Shoichi Annaka

An X-Ray Phase Plate Using Bragg-Case Diffraction

An X-ray phase plate using two-beam Bragg case diffraction is proposed. The variation of the polarization state of the transmitted (forward-diffracted) beam through the incident angle was observed. Left-handed and right-handed circular polarizations whose degree of circular polarizations were ±0.90 were experimentally produced.

Intensity Anomaly of Fluorescent X-Ray Emission Accompanying the Laue Case Reflection from a Perfect Crystal

Intensity change of the fluorescent X-rays accompanying the Laue case reflection from perfect germanium crystals was observed together with intensity profiles of diffracted and transmitted beams, using a double-crystal spectrometer. Observation was made on the intensity variations of K α and K β fluorescent X-rays with rotation of the crystals through the 220 reflection region and with increasing thickness of the crystals. The result showed a behaviour which can be explained in terms of the formation of two types of standing-wave fields of X-rays in the crystals and the Borrmann effect. The obtained results were compared with a theoretical calculation.

Direction Dependence of the Intensity Anomaly of the X-Ray Thermal Scattering Accompanying the Bragg Case Reflection

Using a germanium single crystal and Cu Kα radiation, an intensity of the x-ray thermal scattering accompanying the Bragg case reflection was observed, and found to depend very much on the direction of an observation. This result could be theoretically interpreted as an interference phenomenon between thermal scattering caused by a diffracted beam and that by a transmitted beam in a crystal.

Elliptically Polarized X-Rays Produced by the σ and π Components of Linearly Polarized X-Rays in the Laue Case Dynamical Diffraction

Interference phenomena between the σ and π components of linearly polarized X-rays are studied in the Laue case dynamical diffraction. It is shown experimentally that the polarization characteristics of the diffracted X-rays from Si change clearly with thicknesses of the specimen and elliptically polarized X-rays are produced by phase differences between the σ and π components. Theoretical calculations also confirm the experimental results.

Variations in X-Ray Fluorescence from GaAs and Photocurrent in CdS due to Standing Waves of X-Rays

The intensities of the K-series fluorescence from GaAs and the photocurrent in CdS were measured during the dynamical diffraction of X-rays. Variations in the fluorescence during the 111 and reflections and the photocurrent during the 110 reflection are explained by considering X-ray standing-wave fields in crystals. The effect of the standing waves on the fluorescence yield is emphasized when the fluorescence from layers near the surface is measured. The curve of the variation of the photocurrent in CdS is explained by considering the proper absorption coefficient of electrons in the crystal. A principle for the standing waves in the dynamical diffraction of X-rays is also given.

Study on Temperature Effect on X-Ray Diffraction Curves from Single Crystals by a Triple-Crystal Spectrometer

For the study of the temperature effect on X-ray diffraction for a perfect crystal, precise measurements of the rocking curves were made at room and high temperatures by a triple-crystal spectrometer. The Bragg case diffraction was studied for the 111 and 333 reflections from Ge with Cu K α and the Laue case diffraction for the 220 reflection from Si with Cu K α (µ d =13.85) and Mo K α (µ d =1.03) where µ is the mean absorption coefficient and d the effective thickness of the specimen. The experimental results on the reflection width, peak value, integrated intensity and profiles were in fairly good agreement with the calculated ones in which both the real and imaginary parts of the structure factor were multiplied by the Debye factor exp (- M ).

Rotation of the Electric Vector of the Polarized X-Rays by Diffraction in Crystals

The electric vector ( E-vector) of linearly polarized X-rays rotates after diffraction in a crystal, because the diffraction amplitudes of the σ and π components are different. This rotation phenomenon is important in diffraction experiments using the polarized synchrotron radiation. This phenomenon has experimentally been studied for the Bragg case diffraction of the Bragg angle of 45° with the use of grooved perfect Ge crystals and Cu Kα radiation. Fine structures of the rotation of the E-vector have also been studied, which are due to the difference in the rocking curves for the σ and π states. Modified polarization factors are presented for some cases of the polarized incident X-ray beams.

Measurement of Physical Constants with An X-Ray Three-Crystal Spectrometer

Using steep slopes of dynamical X-ray diffraction curves, piezoelectric constants d36 and d14 of KH2PO4 and electrostrictive constant Q3333 of α-quartz were determined with a three-crystal spectrometer at room temperature. This X-ray method is highly sensitive, and shear angle and change of spacing can be measured directly for each lattice plane. The values obtained are 67.0×10-8, 3.25×10-8 and -3.0×10-12 (cgsesu) for d36, d14 and Q3333 respectively.