An X-ray diffractometer using mirage diffraction

Abstract

Some characteristics are reported of a triple-crystal diffractometer with a (+, −, +) setting of Si(220) using mirage diffraction. The first crystal is flat, while the second and third crystals are bent. Basically, the first crystal is used as a collimator, the second as a monochromator and the third as the sample. The third crystal also works as an analyzer. The advantages of this diffractometer are that its setup is easy, its structure is simple, the divergence angle from the second crystal is small and the energy resolution of the third crystal is high, of the order of sub-meV.

Origin of irregular X-ray mirage fringes from a bent, thin crystal

“…In order to observe mirage interference fringes, a finite divergence angle Á is needed. The divergence angle Á is related to the divergence angle Á B of the beam from the monochromator as jÁ B j ¼ sin 2 B jÁj ð 41Þ (Fukamachi et al, 2014(Fukamachi et al, , 2015(Fukamachi et al, , 2019. By using the Bragg condition, the width ÁE of X-ray energy (E) and the angle width Á B are related as…”

X-ray interference fringes from a weakly bent plane-parallel crystal with negative strain gradient

“…In the experiment, the incident glancing angle () is fixed and the X-ray from the bending magnet is a wave having an energy spread of E and the corresponding deviation of wavenumber jK E j. The divergent angle of the X-ray at the incident point on the crystal surface is related to the energy width E, as discussed by Fukamachi et al (2014Fukamachi et al ( , 2015.…”

“…For simplicity, the glancing angle is assumed to be the same as B . The dispersion surfaces and the diffraction geometry in the more general case are given by Fukamachi et al (2014Fukamachi et al ( , 2015. The vector OH !…”

An X-ray diffractometer using mirage diffraction. Erratum

“…As the last sentence of the caption of Fig. 2 of Fukamachi et al (2014), the following sentence should be added: jK E j is the distance between a 2 and a 4 . Fig.…”

“…Fig. 2 of Fukamachi et al (2014) is updated as Fig. 1 in the current article to reflect the correction.…”