bluuebunny/crossref_metadata_2025_split huggingface dataset:
Medium‐Energy Backscattering and Forward‐Recoil Spectrometry
Authors: Weller Robert A. 
Published: October 2012

Abstract
Medium‐energy backscattering spectrometry is a variation of Rutherford backscattering spectrometry (RBS) using ions with energies ranging from a few tens to a few hundreds of kilo‐electron‐volts. The ion beam, frequently He+, is directed onto a specimen and the number of backscattered ions per incident ion is measured as a function of scattered‐ion energy at one or more angles relative to the beam direction. The fundamental physical process being used is that of a binary collision between the nuclei of an ion in the beam and a near‐stationary atom in the target. In such a collision, the energy of the backscattered ion is determined uniquely by its original energy, the scattering angle (which is the angle between the ion's trajectories before and after the collision), and the ratio of the masses. Consequently, a measurement of the energy of a backscattered ion at a specific angle may be used to infer the mass of the target atom with which it collided. The number of backscattered ions is proportional to the collision cross‐section and the total number of available scattering centers. Since collision cross‐sections are known a priori in this energy range, the number of backscattered ions with a given energy is a direct measure of the number of atoms of the corresponding mass in the target.
The method achieves additional richness as the result of a second physical phenomenon, the gradual loss of kinetic energy through collisions as an ion penetrates through matter. This is measured by stopping power (also called linear energy transfer), which is the average energy lost, typically in electron volts per unit of length (measured in atoms per square centimeter) of trajectory in the target. A second factor controlling the energy of backscattered ions is the depth within the target at which the collision occurs. As a result, it is usually possible to extract quantitative information about the distribution of specific species within the near‐surface region of the specimen. For the purposes of this article, it is sufficient to note that for medium‐energy ions the stopping power is dominated by collisions between the nucleus of the projectile and the electrons of the target, so‐called electronic stopping, which results in relatively uniform loss of energy with minimal angular divergence of the beam. Widely accepted semiempirical procedures are available for computing electronic stopping power.
Particle detection technology is an extremely important issue in medium‐energy ion beam analysis. This article also details time‐of‐flight spectrometry optimized for high‐resolution measurements. Other methods, including magnetic and electrostatic spectrometers, pulsed‐beam accelerator systems, and time‐of‐flight spectrometry optimized for other measurements, are discussed briefly along with several other methods for depth profiling, trace‐element identification, and hydrogen measurement. Throughout, special attention is paid to the relationship between medium‐energy backscattering and conventional high‐energy RBS.
Electrical Measurements on Superconductors by Transport
Authors: Weijers Hubertus W. , Noyes Patrick , Schwartz Justin 
Published: October 2012

Abstract
In this unit, we will focus on techniques for measuring the electrical behavior of technologically important superconducting wires, tapes, and other conductors. Depending on the conditions of measurement, electrical behavior can be interpreted to obtain many technologically important quantities. This article will also discuss the interpretation for some of the most common of these quantities.
Single‐CrystalX‐rayStructure Determination
Authors: Gómez Cesar Pay , Jacobson Robert A. 
Published: October 2012

AbstractThis article is a comprehensive guide to the basics of crystallography and structure determination. We will concentrate here on the use of x‐ray diffraction techniques as would be necessary for the conventional crystal structure investigation; that is, structures which are not twinned, incommensurate, or contain substantial amounts of disorder. A discussion of the basic principles of single‐crystal x‐ray diffraction will be presented first, followed by a discussion of the practical aspects of these techniques. In the course of this discussion, a few of the more widely used methods of overcoming the lack of measured phases, that is, the “phase problem” in crystallography, will be presented.
X‐Ray Photoelectron Spectroscopy
Authors: Weimer Jeffrey J. 
Published: October 2012

AbstractX‐ray photoelectron spectroscopy (XPS) uses x‐rays of a characteristic energy (wavelength) to excite electrons from orbitals in atoms. Photoelectrons are emitted from the material and collected as a function of their exiting kinetic energy. For single‐step excitation processes, the initial binding energy of the photoelectron is related through energy conservation to its kinetic energy and the x‐ray energy. A typical XPS spectrum shows intensity of electrons as number of electrons per time versus electron binding energy. Features appear in the spectrum due to photoemission from specific binding energy states (excitation from orbitals) in the material and to interactions of the escaping photoelectrons within the material. Chemical elements give rise to peaks at defined binding energies that are from their core levels. The total, integrated photoelectron emission from a core level peak is proportional to the number of orbitals in the analysis volume. This relationship is used to quantify the relative elemental composition of the material in atom percent (at%). The binding energy positions and shapes of the core level peaks and of other excitation features can also be analyzed in detail to determine chemical state information, including oxidation states, partial charges, or hybridization of the elements. The ability to provide both quantitative elemental composition and orbital bonding state information makes XPS unique and gives rise to the additional name as electron spectroscopy for chemical analysis (ESCA).
Nuclear Magnetic Resonance: Basic Principles and Liquid State Spectroscopy
Authors: Hoffmann Markus M. 
Published: October 2012

AbstractThermogravimetric analysis (TGA) is an analytical technique for measuring changes in the mass of a material that occur in response to programmed temperature changes. The changes in the mass can be caused by a variety processes such as decomposition, degradation, sublimation, vaporization, adsorption, desorption, oxidation, and reduction. The article explains the principles of TGA and practical aspects of the method that include description of the apparatus, discussion of experimental variables, and applications. Among practical applications, a particular attention is paid to determining composition and thermal stability of materials, evaluating the kinetics of thermally stimulated processes, predicting lifetimes, and studying reactions of materials with gases. The article also addresses the issues of sample preparation as well as of basic analysis and interpretation of data. A special consideration is given to the sources of errors in the mass and temperature measurements as well as to the methods of calibrating both values.
Challenges to Structure Prediction and Structure Characterization at the Nanoscale
Authors: Glotzer Sharon C. , Keys Aaron S. , Jankowski Eric 
Published: October 2012

AbstractThe new revolution in nanoscience, engineering, and technology is being driven by our ability to manipulate matter at the molecular and supramolecular level to create “designer” structures. The parameter space for engineering new materials is indeed vast—structures vary drastically with small changes in interparticle interactions or with small changes to the conditions under which the material is synthesized. Computational simulation offers a means to discover the fundamental principles of how nanoscale systems of molecular building blocks self‐assemble, and how we might control the assembly process to engineer new materials.
Characterizing Micro and Nanomaterials UsingMEMSTechnology
Authors: Isono Yoshitada 
Published: October 2012

AbstractMicro‐ and nanoelectromechanical system (MEMS and NEMS) technology enables the development of smart products. MEMS and NEMS are not electronic devices such as LSI circuits, but they have distinctive features as mechanical systems consisting of actuators, accelerometers, pressure sensors, optical mirrors, power generators, and micromechanical switches with structures of micro/nanometer scale. For example, the accelerometers and pressure sensors detect the elastic deformation of the microscopic structures induced by the external mechanical force acting on the devices as the change of electric resistance or capacitance. Therefore, the development of MEMS and NEMS products requires the structural design of device that ensures the reliable deformation and movement statically and dynamically. In particular, the size effect of device components on their mechanical properties has to be considered in the structural design of MEMS. As a device size is reduced, the surface effect may begin to dominate the material response. In such a case, bulk properties measured on larger specimens are no longer valid. Knowledge of mechanical properties of MEMS and NEMS materials at the scale of the practical use is essential to the design and optimization of devices. In this chapter, technical issues of typical testing methods are introduced for the mechanical characterization of micro/nanometer scale materials including thin films used in MEMS and NEMS. The mechanical characterization technique using MEMS devices as a testing tool for one‐dimensional nanowire materials is also described.
Magnetization Characterization of Superconductors
Authors: Cave J. R. , Lacroix C. 
Published: October 2012

AbstractThe superconducting state occurs for many elements, alloys, and compounds when cooled to sufficiently low temperatures, specifically, below the critical temperature, Tc. The initial discoveries by Onnes in 1911 and 1914 were of the loss of electrical resistance at very low temperatures and of its reestablishment by applying a strong enough magnetic field or a high enough current. A further discovery by Meissner and Ochsenfeld in 1933 was that a magnetic field could be expelled from a superconducting material as it was cooled through its Tc. This perfect diamagnetic behavior coupled with perfect conductivity led to the derivation of London equations describing the superconducting state in 1935.At present, there are many known superconducting materials ranging from pure elements such as lead, that are superconducting at liquid helium temperatures, to complex ceramics such as YBaCuO7‐xoperating at liquid nitrogen temperatures. Also, uses of superconductors vary enormously ranging from sensitive magnetic field detectors to electric power cables. Certain engineered superconducting materials and composites can carry very high transport currents in high magnetic fields and much research at this time is being devoted to the development of commercial and also power utility applications. The characterization of these technological materials is a very important part of these activities. Here, we present some basic features of magnetization characterization of superconductors, in particular high temperature superconductors.
Electrochemical Impedance Spectroscopy
Authors: Barsukov Yevgen , Macdonald J. Ross 
Published: October 2012

AbstractElectrochemical impedance spectroscopy allows access to the complete set of kinetic characteristics of electrochemical systems, such as rate constants, diffusion coefficients, and so on, in single variable‐load experiment. It is restricted to characteristics that describe system behavior in linear range of electrical excitation, for example, when it can be approximated by linear differential equations. It can be contrasted with other methods where explicitly nonlinear properties are investigated, such as cyclic voltammetry (see ChapterCyclic Voltammetry).A common example of linear conditions is voltage excitation below 25 mV, whereV(I) dependency can be approximated as linear. Some of the parameters remain constant over a wide range of conditions, and once found under linear conditions can also be applied to model much wider ranges. An example of such parameters would be ohmic resistance of electrolyte or thickness of passivating film on the electrode.Although impedance spectroscopy is sharing the variable‐load experimental method with many other linear excitation electrochemical techniques, its analysis method is distinct, where a time‐domain signal and response are converted to the frequency domain and their relation is found in the form of complex impedance. Complex impedance values over a range of frequencies form an impedance spectrum. Further analysis strives to derive system parameters from the impedance spectrum, typically by developing a model function connecting the impedance spectrum with system parameters and optimizing parameters to obtain a best fit to the impedance spectrum.This article covers the basics of the experimental implementation of this technique, as well as background and mathematical approaches for developing model functions for most common systems and analysis of the experimental data to obtain system parameters.
X‐Ray Computed Tomography
Authors: Stock Stuart R. 
Published: October 2012

AbstractX‐ray computed tomography (CT) is a powerful technique for noninvasively characterizing materials. This chapter covers x‐ray computed tomography (CT) in its forms spanning large components (booster rockets) to millimeter‐sized material specimens to micrometer‐sized samples. Emphasis is on contrast produced by differences in x‐ray attenuation, although CT using x‐ray phase contrast, x‐ray fluorescence, or x‐ray diffraction is also covered briefly.
Coherent Diffraction Imaging of Strain on the Nanoscale
Authors: Harder Ross 
Published: October 2012

AbstractCoherent diffraction imaging (CDI) in the Bragg geometry has gained a niche in recent years for its ability to image strain in a crystalline lattice on the nanoscale. This development is based on the realization that coherently scattered x‐rays, in the vicinity of a Bragg peak of the crystalline sample, have exquisite sensitivity to distortions of the crystal lattice.The method is dependent on the use of beams of highly brilliant x‐rays available at the third–generation synchrotrons and the new x‐ray–free electron lasers. There are several instruments at these facilities capable of such measurements. Argonne National Laboratory in the United States hosts such an instrument at the Advanced Photon Source.Computational algorithms are used to retrieve the phases lost in the measurement of the coherently scattered x‐rays and, subsequently, produce the images of the sample. These algorithms are a subject of intense development and in many cases are carefully tuned to a specific application. Phase retrieval for Bragg CDI data will be described in some detail, but similar principles are implemented in all forms of CDI.
Fluctuation Electron Microscopy
Authors: Voyles Paul , Hwang Jinwoo 
Published: October 2012

Abstract
Fluctuation electron microscopy (FEM) is a nanodiffraction technique for measuring nanometer scale order in amorphous materials. Either dark‐field transmission electron microscope imaging or coherent electron nanodiffraction in a scanning transmission electron microscope is used to measure the diffracted intensity from the sample with nanometer spatial resolution. Fluctuations in that intensity from place to place on the sample reveal the size, density, and internal atomic arrangements of nanometer‐scale order. Nanometer scale order in glasses is also called medium‐range order (MRO). Fluctuation microscopy is one of the few experimental techniques sensitive to this type of structure in amorphous materials.
Charged‐Particle Irradiation for Neutron Radiation Damage Studies
Authors: Fluss Michael J. , Hosemann Peter , Marian Jaime 
Published: October 2012

AbstractThe use of energetic charged‐particles are a useful experimental method for producing and studying radiation damage. In addition to producing displacement damage via Coulomb‐moderated ballistic collisions, charged‐particles can also be used to implant specific elements thus changing the chemical and compositional nature of the target material. Charged particle beam studies of radiation damage result in specimens that are usually not any more radioactive than prior to the irradiation. The specific aspect of charged‐particle irradiations that makes them a powerful tool for studying the physics of radiation damage accumulation is the high displacement and implantation rates and that the experimenter can vary important variables of the radiation environment. These include the energy and mass of the charged‐particle, the atomic number of the ion, the temperature, the dose and dose rate, and the mechanical stress of the specimen under test. Experiments can be designed to identify and understand the key mechanisms of radiation damage accumulation. Most importantly, the understanding gained from such experiments can inform and validate models that are then used to make science‐based predictions about material performance under other radiation conditions such as those encountered in a fission reactor or as might be expected in a fusion reactor. Particularly, useful examples of charged‐particle irradiation studies are those experiments that follow the growth of helium bubbles and cavities resulting from the combination of helium implantation and displacement damage
Electrostatic Force Microscopy And Kelvin Probe Force Microscopy
Authors: Sadewasser Sascha , Barth Clemens 
Published: October 2012

Abstract
Studying electrostatic and electronic surface properties such as work function (WF) or local charge phenomena is of high importance not only in surface physics and chemistry, but also in materials science and related fields. Electrostatic force microscopy (EFM) and Kelvin probe force microscopy (KPFM) give access to these properties providing resolution on the nanometer lateral length scale, which explains their large success in science.

Both techniques are based on noncontact atomic force microscopy (nc‐AFM) and use an applied bias voltage to excite a cantilever oscillation, whose amplitude depends on the electrostatic force interaction between the AFM tip and the sample. The EFM directly measures this electrostatic force; however, KPFM uses a compensation technique to allow quantitative determination of the local surface potential. A commonly used method is to apply a static (dc) and alternating (ac) voltage between the tip and surface such that the electrostatic tip–surface interaction is modulated, which greatly helps in detecting small electrostatic forces. Two working modes can be used: the
amplitude modulation
mode is directly sensitive to the electrostatic force, while the
frequency modulation
mode detects the electrostatic force gradient. The methods can be applied to a variety of samples. For instance, on conducting surfaces such as metal and semiconductor surfaces the contact potential difference (CPD) is measured, which represents the WF difference between the tip and sample. An image of the CPD reflects variations of the surface WF at the nanometer scale—an important surface property for any field of research. On the other hand, information about the local charge or dipole distribution is also obtained, which is of utmost importance if insulators are considered.

This article gives an introduction into the principles and practical aspects of the EFM and KPFM techniques and provides a number of application examples.
Atomic Excitation Exploited By Energetic‐Beam Characterization Methods
Authors: Jeynes C. , Grime G. W. 
Published: October 2012

AbstractMany disparate methods of compositional analysis of materials are underpinned by the same fundamental atomic processes: the excitation of the electronic system of the atoms followed by its subsequent relaxation. These methods include the electron spectroscopies (XPS, AES) used for surface studies, the electron microscopies used for elemental and structural characterization (SEM using EDS and WDX; TEM using EELS), and the X‐ray methods (XRF, XAS) and ion beam analysis (PIXE) used for elemental and chemical characterization. All rely on measuring the characteristic energy absorbed or emitted by the unknown target atom when its electronic system is excited by ionization due to charged particles or electromagnetic radiation. This excitation is defined by the energy levels of the atomic electrons, determined primarily by the atomic number of the atom. (Atoms can also be excited without ionization, as in optical and infrared spectroscopy: this is outside the scope of this article.)The theoretical description of the electronic structure of atoms is a major intellectual triumph of the twentieth century and this body of knowledge is exploited in the theoretical description of each of these methods, but the treatment of any particular method is usually presented by specialists in that method in isolation from all others. In this article we present a brief synthetic overview of materials analysis using atomic excitation, highlighting those features and physical concepts that underpin all these apparently disparate analysis methods. We hope to encourage modern analysts to appreciate the truly complementary nature of the powerful methods at their disposal.
Neutron Reflectometry*
Authors: Fritzsche Helmut 
Published: October 2012

AbstractNeutron reflectometry (NR) is a versatile technique that has been used in a wide range of research activities in physics, chemistry, biology, and materials science. Specular NR determines the profile of the atomic density and magnetization along the surface normal with nanometer resolution. Therefore, NR experiments address scientific phenomena occurring at the nanoscale, that is, at the surface or interfaces of single thin films or multilayered structures with thicknesses usually in the range from 1 to 100 nm. This provides a brief introduction into the theoretical and practical aspects of specular NR for the nonexpert. A list of references of typical NR experiments covering a wide range of scientific problems is given to help researchers in how NR could be applied to solve scientific problems in their own area of expertise. A few NR experiments are discussed in more detail to showcase the unique capabilities of NR.