Energy-dispersive Diffractometer Research Articles

Energy-dispersive small-angle x-ray scattering for investigating polymer morphology: Static and time-resolved experiments

Energy-dispersive small-angle x-ray scattering couples the information given by small-angle experiments and the advantages of energy-dispersive methods, mainly in carrying out time-resolved experiments. Preliminary small-angle measurements on some semicrystalline polymers using a laboratory-based energy-dispersive diffractometer and the bremsstrahlung continuum generated from a commercial tube as x-ray source are presented. The results are in agreement with those obtained with the classical method. The apparatus utilized could be considered a promising tool to perform both wide and small-angle scattering or diffraction.

A new three-angle energy-dispersive diffractometer

A novel energy-dispersive diffractometer has been designed in which diffraction patterns can be collected simultaneously at three angles. This results in a much wider overall coverage of reciprocal space and a matching of the X-ray source and detection system to chosen regions of a pattern so that quantitative analysis is considerably enhanced. We predict a wide acceptance of the technique for in situ studies and multi-phase analysis.

Conical geometry energy dispersive diffraction: First results

A new energy dispersive diffractometer has been developed. It consists of a solid tungsten carbide conical collimator and a large area annular detector. Diffracted intensities are increased by at least one order of magnitude. Developed for high-pressure studies and their microsamples, the instrument will improve the accuracy of intensity measurements by reducing crystallite statistics effects and the collection of a complete cone of diffraction will greatly facilitate high-pressure single-crystal studies. The results of the first test of the instrument are reported.

A spectrometer for X-ray energy-dispersive diffraction using synchrotron radiation

Describes a white-beam X-ray energy-dispersive diffractometer built for Hasylab in Hamburg, FRG, using the synchrotron radiation from the electron storage ring DORIS. The following features of the instrument are discussed: horizontal or vertical scattering plane, collimators, sample environment, remote control of the goniometer, data acquisition, energy-sensitive detectors using small-area and large-area detector crystals, modes of operation, powder and single crystal diffraction. An example is given from a high-pressure study of YbH2 using a diamond anvil cell.

An X-ray energy-dispersive diffractometer for synchrotron radiation

An X-ray energy-dispersive diffractometer for synchrotron radiation

The temperature dependence of the liquid structure of carbon tetrachloride

In order to study the structure of liquid CCl 4 generally and dynamically, X-ray measurements at low and high temperatures (−20 and 63.5°C) are carried out using an energy-dispersive diffractometer. The results support the existence of fine structure in the scattering intensity and show the validity of a bcc cluster model proposed by Nishikawa and Murata. The motion of molecules in the liquid is also discussed.

High-resolution energy-dispersive diffraction using synchrotron radiation

A high-resolution energy-dispersive diffractometer is described, which uses a synchrotron source and a scanning channel-cut silicon crystal. The technique is demonstrated with a powdered sample of BaTiO3 and analysis of the profiles demonstrates the anomalous particle-size effect reported by Anliker, Brugger & Känzig [Helv. Phys. Acta (1954), 27, 99–124].

The Influence of Surface Roughness on X-Ray Total Reflection Spectra

X-ray total reflection spectra are investigated theoretically and measured using an energy-dispersive diffractometer with an SSD (solid-state detector). As the result of measurements, X-ray total reflection spectra are sensitive to the roughness of sample surface. The energy-dispersive diffractometer is confirmed to be efficiently used for measuring X-ray total reflection spectra.

X-ray intensity measurements on large crystals by energy-dispersive diffractometry. II. Energy dependence of the Friedel pair intensities and their ratio near the absorption edge

It has experimentally and theoretically been confirmed that the intensity ratio rh of Friedel pair reflexions h and {\bar {\bf h}} is given by |Fh|2/|F_{{\bar {\bf h}}}2 in a perfect crystal as well as in a mosaic crystal both in the symmetrical Bragg case and in the symmetrical Laue case. The measurements have been carried out on a nearly perfect GaAs crystal plate in the energy range near the As K absorption edge by the use of the energy-dispersive diffractometer and continuous radiation. These results have shown, a reasonable agreement with the relevant theoretical curves. The limitation of the above relation in tile presence of extinction effects has been considered.

X-ray intensity measurements on large crystals by energy-dispersive diffractometry. I. Energy dependence of diffraction intensities near the absorption edge

The intensity variations of X-rays diffracted from a nearly perfect GaAs plate have been measured in symmetrical Laue and Bragg cases in the energy region near the As K absorption edge with small energy intervals, by the use of an energy-dispersive diffractometer and continuous X-rays from a sealed-off tube. The corresponding intensity variations have been calculated with the dynamical theory. These measurements and calculations have shown a good agreement. Moreover, the curve measured for the Bragg case on the same crystal, but after polishing, has shown good agreement with the corresponding curve calculated by the kinematical theory. However, there is a minor discrepancy in the energy region very near the absorption edge. This is probably due to the fact that the values of anomalous-scattering factors used for calculation are not precise enough to explain fine structures at the edge.

Rapid determination of polarity sense by an energy-dispersive diffractometer: erratum

Rapid determination of polarity sense by an energy-dispersive diffractometer: erratum

Rapid determination of polarity sense by an energy-dispersive diffractometer

The polarity sense of the non-centrosymmetric GaP crystal has rapidly been determined by use of an energy-dispersive diffractometer by choosing a suitable scattering angle, where the anomalous scattering is heavy, for example for the 333 and \bar 3\bar 3\bar 3 reflections in a pair of measurements. The main merits of this method are: (1) The necessary scaling is easily carried out by use of the intensity of even reflections observed simultaneously; (2) Unwanted fluorescence contributions can generally be separated. These make the conclusion more reliable. It was thus established that the less shiny surface is the Ga side when a 111 plate of GaP is treated by an etchant (HF:HNO3 = 5:1).

Escape peaks caused by a Ge(Li) detector in an energy-dispersive diffractometer

The appearance and identification of escape peaks in an energy-dispersive X-ray diffraction spectrum are reported.

The precision of interplanar distances measured by an energy-dispersive diffractometer

According to the papers so far published about diffractometers with energy-dispersive detectors, the precision of a measured lattice spacing has been estimated to be about 0.05% at best. In the present paper, it is shown that a precision of about 0.01% is attainable without much difficulty by the use of a suitable Soller-slit system and a suitable scattering angle. This was demonstrated on an Al powder sample. It has been concluded that the limitation of precision is in the electronics rather than in the detector, when the necessary conditions are realised in the present improved system.