Showing papers on "Scattering published in 2014"
TL;DR: A compact formula for the complete tree-level S-matrix of pure Yang-Mills and gravity theories in arbitrary spacetime dimensions is presented and Gauge invariance is completely manifest as it follows from a simple property of the Pfaffian.
Abstract: A new formula for the scattering of massless particles may simplify predictions and analyses of LHC experiments and shed new light on quantum gravity theories.
828 citations
TL;DR: Grazing incidence X-ray scattering provides unique insights into the morphology of active materials and thin film layers used in organic photovoltaic devices and conjugated polymers, such as poly(3-hexylthiophene) (P3HT).
Abstract: Grazing incidence X-ray scattering (GIXS) provides unique insights into the morphology of active materials and thin film layers used in organic photovoltaic devices. With grazing incidence wide angle X-ray scattering (GIWAXS) the molecular arrangement of the material is probed. GIWAXS is sensitive to the crystalline parts and allows for the determination of the crystal structure and the orientation of the crystalline regions with respect to the electrodes. With grazing incidence small angle X-ray scattering (GISAXS) the nano-scale structure inside the films is probed. As GISAXS is sensitive to length scales from nanometers to several hundred nanometers, all relevant length scales of organic solar cells are detectable. After an introduction to GISAXS and GIWAXS, selected examples for application of both techniques to active layer materials are reviewed. The particular focus is on conjugated polymers, such as poly(3-hexylthiophene) (P3HT).
514 citations
TL;DR: Black phosphorus exhibits a high degree of band anisotropy, however, it is found that its in-plane static screening remains relatively isotropic for momenta relevant to elastic long-range scattering processes.
Abstract: Black phosphorus exhibits a high degree of band anisotropy. However, we find that its in-plane static screening remains relatively isotropic for momenta relevant to elastic long-range scattering processes. On the other hand, the collective electronic excitations in the system exhibit a strong anisotropy. Band nonparabolicity, due to interband couplings, leads to a plasmon frequency which scales as nβ, where n is the carrier concentration, and β<1/2. Screening and charge distribution in the out-of-plane direction are also studied using a nonlinear Thomas-Fermi model.
513 citations
TL;DR: A scattering transform defines a locally translation invariant representation which is stable to time-warping deformation and extends MFCC representations by computing modulation spectrum coefficients of multiple orders, through cascades of wavelet convolutions and modulus operators.
Abstract: A scattering transform defines a locally translation invariant representation which is stable to time-warping deformation. It extends MFCC representations by computing modulation spectrum coefficients of multiple orders, through cascades of wavelet convolutions and modulus operators. Second-order scattering coefficients characterize transient phenomena such as attacks and amplitude modulation. A frequency transposition invariant representation is obtained by applying a scattering transform along log-frequency. State-the-of-art classification results are obtained for musical genre and phone classification on GTZAN and TIMIT databases, respectively.
495 citations
TL;DR: A novel hollow core fiber design based on nested and non-touching antiresonant tube elements arranged around a central core is proposed and it is demonstrated through numerical simulations that such a design can achieve considerably lower loss than other state-of-the-art hollow fibers.
Abstract: We propose a novel hollow core fiber design based on nested and non-touching antiresonant tube elements arranged around a central core. We demonstrate through numerical simulations that such a design can achieve considerably lower loss than other state-of-the-art hollow fibers. By adding additional pairs of coherently reflecting surfaces without introducing nodes, the Hollow Core Nested Antiresonant Nodeless Fiber (HC-NANF) can achieve values of confinement loss similar or lower than that of its already low surface scattering loss, while maintaining multiple and octave-wide antiresonant windows of operation. As a result, the HC-NANF can in principle reach a total value of loss – including leakage, surface scattering and bend contributions – that is lower than that of conventional solid fibers. Besides, through resonant out-coupling of high order modes they can be made to behave as effectively single mode fibers.
432 citations
TL;DR: An unambiguous demonstration of the theoretically predicted crossover from diffuse (particle- like) to specular (wave-like) phonon scattering in epitaxial oxide superlattices, manifested by a minimum in lattice thermal conductivity as a function of interface density is presented.
Abstract: Understanding the thermal transport properties of superlattice structures is relevant to a number of possible practical applications. Now, the scattering of phonons in oxide superlattices is shown to undergo a crossover from an incoherent to a coherent regime, which in turn strongly alters their thermal behaviour.
413 citations
Book•
09 Dec 2014
TL;DR: In this paper, the authors present a survey of applications of PIR in matrix algebra and matrix algebra, including unitary and rotation groups, and coherent stochastic signal analysis.
Abstract: 1. Polarised Electromagnetic Waves 2. Depolarisation and Scattering Entropy 3. Depolarisation in Surface and Volume Scattering 4. Decomposition Theorems 5. Introduction to Radar Interferometry 6. Polarimetric Interferometry 7. Coherence Variation for Surface and Volume Scattering 8. Parameter Estimation using Polarimetric Interferometry 9. Applications of Polarimetry and Interferometry Appendix 1: Introduction to Matrix Algebra Appendix 2: Unitary and Rotation Groups Appendix 3: Coherent Stochastic Signal Analysis
407 citations
TL;DR: An extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods is presented, showing how the interfacial self-assembly and oriented attachment of nanocrystals results in 2D metal chalcogenide semiconductors with a honeycomb superlattice.
Abstract: Oriented attachment of synthetic semiconductor nanocrystals is emerging as a route for obtaining new semiconductors that can have Dirac-type electronic bands such as graphene, but also strong spin-orbit coupling. The two-dimensional (2D) assembly geometry will require both atomic coherence and long-range periodicity of the superlattices. We show how the interfacial self-assembly and oriented attachment of nanocrystals results in 2D metal chalcogenide semiconductors with a honeycomb superlattice. We present an extensive atomic and nanoscale characterization of these systems using direct imaging and wave scattering methods. The honeycomb superlattices are atomically coherent and have an octahedral symmetry that is buckled; the nanocrystals occupy two parallel planes. Considerable necking and large-scale atomic motion occurred during the attachment process.
338 citations
TL;DR: This work combines Kramers–Kronig analysis with analytical scattering theory, extended with Percus–Yevick structure factors that take into account the effect of dependent scattering in whole blood and argues that its calculated spectra may provide a better estimation for μs and g than the compiled spectra from literature for wavelengths between 300 and 600 nm.
Abstract: Optical property measurements on blood are influenced by a large variety of factors of both physical and methodological origin. The aim of this review is to list these factors of influence and to provide the reader with optical property spectra (250–2,500 nm) for whole blood that can be used in the practice of biomedical optics (tabulated in the appendix). Hereto, we perform a critical examination and selection of the available optical property spectra of blood in literature, from which we compile average spectra for the absorption coefficient (μa), scattering coefficient (μs) and scattering anisotropy (g). From this, we calculate the reduced scattering coefficient (μs′) and the effective attenuation coefficient (μeff). In the compilation of μa and μs, we incorporate the influences of absorption flattening and dependent scattering (i.e. spatial correlations between positions of red blood cells), respectively. For the influence of dependent scattering on μs, we present a novel, theoretically derived formula that can be used for practical rescaling of μs to other haematocrits. Since the measurement of the scattering properties of blood has been proven to be challenging, we apply an alternative, theoretical approach to calculate spectra for μs and g. Hereto, we combine Kramers–Kronig analysis with analytical scattering theory, extended with Percus–Yevick structure factors that take into account the effect of dependent scattering in whole blood. We argue that our calculated spectra may provide a better estimation for μs and g (and hence μs′ and μeff) than the compiled spectra from literature for wavelengths between 300 and 600 nm.
337 citations
Patent•
20 Feb 2014
TL;DR: In this article, surface scattering antennas provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure, and the scattering elements are made adjustable by disposing an electrically adjustable material, such as a liquid crystal, in proximity to the scattering element.
Abstract: Surface scattering antennas provide adjustable radiation fields by adjustably coupling scattering elements along a wave-propagating structure. In some approaches, the scattering elements are patch elements. In some approaches, the scattering elements are made adjustable by disposing an electrically adjustable material, such as a liquid crystal, in proximity to the scattering elements. Methods and systems provide control and adjustment of surface scattering antennas for various applications.
315 citations
TL;DR: In this article, the authors investigated the evolution of the Raman spectrum of defected graphene as a function of doping and found that the intensities of the D and D′ peaks decrease with increasing doping.
Abstract: We investigate the evolution of the Raman spectrum of defected graphene as a function of doping. Polymer electrolyte gating allows us to move the Fermi level up to 0.7 eV, as directly monitored by in situ Hall-effect measurements. For a given number of defects, we find that the intensities of the D and D′ peaks decrease with increasing doping. We assign this to an increased total scattering rate of the photoexcited electrons and holes, due to the doping-dependent strength of electron–electron scattering. We present a general relation between D peak intensity and defects valid for any doping level.
TL;DR: A reciprocal effect of spin-orbit coupling is demonstrated when the direction of propagation of a surface plasmon wave, which intrinsically has unusual transverse spin, determines a scattering direction ofspin-carrying photons.
Abstract: The spin Hall effect leads to the separation of electrons with opposite spins in different directions perpendicular to the electric current flow because of interaction between spin and orbital angular momenta. Similarly, photons with opposite spins (different handedness of circular light polarization) may take different trajectories when interacting with metasurfaces that break spatial inversion symmetry or when the inversion symmetry is broken by the radiation of a dipole near an interface. Here we demonstrate a reciprocal effect of spin-orbit coupling when the direction of propagation of a surface plasmon wave, which intrinsically has unusual transverse spin, determines a scattering direction of spin-carrying photons. This spin-orbit coupling effect is an optical analogue of the spin injection in solid-state spintronic devices (inverse spin Hall effect) and may be important for optical information processing, quantum optical technology and topological surface metrology.
TL;DR: Subwavelength layered plasmonic nanospheres can be tuned to excite specific scattering resonances with infinite lifetimes as discussed by the authors, which can be used to generate a specific scattering resonance with infinite lifetime.
Abstract: Subwavelength layered plasmonic nanospheres can be tuned to excite specific scattering resonances with infinite lifetimes.
TL;DR: It is demonstrated, using full-wave simulations, that an anomalous lateral force can be induced in a direction perpendicular to that of the incident photon momentum if a chiral particle is placed above a substrate that does not break any left–right symmetry.
Abstract: Light can exert radiation pressure on any object it encounters and that resulting optical force can be used to manipulate particles. It is commonly assumed that light should move a particle forward and indeed an incident plane wave with a photon momentum ħk can only push any particle, independent of its properties, in the direction of k. Here we demonstrate, using full-wave simulations, that an anomalous lateral force can be induced in a direction perpendicular to that of the incident photon momentum if a chiral particle is placed above a substrate that does not break any left-right symmetry. Analytical theory shows that the lateral force emerges from the coupling between structural chirality (the handedness of the chiral particle) and the light reflected from the substrate surface. Such coupling induces a sideway force that pushes chiral particles with opposite handedness in opposite directions.
TL;DR: In this article, the relationship between surface scattering properties, the bulk band properties, and the formation of interface states is investigated, which can enable the design of systems with interface states in a rational manner.
Abstract: Surface impedance is an important concept in classical wave systems such as photonic crystals (PCs). For example, the condition of an interface state formation in the interfacial region of two different one-dimensional PCs is simply Z_SL +Z_SR=0, where Z_SL (Z_SR)is the surface impedance of the semi-infinite PC on the left- (right-) hand side of the interface. Here, we also show a rigorous relation between the surface impedance of a one-dimensional PC and its bulk properties through the geometrical (Zak) phases of the bulk bands, which can be used to determine the existence or non-existence of interface states at the interface of the two PCs in a particular band gap. Our results hold for any PCs with inversion symmetry, independent of the frequency of the gap and the symmetry point where the gap lies in the Brillouin Zone. Our results provide new insights on the relationship between surface scattering properties, the bulk band properties and the formation of interface states, which in turn can enable the design of systems with interface states in a rational manner.
TL;DR: The strain-tunable valley-orbit coupling implies new structures of exciton condensates, new functionalities of excitonic circuits and mechanical control of valley pseudospin, which point to unique opportunities to study Dirac physics.
Abstract: In monolayer transition metal dichalcogenides, tightly bound excitons have been discovered with a valley pseudospin optically addressable through polarization selection rules. Here, we show that this valley pseudospin is strongly coupled to the exciton centre-of-mass motion through electron-hole exchange. This coupling realizes a massless Dirac cone with chirality index I = 2 for excitons inside the light cone, that is, bright excitons. Under moderate strain, the I = 2 Dirac cone splits into two degenerate I = 1 Dirac cones, and saddle points with a linear Dirac spectrum emerge. After binding an extra electron, the charged exciton becomes a massive Dirac particle associated with a large valley Hall effect protected from intervalley scattering. Our results point to unique opportunities to study Dirac physics, with exciton's optical addressability at specifiable momentum, energy and pseudospin. The strain-tunable valley-orbit coupling also implies new structures of exciton condensates, new functionalities of excitonic circuits and mechanical control of valley pseudospin.
TL;DR: A novel three-dimensional hotspot matrix that can hold hotspots between every two adjacent particles in 3D space is demonstrated, simply achieved by evaporating a droplet of citrate-Ag sols on a fluorosilylated silicon wafer.
Abstract: The “fixed” or “flexible” design of plasmonic hotspots is a frontier area of research in the field of surface-enhanced Raman scattering (SERS). Most reported SERS hotspots have been shown to exist in zero-dimensional point-like, one-dimensional linear, or two-dimensional planar geometries. Here, we demonstrate a novel three-dimensional (3D) hotspot matrix that can hold hotspots between every two adjacent particles in 3D space, simply achieved by evaporating a droplet of citrate-Ag sols on a fluorosilylated silicon wafer. In situ synchrotron-radiation small-angle X-ray scattering (SR-SAXS), combined with dark-field microscopy and in situ micro-UV, was employed to explore the evolution of the 3D geometry and plasmonic properties of Ag nanoparticles in a single droplet. In such a droplet, there is a distinct 3D geometry with minimal polydispersity of particle size and maximal uniformity of interparticle distance, significantly different from the dry state. According to theoretical simulations, the liquid adh...
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TL;DR: A general relation between D peak intensity and defects valid for any doping level is presented, and for a given number of defects, it is found that the intensities of the D and D' peaks decrease with increasing doping.
Abstract: We investigate the evolution of the Raman spectrum of defected graphene as a function of doping. Polymer electrolyte gating allows us to move the Fermi level up to 0.7eV, as monitored by \textit{in-situ} Hall-effect measurements. For a given number of defects, we find that the intensities of the D and D' peaks decrease with increasing doping. We assign this to an increased total scattering rate of the photoexcited electrons and holes, due to the doping-dependent strength of electron-electron scattering. We present a general relation between D peak intensity and defects valid for any doping level
TL;DR: In this article, the pump-probe Kerr rotation dynamics in monolayers were studied and a direct measurement of the exciton valley depolarization time was obtained, at a temperature of 1.5 ps at 125 K.
Abstract: We have experimentally studied the pump-probe Kerr rotation dynamics in ${\mathrm{WSe}}_{2}$ monolayers. This yields a direct measurement of the exciton valley depolarization time ${\ensuremath{\tau}}_{v}$. At $T=4\phantom{\rule{0.28em}{0ex}}\mathrm{K}$, we find ${\ensuremath{\tau}}_{v}\ensuremath{\approx}6$ ps, a fast relaxation time resulting from the strong electron-hole Coulomb exchange interaction in bright excitons. The exciton valley depolarization time decreases significantly when the lattice temperature increases, with ${\ensuremath{\tau}}_{v}$ being as short as 1.5 ps at 125 K. The temperature dependence is well explained by the developed theory, taking into account the exchange interaction and fast exciton scattering time on the short-range potential.
TL;DR: Using resonant x-ray scattering, this paper mapped the evolution of charge density wave correlations in a series of YBa${}_{2}$Cu${}{3}$O${}$6+x}$ single crystals at a wide range of doping levels.
Abstract: Using resonant x-ray scattering, this group maps the evolution of charge density wave correlations in a series of YBa${}_{2}$Cu${}_{3}$O${}_{6+x}$ single crystals at a wide range of doping levels. Their data add important pieces to the cuprate phase diagram puzzle.
TL;DR: In this paper, Epelbaum et al. presented improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-tonext-leading order, which are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space.
Abstract: We present improved nucleon-nucleon potentials derived in chiral effective field theory up to next-to-next-to-next-to-leading order. We argue that the nonlocal momentum-space regulator employed in the two-nucleon potentials of Refs. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\ss}ner, Nucl. Phys. A747 (2005) 362], [D.R. Entem, R. Machleidt, Phys. Rev. C68 (2003) 041001] is not the most efficient choice, in particular since it affects the long-range part of the interaction. We are able to significantly reduce finite-cutoff artefacts by using an appropriate regularization in coordinate space which maintains the analytic structure of the amplitude. The new potentials do not require the additional spectral function regularization employed in Ref. [E. Epelbaum, W. Gloeckle, U.-G. Mei{\ss}ner, Nucl. Phys. A747 (2005) 362] to cut off the short-range components of the two-pion exchange and make use of the low-energy constants c_i and d_i determined from pion-nucleon scattering without any fine tuning. We discuss in detail the construction of the new potentials and convergence of the chiral expansion for two-nucleon observables. We also introduce a new procedure for estimating the theoretical uncertainty from the truncation of the chiral expansion that replaces previous reliance on cutoff variation.
TL;DR: SnO2 hollow microspheres that are utilized as a scattering layer on top of P25 films increase the DSSC photoconversion efficiency from 7.29% to 9.53% due to enhanced light scattering.
Abstract: Quintuple-shelled SnO2 hollow microspheres are prepared by a hard-template method. DSSCs constructed with SnO2 multi-shell photoanodes show a record photoconversion efficiency of 7.18% due to enhanced light scattering. SnO2 hollow microspheres that are utilized as a scattering layer on top of P25 films increase the DSSC photoconversion efficiency from 7.29% to 9.53%.
TL;DR: To the best of the knowledge, this photon source has the highest peak brilliance in the multi-MeV regime ever reported in the literature.
Abstract: We report on the generation of a narrow divergence (${\ensuremath{\theta}}_{\ensuremath{\gamma}}l2.5\text{ }\text{ }\mathrm{mrad}$), multi-MeV (${E}_{\mathrm{max}}\ensuremath{\approx}18\text{ }\text{ }\mathrm{MeV}$) and ultrahigh peak brilliance ($g1.8\ifmmode\times\else\texttimes\fi{}{10}^{20}\text{ }\text{ }\mathrm{photons}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }{\mathrm{mm}}^{\ensuremath{-}2}\text{ }\text{ }{\mathrm{mrad}}^{\ensuremath{-}2}$ 0.1% BW) $\ensuremath{\gamma}$-ray beam from the scattering of an ultrarelativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude ${a}_{0}\ensuremath{\approx}2$). The spectrum of the generated $\ensuremath{\gamma}$-ray beam is measured, with MeV resolution, seamlessly from 6 to 18 MeV, giving clear evidence of the onset of nonlinear relativistic Thomson scattering. To the best of our knowledge, this photon source has the highest peak brilliance in the multi-MeV regime ever reported in the literature.
TL;DR: Inelastic X-ray scattering studies of YBa2Cu3O6.6 reveal strong electron-phonon coupling and an inhomogeneous state made up of charge-density-wave nanodomains, which may explain some anomalous properties of the pseudogap state as mentioned in this paper.
Abstract: Inelastic X-ray scattering studies of YBa2Cu3O6.6 reveal strong electron-phonon coupling and an inhomogeneous state made up of charge-density-wave nanodomains, which may explain some anomalous properties of the pseudogap state.
TL;DR: In this paper, coherent band structure effects can also be used to control phonon transport via the use of periodically nanostructured phononic crystals, which is commonly achieved by introducing scattering centers.
Abstract: Controlling thermal transport is commonly achieved by introducing scattering centres. Here, the authors demonstrate that coherent band structure effects can also be used to control phonon transport, via the use of periodically nanostructured phononic crystals.
TL;DR: SCIATRAN as discussed by the authors is a comprehensive software package for the modeling of radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared including multiple scattering processes, polarization, thermal emission and ocean-atmosphere coupling.
Abstract: SCIATRAN is a comprehensive software package for the modeling of radiative transfer processes in the terrestrial atmosphere and ocean in the spectral range from the ultraviolet to the thermal infrared ( 0.18 – 40 μ m ) including multiple scattering processes, polarization, thermal emission and ocean–atmosphere coupling. The software is capable of modeling spectral and angular distributions of the intensity or the Stokes vector of the transmitted, scattered, reflected, and emitted radiation assuming either a plane-parallel or a spherical atmosphere. Simulations are done either in the scalar or in the vector mode (i.e. accounting for the polarization) for observations by space-, air-, ship- and balloon-borne, ground-based, and underwater instruments in various viewing geometries (nadir, off-nadir, limb, occultation, zenith-sky, off-axis). All significant radiative transfer processes are accounted for. These are, e.g. the Rayleigh scattering, scattering by aerosol and cloud particles, absorption by gaseous components, and bidirectional reflection by an underlying surface including Fresnel reflection from a flat or roughened ocean surface. The software package contains several radiative transfer solvers including finite difference and discrete-ordinate techniques, an extensive database, and a specific module for solving inverse problems. In contrast to many other radiative transfer codes, SCIATRAN incorporates an efficient approach to calculate the so-called Jacobians, i.e. derivatives of the intensity with respect to various atmospheric and surface parameters. In this paper we discuss numerical methods used in SCIATRAN to solve the scalar and vector radiative transfer equation, describe databases of atmospheric, oceanic, and surface parameters incorporated in SCIATRAN, and demonstrate how to solve some selected radiative transfer problems using the SCIATRAN package. During the last decades, a lot of studies have been published demonstrating that SCIATRAN is a valuable tool for a wide range of remote sensing applications. Here, we present some selected comparisons of SCIATRAN simulations to published benchmark results, independent radiative transfer models, and various measurements from satellite, ground-based, and ship instruments. Methods for solving inverse problems related to remote sensing of the Earth's atmosphere using the SCIATRAN software are outside the scope of this study and will be discussed in a follow-up paper. The SCIATRAN software package along with a detailed User's Guide is freely available for non-commercial use via the webpage of the Institute of Environmental Physics (IUP), University of Bremen: http://www.iup.physik.uni-bremen.de/sciatran .
TL;DR: Nonadiabatic ab initio molecular dynamics simulations, which predict carrier-carrier and carrier-phonon scattering time scales of 40 fs and 0.5 ps, respectively, lend support to the assignment of the observed carrier dynamics.
Abstract: Femtosecond optical pump–probe spectroscopy with 10 fs visible pulses is employed to elucidate the ultrafast carrier dynamics of few-layer MoS2. A nonthermal carrier distribution is observed immediately following the photoexcitation of the A and B excitonic transitions by the ultrashort, broadband laser pulse. Carrier thermalization occurs within 20 fs and proceeds via both carrier–carrier and carrier–phonon scattering, as evidenced by the observed dependence of the thermalization time on the carrier density and the sample temperature. The n–0.37±0.03 scaling of the thermalization time with carrier density suggests that equilibration of the nonthermal carrier distribution occurs via non-Markovian quantum kinetics. Subsequent cooling of the hot Fermi–Dirac carrier distribution occurs on the ∼0.6 ps time scale via carrier–phonon scattering. Temperature- and fluence-dependence studies reveal the involvement of hot phonons in the carrier cooling process. Nonadiabatic ab initio molecular dynamics simulations, ...
TL;DR: A detailed Mie theory, finite-difference time-domain, and quasi-static study of plasmon-exciton interactions in a spherical core-shell geometry is presented in this article.
Abstract: We present a detailed Mie theory, finite-difference time-domain, and quasi-static study of plasmon–exciton interactions in a spherical core–shell geometry. In particular, we report absorption, scattering, and extinction cross sections of a hybrid core–shell system and identify several important interaction regimes that are determined by the electromagnetic field enhancement and the oscillator strength of electronic excitations. We assign these regimes to enhanced-absorption, exciton-induced transparency and strong coupling, depending on the nature of the observed spectra of the coupled plasmon–exciton resonances. We also show the relevance of performing single-particle absorption or extinction measurements in addition to scattering to validate the interaction regime. Furthermore, at relatively high, yet realistic oscillator strengths we observe emergence of a third mode, which is not predicted by a classical coupled harmonic oscillator model and is attributed to the geometrical resonance of the structure ...
TL;DR: In this paper, a theoretical study shows that the low electron mobilities are caused by the scattering of electrons by charged impurities and points to high-ensuremath{kappa}$ dielectric coatings as a way to boost the mobilities of high-impurity samples.
Abstract: Atomically thin semiconductors, e.g., MoS${}_{2}$, may be an alternative to silicon in transistor electronics, but their electron mobilities as measured are apparently rather low. A theoretical study shows that the low mobilities are caused by the scattering of electrons by charged impurities and points to high-$\ensuremath{\kappa}$ dielectric coatings as a way to boost the mobilities of high-impurity samples.
University of Hamburg1, Max Planck Society2, Fundamental Research on Matter Institute for Atomic and Molecular Physics3, Kansas State University4, Lund University5, Technical University of Berlin6, SLAC National Accelerator Laboratory7, Uppsala University8, Aarhus University9, Arizona State University10, University of Siegen11
TL;DR: In this paper, the authors reported experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source.
Abstract: We report experimental results on x-ray diffraction of quantum-state-selected and strongly aligned ensembles of the prototypical asymmetric rotor molecule 2,5-diiodobenzonitrile using the Linac Coherent Light Source The experiments demonstrate first steps toward a new approach to diffractive imaging of distinct structures of individual, isolated gas-phase molecules We confirm several key ingredients of single molecule diffraction experiments: the abilities to detect and count individual scattered x-ray photons in single shot diffraction data, to deliver state-selected, eg, structural-isomer-selected, ensembles of molecules to the x-ray interaction volume, and to strongly align the scattering molecules Our approach, using ultrashort x-ray pulses, is suitable to study ultrafast dynamics of isolated molecules