Electron Binding Energies Research Articles

Calculation of the correlation, relativistic, and QED corrections to the total electron binding energy in atoms and their nuclear charge dependence

Calculation of the correlation, relativistic, and QED corrections to the total electron binding energy in atoms and their nuclear charge dependence

Engineering Radiocatalytic Nanoliposomes with Hydrophobic Gold Nanoclusters for Radiotherapy Enhancement.

Chemoradiation therapy is on the forefront of pancreatic cancer care, and there is a continued effort to improve its safety and efficacy. Liposomes are widely used to improve chemotherapy safety, and may accurately deliver high-Z element- radiocatalytic nanomaterials to cancer tissues. In this study, the interaction between X-rays and long-circulating nanoliposome formulations loaded with gold nanoclusters is explored in the context of oxaliplatin chemotherapy for desmoplastic pancreatic cancer. Hydrophobic gold nanoclusters stabilized with dodecanethiol (AuDDT) are efficiently incorporated in nanoliposomal bilayers. AuDDT-nanoliposomes significantly augmented radiation-induced •OH production, which is most effective with monochromatic X-rays at energies that exceed the K-shell electron binding energy of Au (81.7keV). Cargo release assays reveal that AuDDT-nanoliposomes can permeabilize lipid bilayers in an X-ray dose- and formulation-dependent manner. The radiocatalytic effect of AuDDT-nanoliposomes significantly augments radiotherapy and oxaliplatin-chemoradiotherapy outcomes in 3D pancreatic microtumors. The PEGylated AuDDT-nanoliposomes display high tumor accumulation in an orthotopic mouse model of pancreatic cancer, showing promise for nanoliposomes as carriers for radiocatalytic nanomaterials. Altogether, compelling proof for chemo-radiation dose-enhancement using AuDDT-nanoliposomes is presented. Further improving the nanoliposomal loading of high-Z elements will advance the safety, efficacy, and translatability of such chemoradiation dose-enhancement approaches.

Observations on the Electronic Character of Anions and Cations near Water Liquid/Vapor Interfaces.

In recent years, many researchers have become interested in chemical reactions, photon-induced processes, and other events taking place at or near aqueous liquid/vapor or ice/vapor interfaces. Such studies relate to a wide variety of atmospheric, oceanographic, and environmental issues. Near these interfaces, atomic and molecular anions and cations display quite different behaviors than when they are fully solvated in the bulk medium. When they exist near an interface, some cations capture an excess electron to produce new neutral-molecule electronic states. Some such cations can use an attached electron to assist in hydrolyzing one of their first-solvent-shell molecules. Anions residing near an interface are less solvent-stabilized than when in the bulk, causing their electron binding energies to decrease as they approach an interface, as a result of which their ability to act as reducing agents increases. Many multiply charged anions even become electronically metastable with respect to electron loss near an interface. Thus, for both cations and anions, it is important to develop tools for characterizing their varying electronic-state nature as they migrate between bulk solvation and liquid-vapor interface positioning.

Chemochromism and Tunable Acoustic Phonons in Intercalated MoO3: Ag-, Bi-, In-, Mo-, Os-, Pd-, Pt-, Rh-, Ru-, Sb-, and W-MoO3.

Intercalation of several elements (Ag, Bi, In, Mo, Os, Pd, Pt, Rh, Ru, Sb, and W) is used to chemically alter a wide range of properties of two-dimensional layered α-MoO3. Intercalation modifies acoustic phonons and elastic constants, as measured with Brillouin scattering. Intercalation alters electronic bandgaps, color, structure, Raman shifts, and electron binding energies. Optical chemochromism is demonstrated with intercalants changing the color of MoO3 from transparent to brilliant blue (In, Mo, Os, and Ru) and orange (Ag). Correlations are investigated among material properties. There is evidence that in-plane longitudinal stiffness c11 correlates with changes in the bandgap, while various Raman modes appear to be connected to a variety of properties, including shear modulus c55, Mo binding energies, lattice constants, and the preferred crystal structure of the intercalant. The results indicate a surprising degree of complexity, suggesting competition among multiple distinct mechanisms and interactions involving specific intercalant species.

Measurement of core electron binding energies of silver nanoparticles and their modeling with electron propagator calculations of silver clusters

Silver nanoparticles were synthesized by ionic exchange with zeolites and further reduction with hydrogen flux. Core electron binding energies were determined by X-ray photoelectron spectroscopy at different times of the reduction process. Electron propagator calculations of core electron binding energies were performed including scalar relativistic effects using effective core potentials and zero order regular approximation. Theoretical results were compared to the experiment to get insight into the origin of the experimental signals for carbon, oxygen, silicon, aluminum and silver. Small model molecules and zeolite fragments were used for the calculation of core electron binding energies. It is evidenced that although binding energies tend to converge, fluctuations of more than 1 eV are found for non-symmetric structures in neutral and cationic silver clusters. Detailed analysis shows that these fluctuations originate on the different coordination numbers of ionized silver atoms and charge fluctuations.

Deuterium Isotope Effect on Internal Conversion of Ethylene Studied by Time-Resolved Photoelectron Spectroscopy.

The effect of deuterium isotopes on the internal conversion of ethylene is studied by using extreme ultraviolet time-resolved photoelectron spectroscopy. For deuterium-labeled ethylene, the time scale for ultrafast internal conversion is increased by a factor of approximately √2, in agreement with the results of ab initio multiple spawning calculations, indicating the essential role played by hydrogen motion in the conversion process. Following internal conversion, a metastable species with an electron binding energy of ∼9 eV is produced, and it decays with a time constant similar to that for both isotopologues.

Electron Binding Energies of Open-Shell Species from Diagonal Electron-Propagator Self-Energies with Unrestricted Hartree-Fock Spin-Orbitals.

For closed-shell molecules, valence electron binding energies may be calculated accurately and efficiently with ab initio electron-propagator methods that have surpassed their predecessors. Advantageous combinations of accuracy and efficiency range from cubically scaling methods with mean errors of 0.2 eV to quintically scaling methods with mean errors of 0.1 eV or less. The diagonal self-energy approximation in the canonical Hartree-Fock basis is responsible for the enhanced efficiency of several methods. This work examines the predictive capabilities of diagonal self-energy approximations when they are generalized to the canonical spin-orbital basis of unrestricted Hartree-Fock (UHF) theory. Experimental data on atomic electron binding energies and high-level, correlated calculations in a fixed basis for a set of open-shell molecules constitute standards of comparison. A review of the underlying theory and analysis of numerical errors lead to several recommendations for the calculation of electron binding energies: (1) In calculations that employ the diagonal self-energy approximation, Koopmans's identity for UHF must be qualitatively correct. (2) Closed-shell reference states are preferable to open-shell reference states in calculations of molecular ionization energies and electron affinities. (3) For molecular electron binding energies between doublets and triplets, calculations of electron detachment energies are more accurate and efficient than calculations of electron attachment energies. When these recommendations are followed, mean absolute errors increase by approximately 0.05 eV with respect to their counterparts obtained with closed-shell reference orbitals.

The solvation shell probed by resonant intermolecular Coulombic decay

Molecules involved in solvation shells have properties differing from those of the bulk solvent, which can in turn affect reactivity. Among key properties of these molecules are their nature and electronic structure. Widely used tools to characterize this type of property are X-ray-based spectroscopies, which, however, usually lack the capability to selectively probe the solvation-shell molecules. A class of X-ray triggered “non-local” processes has the recognized potential to provide this selectivity. Intermolecular Coulombic decay (ICD) and related processes involve neighbouring molecules in the decay of the X-ray-excited target, and are thus naturally sensitive to its immediate environment. Applying electron spectroscopy to aqueous solutions, we explore the resonant flavours of ICD and demonstrate how it can inform on the first solvation shell of excited solvated cations. One particular ICD process turns out to be a potent marker of the formation of ion pairs. Another gives a direct access to the electron binding energies of the water molecules in the first solvation shell, a quantity previously elusive to direct measurements. The resonant nature of the processes makes them readily measurable, providing powerful new spectroscopic tools.

Easy Scalable Solid-State Synthesis of Highly Efficient Synergetic 2D/1D Micro/Nanostructured g-C3N4/MeS (Me=Cd, Mo) Photocatalysts for Organic Dye Degradation and Hydrogen Evolution

The global reserves of oil, gas, and coal are acknowledged finite, and their consumption rates are increasing each year [1]. Following Fujishima’s groundbreaking discovery of photocatalytic water splitting using TiO2 electrodes in 1972 [2], photocatalysis technology gained recognition as a promising approach for renewable energy and environmental conservation [3]. Since that pivotal moment, significant advancements have been made in developing preparation methods for highly efficient photocatalysts, predominantly centered on semiconductors like metal oxides and sulfides [4].In this study, we introduce effective synergistic photocatalysts, that utilize g-C3N4 and MeS (Me=Cd, Mo) semiconductors featuring a 2D/1D micro/nanostructure. Photocatalysts were successfully produced through solid-state method using planetary ball mill, where reaction of MeS formation occurs on the surface of g-C3N4. A comprehensive analysis of the binding energy of electrons of semiconductors was conducted to understand its impact on the photocatalytic activity of the prepared g-C3N4/MeS. The fabricated materials were used in the photodegradation of organic dyes and demonstrated remarkable efficacy. Regarding photocatalytic hydrogen evolution, the g-C3N4/CdS in conjunction with Pt co-catalyst, achieved a hydrogen evolution rate of up to 2254.54 μmol*h⁻¹ *g⁻¹, accompanied by apparent quantum efficiency of 2.0%. Acknowledgments This research was funded by the Science Committee of the Ministry of Education and Science of the Republic of Kazakhstan (Grant No. АР13068426).

Divalent manganese (Mn2+, 3d5) charge transfer energies and vacuum-referred binding energies in inorganic compounds

Ongoing efforts to develop a predictive model governing the host-referred binding energies (HRBEs) and vacuum-referred binding energies (VRBEs) of transition metal dopants in inorganic host compounds are stymied by a lack of cross-compound data sets that capture transitions between the dopant ions and the valence and conduction bands of the hosts. Herein, we have compiled data consistent with Mn2+ charge transfer processes in 53 different compounds, spanning fluorides, oxides, chlorides, bromides, and nitrides. By assigning these transitions to Mn2+ → conduction band metal-to-metal charge transfer and combining these energies with the binding energies of electrons in the valence and conduction bands of the various hosts, we have calculated the HRBEs and VRBEs of the Mn2+ ion across a range of compounds. We show that variations in the Mn2+ VRBE are small relative to the variations in the VRBE of the valence and conduction bands, which manifests an approximately linear relationship between the Mn2+ HRBE and the bandgap energy of host compounds. We investigated the relationship between the Mn2+ VRBE and the various structures of the host compounds and showed that the chemical shift experienced by the Mn2+ ion depends on the electronegativity of the ligand, the Mn2+ coordination, and the Mn-ligand bond lengths in a predictable manner.

Measuring the Electronic Bandgap of Carbon Nanotube Networks in Non-Ideal p-n Diodes.

The measurement of the electronic bandgap and exciton binding energy in quasi-one-dimensional materials such as carbon nanotubes is challenging due to many-body effects and strong electron-electron interactions. Unlike bulk semiconductors, where the electronic bandgap is well known, the optical resonance in low-dimensional semiconductors is dominated by excitons, making their electronic bandgap more difficult to measure. In this work, we measure the electronic bandgap of networks of polymer-wrapped semiconducting single-walled carbon nanotubes (s-SWCNTs) using non-ideal p-n diodes. We show that our s-SWCNT networks have a short minority carrier lifetime due to the presence of interface trap states, making the diodes non-ideal. We use the generation and recombination leakage currents from these non-ideal diodes to measure the electronic bandgap and excitonic levels of different polymer-wrapped s-SWCNTs with varying diameters: arc discharge (~1.55 nm), (7,5) (0.83 nm), and (6,5) (0.76 nm). Our values are consistent with theoretical predictions, providing insight into the fundamental properties of networks of s-SWCNTs. The techniques outlined here demonstrate a robust strategy that can be applied to measuring the electronic bandgaps and exciton binding energies of a broad variety of nanoscale and quantum-confined semiconductors, including the most modern nanoscale transistors that rely on nanowire geometries.

Facile synthesis of silver doped manganese oxide nanocomposite with superior photocatalytic and antimicrobial activity under visible spectrum

Water pollution and antimicrobial resistance (AMR) have become two global threats; 80% of diseases and 50% of child deaths are due to poor water quality. In this study, hydrothermal processing was employed to manufacture manganese oxide nanorods. Silver dopant was deposited on the surface of manganese oxide. XRD diffractogram confirmed the facile synthesis of Ag/Mn2O3 nanocomposite. XPS survey analysis demonstrated silver content of 9.43 atom %. Photocatalytic measurements demonstrated the outstanding efficiency of the Ag-Mn2O3 compared to virgin oxide particles under visible radiation. Degradation efficiencies Mn2O3 and Ag/Mn2O3 on methyl orange (MO) dye was found to be 53% and 85% under visible spectrum. Silver dopant was found to decrease the binding energy of valence electrons; this action could support electron–hole pair generation under visible spectrum and could promote catalytic performance. Ag/Mn2O3 NPs demonstrated most effective performance (95% removal efficiency) at pH 3; this could be ascribed to the electrostatic attraction between positively charged catalyst and the negatively charged MO. Ag/Mn2O3 demonstrated enhanced antibacterial activity against Gram-positive Staphylococcus aureus (S. aureus) (19 mm ZOI), and Gram-negative Escherichiacoli (E. coli) (22 mm ZOI) respectively; the developed nanocomposite demonstrated advanced anti-film activity with inhibition percentage of 95.5% against E. coli followed by 89.5% against S. aureus.

Solid solutions in disulfide systems Re(IV)S<sub>2</sub>–Ti(IV)S<sub>2</sub>, Re(IV)S<sub>2</sub>–Mo(IV)S<sub>2</sub>, and Re(IV)S<sub>2</sub>–W(IV)S<sub>2</sub>

Objectives. Chalcogenides of transition elements with low oxidation states, as well as their substituted derivatives, remain a poorly studied class of chemical compounds. Rhenium disulfide has many distinctive features and great application potential as a new twodimensional semiconductor. This is due to its unusual structure and unique anisotropic properties. The presence of weak interlayer bonding and a unique distorted octahedral (1T) structure suggests the possibility of creating new phases on its basis. The aim of this work is to obtain and study phases in systems Re(IV)S2–Ti(IV)S2, Re(IV)S2–Mo(IV)S2, and Re(IV)S2–W(IV)S2.Methods. The samples were obtained by high-temperature solid-phase ampoule synthesis in a vacuum. The study was carried out using X-ray phase analysis and X-ray photoelectron spectroscopy.Results. The regions of existence of solid solutions, intercalates and two-phase regions in the resulting systems were established.Diffraction patterns were obtained for the new phases and the crystal lattice parameters were calculated. Based on data relating to the binding energies of core electrons with the nucleus, the study showed the valence states of the elements after synthesis. The study also confirmed that all phases obtained as a result of synthesis contain transition elements in the oxidation state (IV).Conclusions. Intercalated solid solutions are formed in areas rich in rhenium, while in areas close to titanium and molybdenum disulfides, intercalated phases are attained. In the ReS2–WS2 system there is a region of solid solutions, including 30, 50, and 70 mol % rhenium disulfide. Their structure is a polymorphic modification of the structure of the original components. The presence of rhenium, molybdenum, and tungsten in these phases in the oxidation state (+IV) was confirmed. The data obtained on phase formation in dichalcogenide systems can be practically used in the creation of materials with unique electronic, magnetic, and optical properties with a wide range of applications.

Evolution of copper ions in nanostructured Cu[formula omitted]O according to X-ray absorption spectroscopy data

Soft X-ray absorption spectroscopy (Cu L and O K spectra ) was applied to identify changes in the charge states of copper ions in quasi-statically loaded (torsion under pressure) Cu2O. As was found from our X-ray diffraction and X-ray absorption experiments, an increase in the degree of deformation lead to a decrease in the areas of coherent scattering (sizes of nanograins), to partial amorphization of oxides, and to a slight increase in the concentration of Cu2+ ions on the surface of the Cu2O samples. No new phases were detected using X-ray diffraction measurements. The repeated measurements of the Cu L and O K spectra of the nanostructured Cu2O samples after two years showed significantly more intense signals at high photon energies, indicating the appearance of Cu2+ ions on the surface of nanostructured Cu2O, corresponding to the CuO phase. It was shown that two types of Cu2+ ions on the surface of Cu2O samples with different binding energies of Cu 2p electrons could be formed.

Atomic size mismatch induced consecutive compressive strain on intermetallic compound towards boosted hydrogen evolution

AbstractModulating lattice strain in intermetallic compounds could effectively alter their electronic structure and binding energy, thus impacting catalytic activity. Strain is usually induced through lattice mismatch, achieved by constructing core‐shell nanostructures or metal‐substrate interfaces with complex reciprocity and distractors. However, in situ induced strain without interface‐construction or lattice mismatch presents challenges. In this study, we precisely manipulate consecutive compressive strain from −0.5% to −0.8% in CoPt3Pd intermetallic compound by inducing interior atomic radius mismatch. Precise strain control results in a negative shift of d‐band center, dynamic charge distribution, and facilitates water dissociation, leading to enhanced electrocatalytic activity. The CoPt3Pd catalyst with −0.5% compressive strain exhibits exceptional hydrogen evolution activity, with an overpotential of 169 mV at 1 A cm−2. Our approach offers a straightforward method to manipulate compressive strain on intermetallic compounds by atomic size mismatch, with broad implications for catalytic processes.

Reparameterization of GFN1-xTB for atmospheric molecular clusters: applications to multi-acid-multi-base systems.

Atmospheric molecular clusters, the onset of secondary aerosol formation, are a major part of the current uncertainty in modern climate models. Quantum chemical (QC) methods are usually employed in a funneling approach to identify the lowest free energy cluster structures. However, the funneling approach highly depends on the accuracy of low-cost methods to ensure that important low-lying minima are not missed. Here we present a reparameterized GFN1-xTB model based on the clusteromics I-V datasets for studying atmospheric molecular clusters (AMC), denoted AMC-xTB. The AMC-xTB model reduces the mean of electronic binding energy errors from 7-11.8 kcal mol-1 to roughly 0 kcal mol-1 and the root mean square deviation from 7.6-12.3 kcal mol-1 to 0.81-1.45 kcal mol-1. In addition, the minimum structures obtained with AMC-xTB are closer to the ωB97X-D/6-31++G(d,p) level of theory compared to GFN1-xTB. We employ the new parameterization in two new configurational sampling workflows that include an additional meta-dynamics sampling step using CREST with the AMC-xTB model. The first workflow, denoted the "independent workflow", is a commonly used funneling approach with an additional CREST step, and the second, the "improvement workflow", is where the best configuration currently known in the literature is improved with a CREST + AMC-xTB step. Testing the new workflow we find configurations lower in free energy for all the literature clusters with the largest improvement being up to 21 kcal mol-1. Lastly, by employing the improvement workflow we massively screened 288 new multi-acid-multi-base clusters containing up to 8 different species. For these new multi-acid-multi-base cluster systems we observe that the improvement workflow finds configurations lower in free energy for 245 out of 288 (85.1%) cluster structures. Most of the improvements are within 2 kcal mol-1, but we see improvements up to 8.3 kcal mol-1. Hence, we can recommend this new workflow based on the AMC-xTB model for future studies on atmospheric molecular clusters.

Demonstrating the Connection between the Nonvalence Correlation-Bound Anions of Polyaromatic Hydrocarbons and the Image Potential States of Graphene Using a One-Electron Model Hamiltonian.

The ground and excited state nonvalence correlation-bound (NVCB) anion states of the hexagonal polycylic aromatic hydrocarbons and of hexagonal graphene nanoflakes are characterized using a one-electron model Hamiltonian which incorporates atomic electrostatic moments up to the quadrupole, coupled inducible charges and dipoles, and atom-centered Gaussians to describe the short-range repulsive interactions. Extrapolation of the calculated electron binding energies of the lowest energy symmetric and antisymmetric (with respect to the molecular plane) NVCB anions of both the polycylic aromatic hydrocarbons and the carbon nanoflakes to the n → ∞ limit yields binding energies that are in good agreement with those of the most stable symmetric and antisymmetric image potential states of freestanding graphene as determined from two-photon photoemission spectroscopy (2PPE) experiments.

Ultrafast conformation-dependent charge transfer in N, N, N′, N′-tetramethyl-1,3-propanediamine: Effect of flexible carbon skeleton on electron lone pair interactions

Flexible three-carbon skeleton makes N, N, N′, N′-tetramethyl-1,3-propanediamine (TMPDA) an important diamine system to investigate the conformation-dependent electron lone pair interactions and charge delocalization. The charge transfer process linked to structural motions of the three-carbon skeleton has been monitored in real time by the Rydberg electron binding energy (BE) spectra of TMPDA coupled with quantum chemical calculations. Optical excitation to the 3p state with a 200 nm pump pulse initially generated a localized charge on one of the two nitrogen atoms that may partially transfer to the other one. Rapid internal conversion (IC) from the 3p to 3s state occurred within 430 fs, resulting in an initial charge delocalized 3s_h/3s_l population ratio of 23.6 %/76.4 %. A final 3s_h/3s_l (51.9 %/48.1 %) equilibrium proceeded within about 2.64 ps. The 3s_h (TTTT+, GG′TG+ and G′GG′G+) and 3s_l (GG′GG′+ and GG′G′G+) (see text for structure definitions) are identified as the extended and folded conformers, respectively. Two types of electron lone pair interactions, i.e., through-space interaction (TSI) and through-bond interaction (TBI), are found to coexist in TMPDA to drive charge transfer. The GG′GG′+ and GG′G′G+ structures exhibit TSI, while the TTTT+ structure shows TBI. The GG′TG+ and G′GG′G+ structures exhibit both TSI and TBI. Flexible three-carbon skeleton provide more opportunities for the two N-electron lone pairs to overlap in space (i.e., TSI), making TMPDA to be favorable for the most stably folded conformation.

Role of the Binding Energy on Nondipole Effects in Single-Photon Ionization.

We experimentally study the influence of the binding energy on nondipole effects in K-shell single-photon ionization of atoms at high photon energies. We find that for each ionization event, as expected by momentum conservation, the photon momentum is transferred almost fully to the recoiling ion. The momentum distribution of the electrons becomes asymmetrically deformed along the photon propagation direction with a mean value of 8/(5c)(E_{γ}-I_{P}) confirming an almost 100year old prediction by Sommerfeld and Schur [Ann. Phys. (N.Y.) 396, 409 (1930)10.1002/andp.19303960402]. The emission direction of the photoions results from competition between the forward-directed photon momentum and the backward-directed recoil imparted by the photoelectron. Which of the two counteracting effects prevails depends on the binding energy of the emitted electron. As an example, we show that at 20keV photon energy, Ne^{+} and Ar^{+} photoions are pushed backward towards the radiation source, while Kr^{+} photoions are emitted forward along the light propagation direction.

Evolution of Natural Ferroan Brucite Under Different Atmospheres

The study on the evolution of natural ferroan brucite (MgFe(OH)[Formula: see text] was beneficial to discovering the function of brucite in the geologic cycle and directing the reasonable utilization of brucite resources. In this study, natural MgFe(OH)2 was characterized in detail and Rietveld refinement was employed to determine the precise content and existing environment of Fe[Formula: see text]. The reaction products of MgFe(OH)2 under various atmospheric conditions, including CO2, O2 and a mixed atmosphere of CO2 and O2 were innovatively investigated to gain insights into the evolution process and the crucial role played by Fe[Formula: see text]. Accordingly, the evolution mechanism of MgFe(OH)2 under different atmospheres was afforded based on the characterization and molecular simulations like electron transfer and binding energy. Fe[Formula: see text] in MgFe(OH)2 layers could be oxidized by O2 easily and give positive layers, CO[Formula: see text] produced by CO2 dissolving in water simultaneously was attracted to finally produce CO[Formula: see text] intercalated MgFe- layered double hydroxides (MgFe-CO[Formula: see text]-LDHs) which could be used as adsorbents, catalysts and so on. This process was supported by thermodynamics and also the dominant evolution route due to the dynamic reason. The existence of Fe[Formula: see text] in MgFe(OH)2 resulted in the diversity of the evolution products. This work highlighted the composition and structure of evolution products of natural MgFe(OH)2 under different environment as well as its possible application field.