Search

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 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]

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]

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]

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]

Off-axis electron holography is a well-established transmission electron microscopy technique, typically employed to investigate electric and magnetic fields in and around nanoscale materials, which modify the phase of the reconstructed electron wave function. Here, we elaborate on a detailed analysis of the two characteristic intensity terms that are completing the electron hologram, the conventional image intensity and the interference fringe intensity. We show how both are related to elastic and inelastic scattering absorption at the sample and how they may be separated to analyze the chemical composition of the sample. Since scattering absorption is aperture dependent, a quantitative determination of the corresponding attenuation coefficients (reciprocal mean free path lengths) requires the use of holographic image modi with well-defined objective aperture stops in the back-focal plane of the objective lens. The proposed method extends quantitative electron holography to a correlated three-in-one characterization of electric and magnetic fields, Z -contrast and dielectric losses in materials. [ABSTRACT FROM AUTHOR]

Methods are described for measuring accurate absolute experimental inelastic mean free paths and differential cross-sections using DualEELS. The methods remove the effects of surface layers and give the results for the bulk materials. The materials used are VC 0.83 , TiC 0.98 , VN 0.97 and TiN 0.88 but the method should be applicable to a wide range of materials. The data was taken at 200 keV using a probe half angle of 29 mrad and a collection angle of 36 mrad. The background can be subtracted from under the ionisation edges, which can then be separated from each other. This is achieved by scaling Hartree-Slater calculated cross-sections to the edges in the atomic regions well above the threshold. The average scaling factors required are 1.00 for the non-metal K-edges and 1.01 for the metal L-edges (with uncertainties of a few percent). If preliminary measurements of the chromatic effects in the post-specimen lenses are correct, both drop to 0.99. The inelastic mean free path for TiC 0.98 was measured as 103.6±0.5 nm compared to the prediction of 126.9 nm based on the widely used Iakoubovskii parameterisation. [ABSTRACT FROM AUTHOR]

The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion–electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases. [ABSTRACT FROM AUTHOR]

Transmission of electrons through insulating polyethylene terephthalate (PET) nanocapillaries was observed as a function of charge deposition, angular and energy dependence. Two samples with capillary diameters 100 and 200 nm and pore densities 5 × 10 8 /cm 2 and 5 × 10 7 /cm 2 , respectively, were studied for incident electron energies of 300, 500 and 800 eV. Transmission and steady state of the electrons were attained after a time delay during which only a few electron counts were observed. The transmission through the capillaries depended on the tilt angle with both elastic and inelastic electrons going through. The guiding ability of electrons was found to increase with the incident energy in contrast to previous measurements in our laboratory for a similar PET foil. [ABSTRACT FROM AUTHOR]

The electrodisintegration of He 3 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 R T and R T ′ 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. [ABSTRACT FROM AUTHOR]

Ni and Cu KLL Auger spectra excited by X-rays from polycrystalline metal foils were measured with good energy resolution and intensity earlier. Auger spectra of 3d transition metals contain satellite peaks due to the atomic excitation processes. Because of the complexity of the measured spectral shape a complete explanation of the spectra was not given in the previous works. A new analysis of the measured spectra is presented here, with improved description of effects of inelastic electron scattering of the electrons in the solid sample and using complex peak shapes to model the satellite structure that follows each diagram line. The energy loss part of measured spectra due to the bulk plasmon excitations, surface plasmon excitations and intrinsic loss processes was removed using the Partial Intensity Analysis method based on energy loss distributions obtained from experimental reflection electron energy loss spectra of the same Cu and Ni metal foils. Relative Auger-transition energies derived from measured spectra of copper are in good agreement with previous experimental works and the results of cluster molecular orbital multielectron (DV-ME) calculations. The intensity ratio I( 3 P 2 / 3 P 0 ) shows better agreement with the result of relativistic calculations than in previous works. In the case of nickel the relative Auger-transition energies are in good agreement with the previous results. According to the new evaluation four satellite peaks were identified on the low energy side of each diagram line in the Auger spectra of Ni. [ABSTRACT FROM AUTHOR]

In the framework of the slice transition operator technique, a general multislice theory for electron scattering in crystals is developed. To achieve this generalization, we combine the approaches for inelastic scattering derived by Yoshioka [J. Phys. Soc. Jpn. 12 , 6 (1957)] and backscattering based on the formalism of Chen and Van Dyck [Ultramicroscopy 70 , 29–44 (1997)]. A computational realization of the obtained equations is suggested. The proposed computational scheme is tested on elastic backscattering of electrons, where we consider single backscattering in analogy to the computational scheme proposed by Chen and Van Dyck. [ABSTRACT FROM AUTHOR]

A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si 3 N 4 /SiO 2 /Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS. [ABSTRACT FROM AUTHOR]

Quantitative interpretation of structures observed in XPS and AES requires models to correct for various physical processes involved. Besides the initial excitation process in XPS and AES, the measured spectrum is affected by three additional effects: the corehole(s), transport to the surface region and passage through the surface and vacuum regions. These three effects can be calculated by the QUEELS-XPS software (Quantitative analysis of Electron Energy Losses at Surfaces) in terms of energy-differential inelastic electron scattering cross sections. From this and the QUASES software (Quantitative Analysis of Surfaces by Electron Spectroscopy), background contributions and primary excitation spectra are obtained for various transitions (Cu 2p from Cu or CuO and Cu L 3 M 23 M 23 ) and we investigate the separate effect of bulk, surface, and core hole(s) excitations. We show that the shape of the XPS and AES primary spectra and background contributions are modified slightly by surface effects and very strongly by core hole(s) effects. For metals, the intrinsic excitations give rise to a prominent spike in the background close to the XPS-peak energy. This spike will be much reduced for wide band gap insulators. Moreover our method gives an easy procedure to obtain the true primary excitation spectra for XPS and AES. [ABSTRACT FROM AUTHOR]

A new method for the fitting of X-ray photoelectron spectra using an advanced Tougaard-background model for laterally inhomogeneous samples is presented. New is the use of a separate loss function for each spectral component. Additionally, a new Five-parameter inelastic electron scattering cross section (5-PIESCS) including a variable parameter to treat the electronic band gap energy is introduced for a better modelling of the loss structures of insulators. Synthetically generated test spectra using two peaks with strongly different loss structures and measured spectra from different samples are fitted with the traditionally used Shirley background ( B S ), the Tougaard background for homogeneous samples ( B TH ), and the newly developed advanced Tougaard background for laterally inhomogeneous samples ( B TI ). It was found that the fit results for the peak areas and peak positions of the three methods could be strongly different. In many cases the use of the Shirley background and the Tougaard background for homogeneous samples resulted in completely wrong component areas in spite of sometimes rather satisfying residual functions and Abbe criteria. In contrast, the advanced Tougaard background for inhomogeneous samples gave excellent results for all wide range spectra including pronounced loss structures. The new source code of the UNIFIT software (Version 2016 or higher) to calculate the advanced Tougaard-background parameters for inhomogeneous samples was verified. [ABSTRACT FROM AUTHOR]

Modern nanotechnology tools allowed us to prepare slits of 90 nm width and 450 nm spacing in a screen almost completely opaque to 200 keV electrons. Then by covering both slits with a layer of amorphous material and carrying out the experiment in a conventional transmission electron microscope equipped with an energy filter we can demonstrate that the diffraction pattern, taken by selecting the elastically scattered electrons, shows the presence of interference fringes, but with a bimodal envelope which can be accounted for by taking into account the non-constant thickness of the deposited layer. However, the intensity of the inelastically scattered electrons in the diffraction plane is very broad and at the limit of detectability. Therefore the experiment was repeated using an aluminum film and a microscope also equipped with a Schottky field emission gun. It was thus possible to observe also the image due to the inelastically scattered electron, which does not show interference phenomena both in the Fraunhofer or Fresnel regimes. If we assume that inelastic scattering through the thin layer covering the slits provides the dissipative process of interaction responsible for the localization mechanism, then these experiments can be considered a variant of the Feynman which-way thought experiment. [ABSTRACT FROM AUTHOR]

The electric dipole strength distribution in 120 Sn has been extracted from proton inelastic scattering experiments at E p = 295 MeV and at forward angles including 0°. It differs from the results of a Sn 120 ( γ , γ ′ ) experiment and peaks at an excitation energy of 8.3 MeV. The total strength corresponds to 2.3(2)% of the energy-weighted sum rule and is more than three times larger than what is observed with the ( γ , γ ′ ) reaction. This implies a strong fragmentation of the E1 strength and/or small ground state branching ratios of the excited 1 − states. [ABSTRACT FROM AUTHOR]

We present a study of the inelastic effects caused by electron irradiation in monolayer hexagonal boron nitride (h-BN). The data was obtained through in situ experiments performed inside a low-voltage aberration-corrected transmission electron microscope (TEM). By using various specialized sample holders, we study defect formation and evolution with sub-nanometer resolution over a wide range of temperatures, between −196 and 1200 °C, highlighting significant differences in the geometry of the structures that form. The data is then quantified, allowing insight into the defect formation mechanism, which is discussed in comparison with the potential candidate damage processes. We show that the defect shapes are determined by an interplay between electron damage, which we assign to charging, and thermal effects. We additionally show that this damage can be avoided altogether by overlapping the samples with a monolayer of graphene, confirming this for h-BN and providing a way to overcome the well-known fragility of h-BN under the electron beam. [ABSTRACT FROM AUTHOR]

We compute low-energy optical energy loss spectra for the elemental solids zinc and selenium, and for the binary compound zinc selenide. The optical data are transformed via a constrained partial-pole algorithm to produce momentum-dependent electron energy loss spectra and electron inelastic mean free paths. This enables a comparison between the electron scattering behaviour in a compound solid and its constituent elements. Results cannot be explained by aggregation methods or commonly used universal curves, and prove that new approaches are required. Our work demonstrates new capabilities for the determination of fundamental material properties for a range of structures previously inaccessible to established theoretical models, and at energy levels inaccessible to most experimental techniques. [ABSTRACT FROM AUTHOR]

The inelastic scattering of electrons is one route to study the vibrational and electronic properties of materials. Such experiments, also called electron energy-loss spectroscopy, are particularly useful for the investigation of the collective excitations in metals, the charge carrier plasmons. These plasmons are characterized by a specific dispersion (energy–momentum relationship), which contains information on the sometimes complex nature of the conduction electrons in topical materials. In this review we highlight the improvements of the electron energy-loss spectrometer in the last years, summarize current possibilities with this technique, and give examples where the investigation of the plasmon dispersion allows insight into the interplay of the conduction electrons with other degrees of freedom. [ABSTRACT FROM AUTHOR]

Highlights: [•] We present an approach to take damping into account of the energy loss function. [•] We calculate the electron inelastic mean free path for Al, Si, Cu, and Au. [•] We predict the values of damping and lifetime at low energies. [•] Influence of damping is significant in the low-energy region. [•] The damping value is not only energy dependent but also material dependent. [ABSTRACT FROM AUTHOR]

Abstract: The joint effects of the electron–phonon interaction and electron–electron interaction in the Luttinger liquid leads on nonequilibrium transport through a single-molecule transistor in the Kondo regime are investigated by using the improved canonical transformation scheme and equation of motion approach. For weak intralead electron interaction, a pronounced dip around zero bias, accompanied by a series of discrete single-electron tunneling peaks is observed in the differential conductance. With the increase of the intralead interaction, the phonon-assisted peaks turn into dips, which demonstrates a phonon-assisted two-channel Kondo physics. For a certain region of interaction strength the inelastic electron tunneling can dominate electron transport. Our results well explain the experiments of zero bias anomaly. [Copyright &y& Elsevier]

Abstract: The effect of the inelastic electron–phonon interaction on the spin-dependent transport through a ferromagnetic/molecular structure as FM/trans-PA/FM model junction is numerically investigated. Based on a generalized Green's function formalism and also the mapping technique, which transforms the many-body electron–phonon interaction problem into a multi-channels single-electron scattering problem, we found that in the presence of the electron–phonon interaction, the currents are generally reduced and the step-like structure of the current–voltage characteristic are deformed. In addition, our results indicate that the main influence of the inclusion of the electron–phonon interaction is the reduction of the conductance gap of the molecule. Furthermore, it is shown that due to inelastic interactions, the noise power increase and the significant change occurs in the Fano factor. [Copyright &y& Elsevier]

Abstract: A comparative study for the fitting of x-ray photoelectron spectra using different background model functions is presented. Synthetically generated test spectra and measured spectra from an SrTiO3 (STO) sample are fitted with the traditionally used Shirley background and the so-called improved Tougaard background calculated with four fit parameters of the inelastic electron scattering cross section. It was found that the results obtained with both methods are strongly different. In many cases the use of the Shirley background resulted in completely wrong component areas in spite of sometimes rather satisfying residual functions and Abbe criteria. In contrast, the improved Tougaard background gave excellent results for all wide range spectra including pronounced loss structures. The new source code of the current UNIFIT software (Version 2011 or higher) to calculate the Tougaard-background parameters was verified. [Copyright &y& Elsevier]

Abstract: A simple, inelastic electron-scattering dynamical model is presented to account for vibrational excitation in molecular adsorbates. The basic two ingredients of the theoretical model are: (i) the conservation of the total angular momentum, and (ii) the requirement of a critical time to allow for the intra-molecular energy re-arrangement of the transient negative-ion complex. The model is applied to the vibrational excitation dynamics of molecules chemisorbed at sub-monolayer conditions on ordered metal surfaces. This was exemplified for Acrylonitrile adsorbed on Cu(100), whose vibrational excitation was studied via energy loss spectra of low-energy two-photon photoemission (2PPE) electrons, and for ammonia (NH3 and ND3) adsorbed on Cu(100), being probed in a STM experiment. Fits of the model to the data allowed for deducing the energy threshold of the vibrational excitation of the Ce:glyph name="tbnd" />N bonds of the ACN adsorbate molecules, and the threshold for the symmetric ν 1-stretch mode excitation of adsorbed NH3/ND3. Also, information about the temporal dynamics underlying the inelastic electron scattering was gained. [Copyright &y& Elsevier]

Abstract: The spatial resolution and contrast level in electron energy-loss spectroscopy (EELS) imaging depend on the delocalization of the inelastic electron scattering cross sections. Theoretical calculations within the dipole approximation provide the lower limit for the delocalization of low loss signals, and suggest that atomic resolution EELS imaging in the low loss energy regime (<50eV) should be possible. Here, we directly measure the localization of the inelastic electron scattering at different energy loss in the low loss regime using a clean open edge of monolayer graphene. Our results demonstrate that the delocalization depends both on the energy loss and the specific electron excitation mode contributing to the energy loss. While the plasmons are delocalized over 1.2nm, sub-nm enhancement is observed at the edge for the low-loss signal at 11eV, indicating the possible formation of a one-dimensional plasmon (or inter-band transition) at the edge of monolayer graphene. Our results also suggest that if the initial states or final states are atomically localized, atomic resolution EELS imaging could be obtained even in the low loss region of the spectra. [Copyright &y& Elsevier]

Abstract: Total ionization cross sections Q ion of the electron impact on exotic but lesser known targets CN, C2N2, HCN, HNC and BF have been calculated at incident energies E i from ionization threshold (I E ) to 2keV, by employing the Complex potential ionization contribution (CSP-ic) method. Since most of the present results are new, comparable theoretical data are obtained by Additivity Rules and by generating the BEB (Binary Encounter Bethe) values through the Quantemol-N package. A good accord is found among the present and the other results, except in BF. Our ionization cross sections on HCN, HNC and BF are also compared with the available data on iso-electronic 14-electron systems N2, CO and C2H2. Moreover in e−–HCN scattering, the relative contributions of various allowed scattering channels are analyzed at the energy of the peak of ionization (70eV) and presented here as a bar chart. The present work is relevant due to importance in mass spectrometry and in planetary environments. [Copyright &y& Elsevier]

Abstract: The magnitude of the EMC effect measured in electron deep inelastic scattering (DIS) is linearly related to the Short Range Correlation (SRC) scaling factor obtained from electron inclusive scattering. We speculate that the observed correlation is due to the fact that both the EMC effect and SRC are dominated by high momentum nucleons in the nucleus. The observed phenomenological relationship can be used to extract the ratio of the deuteron to the free pn-pair cross sections, the DIS cross section for a free neutron, , the ratio of the free neutron to free proton structure functions, and the u/d ratio in a free proton. [Copyright &y& Elsevier]

Abstract: We report a theoretical analysis of electron transport through a quantum dot with an embedded biaxial single-molecule magnet (SMM) based on mapping of the many-body interaction-system onto a one-body problem by means of the non-equilibrium Green function technique. It is found that the conducting current exhibits a stepwise behavior and the nonlinear differential conductance displays additional peaks with variation of the sweeping speed and the magnitude of magnetic field. This observation can be interpreted by the interaction of electron-spin with the SMM and the quantum tunneling of magnetization. The inelastic conductance and the corresponding tunneling processes are investigated with normal as well as ferromagnetic electrodes. In the case of ferromagnetic configuration, the coupling to the SMM leads to an asymmetric tunneling magnetoresistance (TMR), which can be enhanced or suppressed greatly in certain regions. Moreover, a sudden TMR-switch with the variation of magnetic field is observed, which is seen to be caused by the inelastic tunneling. [Copyright &y& Elsevier]

Abstract: The initial stages of surface oxidation of Fe–17Cr (ferritic stainless steel) were investigated at 323K by X-ray photoelectron spectroscopy (XPS) and inelastic electron background analysis. The results indicated the formation of a mixed iron–chromium oxide layer upon O2 exposure and the formation of a thin chromium oxyhydroxide layer upon H2O exposure. The oxidation of Fe did not occur in the latter case. Moreover, it was found that pre-exposing the Fe–17Cr surface to H2O significantly hinders subsequent oxidation by O2, thus providing a way to control the formation of nanoscale oxides on stainless steel materials. It was concluded that the formation of strongly bound hydroxyl species together with adsorbate-induced segregation of Cr severely limits the reaction between O2/H2O and Fe from the alloy. [Copyright &y& Elsevier]

Abstract: In a dynamical STEM image simulation by the Bloch-wave method, Allen et al. formulated a framework for calculating the cross-section for any incoherent scattering process from the inelastic scattering coefficients: thermal diffuse scattering (TDS) for high-angle annular dark-field (HAADF) and back-scattered electron (BSE) STEM, and ionization for electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (EDX) STEM. Furthermore, their method employed a skilful approach for deriving the excitation amplitude and block diagonalization in the eigenvalue equation. In the present work, we extend their scheme to a layer-by-layer representation for application to inhomogeneous crystals that include precipitates, defects and atomic displacement. Calculations for a multi-layer sample of Si–Sb–Si were performed by multiplying Allen et al.''s block-diagonalized matrices. Electron intensities within the sample and EDX STEM images, as an example of the inelastic scattering, were calculated at various conditions. From the calculations, 3-dimensional STEM analysis was considered. [Copyright &y& Elsevier]

Abstract: The inelastic mean free paths (IMFPs) of electrons at a poly[methyl(phenyl)silylene] thin film surface were determined using elastic peak electron spectroscopy (EPES) and Monte Carlo calculations for a wide electron energy range, 200–1600eV. We considered the surface composition determined from X-ray induced photoelectron spectra (XPS), the hydrogen concentration evaluated by EPES, and a correction for surface excitations. The results compare well to those calculated from the predictive TPP-2M and G1, formulae. Calculations carried out with the quantitative structure–property relationship of Cumpson and the formula of Ashley and Williams provide larger IMFP values, and can be useful only for a rough estimation. [Copyright &y& Elsevier]

Abstract: We concentrate on several relatively new aspects of the study of fast electron and X-ray scattering by atoms and atom-like objects, namely endohedral atoms and fullerenes. However, main attention is given to fast charge particle scattering. We show that the corresponding cross-sections, being expressed via so-called generalized oscillator strengths (GOS), give information on the electronic structure of the target and on the role of electron correlations in it. We consider what sort of information became available when analyzing the dependence of GOS upon their multipolarity, transferred momentum q and energy ω. To obtain theoretical results, we employ both the one-electron Hartree–Fock approximation and account for the multi-electron correlation in the target, using the random phase approximation with exchange. We demonstrate the role of non-dipole corrections in the small-angle fast-electron inelastic scattering. There dipole contribution dominates while non-dipole corrections can be considerably and controllably enhanced as compared to the case of low and medium energy photoionization. We show also that analyses of GOS for discrete level excitations permit to clarify their multipolarity. The results of calculations of Compton excitation and ionization cross-sections are presented. Attention is given to cooperative effects in inelastic fast electron-atom scattering that results in directed motion of the secondary electrons, a phenomenon that is similar to “drag currents” in photoionization. We demonstrate how one should derive GOS for endohedral atoms, e.g. A@C 60 and what is the additional information that can be obtained from corresponding GOS. Most of discussions are illustrated by the results of concrete calculations. [Copyright &y& Elsevier]

Abstract: Total electron-H2 scattering cross sections have been measured from 50 to 5000eV with experimental errors of about 5%. Integral elastic and inelastic cross sections have been calculated with different methods, according to the incident electron energies. For energies up to 40eV an R-matrix procedure has been used, while for intermediate and high energies (10–10000eV) an optical potential method has been applied by assuming an independent atom representation. From a detailed evaluation of the present results and their comparison with previous theoretical and experimental data, a complete set of recommended cross sectional data (elastic, inelastic and total) is provided. By combining the integral cross sections with an average excitation energy derived from the experimental energy loss spectra the stopping power of electrons in H2 has been obtained from 5 to 5000eV. [Copyright &y& Elsevier]

Abstract: Some aspects of the theory and the practical application of the Shirley background correction procedure are reviewed. The ‘classic’ Shirley/Sherwood method is scrutinized, with special emphasis on the physical meaning and the correct implementation. The features of the classic and the cross-section-based Shirley background correction procedures are compared. With a simple modification to the recently discovered Shirley-equivalent inelastic energy loss cross-section a ‘physical’ cross-section is derived and its impact on the practical data evaluation is analyzed. The impact of some frequently used erroneous implementations on the physical meaning of the evaluation procedure as well as the practical results derived using the wrong implementation are discussed and the correct statement on the physical meaning and implementation method is also suggested. [Copyright &y& Elsevier]

Abstract: Atomic location by channeling-enhanced microanalysis (ALCHEMI) is an effective technique to clarify the atomic configurations in multicomponent compounds. Recent development of the theory on the characteristic X-ray emission has made ALCHEMI a more reliable and expansive technique. In this revised ALCHEMI, the characteristic X-ray intensities are measured at various electron-incidence directions, and are compared with the X-ray intensities calculated from first principles. In the present work, this technique was applied to coexistent Heusler and half-Heusler phases in a thermoelectric material, TiNi1.5Sn. The X-ray intensities calculated for both phases were significantly dependent on the fitting parameters of the atomic occupancy on each site and the sample thickness. Using the Levenberg–Marquardt least-squares method, the residual errors between the experimental and the calculated X-ray intensities were minimized to determine the fitting parameters quantitatively. In the Heusler phase, the ordered structure was observed because the atoms of each element almost occupy each site. On the other hand, in the half-Heusler phase, the “Heusler-like” structure was observed because the occupation probabilities of Ni atoms on the Ni-site and on the vacancy-site were measured as 0.49±0.01 and 0.49±0.01, respectively, whereas 1 and 0 is expected for the normal half-Huesler structure. [Copyright &y& Elsevier]

Abstract: Coherence effects in electron energy loss spectrometry (EELS) and in energy filtering are largely neglected although they occur frequently due to Bragg scattering in crystals. We discuss how coherence in the inelastically scattered wave field can be described by the mixed dynamic form factor (MDFF), and how it relates to the density matrix of the scattered electrons. Among the many aspects of “inelastic coherence” are filtered high-resolution images, dipole-forbidden transitions, coherence in plasma excitations, errors in chemical microanalysis, coherent double plasmons, and circular dichroism. [Copyright &y& Elsevier]

Abstract: The process of creating photoelectrons in solids is strongly connected to different kinds of energy loss processes, classified as ‘extrinsic’ and ‘intrinsic’. In measured spectra the peaks are sensitively affected by all these processes. Of course one tries to extract from the spectrum shape as much information on these processes as possible. Unfortunately, the different loss processes are inextricably mixed. In theoretical works it is of course possible to consider these contributions separately, so some authors try to derive these contributions from the experimental spectra, too. The task is hard and the methods used for this goal are not always appropriate. Some popular methods are clearly based on misunderstanding or misusing the popular Shirley background correction method. This work explores the origin of some such problems and explains why those results (like density of states, intrinsic background, inelastic shape, etc.) based on inappropriately used methods are unreliable. [Copyright &y& Elsevier]

Inelastic scattering processes of the two-dimensional electron gas (2DEG) in both normal and inverted n-AlGaAs/GaAs heterojunction FET structures have been studied, for the case where InGaAs dots are embedded in the vicinity of GaAs channel. By analyzing the magnetoresistance data, the inelastic scattering time τin is determined as a function of the concentration N2D of 2D electrons and shown to be reduced by 10–40% by the presence of InGaAs dots. By investigating a GaAs/n-AlGaAs inverted heterojunction FET with embedded InGaAs dots, we have varied the percentage Poc of charged dots filled with an electron and found that τin decreases as Poc increases, indicating that the inelastic scattering rate of 2DEG by charged dots is higher than that by the neutral ones. [Copyright &y& Elsevier]

Recent advances in experimental techniques and theoretical capabilities associated with the study of surfaces show promise for producing in unprecedented detail a picture of electron–phonon coupling. These investigations on surfaces of relatively simple metals can be the platform for understanding functionality in complex materials associated with the coupling between charge and the lattice. In this article, we present an introduction to electron–phonon coupling, especially in systems with reduced dimensionality, and the recent experimental and theoretical achievements. Then, we try to anticipate the exciting future created by advances in surface physics. [Copyright &y& Elsevier]

Abstract: The inelastic mean free path (IMFP) is a fundamental material parameter. Presently the IMFPs calculated by the TPP-2M predictive formula (NIST SRD 71) are generally used. Elastic peak electron spectroscopy (EPES) is proved to be adequate for experimental determination of the IMFP denoted by λe . λe is smaller then λi (TPP-2M) values, due to surface losses, characterized by the SEP (surface excitation) P se material parameter. The present research is focused on the experimental determination of P se based on Tanuma''s work. The Tanuma factor f sT is the ratio of experimental Ie and calculated Ic elastic peak intensities Ie (E)/Ic (E). The detection angle dependent Ic is proportional to ΔΩ, the solid angle of detection. The angular Ic (E,ΔΩ,αd ) was calculated applying the EPESWIN software of Jablonski. In our work, experimental data of Goto were analysed for Si and Ni. Recent angularly resolved AREPES results of Jablonski and Zemek were quantified by fitting them at the 42° CMA (cylindrical mirror analyser) angle to absolute data of Goto and applying f sT. The models and SEP material parameters published by Werner et al., Ding et al., Kwei et al., Jablonski–Zemek and Nagatomi–Goto (Ni) and our data obtained by modifying Chen''s data (Si) have been tested. The best approach was obtained using data of Werner for Si, and data of Nagatomi for Ni. The SEP corrected IMFPs λ eco were deduced. The EPES SEP parameters were valid for AREPES by averaging over αd =35–70°. EPES spectra are quantified by applying the backscattering yield. [Copyright &y& Elsevier]