Theoretical and experimental study of X‐ray acoustic resonance in perfect silicon crystals

Abstract

An experimental investigation of Borrmann effect resonance suppression by transverse ultrasonic vibrations with wavelengths, approximating the extinction length is carried out. A theory of this phenomenon is developed. It is shown that X-ray acoustic resonance allows to measure the X-ray atomic scattering factor with a relative accuracy of iz IY-,, as well as to investigate the shape of the dispersion surface of X-ray dynamical diffraction.IIposeneHo a~c n e p n~e~~a n b~o e nccnenoBame p e 3 o~a~c~o r o nonaBneHm a @ @ e~~a BOpMaHa IIOIIepe ¶HbIMU YJIbTpa3BYKOBbIMU KOne6aHHHMH C DJIEIHaMH BOJIH, 6JIU3HUMU H AJIUHe 3KCTUHKqHU. Pa3BHTa TeOpHR BTOrO IIBJIeHHII. n O K a 3 a H 0 , ¶TO peHTreEOaKyCTUW3CHIlfi pe3OHsuIC IIO3BOJIHeT E3MepHTb aT0-m @aKTOp PaCCeHIWU peIiTlY!HOBCK€iXnticnepcuomiofi nosepxHocTH nmaMurIecKofi na@paKqmi pemreHoBcmx nysefi.

Bragg and diffuse components of X-ray reflection measured using acoustic excitation of an Si crystal with oxide precipitates

“…Under X-ray acoustic resonance conditions (Entin, 1977(Entin, , 1978(Entin, , 1985(transverse ultrasound wave with wave vector lying in the reflecting plane perpendicular to the diffraction vector, with wavelength As equal to the extinction length A), the Borrmann effect is suppressed almost completely by extremely weak oscillations with an amplitude of the order of 10-12 m. The resonance is caused by the interferometric amplification of the interbranch scattering of Bloch waves when the quasimomentum conservation law, Ks = dKo (i.e. As = A), is fulfilled (Ks is the ultrasound wave vector, Ks = 2rr/As, AKo is the minimal value of the dispersion surface splitting, dKo = 2re~A).…”

Silicon-crystal rocking curves under X-ray acoustic resonance conditions

“…The obtained results show that rocking-curve measurement represents a technique of X-ray acoustic (Entin, 1978b) permit the measurement of the parameters of X-ray dynamical diffraction and the study of the dispersion surface shape. In addition, the results allow a possibility of effectively controlling an X-ray beam by means of a weak acoustic influence.…”

“…The X-ray acoustic resonance theory was developed (Entin, 1978b) on the basis of the Takagi (1962) equation system analysis for the case of a sinusoidal displacement field. Another approach to the problem involves the multiwave dynamical diffraction theory (Entin, 1979).…”

Structure Perfection Study of Crystals Containing Micro- and Macrodistortions by X-Ray Acoustic Method

“…The values of extinction lengths A may be calculated from Δx(vs ) rather exactly [9]. It should be noted that original measurements of dependencies Δx(vs) for perfect crystals were performed in [11]. The comparison of the A and Ap values enables to identify the predominate type of stucture disturbances for a crystal under investigation (Λ > Ap and A < Ap in the cases of localized or distributed deformations, respectively [4,12]).…”