In 1962, it was been observed that in-bone grafts sterilized by high-energy electron beams, the EPR signal appears and remains stable at room temperature. It also has been proven by the same authors that the signal is still seen after 12 weeks of storing the grafts at ambient temperature with air access. Later, similar EPR signals were identified in other mineralized tissues exposed to ionizing radiation as teeth and bones of mammals and birds, in mollusk shells, in crustacean shells, and even in egg shells. The signal was found extremely stable, surviving unchanged in bone tissue for tens while in teeth for thousands of years. It is presently postulated that the signal is mostly derived from CO2− radical ions stabilized in hydroxyapatite or calcite crystalline networks. High stability and specificity of this EPR signal makes it a suitable tool and a marker applied successfully in medical research to search the dynamics of the rebuilding process of radiation-sterilized bone grafts in the host body as well as to study the development of some pathologic processes in bone and to determine radiation doses in human bones and teeth in nuclear- or radiation-involved accidents. It was found effective in the dating of ancient human and mammalian remains as well.
Nitrogen and nitrogen-vacancy paramagnetic defects in crystals and nanocrystals of diamonds, as well as paramagnetic centers localized on the surface of nanoparticles, were studied by electron paramagnetic resonance (EPR) and electron-nuclear double resonance (ENDOR) methods. The spin optical polarization effect is explained qualitatively by the action of nondiagonal components of the Zeeman interaction, leading to mixing of the wave functions of the ground state. Relaxation-time dependencies are shown for NV− centers. High-frequency (94 GHz) EPR studies of nanodiamonds resolved spectrally three components related to defects in the crystalline core of a nanoparticle, on its surface and in the surface layer. Examples of ENDOR application for control of diamond nanoparticles surface modification by hydrogen and fluoride are demonstrated.
Nanotechnology is broadly defined as the practical applications of nanoscale objects having dimensions from ca. 1 to 100 nm. At such atomic scale small clusters of atoms and molecules are exhibiting some rather intriguing physical, chemical, and biological properties that are absent in bulk materials of the same composition and the surface interactions become the dominant factors. Furthermore, one can combine manmade nanoobjects with genetically programmed self-assembled biomacromolecules to produce bionanomaterials – a fruitful avenue of research and technology development. The growth in bionanomaterials’ research creates additional demands for spectroscopic and analytical methods capable of characterizing the nanoscale objects and especially interfacial phenomena in a non-destructive way. Electron paramagnetic resonance (EPR) is one of the techniques that could meet this challenge. This chapter discusses some recent applications of EPR in studies bionanomaterials with particular emphasis on the interfacial properties of the nanoobjects and their interactions with biomacromolecules.
High-pressure science encompasses many different areas of research, and its use in neutron scattering experiments dates back to the 1960s. Technical advances have always driven the field, which saw dramatic expansion in the early 1980s as synchrotron light became available. At the present time, a similar revolution is occurring with neutron sources, which has the potential to catapult high-pressure neutron science to new frontiers. In this chapter, the evolution of high-pressure technology and its implementation at neutron sources is explored. Detailed consideration of some of the sample environment used generate high pressures is given, along with some of the practical issues of data reduction. In addition, a brief survey of some rapidly evolving high-pressure science in the fields of biology, chemistry, and material science will be conducted. All of this provides a context to examine future directions and exciting opportunities that look set to become available in the near future.
Neutron scattering techniques are important tools for studying the structure and dynamics of high-temperature melts. However, studies are often restricted by high-temperature limits of standard furnaces and possible contamination of the sample by the container. These problems can be overcome by using levitation techniques that allow also to avoid heterogeneous nucleation giving the possibility to undercool hot liquids down to several hundred of degrees below their equilibrium freezing point. Various containerless methods have been developed, and their integration at neutron sources provides powerful tools to study the structure and dynamics of molten materials. This chapter presents an overview of the levitation techniques routinely combined with neutron techniques and experimental results obtained on various metallic and oxide melts.
Soft condensed matter is a very suitable system to be investigated with a probe of “neutron.” Typical energy range associated with soft condensed matter is tens of kJ (or a few meV), which is of the same order as those of cold neutrons. In addition, soft condensed matter consists of organic compounds and hence inevitably contains hydrogen. Since neutron is a “hydrogen” probe, neutron scattering has been used for investigations of the structure and the dynamics of soft condensed matter since its first application in the 1970s. Comprehensive theories of neutron scattering and a brief review of instrumentations and methodologies on soft condensed matter systems are provided mostly from materials science points of view, including polymeric systems, rubbers, and gels, which are followed by demonstrations of breakthrough works in soft condensed matter physics, recent topics, and future directions. Furthermore, appendixes dealing with scattering functions for particulate systems having various types of interparticle interactions and with contrast variation small-angle neutron-scattering method are given for the convenience of the reader.
Neutron scattering methods are excellent for probing the detailed structure of biological systems, which rely on the intricate interplay of a large number of molecules from proteins and nucleic acids to lipids, hormones, and metabolites. With recent instrument developments and emergence of both new neutron sources and techniques, many biological systems that are not yet amenable to characterization by neutron scattering will become accessible in the near future, which will allow new experiments to be developed with a range of biologically relevant samples, offering new insights in life science. In this chapter, we will describe neutron methods for biological structure characterization on different length scales from atomic resolution to macromolecular length scales-up to micrometers. The dynamics of biological molecules are described by Seydel in Chapter 2 of this thematic volume.
Engineering applications in neutron scattering started in the 1980s because of the need to quantify residual stress distribution in industrial components. Over the years, the field of engineering applications has expanded dramatically, from residual stress determination, to fundamental studies of deformation behaviors in polycrystalline structural materials, to mechanical response to electric and magnetic fields in function materials, and lately to the dynamics of structure evolution during phase transition or precipitation. In this chapter, the methodology of neutron diffraction as applied to engineering problems is reviewed, and selected examples are highlighted to illustrate the diverse applications. Technical issues and good practice in precise measurements are discussed. An outlook is provided, along with a discussion of the technical challenges.
Ionic liquids represent an exciting class of compounds that are composed solely of ionic species and are liquid below 100°C. They are attracting great attention as environmentally responsible solvent media, and as such, they are the focus of a profusion of research activities. Aiming at relating their appealing macroscopic properties, in terms of micro- and mesoscopic features, neutron scattering techniques have been successfully applied in the last decade to explore these compounds. In this contribution, an overview of fundamental structural (over the spatial scale ranging from angstrom to several nanometers) and dynamic (across the window from fraction of picosecond to several nanosecond) studies are accounted for, aiming at revealing the contribution that neutron scattering can provide in complementing and extending the level of understanding so far reached.
Microporous catalysts, in particular zeolites, are among the most intensively investigated systems in materials chemistry owing to the intrinsic challenges they provide in the characterization of their structures and properties, and to their major industrial applications. As discussed below, the microporous structure of the materials allows for the adsorption and diffusion of small- to medium-sized molecules into their pores—processes that are of crucial importance for the applications in both separations and catalysis. Studies of molecular diffusion are therefore a core area of zeolite science. As sorption and diffusion studies in zeolites are strongly focussed on hydrogen-containing molecules, neutron-based techniques have proved to be particularly effective in elucidating and quantifying the microscopic processes of molecular diffusion; and the interpretation of the data obtained from these techniques can be significantly enhanced by the concerted use of molecular simulation techniques. This chapter therefore outlines some notable studies using quasielastic neutron scattering probing molecular transport and dynamics in zeolites, which we place into the broader context of the investigation of sorbate behavior in these widely studied materials. Though we have focused on this specific class of materials, we note the applicability of all the following techniques to other classes of porous or framework materials (e.g., metal organic frameworks, carbon nanotubes, clathrates, polymers, and porous carbons).
