Strength tuning of multiple waves in crystals

Abstract

In this work, the linear polarization of synchrotron radiation is explored as a tuning key for the strength of the simultaneously diffracted X-ray waves in crystals. The relative strength of the waves has been de®ned by the re¯ectivities of the Bragg re¯ections involved in each multiple-diffraction case and it has limited the applicability of the multiple-diffraction phenomenon. With a proper choice of the wavelength and the polarization direction of the incident synchrotron radiation, it is demonstrated how the intensity ratios of the simultaneously diffracted beams can be drastically changed.

Emission spectroscopy of ZnO inverse opal photonic crystals

“…The peak in reflection in s-polarization roughly corresponds to the avoided crossing of the s-bands, suggesting that it is related to multiple diffraction involving the (200) planes. One possible explanation for this different behavior can be found from the theory of multiple X-ray diffraction [22]: Coherent scattering of p-polarized EM waves is forbidden by polarization if θ=45°, since according to Maxwell's equation an accelerated charge does not emit in the direction of its acceleration. (In optics this is more commonly known as Brewster angle effect.)…”

Enhanced X-Ray Phase Determination by Three-Beam Diffraction

“…1) and another with a much weaker secondary wave ͑R 0.332͒ from the 226 1400 reflections. The latter is a very extreme case since at x 50.8 ± the 226 reflection is a polarization forbidden reflection (y d 0͒ [15]. Only the Auf hellung effect will be observed at this polarization.…”

“…For practical applications, these techniques are time-consuming and limited to a few n-BDs that present good phase sensitivity. Very recently, several authors have demonstrated that the linear polarization of synchrotron radiation can be used to change the relative strength of multiple diffracted waves [14,15] and/or improve phase sensitivity in some cases [16]. Polarization resolved n-BD has also been considered for enhancing phase sensitivity [17].…”

“…Besides the most obvious reason for using such scattering geometry, which is the possibility of tuning the strength of the primary wave from zero to its maximum value ͑D A ͒ [15], it also allows a direct measurement of the intensity ratio, R D 2 BC ͞D 2 A , and an adjustment of the g angle (Fig. 1).…”

“…The x-table rotation axis is lined up with the incident beam, and the inclination of the table allows the adjustment of the x angle in the required range of 290 ± to 190 ± (see Ref. [15] for more details). A GaSb ͑001͒ crystal was chosen as a sample, the226 reflection as the primary reflection (A reflection in Fig.…”