X-ray diffraction in crystals in the presence of laser-induced dynamic gratings

Abstract

A theory of x-ray diffraction (XRD) in the presence of optically induced superlattices has been developed both in the case of thin, non-absorbing and thick crystals. The main features of this process have been analysed. Experimental requirements to observe coherent influence of the optically induced superlattices on the process of XRD were formulated. It was shown that the resonance influence of the optically induced dynamical gratings on XRD can be observed under experimentally feasible conditions.}

Effect of absorption on dynamical Bragg diffraction of x-rays on a crystal modulated by strong ultrasound

“…that is very similar to the corresponding expression in Laue geometry (see, for example [17,27]). In both cases a growth of the normalized integrated intensity I (0)/I (τ • a) due to AW action is determined by a sum of Bessel functions:…”

“…Following the theoretical approach developed in [25][26][27], the x-rays diffraction spectrum R( ) emerging from a crystal excited by AWs, can be written in the Bragg case as…”

X-ray Bragg Diffraction in a Strong Acoustic Field

“…Under ultrasonic excitation, a set of satellites related to the inelastic scattering processes with wavevector transfer, H + px (p = +1, -t-2 .... ), appears in the diffraction spectrum, each satellite having a width, Gp, proportional to the Bessel function of the pth order, Jp (HW), and the height, Ip < 1, reduced due to the X-ray absorption on the characteristic length, Lp (Polikarpov, 1996):…”

“…Detailed theoretical analysis (Polikarpov, 1996;Polikarpov & Zolotoyabko, 1997) allowed the derivation of expressions describing the diffraction spectrum and integrated diffraction intensity in the form of a series over parameter p. Generally, these expressions may be used for computer simulations and selected examples of such calculations are given in Fig. 7.…”

“…Under ultrasonic excitation, a set of satellites related to the inelastic scattering processes with wavevector transfer, H + px (p = +1, -t-2 .... ), appears in the diffraction spectrum, each satellite having a width, Gp, proportional to the Bessel function of the pth order, Jp (HW), and the height, Ip < 1, reduced due to the X-ray absorption on the characteristic length, Lp (Polikarpov, 1996): L, (10) Lp _ [~(HW) + $2] 1/2" Excitation of satellites leads to considerable modifications in spectrum width and integrated intensity. Detailed theoretical analysis (Polikarpov, 1996;Polikarpov & Zolotoyabko, 1997) allowed the derivation of expressions describing the diffraction spectrum and integrated diffraction intensity in the form of a series over parameter p. Generally, these expressions may be used for computer simulations and selected examples of such calculations are given in Fig. 7.…”