X Ray And Neutron Scattering Studies Of Artifically Grown Low Dimensional Nanostructures

This research monograph presents the latest results related to the characterization of low dimensional systems. Low-angle polarized neutron scattering and X-ray scattering at grazing incidence are used as the two main techniques to explore various physical phenomena of these systems. Special focus is put on systems like thin film transition metal and rare-earth layers, oxide heterostructures, hybrid systems, self-assembled nanostructures and self-diffusion. Readers will gain in-depth knowledge about the usage of specular scattering and off-specular scattering techniques. Investigation of in-plane and out-of-plane structures and magnetism with vector magnetometric information is illustrated comprehensively. The book caters to a wide audience working in the field of nano-dimensional magnetic systems and the neutron and X-ray reflectometry community in particular.

The theoretical and experimental study of low-dimensional systems has dominated much of modern condensed matter physics. Such systems present a range of different phenomena which are not observed in more isotropic, three-dimensional materials. This thesis constitutes the study of the excitations of two types of low-dimensional system: the magnetic excitations in the one-dimensional S = 1/2 antiferromagnetic chain compound Sr2CuO3 as studied using inelastic neutron scattering, and the phonons in quasi-two-dimensional graphite intercalation compounds CaC6 and BaC6 studied using inelastic X-ray scattering. Initially an introduction to the vast field of low-dimensional systems is provided, followed by a description of the neutron and X-ray scattering technique. Spinon excitations in Sr2CuO3 have been measured up to ≈ 600 meV, and are found to be well-described by the Heisenberg model. A new version of the magnetic form factor for Cu2+ in Sr2CuO3 provides an explanation for the considerable reduction in the measured inelastic neutron scattering intensity, which may have significant consequences for past and future work on other related materials. The phonons in superconducting CaC6 (Tc = 11.5 K) are found to be in reasonable agreement with Density Functional Perturbation Theory calculations, but the measured dispersions in non-superconducting BaC6 are significantly different to those predicted. No direct evidence for electron-phonon coupling is found in either compound. It is concluded that the X-ray data supports the validity of the theoretical description of CaC6, but the use of significantly inaccurate lattice parameters for BaC6 in the calculation may provide an explanation of the poor agreement in this case.

Understanding and manipulating the properties of materials naturally occurring in our world and artificially produced by modern technologies requires detailed information on their properties on the atomic scale. This information is the basis for any kind of research in physics, chemistry, biology, engineering, metallurgy, and ceramics. Among the various experimental methods, neutron and photon scattering have become the key techniques of choice.This book provides an overview of the complementarity between neutron and synchrotron x-ray scattering. The most important topics are covered, including structure determination, magnetic correlations, polymer dynamics, thin films and multilayers, photoemission studies, etc; they are thoroughly introduced and discussed by experts from both the experimental and the theoretical side.

This book describes all aspects of the technique of small-angle scattering of X-rays and neutrons, including instrumentation, sample requirements, data interpretation and modelling methods, in a comprehensive way and gives examples of applications in various fields of biophysics and biochemistry.

I. Theoretical principles of neutron and synchrotron X-ray scattering. Neutron- and synchrotron X-ray scattering (the theoretical principles) / W. E. Fischer -- II. Structure determination. Structure determination by powder synchrotron X-ray diffraction / A. N. Fitch -- Structure determination by powder neutron diffraction / E. Gray and E. Kisi -- Seminar on "structure" / K. Yvon -- III. Magnetism. Magnetic neutron and synchrotron X-ray scattering / W. G Stirling -- Magnetic excitations through the eye of the neutron / W. J. L. Buyers -- Topological excitations in low dimensional magnets / H. B. Braun -- Seminar on "magnetism" / G. H. Lander -- IV. Correlated electron systems. Elastic and inelastic X-ray scattering from correlated electrons: A theoretical perspective / M. Altarelli -- SANS measurements on vortices in superconductors. What can we learn? / V. B. Geshkenbein -- Seminar on "electronic structures" / J. Mesot -- V. Multilayers. From thin films to superlattices studied with X-rays and neutrons / D. E. McMorrow -- Seminar on "multilayers" / S. K. Sinha -- VI. Other topics in condensed matter research. From entropy driven motion to reptation - Large scale dynamics in polymer melts / D. Richter -- Small-angle and surface scattering from porous and fractal materials / S. K. Sinha -- Hot topics in condensed matter physics / H. R. Ott -- Seminar on "dynamics" / B. Dorner -- VII. Beam optics. Neutron beam optics / P. Boni -- Synchrotron X-ray beam optics / A. Freund -- VIII. Summary. Summary lecture: Some features of the scattering and absorption of beams of neutrons and beams of X-rays / S. W. Lovesey

All papers have peer-reviewed. Neutron, especially together with X-ray scattering techniques have been showing the elegant and tremendous achievements in revealing the static and dynamic structures in the wide range of materials, i.e. alloys, ceramics, polymers, composites, and also biological materials for advanced purposes. With the intention on establishing the techniques due to the availibility of the facilities at neutron scattering laboratory in Indonesia and a light X-ray synchrotron laboratory in Singapore, then the next future works and collaborations, especially in the southeast Asian region will be strengthened and enlightened.

In these proceedings from the symposium of November-December 2004, participants describe their work in x-rays and neutrons as probes of local atomic order and dynamics, in the dynamics and structure of polymers (including a paper on large-scale morphology of dispersed layered silicates), biopolymers and composites, in x-rays and neutrons as probes of electronic and magnetic structure, novel methods and nanomaterials, and x-ray and neutron investigations of microstructure and strain, including a paper on 2D and 3D x-ray structural microscopy using submicron-resolution Laue microdiffraction. Annotation : 2004 Book News, Inc., Portland, OR (booknews.com).