particularly important.

The present paper describes an energy-dispersive x-ray fluorescence method for measuring tin in bis(tri-n-butyl)tin-oxide impregnated wood. The proposed method is of the backscatter/fundamental parameter type. Its versatility, precision, and accuracy is demonstrated by analyses of eleven samples of sapwood of Baltic Redwood. The results obtained are compared with those from neutron activation analysis.

The present paper studies the precision and accuracy that can be achieved using energy-dispersive x-ray fluorescence spectrometry for the determination of total sulphur content in BCR 38 Fly Ash issued by the European Community Bureau of Reference.

For the period after about 100 B.C., the Southwest has been broadly divided into four culturally distinct regions: the Anasazi, Mogollon, Hohokara, and prehistoric Yuman culture areas. Definition and identification of these areas has been based largely on extant material culture, particularly pottery and house-types. Pottery is especially important in archaeological investigations because it is unquestionably man-made and it is virtually indestructible in the dry Southwestern climate. The pottery produced by the inhabitants of the Southwest is also highly variable through time and across space, so that over 900 distinct ceramic types have been defined for Southwestern culture groups. And since potters tended to use materials available in the vicinity of their villages, materials analysis of plastic and nonplastic constituents of ceramics can aid in evaluating where pottery was made.

X-ray fluorescence (XRF) was required to analyze vehicle exhaust particulate samples deposited on filters to determine the trace element content of the emissions. These samples were collected as part of a study to assess the role of vehicular particulate emissions in the Denver “Brown Cloud” problem. This study was an adjunct to an earlier study of vehicular gaseous emissions at high and low altitudes. The earlier program involved complete certification testing of a fleet of twenty five (25) 1970, non-catalyst vehicles but did not include analysis of exhaust particulate emissions. Consequently, a subset of the original vehicles was selected for retesting at high and low altitudes. A complete analysis was necessary to compare the ratio of particulate carbon to lead in the vehicle particulate emissions at the Denver test site.

The chemical and mineral analyses of river and stream sediments are often employed for geochemical exploration. Their contents are considered to be representative of part or all of the catchment area. In environmental science the analysis of sediments provides information concerning the hydrochemical and ecological interactions of the water and their changes with time. Local and/or time dependent contamination of water bodies can also be determined by analysis of their sediments.

In this work, we have first performed qualitative elemental scans by both energy dispersive (radioisotope excited) and conventional wavelength dispersive X-ray fluorescence of the different grain size fractions.

Several kilometers of drill core are sometimes obtained when the geology of a particular area is explored. The cores are visually inspected and a limited number of samples are taken for laboratory analysis. Accurate chemical analyses are usually performed on only a small number of core sections because of the expense involved. A chemical profile along the core may provide useful information not available by any other means. This information may be of primary value for geological investigations or it may provide an additional basis for selecting samples for detailed laboratory analyses.

A modern analytical laboratory of a large corporation manufacturing paper, construction materials and chemicals must be sufficiently diversified in methodology to provide accurate results in the shortest possible time. Among other techniques the implementation of an automated “menu” driven wavelength dispersive spectrometer allowed for the setting-up of a variety of quantitative X-ray fluorescence methods.

The use of diatomaceous earth in industry as filtering aids, mineral fillers, catalyst carriers, chromatographic supports, and paint additives is well documented. The diatomite matrix is well suited to x-ray analysis, but this application has not been cited in the literature. In our laboratory, x-ray fluorescence spectrometry has been used to support the analytical needs of diatomite product development. Lithium borate fusion and pressed powder techniques have been used to determine major, minor, and trace elements in diatomite and synthetic silicate samples. Conventional matrix correction models and fundamental parameters have been used to reduce x-ray measurements to accurate chemical analyses.

Fundamental parameters calculations are used for the analysis of europium in the concentration range of 0.1 WT% to 30.0 WT% in the oxidic catalyst supports alumina, calcia, magnesia lanthania, and thoria. The precision and accuracy of this method is dependent on how the sample matrix is defined in the fundamental parameters program and the number and concentration of the standards used. Results comparable to the multiple regression method are obtained when the matrix stoichiometry is defined as Eu2O3 and the catalyst oxide (i.e. Al2O3 etc). It is also necessary to use standards which bracket the europium concentration in the samples. When these conditions are met, the results are comparable to those obtained from a ten point multiple regression calibration curve but with a considerable saving of standard preparation time. The precision is better than ±2% relative. The % relative difference between the fundamental parameters and multiple regression results is also 2%. Data is presented which illustrates the effect of defining the sample stoichiometry in the XRF11 computer program.

The combination of the energy-dispersive x-ray fluorescence technique and a backscatter/fundamental parameter-based matrix correction approach provides a new and unique solution to elemental analyses of fertilizers. This is demonstrated by means of results obtained for three reference materials and a range of in-house fertilizers. The results further demonstrate problems of sample preparation as well as the precision and accuracy of the method.

Rapid X-ray fluorescence (XRF) analytical methods have been developed for analyzing wet-process phosphoric acid liquid samples and by-product calcium sulfate filter-cake solids. Liquid acid samples are neutralized by lithium carbonate and pressed-pellet, dry sample wafers are prepared for a nine-element analysis. Filter-cake solids are dehydrated to anhydrous calcium sulfate for a ten-element analysis. Hovel sample preparation techniques are described which permit maximum use of the automated XRF system for process control. Precision obtained for typical materials is compared with results of conventional chemical analyses.

Over the past 25 years, numerous studies utilizing both X-ray diffraction (XRE) and differential scanning calorimetry (DSC) have been reported In the literature. Generally, conventional high-temperature X-ray data identifies solid-state transitions, then attempts to correlate them with thermal events observed by the calorimeter. Since changes occur in the sample during studies such as these, separate portions of the sample must be used for XRD and DSC experiments. When comparing results of the two experiments, questions arise concerning sample homogeniety as well as temperature and environmental differences. In fact, no conventional high-temperature X-ray diffraction instrument can give the precise control over temperature and heating rate available with a DSC, The problems of sample inhomogeneltles and Instrumental differences could be avoided if X-ray diffraction and DSC could be performed simultaneously on one sample.

Annular counters are finding increasing application in x-ray diffraction. They are well suited for detection of weak diffracted beams because of their ability to capture an entire Debye ring. This is especially true in the case of microfocus diffractometers, where the Illuminated sample area may be a spot less than 100 microns in diameter. Unfortunately, the geometry of the annular counter precludes the use of a diffracted beam, monochromator. However, near monochromatic conditions can be achieved by using balanced filters to bracket the K alpha line, or any other line of interest. We discuss here the application of balanced filters to the Rigaku microdiffractometer, which uses Debye-Scherrer optics.

We have automated a Seeman-Bohlin Guinier x-ray diffractometer by interfacing it to a minimally configured PDP 11/23 computer. The programs that run on the microcomputer to control the operation of the diffractometer are stored on a mainframe host running the UNIX+ operating system. A software interface allows a particular data acquisition program to be downloaded from the UNIX host and executed on the satellite processor. This same interface allows the collected data to be periodically off-loaded to the host for processing and storage.

In August of 1982, a single-user, dual-translator, automated powder diffraction system was purchased by the Denver Research Institute for use on project work in the Chemical and Materials Sciences Division. Within a short period of time, the system had already become saturated with users. Scheduling conflicts arose around the need for one user to be reducing data while another was acquiring or the need of a user to begin a data collection run on one goniometer after another had already been started. In view of these problems, an answer was sought in the form of hardware and software changes which would allow many users access to the system simultaneously, either for the purpose of data collection, data reduction or program development. A low-cost, minimum impact solution was eventually found which we feel, has significantly increased the utility of the basic L-11 system without sacrificing either flexibility or speed.