Search

Technological opportunities are explored to enhance detection schemes in transmission electron microscopy (TEM) that build on the detection of single-electron scattering events across the typical spectrum of interdisciplinary applications. They range from imaging with high spatiotemporal resolution to diffraction experiments at the window to quantum mechanics, where the wave-particle dualism of single electrons is evident. At the ultimate detection limit, where isolated electrons are delivered to interact with solids, we find that the beam current dominates damage processes instead of the deposited electron charge, which can be exploited to modify electron beam-induced sample alterations. The results are explained by assuming that all electron scattering are inelastic and include phonon excitation that can hardly be distinguished from elastic electron scattering. Consequently, a coherence length and a related coherence time exist that reflect the interaction of the electron with the sample and change linearly with energy loss. Phonon excitations are of small energy (

The electrodisintegration of He3 is considered focusing on the effects of the Δ isobar excitation which is treated dynamically on the same footing as nucleons. In the region beyond the quasi-elastic peak the predicted transverse response functions RT and RT′ are visibly affected. This leads to sizable Δ isobar effects for inclusive and exclusive electron polarization asymmetries in particular kinematic regions. A measurement performed in the proposed regime could provide judgment for models of nuclear forces and currents.

Short range effects on inelastic C2 form factors in some open fp nuclei ( 4 6 − 5 0 Ti, 5 0 − 5 4 Cr, 5 4 − 5 6 Fe and 6 4 − 6 8 Zn) have been researched. The charge densities in these isotopes have been also researched by the one and two particle components of cluster series using single-particle wavefunctions of the harmonic oscillator potential. The short range effects have been inserted into the two particle components of cluster series employing the Jastrow form correlation. The total form factors of isotopes under consideration arise from the model space and core-polarization participations. The one-body density matrix elements (which are needed for computing the model space transition charge density) of valence nucleons for the transition 0 + → 2 + have been computed by accomplishment of shell model calculations using the OXBASH code with various interactions. The shape of Tassie model has been adopted for computing the core-polarization transition charge density. The present computations are reliant on b (oscillator parameter) and β (correlation parameter), where these parameters have been created independently for each individual nucleus by fitting the computed elastic form factors to those of experimental ones. This study provides a proof for strong ascendancy of short range effects on the present calculations, where inclusion of short range correlations on computations seems to be required for performing a notable modification in the computed outcomes which sequentially causes to elucidate the experimental data astoundingly in the momentum transfer under consideration. [ABSTRACT FROM AUTHOR]

The electromagnetic properties of some even neutron rich Sulfur-isotopes 32−42 S are studied through the electric quadrupole transition ( 0 + 1 → 2 + 1 ) . In particular, excitation energies Ex and the coulomb inelastic electron scattering form factors are calculated for the adopted isotopes within the framework of shell model. The shell model calculations are performed with full sd-model space, psd - and sdpf - cross shell, using different interactions. The results are based on sdba and psdmk interactions for sulfur with N ≤ 20, while sdpfk and sdpfu interactions are dependent for sulfur with N > 20. The core polarization effects (CP) are included through the Boher-Mottelson (B − M) and standard (ST) effective charges to obtain a reasonable description of the electric quadrupole moments and C2 form factors. The results of psdmk and sdba-interactions fail to reproduce the measured B(E2) strengths and deformation β2 and the coulomb inelastic electron scattering form factors are calculated for the adopted isotopes within the framework of shell model. The shell model calculations are performed with full sd-model space, psd - and sdpf - cross shell, using different interactions. The results are based on sdba and psdmk interactions for sulfur with N ≤ 20, while sdpfk and sdpfu interactions are dependent for sulfur with N > 20. The core polarization effects (CP) are included through the Boher-Mottelson (B − M) and standard (ST) effective charges to obtain a reasonable description of the electric quadrupole moments and C2 form factors. The results of psdmk and sdba-interactions fail to reproduce the measured B(E2) strengths and deformation β2 for 32−36 S, except for 36 S nucleus is close to the measured value. The results for 38−42 S with both sdpf k and sdpfu interactions nicely confirm the measured values of B(E2) strengths and deformation β2 within the experimental error. The influence of the nuclear deformation parameter β2 on the location of the diffraction minima of C2 form factors are also indicated [ABSTRACT FROM AUTHOR]

Modelling the inelastic scattering of electrons in water is fundamental, given their crucial role in biological damage. In Monte Carlo track-structure (MC-TS) codes used to assess biological damage, the energy loss function (ELF), from which cross sections are extracted, is derived from different semi-empirical optical models. Only recently have first ab initio results for the ELF and cross sections in water become available. For benchmarking purpose, in this work, we present ab initio linear-response time-dependent density functional theory calculations of the ELF of liquid water. We calculated the inelastic scattering cross sections, inelastic mean free paths, and electronic stopping power and compared our results with recent calculations and experimental data showing a good agreement. In addition, we provide an in-depth analysis of the contributions of different molecular orbitals, species and orbital angular momenta to the total ELF. Moreover, we present single-differential cross sections computed for each molecular orbital channel, which should prove useful for MC-TS simulations.

Due to the lack of the long-range order in their molecular structure, amorphous polymers possess a considerable free volume content in their inter-molecular space. During finite deformation, these free volume holes serve as the potential sites for localized permanent plastic deformation inclusions which are called shear transformation zones (STZs). While the free volume content has been experimentally shown to increase during the course of plastic straining in glassy polymers, thermal analysis of stored energy due to the deformation shows that the STZ nucleation energy decreases at large plastic strains. The evolution of the free volume, and the STZs number density and nucleation energy during the finite straining are formulated in this paper in order to investigate the uniaxial post-yield softening-hardening behavior of the glassy polymers. This study shows that the reduction of the STZ nucleation energy, which is correlated with the free volume increase, brings about the post-yield primary softening of the amorphous polymers up to the steady-state strain value; and the secondary hardening is a result of the increased number density of the STZs, which is required for large plastic strains, while their nucleation energy is stabilized beyond the steady-state strain. The evolutions of the free volume content and STZ nucleation energy are also used to demonstrate the effect of the strain rate, temperature, and thermal history of the sample on its post-yield behavior. The obtained results from the model are compared with the experimental observations on poly(methyl methacrylate) which show a satisfactory consonance. [ABSTRACT FROM AUTHOR]

We compare the adsorption of oxygen molecules on Ag(100) at 60 K and at 100 K. At both temperatures, the molecules form islands. Differences between the species adsorbed at the two temperatures in both low-temperature scanning tunneling microscopy and inelastic electron tunneling spectroscopy are attributed to two different adsorption states, a chemisorbed state after 100 K adsorption and a physisorbed state after 60 K adsorption. [ABSTRACT FROM AUTHOR]

Copyright of Journal of University of Anbar for Pure Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The subject of this paper is a comparative analysis of the plasma parameters inferred from the classical Langmuir probe procedure, from different theories of the ion current to the probe, and from measured electron energy distribution function (EEDF) obtained by double differentiation of the probe characteristic. We concluded that the plasma parameters inferred from the classical Langmuir procedure can be subjected to significant inaccuracy due to the non-Maxwellian EEDF, uncertainty of locating the plasma potential, and the arbitrariness of the ion current approximation. The plasma densities derived from the ion part of the probe characteristics diverge by as much as an order of magnitude from the density calculated according to Langmuir procedure or calculated as corresponding integral of the measured EEDF. The electron temperature extracted from the ion part is always subjected to uncertainty. Such inaccuracy is attributed to modification of the EEDF for fast electrons due to inelastic electron collisions, and to deficiencies in the existing ion current theories; i.e., unrealistic assumptions about Maxwellian EEDFs, underestimation of the ion collisions and the ion ambipolar drift, and discounting deformation of the one-dimensional structure of the region perturbed by the probe. We concluded that EEDF measurement is the single reliable probe diagnostics for the basic research and industrial applications of highly non-equilibrium gas discharge plasmas. Examples of EEDF measurements point up importance of examining the probe current derivatives in real time and reiterate significance of the equipment technical characteristics, such as high energy resolution and wide dynamic range. [ABSTRACT FROM AUTHOR]

Inelastic electron tunneling spectroscopy (IETS) of a single hydrogen atom on the Cu(100) surface in a scanning tunneling microscopy (STM) configuration has been investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. The electronvibration interaction is treated at the level of lowest order expansion. Our calculations show that the single peak observed in the previous STM-IETS experiments is dominated by the perpendicular mode of the adsorbed H atom, while the parallel one only makes a negligible contribution even when the STM tip is laterally displaced from the top position of the H atom. This propensity of the IETS is deeply rooted in the symmetry of the vibrational modes and the characteristics of the conduction channel of the Cu-H-Cu tunneling junction, which is mainly composed of the 4s and 4pz atomic orbitals of the Cu apex atom and the 1s orbital of the adsorbed H atom. These findings are helpful for deepening our understanding of the propensity rules for IETS and promoting IETS as a more popular spectroscopic tool for molecular devices. [ABSTRACT FROM AUTHOR]

The correspondence between the isoscalar monopole (IS0) transition strengths and |$\alpha$| inelastic cross sections, the |$B({\rm IS0})$| – |$(\alpha,\alpha')$| correspondence, is investigated for |$^{24}$| Mg(⁠|$\alpha,\alpha'$|⁠) at 130 and 386 MeV. We adopt a microscopic coupled-channel reaction framework to link structural inputs, diagonal and transition densities, for |$^{24}$| Mg obtained with antisymmetrized molecular dynamics to the (⁠|$\alpha,\alpha'$|⁠) cross sections. We aim at clarifying how the |$B({\rm IS0})$| – |$(\alpha,\alpha')$| correspondence is affected by the nuclear distortion, the in-medium modification to the nucleon–nucleon effective interaction in the scattering process, and the coupled-channel effect. It is found that these effects are significant and the explanation of the |$B({\rm IS0})$| – |$(\alpha,\alpha')$| correspondence in the plane wave limit with the long-wavelength approximation, which is often used, makes no sense. Nevertheless, the |$B({\rm IS0})$| – |$(\alpha,\alpha')$| correspondence tends to remain because of a strong constraint on the transition densities between the ground state and the |$0^+$| excited states. The correspondence is found to hold at 386 MeV with an error of about 20%–30%, while it is seriously compromised at 130 MeV, mainly by the strong nuclear distortion. It is also found that when a |$0^+$| state that has a different structure from a simple |$\alpha$| cluster state is considered, the |$B({\rm IS0})$| – |$(\alpha,\alpha')$| correspondence becomes less valid. For a quantitative discussion on the |$\alpha$| clustering in |$0^+$| excited states of nuclei, a microscopic description of both the structure and reaction parts will be necessary. [ABSTRACT FROM AUTHOR]

We have measured the surface phonon dispersion curves on the hydrogen-terminated Si(110)-(1×1) surface with the two-dimensional space group of p2mg along the two highly symmetric and rectangular directions of ΓX and ΓXΓ using high-resolution electron-energy-loss spectroscopy. All the essential energy-loss peaks on H:Si(110) were assigned to the vibrational phonon modes by using the selection rules of inelastic electron scattering including the glide-plane symmetry. Actually, the surface phonon modes of even-symmetry to the glide plane (along ΓX) were observed in the first Brillouin zone, and those of odd-symmetry to the glide plane were in the second Brillouin zone. The detailed assignment was made by referring to theoretical phonon dispersion curves of Gräschus et al. [Phys. Rev. B 56, 6482 (1997)]. We found that the H-Si stretching and bending modes, which exhibit highly anisotropic dispersion, propagate along ΓX direction as a one-dimensional phonon. Judging from the surface structure as well as our classical and quantum mechanical estimations, the H-Si stretching phonon propagates by a direct repulsive interaction between the nearest neighbor H atoms facing each other along ΓX, whereas the H-Si bending phonon propagates by indirect interaction through the substrate Si atomic linkage. [ABSTRACT FROM AUTHOR]

We present a manageable approach to include, within the context of optical-data models of the dielectric response function, exchange and correlation (XC) effects in inelastic electron scattering, thus, going beyond the standard random-phase approximation (RPA). The many-body local-field correction in its static limit, G(q), is employed to incorporate XC effects to all orders in q at both the level of 'screening' and the level of 'scattering' by computing the so-called test-charge-test-charge (t-t), electron-test-charge (e-t), and electron-electron (e-e) dielectric functions. Some of the most used analytic approximations for G(q) are examined, ranging from the early Hubbard-like expressions to more recent parameterized formulations that satisfy some of the known asymptotic limits. The effect of the different G(q) models upon the inelastic scattering of low-medium energy electrons in condensed matter is examined using solid (amorphous) carbon as an example. It is shown that when XC corrections at all levels are considered, a net reduction of the inelastic scattering cross section by up to 20%-30% from the corresponding RPA value is obtained. Interestingly, a screened Hubbard approximation to G(q) reproduces (to a few %) the results of more accurate representations. Based on the present results, the controversial high-q asymptotic behaviour of G(q) is inconsequential to inelastic electron scattering in the examined energy range. [ABSTRACT FROM AUTHOR]

It was recently shown that the affinity of doubly charged, 1-3 diaminopropane (Dap2+) for DNA permits the growth on highly ordered pyrolitic graphite (HOPG) substrates, of plasmid DNA films, of known uniform thickness [O. Boulanouar, A. Khatyr, G. Herlem, F. Palmino, L. Sanche, and M. Fromm, J. Phys. Chem. C 115, 21291-21298 (2011)]. Post-irradiation analysis by electrophoresis of such targets confirms that electron impact at 10 eV produces a maximum in the yield of single strand breaks that can be associated with the formation of a DNA- transient anion. Using a well-adapted deterministic survival model for the variation of electron damage with fluence and film thickness, we have determined an absolute cross section for strand-break damage by 10 eV electrons and inelastic scattering attenuation length in DNA-Dap complex films. [ABSTRACT FROM AUTHOR]

Tuning of electronic density-of-states singularities is a common route to unconventional metal physics. Conceptually, van Hove singularities are realized only in clean two-dimensional systems. Little attention has therefore been given to the disordered (dirty) limit. Here, we provide a magnetotransport study of the dirty metamagnetic system calcium-doped strontium ruthenate. Fermi liquid properties persist across the metamagnetic transition, but with an unusually strong variation of the Kadowaki-Woods ratio. This is revealed by a strong decoupling of inelastic electron scattering and electronic mass inferred from density-of-state probes. We discuss this Fermi liquid behavior in terms of a magnetic field tunable van Hove singularity in the presence of disorder. More generally, we show how dimensionality and disorder control the fate of transport properties across metamagnetic transitions. Strongly correlated materials can exhibit deviations from Fermi-liquid behavior partly due to anomalies in the density of states at the Fermi level, such as van Hove singularities. Here, the authors investigate the unusual Fermi liquid behavior of calcium-doped strontium ruthenate and find an unusual variation of the Kadowaki-Woods ratio which may originate from disorder. [ABSTRACT FROM AUTHOR]

We analyze how functionality could be obtained within single-molecule devices by using a combination of non-equilibrium Green's functions and ab initio calculations to study the inelastic transport properties of single-molecule junctions. First, we apply a full non-equilibrium Green's function technique to a model system with electron-vibration coupling. We show that the features in the inelastic electron tunneling spectra (IETS) of the molecular junctions are virtually independent of the nature of the molecule-lead contacts. Since the contacts are not easily reproducible from one device to another, this is a very useful property. The IETS signal is much more robust versus modifications at the contacts and hence can be used to build functional nanodevices. Second, we consider a realistic model of a organic conjugated molecule. We use ab initio calculations to study how the vibronic properties of the molecule can be controlled by an external electric field which acts as a gate voltage. The control, through the gate voltage, of the vibron frequencies and (more importantly) of the electron-vibron coupling enables the construction of functionality: nonlinear amplification and/or switching is obtained from the IETS signal within a single-molecule device. [ABSTRACT FROM AUTHOR]

We have employed a unique spectroscopic approach, a resonant inelastic soft x-ray scattering (RIXS) map, to identify and separate electron-hole correlation effects in core-level spectroscopy. With this approach, we are able to derive a comprehensive picture of the electronic structure, separating ground state properties (such as the HOMO-LUMO separation) from excited state properties (such as the C 1s core-exciton binding energy of C60). In particular, our approach allows us to determine the difference between core- and valence exciton binding energies in C60 [0.5 (±0.2) eV]. Furthermore, the RIXS map gives detailed insight into the symmetries of the intermediate and final states of the RIXS process. [ABSTRACT FROM AUTHOR]

We have performed rigorous quantum five-dimensional (5D) calculations and analysis of the translation-rotation (T-R) energy levels of one H2, D2, and HD molecule inside the small dodecahedral (H2O)20 cage of the structure II clathrate hydrate, which was treated as rigid. The H2- cage intermolecular potential energy surface (PES) used previously in the molecular dynamics simulations of the hydrogen hydrates [Alavi et al., J. Chem. Phys. 123, 024507 (2005)] was employed. This PES, denoted here as SPC/E, combines an effective, empirical water-water pair potential [Berendsen et al., J. Phys. Chem. 91, 6269 (1987)] and electrostatic interactions between the partial charges placed on H2O and H2. The 5D T-R eigenstates of HD were calculated also on another 5D H2-cage PES denoted PA-D, used by us earlier to investigate the quantum T-R dynamics of H2 and D2 in the small cage [Xu et al., J. Phys. Chem. B 110, 24806 (2006)]. In the PA-D PES, the hydrogen-water pair potential is described by the ab initio 5D PES of the isolated H2–H2O dimer. The quality of the SPC/E and the PA-D H2-cage PESs was tested by direct comparison of the T-R excitation energies calculated on them to the results of two recent inelastic neutron scattering (INS) studies of H2 and HD inside the small clathrate cage. The translational fundamental and overtone excitations, as well as the triplet splittings of the j=0→j=1 rotational transitions, of H2 and HD in the small cage calculated on the SPC/E PES agree very well with the INS results and represent a significant improvement over the results computed on the PA-D PES. Our calculations on the SPC/E PES also make predictions about several spectroscopic observables for the encapsulated H2, D2, and HD, which have not been measured yet. [ABSTRACT FROM AUTHOR]

A fluid model to prescribe microwave plasma is proposed. The conservation equations for electron are reduced to only one differential equation. Therefore, the computational cost is also reduced as small as possible. One may extend functions of existing program for vacuum field analysis to microwave plasma simulator by coupling this differential equation with Maxwell equations. While the model is quite simple, this model can prescribe distributions of electron temperature as well as the number density, whereas effects of inelastic collisions with ions and neutrals are taken into account. Test calculation is carried out in three dimensional system and well reproduces experimental observation and prediction obtained by other model. [ABSTRACT FROM AUTHOR]

We describe a wide-gap multichannel cylindrical deflection electron energy analyzer suitable for measuring the weak signals characteristic of electronically inelastic electron energy loss spectra. The analyzer has nearly ideal fringing field termination, and its resolution and energy dispersion were characterized as a function of energy by solving numerically the equation of motion of electrons in an ideal cylindrical electric field. The numerical results for the radial location of the electrons at the detector as a function of the entrance location, angle, and energy are closely approximated by a second order polynomial, and match closely with those observed. The detection efficiency of the analyzer is 100–150 times better than that of an equivalent single-channel instrument, but limited energy transmission of the zoom lens system used in our case reduced it by a factor of about 2. The performance of the new instrument was demonstrated by measuring the 3E1u electronic spectrum of benzene in only 2 min and the spectrum of endo-benzotricyclo[4.2.1.02.5]nonane. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Vibrational electron energy loss spectra were measured for propane at incident energies of 3, 6, 10, 15, 20, and 25 eV at scattering angles of 40°, 55°, 70°, 85°, and 100°. The spectra are compared with the results of ab initio calculations using a recently developed two-channel discrete momentum representation method. Good agreement between theory and experiment was found for large scattering angles and energies above the resonant region. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Multi‐slice simulations of electron diffraction by three‐dimensional protein crystals have indicated that structure solution would be severely impeded by dynamical diffraction, especially when crystals are more than a few unit cells thick. In practice, however, dynamical diffraction turned out to be less of a problem than anticipated on the basis of these simulations. Here it is shown that two scattering phenomena, which are usually omitted from multi‐slice simulations, reduce the dynamical effect: solvent scattering reduces the phase differences within the exit beam and inelastic scattering followed by elastic scattering results in diffusion of dynamical scattering out of Bragg peaks. Thus, these independent phenomena provide potential reasons for the apparent discrepancy between theory and practice in protein electron crystallography. [ABSTRACT FROM AUTHOR]

Abstract We report electron transport measurements through a metal-molecule-metal junction of free base or zinc porphyrin molecules. Junctions are formed by zig-zag electromigration of a gold nanowire. Inelastic electron tunneling spectroscopy measurements were performed at 4.3 K to confirm the presence of molecules in the junction and to measure the vibrational modes of the molecular junction. Temperature dependent current/voltage measurements are performed in order to determine that the electron conduction mechanism through these molecular junctions is direct tunneling. The electron attenuation coefficient ( β 0 ) was also calculated; the average β 0 for free base and zinc porphyrin was 0.231 ± 0.133 Å−1 and 0.188 ± 0.049 Å−1, respectively. The barrier height was experimentally found to be 1.6 eV and 1.1 eV for FBP and Zn-P SAMs on Au, respectively. Graphical abstract Image 1 Highlights • IETS measurements are reported for electromigrated porphyrin molecular junctions and compared to molecular vibrational modes. • The electron conduction mechanism through the molecular junctions was identified as direct tunneling. • The electron attenuation coefficient calculated was 0.231 ± 0.133 Å-1 for free base porphyrin and 0.188 ± 0.049 Å-1 for Zn-P. [ABSTRACT FROM AUTHOR]

Abstract Excited states in the T z = − 1 nucleus 70Kr have been populated using inelastic scattering of a radioactive 70Kr beam as well as one- and two-neutron removal reactions from 71,72Kr at intermediate beam energies. The level scheme of 70Kr was constructed from the observed γ -ray transitions and coincidences. Tentative spin and parity assignments were made based on comparison with the mirror nucleus 70Se. A second 2 + state and a candidate for the corresponding 4 2 + state suggest shape coexistence in 70Kr. [ABSTRACT FROM AUTHOR]

Nanoscale silicon wires with high aspect ratio are beneficial in light harvesting for high responsivity in photoelectronic detectors. Reduction of wire width increases the surface-to-volume ratio, but introduces inelastic electron-boundary scattering caused by line edge roughness, limiting the photoconductivity at the same time. This paper is motivated by these structural effects on the device performance, aiming to develop the photoelectronic detectors with ultra-fine Si nanowires with high aspect ratio. Electron beam lithography assisted by Monte Carlo simulation was carried out on HSQ, which was used as etch mask for forming high aspect ratio Si nanowires by reactive ion etch. As narrow as 5 nm HSQ lines with the line edge roughness of sub-3.6 nm was achieved. Masked by the replicated HSQ lines, silicon nanowires with the width from 75 nm down to sub-10 nm and the aspect ratio of 30:1 were achieved through a dry etch process. Characterization of photo-electronic responsivity of the fabricated Si nanowires in visible wavelength demonstrates the maximum responsivity can be achieved in an optimized width with which the surface-to-volume ratio is balanced by the sidewall roughness. The milestone established in this work covers not only the technical advances of Si nanowires with high aspect ratio but also physical understanding of the structural effect on the device performance. [ABSTRACT FROM AUTHOR]

In this study, the integral expression of inelastic transport, which combined with nonequilibrium Green's function and density functional theory, is extended to investigate the inelastic electrical transport properties of single-molecule device. Results show that the height of the current plateau will increase along with the temperature. It is found that this increase in the height of the current plateau is caused by inelastic resonant tunneling rather than the decoherence mechanism of the quantum interference effect. And we find that some small steps and the tilt in the main current plateau are also responsible by the inelastic processes. These results help us to understand the electrical transport mechanisms in single-molecule devices. [ABSTRACT FROM AUTHOR]

The scanning-tunneling-microscope-induced luminescence emerges recently as an incisive tool to measure the molecular properties down to the single-molecule level. The rapid experimental progress is far ahead of the theoretical effort to the observed phenomena. Such incompetence leads to a significant difficulty in quantitatively assigning the observed feature of the fluorescence spectrum to the structure and dynamics of a single molecule. This work is devoted to revealing the microscopic origin of the molecular excitation via inelastic scattering of the tunneling electrons in the scanning tunneling microscope. The theory proposed here excludes the inelastic electron scattering as the origin of the observed larger photon-counting rate at the positive bias than that at the negative bias voltage.

The present work aims to study the nonlinear behavior of reinforced concrete structures via Refined Plastic Hinge Method (RPHM). Pseudo-springs are used at the finite element ends, where the gradual loss of stiffness is determined by the combination of the normal force and bending moment (NM) in the cross section. The limiting of the uncracked, elastic and plastic regimes is done in the NM diagram. The concrete cracking is explicitly simulated with two approaches to calculate the effective moment of inertia of the cross section. The displacement-based formulation is referenced to the co-rotational system and coupled with continuation strategies to allow to overcome the possible critical points in the equilibrium paths. For validation of the numerical simulations, the results found with the proposed formulation are confronted with experimental and numerical data present in literature. [ABSTRACT FROM AUTHOR]

Using self-consistent Non-Equilibrium Green's Function formalism, the effect of the inelastic scattering due to electron-phonon interaction on the transfer and output characteristics of a coaxially gated generic nanowire field effect transistor has been studied in detail. The scattering strength D o is varied from 0.003 eV 2 to 0.3 eV 2 . There is change in the threshold voltage and suppression of channel current with increasing scattering strength. We also studied the effect of channel inhomogeneities on electron energy. The channel inhomogeneities are invoked by introducing potential step inside the channel. We study the energy relaxation due to inelastic scattering and channel inhomogeneities by comparing the normalized terminal current per energy for the source and drain terminals. [ABSTRACT FROM AUTHOR]

The particle spectrometer SONIC for particle- γ coincidence measurements was commissioned at the Institute for Nuclear Physics in Cologne, Germany. SONIC consists of up to 12 silicon Δ E - E telescopes with a total solid angle coverage of 9%, and will complement HORUS, a γ -ray spectrometer with 14 HPGe detectors. The combined setup SONIC@HORUS is used to investigate the γ -decay behaviour of low-spin states up to the neutron separation threshold excited by light-ion inelastic scattering and transfer reactions using beams provided by a 10 MV FN Tandem accelerator. The particle- γ coincidence method will be presented using data from a 92 Mo(p,p’ γ ) experiment. In a 119 Sn(d,X) experiment, excellent particle identification has been achieved because of the good energy resolution of the silicon detectors of approximately 20 keV. Due to the non-negligible momentum transfer in the reaction, a Doppler correction of the detected γ -ray energy has to be performed, using the additional information from measuring the ejectile energy and direction. The high sensitivity of the setup is demonstrated by the results from a 94 Mo(p,p’ γ ) experiment, where small γ -decay branching ratios have been deduced. [ABSTRACT FROM AUTHOR]

We have employed noise thermometry for investigations of thermal relaxation between the electrons and the substrate in nanowires patterned from 40-nm-thick titanium film on top of silicon wafers covered by a native oxide. By controlling the electronic temperature $$T_\mathrm{e}$$ by Joule heating at the base temperature of a dilution refrigerator, we probe the electron-phonon coupling and the thermal boundary resistance at temperatures $$T_\mathrm{e}= 0.5$$ -3 K. Using a regular $$T^5$$ -dependent electron-phonon coupling of clean metals and a $$T^4$$ -dependent interfacial heat flow, we deduce a small contribution for the direct energy transfer from the titanium electrons to the substrate phonons due to inelastic electron-boundary scattering. [ABSTRACT FROM AUTHOR]

The regularities of the electron energy dissipation found in the subsurface atomic layer are valid in the bulk of a solid, too. On the example of model graphite-based materials it is shown that energy losses in X-ray photoelectron spectra agree with the calculated valence electron excitation spectra in analogous unit cells. The control of conjugate electron transitions opens the way to gain new data on the geometry, character, and order of bonding between atoms in the sample by the conventional electron spectroscopy and quantum chemistry methods. [ABSTRACT FROM AUTHOR]

We investigate the energetics of the atom exchange reaction in the SrF + alkali-metal atom and CaF + alkali-metal atom systems. Such reactions are possible only for collisions of SrF and CaF with the lithium atoms, while they are energetically forbidden for other alkali-metal atoms. Specifically, we focus on SrF interacting with Li, Rb, and Sr atoms and use ab initio methods to demonstrate that the SrF + Li and SrF + Sr reactions are barrierless. We present potential energy surfaces for the interaction of the SrF molecule with the Li, Rb, and Sr atoms in their energetically lowest-lying electronic spin states. The obtained potential energy surfaces are deep and exhibit profound interaction anisotropies. We predict that the collisions of SrF molecules in the rotational or Zeeman excited states most likely have a strong inelastic character. We discuss the prospects for the sympathetic cooling of SrF and CaF molecules using ultracold alkali-metal atoms. [ABSTRACT FROM AUTHOR]

Electron scattering is always applied as one of the routines to investigate nanostructures. Nowadays the development of hardware offers more and more prospect for this technique. For example imaging nanostructures with inelastic scattered electrons may allow to produce component-sensitive images with atomic resolution. Modelling inelastic electron scattering is therefore essential for interpreting these images. The main obstacle to study inelastic scattering problem is its complexity. During inelastic scattering, incident electrons entangle with objects, and the description of this process involves a multidimensional array. Since the simulation usually involves fourdimensional Fourier transforms, the computation is highly inefficient. In this work we have offered one solution to handle the multidimensional problem. By transforming a high dimensional array into twodimensional array, we are able to perform matrix diagonalization and approximate the original multidimensional array with its twodimensional eigenvectors. Our procedure reduces the complicated multidimensional problem to a twodimensional problem. In addition, it minimizes the number of twodimensional problems. This method is very useful for studying multiple inelastic scattering. [ABSTRACT FROM AUTHOR]

We calculated electron inelastic mean free paths (IMFPs) for liquid water from its optical energy-loss function (ELF) for electron energies from 50 eV to 30 keV. These calculations were made with the relativistic full Penn algorithm that has been used for previous IMFP and electron stopping-power calculations for many elemental solids. We also calculated IMFPs of water with three additional algorithms: the relativistic single-pole approximation, the relativistic simplified single-pole approximation, and the relativistic extended Mermin method. These calculations were made by using the same optical ELF in order to assess any differences of the IMFPs arising from choice of the algorithm. We found good agreement among the IMFPs from the four algorithms for energies over 300 eV. For energies less than 100 eV, however, large differences became apparent. IMFPs from the relativistic TPP-2M equation for predicting IMFPs were in good agreement with IMFPs from the four algorithms for energies between 300 eV and 30 keV, but there was poorer agreement for lower energies. We calculated values of the static structure factor as a function of momentum transfer from the full Penn algorithm. The resulting values were in good agreement with results from first-principle calculations and with inelastic X-ray scattering spectroscopy experiments. We made comparisons of our IMFPs with earlier calculations from authors who had used different algorithms and different ELF data sets. IMFP differences could then be analyzed in terms of the algorithms and the data sets. Finally, we compared our IMFPs with measurements of IMFPs and of a related quantity, the effective attenuation length. There were large variations in the measured IMFPs and effective attenuation lengths (as well as their dependence on electron energy). Further measurements are therefore required to establish consistent data sets and for more detailed comparisons with calculated IMFPs. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Generalized oscillator strengths (GOSs) of the valence shell excitations to the A 1 Σ − + B 1 Δ , C 1 Π , D 1 Σ + and 2 1 Π states in nitrous oxide have been determined by employing an angle-resolved electron energy loss spectrometer operated at an incident energy of 1500 eV and an energy resolution of about 80 meV. Detailed comparisons with the previous data indicate that the higher-order Born terms play a significant role in the GOSs of C 1 Π and D 1 Σ + states at either low impact energies or large momentum transfers, and the GOSs of A 1 Σ − + B 1 Δ and C 1 Π states measured with the gas cell may suffer from the pressure effect. The measured GOS data are fitted with the Lassettre formula to determine the corresponding optical oscillator strengths (OOSs) and calculate the integral cross sections (ICSs) based on the BE-scaling method. The oscillator strengths and cross sections in this work provide a cross check on the previous data and can serve as a benchmark for testing the developed theoretical models and computational codes. [ABSTRACT FROM AUTHOR]

X-ray photoelectron spectra, reflection electron energy loss spectra, and inelastic electron scattering cross section spectra of iron monosilicide FeSi are investigated. It is shown that the spectra of inelastic electron scattering cross section have advantages over the reflection electron energy loss spectra in studying the processes of electron energy losses. An analysis of the fine structure of the inelastic electron scattering cross section spectra allows previously unresolved peaks to be identified and their energy, intensity, and nature to be determined. The difference between energies of fitting loss peaks in the spectra of inelastic electron scattering cross section of FeSi and pure Fe are more substantial than the chemical shifts in X-ray photoelectron spectra, which indicates the possibility of application of the fine structure of the spectra of inelastic electron scattering cross section for elemental analysis. [ABSTRACT FROM AUTHOR]

The methodology of probabilistic fatigue life prediction for notched components based on smooth specimens is presented. Weakestlink theory incorporating Walker strain model has been utilized in this approach. The effects of stress ratio and stress gradient have been considered. Weibull distribution and median rank estimator are used to describe fatigue statistics. Fatigue tests under different stress ratios were conducted on smooth and notched specimens of titanium alloy TC11. The proposed procedures were checked against the test data of TC11 notched specimens. Prediction results of 50 % survival rate are all within a factor of two scatter band of the test results. [ABSTRACT FROM AUTHOR]

The inelastic electron tunneling spectroscopy (IETS) of bi-octane-monothiol junctions is theoretically studied based on first-principles calculations. The results reveal that IETS is very sensitive to the vertical and lateral distance of the two molecules in the bimolecular junctions owing to the changes of interaction between the two molecules. It is further demonstrated that the transverse vibrational modes ν(C-H) around 0.38 V will be triggered when the two molecules are close to each other and open a new path for electron tunneling. Our theoretical results provide new insight into understanding the origin of the IETS peaks around 0.38 V. [ABSTRACT FROM AUTHOR]

The most established approach for 'practical' calculations of the inelastic mean free path (IMFP) of low-energy electrons (~10 eV to ~10 keV) is based on optical-data models of the dielectric function. Despite nearly four decades of efforts, the IMFP of low-energy electrons is often not known with the desired accuracy. A universal conclusion is that the predictions of the most popular models are in rather fair agreement above a few hundred electron volts but exhibit considerable differences at lower energies. However, this is the energy range where their two main approximations, namely, the random-phase approximation (RPA) and the Born approximation, may be invalid. After a short overview of the most popular optical-data models, we present an approach to include exchange and correlation (XC) effects in IMFP calculations, thus going beyond the RPA and Born approximation. The key element is the so-called many-body local-field correction (LFC). XC effects among the screening electrons are included using a time-dependent local-density approximation for the LFC. Additional XC effects related to the incident and struck electrons are included through the vertex correction calculated using a screened-Hubbard formula for the LFC. The results presented for liquid water reveal that XC may increase the IMFP by 15-45% from its Born-RPA value, yielding much better agreement with available experimental data. The present work provides a manageable, yet rigorous, approach to improve upon the standard models for IMFP calculations, through the inclusion of XC effects at both the level of screening and the level of interaction. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Seismic design of buildings has traditionally been force-based. It is widely understood now that it is not the force but displacement, which can be directly related to damage. The alternative design approaches are gradually becoming popular in recent times. Design Methodology for Direct Displacement Based Design Method (DDBD) has been presented here in the context of IS code as an alternative to conventional Forced Based Design (FBD). The paper attempts to design moment resisting RC frame using Displacement Based Design method. Regular RC frames of 4,6,8, 10,12 and 15 stories were designed using FBD and DDBD procedure for the parametric study. Evaluation of Response Modification Factor is done using static nonlinear pushover analysis. Also Nonlinear Time History Analysis (NLTHA) was performed for a set of seven ground motions from past Indian Earthquake. Pushover Analysis and NLTHA were carried out using DRAIN-2DX program for performance evaluation of these RC frames. It is observed that design base shear of the frames designed by DDBD is less compared to those designed by FBD. Further, the DDBD designed frames yield higher Response Modification Factor as compared to FBD, implying higher capacity of structure to dissipate energy through inelastic behavior. [ABSTRACT FROM AUTHOR]