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The substrate effects on the electronic transport properties of single-layer graphene on TiO2/Si substrate have been studied. The Hall mobility, sheet carrier density, and transport lifetime were obtained from the temperature-dependent Hall measurements, while the in-plane effective mass, quantum lifetime was obtained from the temperature-dependent variation of the Shubnikov de Haas (SdH) oscillations that were made at 1.8 to 45 K temperature range and up to the magnetic field of 11 T. The measurement results showed that in SLG/TiO2/Si sample, there were 2.36 ± 0.12x1016 m-3 amounts of 3D carriers coming from the substrate. In our previous studies, 3D carrier densities were measured as 6.07x1016 m-3 and zero for SLG/SiO2/Si and SLG/SiC sample, respectively. This result shows that the 3D carriers formed in the structure are significantly changed by a substrate. The scattering mechanisms were determined using the τ t / τ q ratio. The ratio values obtained as 3.66. This value obtained was compared with the values we found for SLG/SiC ( τ t / τ q =1.36) sample and SLG/TiO2/Si ( τ t / τ q =3.08) sample our previous study. The results show that small-angle scattering is dominant in SLG/SiC sample, but large-angle scattering is dominant in SLG/SiO2/Si and SLG/TiO2/Si samples. The charged impurity scattering is the dominant scattering mechanism in SLG/TiO2/Si and SLG/SiO2/Si samples, whereas in SLG/SiC samples, a short-range scattering mechanism such as lattice defects can be said to affect the electronic transport.

Sophisticated high-energy and large momentum-transfer scattering experiments combined with ab-initio calculations can reveal the short-distance behavior of nucleon pairs in nuclei. On an opposite energy and resolution scale, elastic electron scattering experiments are used to extract the charge density and charge radius of different nuclei. We show that even though the charge density has no obvious connection with nuclear short-range correlations, it can be used to extract properties of such correlations. This is accomplished by using the nuclear contact formalism to derive a relation between the charge density and the proton–proton nuclear contacts that describe the probability of two protons being at close proximity. With this relation, the values of the proton–proton contacts are extracted for various nuclei using only the nuclear charge density and a solution of the two-nucleon Schroedinger equation as inputs. For symmetric nuclei, the proton–neutron contacts can also be extracted from the charge density. Good agreement is obtained with previous extractions of the nuclear contacts. These results imply that one can predict (with reasonably good accuracy) the results of high-energy and large momentum-transfer electron-scattering experiments and ab-initio calculations of high momentum tails using only experimental data of elastic scattering experiments. Keywords: Short range correlations, Contact formalism, Charge density

Motivated by the recent result of XENON1T collaboration with full exposure, 279 life days, that sets the most stringent limit on the spin-independent dark matter-nucleon scattering cross section we discuss a dark $E_6$-inspired model that features the presence of a $U(1)_{d-u}$ gauge symmetry. The dark matter candidate is a Dirac fermion that interacts with Standard Model fermions via a massive Z' that preserves the quantum number assignments of this symmetry. We compute the spin-independent scattering cross section off xenon nucleus and compare with the XENON1T limit; find the LHC bound on the Z' mass as well as the projection sensitivity of high-energy and luminosity LHC; and derive the Fermi-LAT bounds on the dark matter annihilation cross section based on the observation of gamma-rays in the direction of Dwarf Spheroidal galaxies. We exploit the complementarity between these datasets to conclude that the new bound from XENON1T severely constrain the model, which combined with the LHC upgrade sensitivity rules out this WIMP realization setup below 5 TeV., Comment: 7 pages, 3 figures

Planar temperature images using laser Rayleigh scattering have been obtained to determine the spatial distribution of temperature in a constant volume combustion chamber. Burning velocities were also measured from measured pressures and calculated flame surface area from Rayleigh scattering images. A high power KrF excimer laser was used as a light source and a high gain ICCD camera was used to obtain temperature images. Methane/air premixed combustion at different equivalence ratios and initial pressures were tested. Since the thermodynamics are well known, a constant volume chamber can be used as a reference device for diagnostics in high temperatures and pressures combustion. With the Rayleigh scattering technique, temperature and burning velocity can be measured simultaneously using a single-shot laser light. An additional laser Rayleigh experiment is described which yields scattering cross sections at the wavelength of 248 nm. The experimental results show an excellent agreement with previous data.

The phonon behavior of various Ge-based samples has been investigated in great detail. The study comprised Ge films (amorphous and partially crystallized and alloyed with oxygen), crystalline Ge wafers (pristine and alloyed with oxygen), and GeO2 powder. The oxygen-containing samples obtained after thermal annealing the Ge film and Ge wafer correspond to sub-stoichiometric GeO2, or the so-called Ge + GeOx system, in which case [O] ∼40 at.%. A thorough examination of this Ge + GeOx system – as provided by temperature-dependent Raman scattering, their analysis according to the existing theoretical models (involving anharmonic phonon coupling and thermal expansion processes), and a critical review of the literature – indicates the coexistence of practically independent Ge–Ge- and Ge–O-related structures and confirms the presence of both structural and chemical (dis)order. Moreover, the main features regarding the phonon frequencies ( ω ), line widths ( γ ), and scattering intensities ( I S ) of the Ge + GeOx system suggest their suitability in temperature sensing applications. Accordingly, experimentally determined reference curves (i.e., ω T , γ T , and I S T data described in terms of simple mathematical functions) gave rise to temperature accuracies on the order of 20 K. Everything considered, in its current form, this work presents the first comprehensive analysis-discussion regarding the Ge + GeOx system that, additionally, is being proposed as an effective medium for optical thermometric applications.

The anti-kaon nucleon scattering lengths resulting from a Hamiltonian effective field theory analysis of experimental data and lattice QCD studies are presented. The same Hamiltonian is then used to compute the scattering length for the $K^- d$ system, taking careful account of the effects of recoil on the energy at which the $\bar{K}N$ T-matrices are evaluated. These results are then used to estimate the shift and width of the $1S$ levels of anti-kaonic hydrogen and deuterium. The $K^- p$ result is in excellent agreement with the SIDDHARTA measurement. In the $K^- d$ case the imaginary part of the scattering length and consequently the width of the $1S$ state are considerably larger than found in earlier work. This is a consequence of the effect of recoil on the energy of the $\bar{K}N$ energy, which enhances the role of the $\Lambda(1405)$ resonance., Comment: 7 pages, 3 figures, published version

UKRmol+ is a new implementation of the UK R-matrix electron-molecule scattering code. Key features of the implementation are the use of quantum chemistry codes such as Molpro to provide target molecular orbitals; the optional use of mixed Gaussian -- B-spline basis functions to represent the continuum and improved configuration and Hamiltonian generation. The code is described, and examples covering electron collisions from a range of targets, positron collisions and photionisation are presented. The codes are freely available as a tarball from Zenodo., 79 pages, 12 figures

Publisher Summary This chapter focuses on spontaneous light scattering and acoustooptics. Spontaneous light scattering means light scattering under conditions such that the optical properties of the material system are unmodified by the presence of the incident light beam. Several physical processes can lead to light scattering. One of the processes is Raman scattering that results from the interaction of light with the vibrational modes of the molecules constituting the scattering medium. Raman scattering can equivalently be described as the scattering of light from optical phonons. Brillouin scattering is the scattering of light from sound waves, that is, from propagating pressure (and hence density) waves. Brillouin scattering can also be considered to be from acoustic phonons. In RayLeigh scattering or Rayleigh-center scattering, light is scattered because of nonpropagating density fluctuations. Formally, it can be described as scattering from entropy fluctuations. It is known as quasielastic scattering because it induces no frequency shift. The scattering of light from sound waves can also be applied to the situation, in which the sound wave is applied to the interaction region externally by means of a transducer. Such acoustooptic devices are useful as intensity or frequency modulators for laser beams or as beam deflectors. Acoustooptic devices are commonly classified as falling into one of two regimes; namely, Bragg scattering and Raman-Nath scattering.

This chapter covers the basic concepts of the scattering of light and other electromagnetic waves by spheres and cylinders, based on the exact calculation method of Gustav Mie. Results provide the scattered field complex amplitudes, as well as the angular distribution of scattered intensities and the scattering cross-sections taking into account the different polarizations of the incident and scattered waves. Morphology dependent resonances, such as localized surface plasmons and whispering gallery modes, are addressed. Then the dipolar formulation for small particles is reviewed, introducing the concept of particle polarizabilities. The Rayleigh and quasistatic approximations for very small particles are presented, emphasizing its distinction from the dipolar approximation. Further, the interplay of quadrupolar and dipolar resonant excitations, leading to interference phenomena like the Fano lines and Kerker effects, all related to directional scattering, are discussed.

This chapter reviews the fundamental physics and associated limitations of semiconductor lasers operating across the mid-infrared (MIR) range of 2–20 μm. Using a combination of temperature and hydrostatic pressure dependence techniques, we have shown how short-wavelength 1.9–3.7-μm type I quantum well interband devices are dominated by Auger recombination, the nature and type of which depends upon the wavelength. In the intermediate wavelength range (3–7 μm), interband type II “W” lasers offer significant performance improvements despite the reduced wavefunction overlap. Quantum cascade lasers dominate at the longest MIR wavelengths with performance limited by intervalley scattering and leakage processes.

Hyper-Rayleigh scattering (HRS) is a parametric optical effect in which two incident photons of frequency ω are annihilated to create a scattered photon of frequency 2ω. Unlike second harmonic generation (SHG), the HRS signal is isotropic, incoherent, and dephased with the excitation photon. HRS has been widely used to investigate novel materials with potential for the development of technologies, such as more efficient frequency doubling, high-resolution microscopy, fast electro-optic modulation, ultrafast lasers, and even to identify the interaction and affinity between biological molecules. In this chapter, we describe the potential of the HRS technique to investigate the first-order hyperpolarizability of organic molecules. For that, we initially present fundamentals of the first-order hyperpolarizability in materials. Theoretical approaches applied to estimate the first-order hyperpolarizability are also presented. These approaches employ different quantum chemical methods combined with a numerical or analytical scheme. Three of the most commonly used schemes, namely the finite field (FF) scheme, the sum-over-states (SOS) scheme, and the coupled-perturbed scheme, are briefly described. These approaches are used to aid in the understanding of the fundamental aspects that can be exploited, at the molecular level, to reach remarkable first-order hyperpolarizability (>10−27 cm5/esu). Moreover, we present in detail different experimental setups used to quantify in HRS experiments. Finally, recent results about the first-order hyperpolarizability are described and discussed for organic molecules with distinct molecular structures, as well as the use of the HRS effect as a technique to quantify specific interactions of biological materials.

We calculate a class of polarized fermion string scattering amplitudes (PFSSA) at arbitrary mass levels. We discover that, in the hard scattering limit, the functional forms of the non-vanishing PFSSA at each fixed mass level are independent of the choices of spin polarizations. This result justifies and extends Gross conjecture on high energy string scattering amplitudes to the fermionic sector. In addition, this peculiar property of hard PFSSA is to be compared with the usual spin polarization dependence of the hard polarized fermion field theory scatterings., Comment: 15 pages, no figure

Stimulated Raman scattering (SRS) excited by incoherent light is studied via particle-in-cell simulations. It is shown that a large bandwidth of incoherent light can reduce the growth of SRS and electron heating considerably in the linear stage. However, different components of the incoherent light can be coupled by the Langmuir waves, so that stimulated Raman backward scattering can develop. When the bandwidth of incoherent light is larger than the Langmuir wave frequency, forward SRS can be seeded between different components of the incoherent light. The incoherent light can only increase the time duration for nonlinear saturation but cannot diminish the saturation level obviously. Keywords: Stimulated Raman scattering, Instability suppression, Incoherent light, Inertial confinement fusion, PACS Codes: 52.25.Os, 52.35.-g, 52.38.Bv

Optics studies the behavior of light, or the properties of transmission and deflection of other forms of radiation. It forms the basis of optical transducers used in a variety of applications from imaging and spectroscopy to light-based manipulation and manufacturing in life sciences, chemistry, physics, and engineering. Optical transducers typically offer high sensitivity, combined spatial and spectral measurements, and detection with no direct contact to the objects under investigation. There are many types of optical transducers. In optical waveguides, there are several high-contrast modes available for light transmission, sensing, and imaging. Disadvantages include the need for the optical transducers to be transparent at the wavelength used for sensing, the use of labels, interferences, and issues arising from fluorophore decay in fluorescence imaging. In this chapter, we describe molecular sensors based on optical transduction. Lights interact with molecules in various ways, which are observed as transmission, scattering, fluorescence, and other forms of optical readout. We explain principles of optics used for molecular sensing and describe the instrumentation for optical measurements. The chapter starts with the introduction of the basic electromagnetic theory, followed by discussions on waveguides and sensors based on waveguide structures, and surface plasmon resonance-based (SPR) sensors. Lastly, theories and practices of optical spectroscopy techniques are described. Methods discussed include absorption and fluorescence microscopy and spectroscopy, static and dynamic light scattering, Doppler velocimetry, Raman spectroscopy, and near-field optical microscopy.

This chapter gives an overview of the principles of small-angle X-ray and neutron scattering. The description of these scattering experiments is based on the interference of coherently scattered waves. The phase difference of waves that come from different scattering centers is based on the path length difference. The Rayleigh–Debye–Gans theory of scattering is the rigorous application of the idea of coherent interference to scattering, assuming that the wave propagates into and through the particle regularly and homogeneously. Here we are dealing only with dilute, monodisperse, nonoriented systems. This means one has to average over all orientations in space, and particle interactions can be ignored. The angle-dependent scattering intensity, the form factor, is related to the particle pair–distance distribution function by a Fourier transformation. The scatterers may also be characterized by their correlation function, correlation length, and chord distribution in real space, or by their second moment—the invariant—in reciprocal space.

This chapter is an extension of the previous chapter where the physics of the propagation of the wave is explained. Starting with the electrical polarization created within the material as a result of the incident electric field, this chapter derives the relation between different related parameters. It states the definition of a perfect dielectric. Further, it also considers a practical dielectric with finite conductivity and sets the conditions for which it behaves as a conductor or as a dielectric. The dispersive nature of the electric parameters of the material medium is also described to finally demonstrate their relation to the causes of the propagation impairments. At the end, the Rayleigh and Mie scattering and diffraction is discussed.

Based on Biot's poroelastic theory, an investigation into the dynamic response of a rigid circular foundation on poroelastic soil excited by incident fast P waves, SV waves, and Rayleigh waves is described in this chapter. The incident and reflected wave fields are obtained by introducing potential functions. The radiation field and rigid-body scattering field are introduced in order to consider the dynamic interaction between the foundation and the underlying soil, as well as the scattering phenomena caused by the existence of the foundation. The motion of the soil is supposed to be governed by Biot's dynamic poroelastic theory, while the boundary conditions along the contact surface between the soil and bottom of the foundation are assumed to be perfectly bonded for the skeleton and hydraulically drained for the fluid. Combining with the mixed boundary-value condition and the dynamic equilibrium equation of the foundation, the expression of the vertical and rocking dynamic amplitude of the foundation subjected to the incident waves is obtained by solving the control equations using Hankel transforms. The influences of incident angle, the mass of the foundation and the permeability of the soil on the vertical vibrations of the foundation are thus determined through numerical calculations.

Transmission Raman spectroscopy is a mode of Raman spectroscopy that is especially beneficial to probe the bulk content of diffusely scattering samples. It decreases the issue of sub-sampling, which has been an obstacle for quantitative analysis of solid bulk samples for Raman systems with focused optics, and has mainly found applications not only in the pharmaceutical, agricultural, and polymer fields but also in the medical area. This chapter gives an overview of the principle, advantages, limitations, and applications of transmission Raman spectroscopy.

The understanding of the physical principles of light guidance and its interactions with surrounding matter is the main requirement for a detailed study of polymer-optical fibres (POFs). This chapter briefly summarises the physical fundamentals of light and the application of physical laws in optical fibres. Beginning with Maxwell equations and a definition of electromagnetic (EM) waves, interactions in solid matter in the form of polarisation and magnetisation will be discussed. The EM wave equations in vacuum and solid-state media are motivated as fundamental physical law of light's propagation. Scattering phenomena like Mie and Rayleigh scattering occurring in optical fibres are discussed afterward, and their influence onto the fibres' performances is deduced. As it is essential for data transport and signal transmission in optical fibres, boundary phenomena in the form of Snell's law and total reflexions are described by using mathematical and geometrical approaches. Finally, an overview of anisotropic effects like birefringence and the dispersion of light in real media is given in order to finalise the understanding of physical processes in POFs. A summary of the importance of physical effects in optical fibres is made which enables a qualitative understanding of the parameters which determine the efficiency of optical fibres and the currently existing bottlenecks and challenges towards high-performance polymer-optical fibres.

In this chapter we will review the basic concepts of linear acoustics. We will start by deriving the acoustic wave equation for small linear perturbations in a stationary fluid and then discuss the general characteristics of sound propagation, the sound radiation from volume displacement and dipole sources, the far field approximation, and acoustic scattering. We will also introduce the concept of Green's functions and solutions to the wave equation in both the time and the frequency domains. Finally the concept of Fourier transforms and their application in acoustics will be discussed.

Surface enhanced Raman scattering (SERS) is a sensitive and selective spectroscopic technique for the detection and characterization of analytes, which are adsorbed on suitable metal surfaces. The effect was first discovered experimentally in 1974 by Fleischmann et al., who reported very intense Raman bands from pyridine adsorbed onto an electrochemically roughened silver surface. They attributed this strong signal to the presence of a large number of pyridine molecules present at the roughened electrode surface due to its large surface area. However, in 1977 Jeanmaire and Van Duyne, and Albrecht and Creighton, independently recognized that the increase in intensity could not be accounted for simply by the number of scatterers present. They observed that compared with Raman scattering from the equivalent concentration of pyridine in solution, SERS gives an enhancement of ∼ 106 and concluded that an intrinsic surface enhancement effect played a fundamental role in producing the enhanced Raman scattering. In the basic process of SERS, the analyte is adsorbed onto a roughened metal surface of a suitable metal, usually silver or gold. On excitation of this surface with a laser beam, a change in polarizability of the analyte occurs in a direction perpendicular to the surface, leading to the enhanced scattering. The rough surface required for scattering can be provided in many ways. Common methods use aggregated colloidal particles, roughened electrodes, or thin cold-deposited metal films. However there are now many specially designed surfaces some of which are available commercially. With a technique which was discovered experimentally and which involves both the physics and chemistry of the interaction of light with a roughened surface and of the adsorption an analyte on a metal surface in water, air or vacuum at the molecular level it was perhaps inevitable that in the early stages of development the theory would be hotly disputed. However the process is now much better understood and it is possible to use the advantages of SERS to develop very sensitive and informative detection methods.

In this paper we give estimates for the proton--proton cross sections into pairs of quarkonium states $J/\psi$, $\psi(2S)$, $\Upsilon(1S)$ and $\Upsilon(2S)$ at the scheduled AFTER@LHC energy of $115$GeV. The estimates are based on the intrinsic heavy flavor mechanism which is observable for high values of $x_F$, a range outside the dominance of single parton and double parton scattering., Comment: 11 pages, 2 figures, version to be published

This article describes a quantum mechanical reactive scattering program for atom–diatom chemical reactions that we have written during the past several years. The program uses a coupled-channel hyperspherical coordinate method to solve the Schrodinger equation for the motion of the three nuclei on a single Born–Oppenheimer potential energy surface. It has been tested for all possible deuterium-substituted isotopomers of the H + H 2 , F + H 2 , and Cl + H 2 reactions, and tried and tested potential energy surfaces for these reactions are included within the program as Fortran subroutines.

Multicircle diffractometry uses high-resolution angle-positioning instruments to collect scattering data from crystalline samples. This article describes several common diffractometer geometries, beginning with the basic four-circle Eulerian diffractometer, detailing the calculations used to convert between the reciprocal space of the sample and the angle space of the instrument. Options and requirements for selection of angles for a given diffraction condition are discussed.

Amorphous materials do not possess long-range order, so that understanding their structures at different length scales requires application of different diffraction and spectroscopic techniques, combined with computational modeling. Vibrational spectroscopy provides a detailed probe of molecular structure and bonding in amorphous solids and liquids as well as molecules and crystals. Infrared spectroscopy and Raman scattering are convenient laboratory techniques for studying vibrational excitations in these systems. Inelastic neutron and X-ray scattering give additional information on the dynamics of disordered materials. Molecular dynamics simulations and ab initio calculations give further insights into the nature of vibrations in glasses and liquids, as well as on relaxation processes.

This article is a review of the state of experimental knowledge of thermopower in metallic materials at high temperatures. It is assumed that the boundary between the high- and the low-temperature region is determined by the characteristic energy of the most important temperature-induced scattering mechanism. In crystalline conductors the most common temperature-induced scattering mechanism is the scattering of conduction electrons with lattice vibrations. The characteristic temperature of lattice vibrations (called Debye temperature) of most metals falls in the range 100–400 K. This is why in practice the boundary between low and high temperatures is about 300 K. The article contains a short theoretical introduction, and collection of the experimental results on the thermopower of pure metals, metallic continuous binary solid solutions, and examples of the data for intermetallic compounds at temperatures up to 2000 K.

When monochromatic light is scattered by a molecule or crystal, photons of the incident radiation may be annihilated and, at the same time, remitted as dipole radiation with a different energy or frequency. This frequency shift with respect to the incident radiation is balanced by excitations of the scattering medium, as phonons, magnons or electronic excitations. Raman light scattering (RS) is frequently used as a nondestructive characterization technique with a very high sensitivity for optical phonons with small wave vectors close to the center of the Brillouin zone.

This chapter focuses on the physio-optical properties of particles and gases. It starts with basic concepts such as color, electromagnetic energy properties such as wavelength, frequency, and speed, and the idea of radiometric and photometric units. A qualitative discussion of the interaction of light with particles is presented along with the ideas of particle diffraction, refraction, and absorption of electromagnetic energy. Rayleigh and Mie scattering are introduced, and the consequential effects of particle size on the efficiency with which particles scatter light and the effects of size on directional scattering are discussed. These effects are highlighted with real-world photos. The next sections present a mathematical treatment of the relationship between mass size distributions and their physical characteristics with particle scattering and absorption. Many commonly used physio-optical variables such as extinction, scattering, and absorption coefficients, volume scattering function, mass extinction efficiency, and the relative humidity enhancement factor f ( RH ) are introduced. The concept of partial mass extinction/scattering efficiency is defined and explored as it relates to the change expected from removing (or adding) a chemical species to (or from) the atmosphere. Real-world examples are given. A summary of hundreds of measurements and calculations of mass extinction coefficients is presented. The chapter closes with a discussion of two simple methods for estimating atmospheric extinction from filter-based, species-specific, aerosol mass concentrations.

This study presents a theoretical investigation of the effect of the aerosol vertical distribution on the aerosol radiative effect (ARE). Four aerosol composition models (dust, polluted dust, pollution and pure scattering aerosols) with varying aerosol vertical profiles are incorporated into a radiative transfer model. The simulations show interesting spectral dependence of the ARE on the aerosol layer height. ARE increases with the aerosol layer height in the ultraviolet (UV: 0.25–0.42 μm) and thermal-infrared (TH-IR: 4.0–20.0 μm) regions, whereas it decreases in the visible-near infrared (VIS-NIR: 0.42–4.0 μm) region. Changes in the ARE with aerosol layer height are associated with different dominant processes for each spectral region. The combination of molecular (Rayleigh) scattering and aerosol absorption is the key process in the UV region, whereas aerosol (Mie) scattering and atmospheric gaseous absorption are key players in the VIS-NIR region. The longwave emission fluxes are controlled by the environmental temperature at the aerosol layer level. ARE shows maximum sensitivity to the aerosol layer height in the TH-IR region, followed by the UV and VIS-NIR regions. These changes are significant even in relatively low aerosol loading cases (aerosol optical depth ∼0.2–0.3). Dust aerosols are the most sensitive to altitude followed by polluted dust and pollution in all three different wavelength regions. Differences in the sensitivity of the aerosol type are explained by the relative strength of their spectral absorption/scattering properties. The role of surface reflectivity on the overall altitude dependency is shown to be important in the VIS-NIR and UV regions, whereas it is insensitive in the TH-IR region. Our results indicate that the vertical distribution of water vapor with respect to the aerosol layer is an important factor in the ARE estimations. Therefore, improved estimations of the water vapor profiles are needed for the further reduction in uncertainties associated with the ARE estimation.

Consider a scattering problem for the Dirac equation with a nonlocal term including the Hartree type in two dimensions. We show the existence of scattering operators for small data in the subcritical and critical Sobolev spaces.

The energy response of plastic scintillators (Eljen Technology EJ-204) to polarized soft gamma-ray photons below 100 keV has been studied, primarily for the balloon-borne polarimeter, PoGOLite. The response calculation includes quenching effects due to low-energy recoil electrons and the position dependence of the light collection efficiency in a 20 cm long scintillator rod. The broadening of the pulse-height spectrum, presumably caused by light transportation processes inside the scintillator, as well as the generation and multiplication of photoelectrons in the photomultiplier tube, were studied experimentally and have also been taken into account. A Monte Carlo simulation based on the Geant4 toolkit was used to model photon interactions in the scintillators. When using the polarized Compton/Rayleigh scattering processes previously corrected by the authors, scintillator spectra and angular distributions of scattered polarized photons could clearly be reproduced, in agreement with the results obtained at a synchrotron beam test conducted at the KEK Photon Factory. Our simulation successfully reproduces the modulation factor, defined as the ratio of the amplitude to the mean of the distribution of the azimuthal scattering angles, within ∼ 5 % (relative). Although primarily developed for the PoGOLite mission, the method presented here is also relevant for other missions aiming to measure polarization from astronomical objects using plastic scintillator scatterers.

This manuscript reports the analysis of the G′ band profile in the Raman spectra of nanographites with different degrees of stacking order. Since the G′ band scattering coming from the 2D and 3D phases coexisting in the same sample can be nicely distinguished, the relative volumes of 3D and 2D graphite phases present in the samples can be estimated from their Raman spectra. The comparison between Raman scattering and X-Ray diffraction data shows that Raman spectroscopy can be used as an alternative tool for measuring the degree of stacking order of graphitic systems.

In this manuscript we investigate the capabilities of the Discrete Dipole Approximation (DDA) to simulate scattering from particles that are much larger than the wavelength of the incident light, and describe an optimized publicly available DDA computer program that processes the large number of dipoles required for such simulations. Numerical simulations of light scattering by spheres with size parameters x up to 160 and 40 for refractive index m=1.05 and 2 respectively are presented and compared with exact results of the Mie theory. Errors of both integral and angle-resolved scattering quantities generally increase with m and show no systematic dependence on x. Computational times increase steeply with both x and m, reaching values of more than 2 weeks on a cluster of 64 processors. The main distinctive feature of the computer program is the ability to parallelize a single DDA simulation over a cluster of computers, which allows it to simulate light scattering by very large particles, like the ones that are considered in this manuscript. Current limitations and possible ways for improvement are discussed., Comment: 13 pages, 10 figures

Deuteron-deuteron elastic scattering and transfer reactions in the energy regime above four-nucleon breakup threshold are described by solving exact four-particle equations for transition operators. Several realistic nuclear interaction models are used, including the one with effective many-nucleon forces generated by the explicit $\Delta$-isobar excitation; the Coulomb force between protons is taken into account as well. Differential cross sections, deuteron analyzing powers, outgoing nucleon polarization, and deuteron-to-neutron polarization transfer coefficients are calculated at 10 MeV deuteron energy. Overall good agreement with the experimental data is found. The importance of breakup channels is demonstrated., Comment: 5 figures

The size of colloidal particles in food products has a considerable impact on the product's physicochemical, functional and sensory characteristics. Measurement techniques to monitor the size of suspended particles could, therefore, help to further reduce the variability in production processes and promote the development of new food products with improved properties. Visible and near-infrared (Vis/NIR) spectroscopy is already widely used to measure the composition of agricultural and food products. However, this technology can also be consulted to acquire microstructure-related scattering properties of food products. In this study, the effect of the fat globule size on the Vis/NIR bulk scattering properties of milk was investigated. Variability in fat globule size distribution was created using ultrasonic homogenization of raw milk. Reduction of the fat globule size resulted in a higher wavelength-dependency of both the Vis/NIR bulk scattering coefficient and the scattering anisotropy factor. Moreover, the anisotropy factor and the bulk scattering coefficients for wavelengths above 600 nm were reduced and were dominated by Rayleigh scattering. Additionally, the bulk scattering properties could be well (R(2) ≥ 0.990) estimated from measured particle size distributions by consulting an algorithm based on the Mie solution. Future research could aim at the inversion of this model to estimate the particle size distributions from Vis/NIR spectroscopic measurements. publisher: Elsevier articletitle: Effect of ultrasonic homogenization on the Vis/NIR bulk optical properties of milk journaltitle: Colloids and Surfaces B: Biointerfaces articlelink: http://dx.doi.org/10.1016/j.colsurfb.2015.01.004 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Colloids and Surfaces B, Biointerfaces vol:126 pages:510-519 ispartof: location:Netherlands status: published

Ultrasonic guided waves are used in the non-destructive testing of pipelines. This involves launching an elastic wave along the wall of the pipe and then capturing the returning wave scattered by a defect. Numerical study of wave scattering is often computationally expensive because the shortest wavelength is often very small compared to the size of the pipe in the ultrasonic frequency range. Furthermore, the number of the scattered wave modes from a non-axisymmetric defect in the pipe can be large and separation of these modes is difficult in a conventional finite element method. Accordingly, this article presents a model suitable for studying elastic wave propagation in waveguides with an arbitrary cross-section in the time and frequency domain. A weighted residual formulation is used to deliver an efficient hybrid numerical formulation, which is applied to a long pipeline containing a defect of arbitrary shape. The problem is solved first in the frequency domain and then extended to the time domain using an inverse Fourier transform. To separate the scattered wave modes in the time domain, a technique is proposed whereby measurement locations are arranged axially along the pipe and a two dimensional Fourier transform is used to present data in the wavenumber-frequency domain. This enables the separation of highly dispersive modes and the recovery of modal amplitudes. This has the potential to reveal more information about the characteristics of a defect and so may help in distinguishing between different type of defects, such a cracks or regions of corrosion, typically found in pipelines. A hybrid numerical formulation is proposed to study wave scattering from defects.Finite element method and modal expansion solutions are combined.Predictions are presented both in the frequency and time domain.A two dimensional Fourier transform is used to determine modal amplitudes.Problems associated with dispersion can be avoided in the converted k - ω domain.

The conformational ensemble of a macromolecule is the complete description of the macromolecule's solution structures and can reveal important aspects of macromolecular folding, recognition, and function. However, most experimental approaches determine an average or predominant structure, or follow transitions between states that each can only be described by an average structure. Ensembles have been extremely difficult to experimentally characterize. We present the unique advantages and capabilities of a new biophysical technique, X-ray scattering interferometry (XSI), for probing and quantifying structural ensembles. XSI measures the interference of scattered waves from two heavy metal probes attached site specifically to a macromolecule. A Fourier transform of the interference pattern gives the fractional abundance of different probe separations directly representing the multiple conformation states populated by the macromolecule. These probe–probe distance distributions can then be used to define the structural ensemble of the macromolecule. XSI provides accurate, calibrated distance in a model-independent fashion with angstrom scale sensitivity in distances. XSI data can be compared in a straightforward manner to atomic coordinates

Starting with the Chern-Simons formulation of (2+1)-dimensional gravity we show that the gravitational interactions deform the Poincare symmetry of flat space-time to a quantum group symmetry. The relevant quantum group is the quantum double of the universal cover of the (2+1)-dimensional Lorentz group, or Lorentz double for short. We construct the Hilbert space of two gravitating particles and use the universal R-matrix of the Lorentz double to derive a general expression for the scattering cross section of gravitating particles with spin. In appropriate limits our formula reproduces the semi-classical scattering formulae found by 't Hooft, Deser, Jackiw and de Sousa Gerbert., Comment: 45 pages, amslatex

International audience; We modeled the Synthetic Aperture Radar (SAR) response of linear dunes of the Great Sand Sea in Egypt using a single surface scattering term, based on Integral Equation and Physical Optics Models. Using multi-frequency SIR-C/X-SAR radar scenes and topography obtained from the Shuttle Radar Topography Mission (SRTM), we were able to estimate reasonable values for the parameters describing the surface roughness of the dunes. As the linear dunes of the Great Sand Sea are relevant analogs for the linear dunes observed on Titan by the Cassini Radar instrument, these results were thus used as a starting point to simulate the radar response of Titan's dunes, as imaged by the Radar instrument onboard the Cassini spacecraft during the T8 flyby in October 2005. We show that a single surface scattering term is not sufficient to simulate the radar signal backscattered by the dunes on Titan: one has to add a diffuse scattering term, indicating that Titan's dunes are likely to have somewhat inhomogeneous internal structures related to porosity and/or internal layering. Our results also indicate that the dunes on Titan should be close to perfectly smooth, possibly because of the formation of smaller ripples than on Earth, plus smoothing resulting from precipitation events.

This chapter reviews Raman scattering (RS) from single-walled carbon nanotubes (SWCNTs) and graphene as it relates to their phonon structure and to resonance excitation. Basic concepts of RS including double resonance and the phonon structures of the two systems are described. For the most important Raman lines a review is presented. In detail special Raman experiments are discussed such as scattering from double-walled carbon nanotubes (DWCNTs), carbon nanotubes (CNTs) with ultrahigh curvature, pressure and temperature effects, tip-enhanced RS (TERS), electronic RS, orientation-dependent RS and scattering from metal-semiconductor separated tubes. In the sections on graphene the importance of lineshape analysis from the 2D line is elucidated as it can be used for the determination of layer numbers in few-layer graphene (FLG). Other characteristic Raman features are reviewed as well. Some of them also exhibit a characteristic dependence on layer numbers. Such features are C lines and N lines and several combination tones. Eventually the I lines are discussed which exhibit a dependence on stacking order.

Strong carrier scattering perturbs the intrinsic response of Dirac fermions in graphene and limits potential applications of graphene-based devices. Multiple scattering mechanisms including Coulomb scattering, lattice disorder scattering and electron–phonon scattering play roles in realistic graphene devices. Moreover, different types and preparations of graphene are characterized by different dominant scattering mechanisms. In this chapter, we review the recent progress towards reduction of carrier scattering in graphene. We start by discussing different metrics – such as carrier mobility, mean free path, and scattering time – that are used to quantify the scattering strength. Then, we review the strategies to reduce scattering and to improve carrier mobility. These strategies include: lowering defect density, suspending graphene, depositing graphene onto high-quality substrates, and covering it with high- k dielectrics. Finally, we briefly address the physical phenomena and device applications that are specific to ultraclean high-mobility graphene.

This chapter describes the role of grain boundaries and surfaces in the resistivity of metallic thin films, focusing on the increase in resistivity as the characteristic dimensions (e.g., grain size and film thickness) of the metal are reduced, a phenomenon known as the classical size effect. The electrical conduction in bulk metals is briefly described using Boltzmann’s transport equation. Extensions of that understanding to include the additional scattering from surfaces and grain boundaries are developed. Several quantitative models of classical size effect are reviewed based on differing physical assumptions and quantitative comparisons of experimental data to the models are made to provide an increased physical understanding.

In this work we provide explicit calculations that support the conclusions stated in Phys. Rev. Lett. 111, 039102 (2013) (comment), regarding recent literature on transverse polarization. We also compare and contrast two methods of deriving spin sum rules., 11 pages, Latex

Starting from basic phase space physics, the transport of particles in six-dimensional coordinates and velocity, or energy and direction space are described based on the equation of continuity. The different steps in the development of the Vlasov, Liouville, and Boltzmann equations are described along with some of their main applications. Special attention is given to the generalized Fermi–Eyges solution of the Fokker–Planck approximation of the Boltzmann equation owing to its importance in describing the physics of narrow elementary pencil beams of charged particles. The solution is applicable to both electrons and ions taking into account all major interactions from energy loss and attenuation to small-angle multiple Columb scattering. In the last section, many of these transport results are applied to make dosimetry accurate such as in Fano’s theorem and for obtaining a consistent and coherent definition of an effective reference volume concept allowing the accurate definition and separation of the effective point of measurement from the fluence perturbation factor at the same time as the application of traditional stopping-power ratio tabulations. Many of the fluence perturbation factors are derived based on the generalized Fermi–Eyges solution of the Boltzmann equation.

In Doppler ultrasound, the Doppler shift from moving blood is utilized to measure blood flow velocities and direction and to extract the weak scattering from blood from much stronger echoes from the vessel wall and other larger tissue structures in the human body. Continuous-wave and pulsed-wave Doppler give velocity waveforms in a spectrum display, whereas color Doppler imaging gives a color map overlay to the B-mode image, showing the vessel geometry and flow direction.

Based on the superpositional principle of the classical Hamaker–De Boer approach to the Van der Waals interaction, an equation for the interaction energy between two identical composite particles in a medium has been developed. The particles are supposed to be composed of an arbitrary number of components that are intimately mixed to avoid appreciable scattering of interacting EM waves. A discussion is presented on how intimately the components have to be mixed for the theory to be applicable. As an example, the main theoretical result is applied to porous polystyrene particles in water, while the pores are not filled with water (‘non-wetting surface’). Numerical results for composite particles are evaluated, using interaction parameters as obtained by various methods that are based on either the Hamaker–de Boer or the Lifshitz approach.

In this work, an exact scattering model for a system of clusters of spherical particles, based on the Rayleigh-Gans approximation, has been parameterized in such a way that it can be solved in inverse form using Thikhonov Regularization to obtain the morphological parameters of the clusters. That is to say, the average number of particles per cluster, the size of the primary spherical units that form the cluster, and the Discrete Distance Distribution Function from which the z-average square radius of gyration of the system of clusters is obtained. The methodology is validated through a series of simulated and experimental examples of x-ray and light scattering that show that the proposed methodology works satisfactorily in unideal situations such as: presence of error in the measurements, presence of error in the model, and several types of unideallities present in the experimental cases. Fil: Elicabe, Guillermo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Mar del Plata. Instituto de Investigación en Ciencia y Tecnología de Materiales (i); Argentina; Universidad Nacional de Mar del Plata; Argentina

WOS: 000307091100007, In this study, the effective atomic number (Z(eff))has been calculated for some boron compounds, such as concentrate colemanite, tincal, ulexite, boric acid, probertite and TSW (Trommel Sieve Waste) by means of ZXCOM at incident beam energy (E-0=59.543 key) and scattering angle (theta=35 degrees). We present and discuss the (Z(eff)) obtained by Rayleigh/Compton (R/C) ratio and evaluated for the purpose of radiation shielding which contains boron compounds, which are commonly used as shield materials. (C) 2012 Elsevier B.V. All rights reserved., Yildiz Technical UniversityYildiz Technical University [2011-01-01-KAP02], This work was supported by the Yildiz Technical University under award number 2011-01-01-KAP02.

The porosity of a typical activated carbon is investigated with small angle neutron scattering (SANS), using the contrast matching technique, by changing the hydrogen/deuterium content of the absorbed liquid (toluene) to extract the carbon density at different scattering vector (Q) values and by measuring the p/p0 dependence of the SANS, using fully deuterated toluene. The contrast matching data shows that the apparent density is Q-dependent, either because of pores opening near the carbon surface during the activation processor or changes in D-toluene density in nanoscale pores. For each p/p0 value, evaluation of the Porod Invariant yields the fraction of empty pores. Hence, comparison with the adsorption isotherm shows that the fully dry powder undergoes densification when liquid is added. An algebraic function is developed to fit the SANS signal at each p/p0 value hence yielding the effective Kelvin radii of the liquid surfaces as a function of p/p0. These values, when compared with the Kelvin Equation, show that the resultant surface tension value is accurate for the larger pores but tends to increase for small (nanoscale) pores. The resultant pore size distribution is less model-dependent than for the traditional methods of analyzing the adsorption isotherms.

In this review, some recent progress concerning the direct and inverse problems in the theory of light scattering are discussed. The basic theory of light scattering is presented within the accuracy of the first-order Born approximation, and the properties of the scattered field are studied. The scattering medium may be either isotropic or anisotropic, and the incident light wave can be scalar or electromagnetic. In addition, the application of light scattering to the determination of the structure of the scattering medium is discussed.