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Incipient Anion Intercalation of HOPG Close to the Oxygen Evolution Potential. A Combined X-ray Photoemission and Raman Spectroscopy Study
摘要： In the present work we used two different electrochemical (EC) techniques, namely cyclic voltammetry (CV) and normal pulsed voltammetry (NPV), applied to a highly oriented pyrolytic graphite (HOPG) electrode for anion intercalation in two different aqueous electrolytes (i.e. perchloric and sulphuric acid). We performed comparative X-ray photoemission (XPS) and Raman spectroscopy studies at various EC potentials. The chemical analysis obtained by XPS and Raman, the latter applied in-situ and in real-time during the electrochemical processes, indicates that at oxygen evolution potential (i.e. before reaching the well-known intercalation stage potentials) the HOPG intercalation process is already active. These results suggest that the intercalated compound is efficiently obtained before reaching higher potentials, which usually cause a detriment of the graphite crystal.
关键词： HOPG,Raman spectroscopy,X-ray photoemission,anion intercalation,normal pulsed voltammetry,cyclic voltammetry
更新于2025-09-04 15:30:14
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Nanoparticles at Biomimetic Interfaces: A Combined Experimental and Simulation Study on Charged Gold Nanoparticles/Lipid Bilayers Interfaces
摘要： The poor understanding of the interaction of nanomaterials with biologically relevant interfaces is recognized as one of the major issues currently limiting the development of nanomedicine. The central purpose of this study is to compare experimental (Confocal Microscopy, Fluorescence Correlation Spectroscopy, X-ray Reflectivity) and computational (Molecular Dynamics simulations) results to thoroughly describe the interaction of cationic gold nanoparticles (AuNP) with mixed zwitterionic/anionic lipid membranes. The adhesion of AuNPs to the lipid membrane is investigated on different length scales from a structural and dynamical point of view; with this approach, a series of complex phenomena, spanning from lipid extraction, localized membrane disruption, lateral phase separation and slaved diffusion, are characterized and interpreted from a molecular level to macroscopic observations.
关键词： Nanoparticles,Gold Nanoparticles,Molecular Dynamics,X-ray Reflectivity,Fluorescence Correlation Spectroscopy,Lipid Bilayers,Biomimetic Interfaces,Confocal Microscopy
更新于2025-09-04 15:30:14
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MBE Growth and Optical Properties of Isotopically Purified ZnSe Heterostructures
摘要： Wide-gap II/VI heterostructures (HS) and quantum wells (QW) composed of ZnSe, CdSe, MgSe and their ternary and quaternary compounds are attractive candidates for modern quantum optical devices such as single photon sources and optically controlled spin qubits in the visible spectral range. In contrast to similar III/V semiconductor based devices, generally, most of the II/VI compounds allow for isotope purification towards zero nuclear spin species in the semiconductor environment. Using the same molecular beam epitaxy (MBE) system for natural and isotopically purified materials opposes the challenge to achieve superior isotope purity for example of Zn and Se species on the background of operation of the other effusion cells filled with natural isotopes. Here we report on the crystallographic and optical properties of ZnMgSe/ZnSe heterostructures and quantum wells grown by using 64Zn and 80Se isotopes and Mg with natural isotope distribution. We present a detailed quantitative secondary ion mass spectrometry (SIMS) analysis, which confirms that an extremely high grade of isotope purification of the ZnSe can be maintained although naturally and enriched Zn and Se elements are used in the same MBE system. This pioneering growth study forms a solid base to generate a spin vacuum ZnSe host crystal that is particularly suited for future studies on the dynamics of localized spins in II/VI heterostructures on a strongly extended coherence time scale.
关键词： Heterostructures,Molecular beam epitaxy,Optical properties,Crystal structure,X-ray diffraction,Isotope purification,Elementary analysis
更新于2025-09-04 15:30:14
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Electronic structure of the polymer-cathode interface of an organic electroluminescent device investigated using operando hard x-ray photoelectron spectroscopy
摘要： The electronic structure of a polymer-cathode interface of an operating organic light-emitting diode (OLED) was directly investigated using hard X-ray photoelectron spectroscopy (HAXPES). The potential distribution pro?le of the light-emitting copolymer layer as a function of the depth under the Al/Ba cathode layer in the OLED depended on the bias voltage. We found that band bending occurred in the copolymer of 9,9-dioctyl?uorene (50%) and N-(4-(2-butyl)-phenyl)diphenylamine (F8-PFB) layer near the cathode at 0 V bias, while a linear potential distribution formed in the F8-PFB when a bias voltage was applied to the OLED. Direct observation of the built-in potential and that band bending formed in the F8-PFB layer in the operating OLED suggested that charges moved in the F8-PFB layer before electron injection from the cathode.
关键词： polymer-cathode interface,band bending,organic light-emitting diode,electronic structure,hard X-ray photoelectron spectroscopy
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Measurement of total electronic cross-section, total atomic cross-section, effective atomic numbers and effective electron densities for some Sm compounds
摘要： Total electronic cross-section, total atomic cross-section, effective atomic number, and effective electron density were determined experimentally and theoretically for Sm2O3, SmI2, and SmCl3 compounds. The mass attenuation coefficient and total atomic cross section were calculated experimental values for Sm2O3, SmI2, and SmCl3 compounds. Theoretical mass attenuation coefficient values were computed from the XCOM data program. Exciting Sm compounds were measured using a Si(Li) detector with γ photons at 59.543 keV from 241 Am annular source. We have performed the measurements for the calculations of these values in attenuation and direct excitation experimental geometry. The effective atomic number and electron density for Sm compounds are being reported here for the first time.
关键词： effective atomic number,X-ray fluorescence,electron density,mass attenuation coefficient
更新于2025-09-04 15:30:14
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - L X-ray relative intensity ratios of uranium, lead, hafnium and samarium
摘要： In this study the L shell X-ray relative intensities ((cid:1835)(cid:3013)(cid:3287)(cid:512)(cid:1835)(cid:3013)(cid:3330), (cid:1835)(cid:3013)(cid:3328)(cid:512)(cid:1835)(cid:3013)(cid:3330) and (cid:1835)(cid:3013)(cid:3329)(cid:512)(cid:1835)(cid:3013)(cid:3330)) for uranium, lead, hafnium and samarium have been measured for several scattering angles (85°, 95°, 105°, 115°, 125° and 135°) at 59.54 keV photon energy by using a Si(Li) detector which has a resolution of 160 eV at 5.9 keV. In previous studies, the (cid:1838)(cid:3082) X-rays were usually found independ on the scattering angles, therefore we found reasonable to give the ratio to the (cid:1838)(cid:3082) X-rays.
关键词： L X-ray,samarium,relative intensity ratios,uranium,lead,hafnium,scattering angles
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Hybrid Physical Optics-Ray Tracing Method for the RCS Calculation of Electrically Large Objects Covered with Radar Absorbing Materials
摘要： A hybrid method based on Ray Tracing and Physical Optics for the estimation of the radar cross section of large metallic targets covered with radar absorbing materials is presented. The reflection coefficient of the multilayer structure composed by the metallic layer covered with radar absorbing materials is analytically evaluated through a transmission line model. The accuracy of the Radar Cross Section estimation is validated by full-wave simulations based on the Method of Moments. A corner reflector coated with Radar Absorbing Material (RAM) is used as a test-case of the proposed method. The obtained results exhibit a good agreement if compared against full-wave simulations.
关键词： Physical Optics (PO),Impedance Boundary Condition (IBC),Ray Tracing (RT),Radar Absorbing Material (RAM),Frequency Selective Surface (FSS)
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Efficient RF Coverage Prediction through a fully Discrete, GPU-Parallelized Ray-Launching model
摘要： A fully discrete Ray Launching field prediction algorithm that takes advantage of environment visibility preprocessing for both diffuse and specular interactions is presented and used to perform efficient RF coverage prediction in large environments. The algorithm, being discrete, has been parallelized in a straightforward way on NVIDIA-compatible Graphical Processing Units. These innovative features combined allow to achieve a computation time reduction of about three orders of magnitude compared to conventional algorithms, while retaining the same accuracy level.
关键词： RF prediction,GPU,ray launching,propagation,measurement
更新于2025-09-04 15:30:14
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Modeling core-level excitations with variationally optimized reduced-density matrices and the extended random phase approximation
摘要： The information contained within ground-state one- and two-electron reduced-density matrices (RDMs) can be used to compute wave functions and energies for electronically excited states through the extended random phase approximation (ERPA). The ERPA is an appealing framework for describing excitations out of states obtained via the variational optimization of the two-electron RDM (2-RDM), as the variational 2-RDM (v2RDM) approach itself can only be used to describe the lowest-energy state of a given spin symmetry. The utility of the ERPA for predicting near-edge features relevant to x-ray absorption spectroscopy is assessed for the case that the 2-RDM is obtained from a ground-state v2RDM-driven complete active space self-consistent field (CASSCF) computation. A class of killer conditions for the CASSCF-speci?c ERPA excitation operator is derived, and it is demonstrated that a reliable description of core-level excitations requires an excitation operator that ful?lls these conditions; the core-valence separation (CVS) scheme yields such an operator. Absolute excitation energies evaluated within the CASSCF/CVS-ERPA framework are slightly more accurate than those obtained from the usual random phase approximation (RPA), but the CVS-ERPA is not more accurate than RPA for predicting the relative positions of near-edge features. Nonetheless, CVS-ERPA is established as a reasonable starting point for the treatment of core-level excitations using variationally optimized 2-RDMs.
关键词： reduced-density matrices,extended random phase approximation,v2RDM,CASSCF,core-level excitations,x-ray absorption spectroscopy
更新于2025-09-04 15:30:14
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Elemental Analysis of Six Mines in Erzincan Region Using Wavelength-Dispersive X-Ray Fluorescence Spectrometry
摘要： This investigation concentrated on mines in the eastern Erzincan region of Anatolia, Turkey. Wavelength-dispersive X-ray fluorescence spectrometry was used to determine elemental concentrations of the ores taken from six different mines. The presence of C, O, Mg, Al, Si, P, Cl, K, Ca, Ti, V, Cr, Mn, Zn, As, Sr and Ba elements in ores were found. The relative errors for results have been given ± 7 %.
关键词： Ore,Wavelength-dispersive X-ray fluorescence
更新于2025-09-04 15:30:14