The interpretation of solar x-ray data obtained from KAP crystal spectrometers requires new laboratory measurements. We used a plasma x-ray source and a KAP spectrometer similar to solar spectrometers and measured the following.

The results of two crystal measurements of potassium acid phthalate crystal first order parallel position rocking curves, percent reflections, and reflection coefficients are presented. They cover the 4-24 Ǻ wavelength range and are typical of results with cleaved crystals illuminated over areas of one-half to two square inches. The energy resolution available with these crystals is shown to be nearly constant at about two-thirds of an electron volt over most of the energy range studied and the coefficient of reflection is also nearly constant at about 1 x 10-4 radians. A pronounced line-like reflectivity structure at 23.3 Ǻ is exhibited which is probably associated with oxygen atom K-shell absorption.

A programme of grazing incidence grating studies is described, undertaken in collaboraion with A.W.R.S. Aldermaston, U.K.A.E.A. Culham and N.P.L. Teddington. The wavelength range of interest is from lǺ - 300Ǻ with special emhasis placed on focusing systems for use below 5Ǻ.

The results reviewed in this article were obtained by means of the ESCA technique at the Institute of Physics, University of Uppsala, Uppsala, Sweden and at the Department of Physics, Vanderbilt University, Nashville, Tennessee, USA.

The ESCA technique is basically the study of induced emission of photo and Auger electrons from a sample irradiated with x-rays. If the incident radiation is monochromatic (e.g. an x-ray emission line) the spectrum of these electrons gives precise information about the energy states of the electrons in the sample. To extract this information, high resolution electron spectroscopy is necessary. Instruments for such spectroscopy have therefore been extensively developed during the last decade.

A new type of x-ray photoelectron spectrometer has been designed. Although smaller in size, the new instrument shows a considerable improvement in sensitivity compared to other photoelectron spectrometers. This has been achieved through the provision of several new features: The photoelectrons are retarded to low energy (10 eV through 100 eV) before entering the deflecting energy analyzer. A spherical electrostatic analyzer in figure of rotation is used. Annular slits at both source and detector provide a large effective source area. The instrument is shielded against external magnetic fields (earth magnetic field and a.c. fields) by a double layer of mu-metal, thus avoiding the installation of large Helmholtz coils.

The possibility of obtaining Auger spectra excited by a Po 210 α-source has been investigated. The obvious advantages in the use of radioactive α-sources are simplicity, stability, and high ionization cross section for light elements. Typical spectra obtained with this method, as well as parameters affecting the characteristics of these spectra, are presented and discussed The following observations have been made: the intense low energy continuum background make it difficult to detect the presence of Auger lines in this region; the abundance of Auger lines in the above region makes identification difficult; the intensity of higher energy Auger lines is too low to be observed with the present α-source and low vacuum system; thus the practicability of α-excited Auger spectroscopy will need further investigation.

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,

In a number of laboratories data from the X-ray pole-figure goniometer are now processed numerically to obtain a suite of complete and normalized pole- figures. From these pole-figures the preferred orientat ion of the grains in a monomineralic aggregate is determined using spherical harmonic analysis and represented as a frequency distribution of the Euler angles Ψ, θ, ø, termed the “orientation distribution function” (ODF),When the frequency density of grain orientations is plotted in a Cartesian coordinate system with Ψ, θ, ø, as axes,it must have a translation periodicity Of 2π or less along each of the axes, because the Euler Angles are angles of rotation.

A commercial powder diffractometer linked to an IBM 1800 time sharing computer is used for the precision determination of lattice parameters on single crystals with Bond's method of measuring the angle between two diffracting positions of the crystal, symmetric to the incident x—ray beam. A remote x-ray tube and collimator allows a high angle Bragg reflection to be measured easily in these two positions with only one detector. After scanning the two diffraction line profiles, the peak positions and the lattice parameter are determined on line by the computer. Several methods for determining the peak position are discussed. Using these techniques, the lattice parameter of silicon has been determined on two crystals of high purity and perfection to a0 = 5.43093 ± 0.00002 Å and a0 = 5.43095 ± 0.00002 Å at 25°C. These values are in excellent agreement with Bond's result, a0 = 5.430935 ± 0.000019 Å, and they differ slightly from the value a0 = 5.43074 ± 0.00017 Å, the mean value of, lattice parameters measured on silicon powder in 16 laboratories under the I.U.Cr. precision lattice parameter project.

The development of materials with optimum fatigue characteristics hinges on a better understanding of the fatigue mechanism ( i .e ., fatigue crack nucleation and propagation) under specific loading conditions. A correlation was established between the residual macroscopic stress level--as measured by x-ray diffraction analysis, the fatigue damage in the form of slip-band formation and intensification, and the fatigue life at various applied stress levels of pure iron and low-carbon steel.

Residual stresses were measured by an automated diffractometer technique (Fe 211 Kα reflection, Cr radiation) and computer calculation of both macroscopic (line shift) and microscopic (line broadening) stresses . Surface fatigue damage was observed by optical microscopy.

X-ray stress factors for a carburized steel were determined experimentally as a function of tempering temperature from loaded cantilever specimens . The standard X-ray stress expressions were modified to account for both the applied calibrating stresses and the biaxial residual stresses present in the surface of these specimens. The resulting equations permitted calculation of the ﹛ 211 ﹜ stress - free interplanar spacing, elastic modulus and Poisson's ratio from the X-ray data.

Tempering to higher temperatures reduced significantly the surface residual compressive stresses and stress - free spacing. The change in spacing with tempering of these specimens must be considered when determining elastic stresses by the one-exposure X-ray technique. Tempering also produced a linear relationship between the tempered hardness and ﹛ 211 ﹜ interplanar spacing.

X-ray diffraction topographs of modes in rectangular AT-cut quartz plates are shown. The change in the resulting patterns when different Bragg planes are used is demonstrated. Diffracted x -ray intensity was measured as a function of strain in a vibrating quartz plate . The Lame solutions for quartz plates are briefly described and some experiments suggested for x -ray topography. Finally modes in quartz plates with multiple electrodes are shown indicating the complexity of this type of vibration problem.

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 .

Since for most real systems, solid solution effects influence the position and intensity of the x-ray powder diffraction pattern, it is desirable and necessary to have an automatic system which will identify standard reference phases regardless of the amount of solid solution. Using the system CdS-ZnS, where the lattice parameter a0 changes from 4.136 to 3.820Å, with complete solid solution over the entire range of composition, an illustrative study was made. This work presents the results obtained from a computer analysis of the powder pattern obtained. It has been found that if the starting chemistry is known and the end members of the series are in the ASTM Powder Diffraction File, that the solid solution can be identified. Once the phases present are identified, a plot following Vegard's law yields the approximate composition of the sample under consideration. These two methods of compositional determination agree quite well. Examples of the computer system and description of the program input and output with interpretation of the results will be discussed.

An interchangeable Bragg-Brentano:Seeman-Bohlin diffractometer, with variable specimen setting, has been constructed. A study of the influence of the geometry on the resolution, angular displacement and intensity of diffraction profiles clearly demonstrates that the standard Bragg-Brentano method is to be preferred when recording Bragg reflections below 40°,2θ. At higher Bragg angles, which permit the specimen to be set further away from the X-ray source, it is demonstrated that the diffracted intensity of the Seeman-Bohlin method can be increased above that of the Bragg- Brentano because the use of an increased divergent angle does not reduce the resolution. A study of the effect of specimen setting on the systematic errors associated with the Seeman- Bohlin geometry indicates that a setting of 60° (half-angle from the X-ray source) gives optimum resolution with minimum displacement error.

The long range order parameter (S) has been measured at room- temperature on the γ’ phase extracted from IN-731 and alloys 713C and 713LC by x-ray diffraction techniques. Measurements were obtained from specimens of IN-731 and alloy 713LC in the as-cast condition and after long time rupture testing. The alloy 713 c specimens were in the as-cast and high temperature heat treated conditions.

It was found that long range order in the γ’ phase of IN-731 and alloy 713LC was changed very little after long time rupture testing, and after high temperature heat treatment in the case of alloy 713C.

Many of the chemical and physical interactions that take place in natural soil-water systems are strongly influenced by the presence of natural organic polyelectrolytes. The most common of these organic polyelectrolytes is humic acid, which is defined as the alkali soluble, acid insoluble fraction of soil organic matter. Over a hundred years of experimental data have demonstrated that a wide variety of different materials having different physical and chemical properties fit this definition. If we are to make any progress in understanding the role of humic materials in soil-water systems, then we must have a classification system which, as far as possible, provides a unique taxonomic definition for each separate molecular species that falls into the category of humic acid.

A small-angle X-ray scattering apparatus is described which is based on a Guinier focusing arrangement, utilizing a fine-focus tube, a Johann-type curved-crystal monochromator, two goniometermounted beam-defining slits and proportional detection. It differs from previously described instruments in important respects. Using a horizontal goniometer, it affords ease of access and mechanical stability to mounted parts, such as slits and beam stop. The major instrument assemblies--the horizontal tube housing producing the vertical line-shaped beam, and the goniometer table--are mounted on a granite surface plate for stability. For ease, precision and reproducibility in alignment, fine adjustments, with micrometer heads or dial indicators where advisable, are provided for all pertinent rotational and translational motions of the various subassemblies. In particular, provision is made for fine adjustment of the goniometer as a whole with respect to the X-ray source, to facilitate threading the monochromator-focused beam through the slit system and the center of rotation of the detector arm.

For quantitative electron probe analysis, the raw intensity ratios must be corrected to take into account deviations due to absorption, fluoresecnce and electron beam penetration. The major correction is usually the absorption correction, so that for best results, accurate mass absorption coefficients are required. Many tables of absorption coefficients are calculated by interpolation or extrapolation from available measured values, and therefore new measurements are required for increased reliability. The region which requires the most attention for present-day probe analysis is the 2 to 10 Å range.

Thin foils of the lighter metals are available for mass absorption coefficient measurements, but heavy metal foils, which must be extremely thin, are not obtainable, A method has been developed to prepare thin films of heavy metals on a suitable substrate by pyrolytic decomposition of metal organic compounds.

Physical and chemical analysis, X-ray astronomy and high temperature plasma diagnostics which utilize the ultrasoft X-radiations hare made evident a strong need for filling the gap in measured absorption coefficient data for the radiations between the conventional X-rays and the extreme ultraviolet. More than one hundred new coefficients have been measured in this laboratory on the gas state, atomic or molecular, containing He, C, N, 0, F, Ne, S, Cl, Ar, Kr and Xe using eleven fluorescent, characteristic wavelengths Al-Kα (8.34 A) through Be-K (113.8 A). The radiations were isolated by Bragg reflection from multilayer analyzers of the Langmuir-Blodgett type and by pulse height discriminating proportional counter intensity measurements.