Micro x-ray small-angle scattering with synchrotron radiation

Abstract

Three small-angle scattering cameras based on mirror/monochromator optics, a circular Bragg-Fresnel (BF) lens, and a microcollimation system combined with a double-focusing mirror have been tested for microfocusing applications. In order to reach a focal spot less than or equal to 10 μm. a microcollimation system provides a flexible solution for medium-resolution applications. When using a glass capillary as a collimation system, a minimum s-value of 5·10^?2 nm^?1 was attained. Scanning small-angle x-ray scattering (SAXS) patterns from a poly(tetramethyl-p-silphenylene)-siloxane spherulite and a 40-μm polyethyl-eneterephthalate fiber were obtained in a few seconds per pattern with a 4 μm diameter beam at a wavelength of λ = 0.095 nm.     

Perturbed nuclear scattering of synchrotron radiation

Mössbauer spectroscopy in the time domain with SR as a source may become a powerful tool in investigations of time-dependent hyperfine interactions caused by external perturbations. This is firstly due to the easy possibility to synchronize the excitation of the nuclei with an external perturbation and secondly due to the insensitivity of Mössbauer time spectra to mechanical vibrations which are generated in samples by these perturbations. As a particular case of perturbed nuclear scattering, the coherent scattering under conditions of 90°- and 180°-switching of the magnetic hyperfine field direction is considered. The results of the first experimental studies are discussed.     

High-pressure studies with nuclear scattering of synchrotron radiation

Hyperfine Interactions - The nuclear forward scattering (NFS) of synchrotron radiation is especially suited for probing magnetism at high pressure (h.p.), here in the Mbar range, by the nuclear...     

Transverse coherence in nuclear resonant scattering of synchrotron radiation

Hyperfine Interactions - We discuss the effects of transverse coherence in time domain nuclear resonant scattering experiments using synchrotron radiation. The importance of source and detector...     

Introduction to nuclear resonant scattering with synchrotron radiation

The concepts leading to the application of synchrotron radiation to elastic and inelastic nuclear resonant scattering are discussed. The resulting new experimental techniques are compared to conventional Mössbauer spectroscopy. A survey of situations that favor experiments with synchrotron radiation is offered.

     

Monochromatization of synchrotron radiation for nuclear resonant scattering experiments

An introduction to monochromatization of synchrotron radiation in the energy range of 5–30 keV is presented for applications involving nuclear resonant scattering. The relevant relationships of the dynamical theory of Xray diffraction are used to explain basic concepts of monochromatization. These relations are combined with raytracing techniques to design highenergyresolution monochromators. Transmissionoptimized and energyresolutionoptimized designs that achieve high energy resolutions (10⁶)< E/E < 10⁸) are discussed separately. Practical silicon monochromators of both types are presented for a variety of nuclear resonances in this energy range.     

Basic features of coherent nuclear resonant scattering of synchrotron radiation

The time dependences of spatially coherent nuclear resonant scattering of synchrotron radiation show a wealth of characteristic features which originate from the interference of several radiation components and from dynamical nuclear scattering. These effects will be of importance for the future fields of time domain Mössbauer spectroscopy and of nuclear resonant -ray optics. The basic features are discussed and experimental evidence is reviewed.     

Hybrid forms of beat phenomena in nuclear forward scattering of synchrotron radiation

In nuclear forward scattering (NFS) of synchrotron radiation, inter-resonance interference leads to a quantum beat (QB), and intra-resonance interference to a dynamical beat (DB). In general both interference processes determine the time evolution of NFS. Only in the case of far distant resonances the resulting interference pattern can be interpreted as a well distinguishable combination of QB and DB. Multiple scattering by near neighbouring resonances, by contrast, leads to a hybridisation of QB and DB. In particular, asymmetrical continuous distributions of resonances make QB and DB blend into a fast hybrid beat with thickness dependent period and distribution sensitive modulation.

     

169Tm-A new candidate for monochromatization of synchrotron radiation by nuclear Bragg diffraction

Thulium containing crystals with appropriate structure should be feasible for monochromatizing synchrotron radiation by nuclear Bragg diffraction. Thulium iron garnet and thulium gallium garnet were investigated by MB-transmission spectroscopy. The evaluated hyperfine interactions are discussed with respect to the crystal structure. The occurrence of pure nuclear reflections is predicted and theoretical time spectra are calculated by the dynamical theory of MB-optics.     

Multiple nuclear Bragg scattering

Multiple nuclear resonant scattering from an ⁵⁷FeBO₃ single crystal has been observed in the three-beam case. A change of the lifetime and a modulation of the quantum beat were observed in our study. The high brilliance of synchrotron radiation and the high perfection of the synthetic ⁵⁷FeBO₃ single crystal enabled us to observe such an effect. This revised version was published online in August 2006 with corrections to the Cover Date.     

Modulation effects of rotating radiofrequency field in forward nuclear scattering of synchrotron radiation

The quantization of a nuclear angular momentum in the rotating hyperfine (HF) field of any frequency is theoretically studied in resonant forward scattering of synchrotron radiation (SR). The adiabatically slow rotation of the quantization axis does not perturb the multilevel structure of nuclear states created by the static hyperfine interaction. It follows directly from the pattern of quantum beats of a resonant response (RR) to an SR pulse. When the rotation frequency is of the order of the Larmor frequencies, determining the stationary HF sublevels, the pattern of quantum beats of an RR is formed by the nuclear resonant transitions between quasienergy levels. At the rotation frequency much larger than the Larmor frequencies the multilevel structure of nuclear states results from the quadrupole interaction only. This revised version was published online in August 2006 with corrections to the Cover Date.     

Parametric x-ray radiation along the velocity of relativistic electron in a Bragg scattering geometry

Based on the dynamic scattering theory, forward parametric x-ray radiation (FPXR) of a relativistic electron is investigated in a single crystal plate in a Bragg scattering geometry. Analytical expressions for the spectral-angular distribution of FPXR and transition radiation (TR) including the crystal surface orientation with respect to a system of diffracting atomic planes are derived, which allow one to identify the conditions under which a contribution from FPXR is considerable even in the case of a thick absorbing crystal. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 48–56, June, 2007.     

Tin–DNA complexes investigated by nuclear inelastic scattering of synchrotron radiation

Nuclear inelastic scattering (NIS) of synchrotron radiation has been used to investigate the dynamics of tin ions chelated by DNA. Theoretical NIS spectra have been simulated with the help of density functional theory (DFT) calculations using 12 models for different binding sites of the tin ion in (CH₃)Sn(DNA_Phosphate)₂. The simulated spectra are compared with the measured spectrum of the tin–DNA complex.