2p States Research Articles

Investigations of Λ states with spin-parity 32±

The present study provides spectroscopic investigations of spin-32 Λ baryons with both positive and negative parities. The analysis mainly focuses on three states, namely 1P, 2P, and 2S, and corresponding masses are calculated using the QCD sum rule method. To implement the method, we apply two types of interpolating currents with octet and singlet quantum numbers and compare the corresponding results with the reported masses of experimentally observed states. From the comparisons, it is extracted that the results of interpolating current with octet quantum numbers are in good agreement with the experimentally measured masses. The masses obtained with this interpolating current are m=1513.64±8.76 MeV for 1P state with JP=32−, m′=1687.91±0.31 MeV for 2P state with JP=32− and m˜=1882.37±11.95 MeV for 2S state with JP=32+ and they are consistent with the experimental masses of Λ(1520), Λ(1690), and Λ(1890), respectively, which confirm their spin-parity quantum numbers. Besides, we calculate the corresponding current coupling constants, which are utilized as inputs in the calculations of different form factors defining the widths of the states under study. Published by the American Physical Society 2024

Interaction of an electron and a uniformly charged spherical donor impurity

In this study, we propose an interaction potential between an electron and a uniformly charged spherical donor impurity in a quantum dot and numerically solve the Schrödinger equation using the finite difference method. We investigate the effects of the potential depth, donor radius, temperature, and hydrostatic pressure on the electronic and optical properties of an electron-donor impurity in a quantum dot, including absorption coefficients and the total change in the relative refractive index during the transition of an electron from the ground (1s) to excited (2p) states in the conduction band. Our findings indicate that an increase in donor radius or temperature leads to a red shift in the optical response, holding the parameters constant. Conversely, an increase in potential depth or hydrostatic pressure induces a blue shift in the optical response under the constant parameters.

High-efficiency photocatalyst based on Au nanoparticles loaded on defective ZnO nanorods

Optimizing the semiconductor-metal interaction is the key to developing metal single-atom cocatalysts with 100 % metal atom utilization and unique electronic properties. Metal atom sites are exclusively coordinated with semiconductor, featuring a chemical-bond-driven tunable interaction. Here vacancy defect-rich ZnO nanorods (NRs) are fabricated by a facile hydrothermal approach. Au nanoparticles (NPs) are preferentially anchored on surface zinc vacancy sites of ZnO NRs in an ultra-low concentration (10−4 mol/L) of HAuCL4 solution. The Au/ZnO nanohybrids exhibit an excellent photocatalytic activity toward removal of Rhodamine B and levofloxacin. Combining ferromagnetism and valence-band XPS spectra analysis, it is demonstrated that the strong interaction of surface vacancy defects in ZnO and Au generates a distinct upshift of the valence band edge, resulting from the antibonding interaction between O 2p and Au 5d orbitals which significantly weakens the Au–O bonds. This facilitates the release of the lattice oxygen and thus generates more oxygen vacancies. The remarkable photoactivity of defective Au/ZnO is due to the synergistic interaction between the intrinsic oxygen vacancy and Au. Optimizing the hybridization of transition metal d and O 2p states at the atomic scale can induce more active-sites, improve atomic utilization efficiency and thus provide a new approach for enhancing photoactivity.

Electronic structures of skyrmionic polycrystalline MnSi thin film studied by resonance photoemission and x-ray near edge spectroscopy

Magnetic nanometric skyrmions are small complex vortex-like topological defects, mainly found in non-centrosymmetric crystals such as MnSi. They have potential applications for future spintronic devices. In this article, the structural, electronic, and magnetic states of the Mn atoms in a polycrystalline MnSi thin film facing a c-sapphire substrate were studied using x-ray diffraction, x-ray photo-emission spectroscopy, resonance photoemission spectroscopy (RPES), and extended x-ray absorption fine structure (EXAFS). The valence band spectra indicate the metallic nature of the film. The RPES study reveals the presence of major itinerant Mn 3d states near EF and also the mixed Mn 3d and Si 3s–3p states from 5.3 to 11.3 eV. The EXAFS spectrum does not show the existence of oxygen vacancies in the system, and the obtained magnetic moment in the non-stoichiometric MnSi thin film is a combination of the partially itinerant and partially localized Mn 3d states.

Triggering cationic/anionic hybrid redox stabilizes high-temperature Li-rich cathodes materials via three-in-one strategy

Efficiently advancing lithium-ion batteries toward high energy density entails overcoming challenges in Li-rich layered oxides, including severe voltage and capacity fading, irreversible oxygen escape and compromised thermal robustness due to the uncontrollable oxygen anionic redox (OAR). Herein, a three-in-one modification strategy, aim at strengthening the reversibility of OAR and structural integrity of MnO6 octahedron, is rationally introduced on Li1.2Mn0.53Ni0.20Co0.07O2 cathode through a universal H3BO3-treatment. Through the introduction of oxygen vacancies and gradient B-doping, the energy level of unhybridized O 2p states is decreased to narrow the band energy gap with transition metal (TM) band, which triggers cationic/anionic hybrid redox at high voltage, thereby stabilizing the peroxo-like (O2)n- species and hindering irreversible oxygen escape, while the lithium borate nano-coating serves to mitigate side reactions, particularly during charging at elevated temperatures. As a result, the modulated cathode exhibits notable capacity retention of 96.3 % after 500 cycles at 1 C with limited voltage fading rate (1.73 mV per cycle) and even stable cyclic performance at high temperature (60 °C). This approach provides an effective and straightforward method to tackle the voltage decay and capacity fading of high-energy Li-rich layered cathode materials.

The Spin-Orbit Effect on the Electronic Structures, Refractive Indices, and Birefringence of X2PO4I (X = Pb, Sn, Ba and Sr): A First-Principles Investigation.

Introducing post-transition metal cations is an excellent strategy for enhancing optical properties. This paper focuses on four isomers, namely the X2PO4I (X = Pb, Sn, Ba, and Sr) series. For the first time, the paper's attention is paid to the changes in electronic structure, as well as refractive indices and birefringence, with and without the inclusion of spin-orbit effects in this series. The first-principles results show that spin-orbit effects of the 5p and 6p states found in these compounds lead to splitting of the bands, narrowing of the band gap, enhancement of the lone-pair stereochemistry, and enhancement of the refractive indices and birefringence. Moreover, a comparison of the lone-pair electron phosphates, X2PO4I (X = Pb and Sn), and the isomeric alkaline earth metal phosphates, X2PO4I (X = Ba and Sr), reveals that changes in the band structure have a greater effect on the enhancement of the birefringence than the slight enhancement of the lone-pair stereochemical activity. This study has important implications for a deeper understanding of the optical properties of crystals and the design of novel optical materials.

Reaction solution mediated photo-degradation process and mechanism of tetracycline via semiconductor-insulator composite ZnO:N-BaSO4

Research in contaminants photo-degradation has witnessed significant progress, recently insulator-based catalysts gaining prominence. In this study, N-containing p-type ZnO decorated BaSO4 (ZnO:N-BaSO4) were synthesized and presented a pseudo-first-order kinetic constant of 1.30 × 10−2 min−1 for TC degradation, surpassing that of ZnO:N and their physical mixture by four and seven-fold, respectively. Impressively, the electron transfer in ZnO:N/TC solution interface led to band bending on ZnO:N surface and realized the band matching between ZnO:N and BaSO4. Density functional theory (DFT) calculations unveiled that the strong Zn-O covalent interaction involving 4s states of Zn atoms and 2p states of O atoms, established a distinctive pathway for electron transfer from semiconductor to insulator. Moreover, the catalysts demonstrated robust activity and sustained long-term stability in real wastewater and surface water. This research illuminates the role of wastewater redox potential in semiconductor band adjustment and highlights abundant, eco-friendly insulators as co-catalysts for selective photo-degradation.

Semirelativistic study of the semileptonic decays of Bq mesons to orbital excited heavy tensors

Based on the method of solving the complete Salpeter equation, we study the semileptonic decays of a 0− heavy meson to 1P, 2P, or 3P heavy-tensor mesons, Bq→(c¯q)(nP)ℓ+νℓ (q=u,d,s,c;n=1,2,3). The obtained branching ratio of B(B→D2⋆(2460)ℓ+νℓ) agrees with the experimental data. We predict B(Bs0→Ds2⋆−(1P)ℓ+νℓ)=3.76×10−3 and B(Bc+→χc2(1P)ℓ+νℓ)=1.82×10−3. The branching ratios of decays to 2P and 3P final states are found to be very small. The ratios R(D¯2⋆0)=0.045, R(Ds2⋆)=0.048 and R(χc2)=0.059 are also obtained. This study focuses on the contribution of relativistic corrections. The wave function of the pseudoscalar includes nonrelativistic S-wave and relativistic P-wave. While for a tensor, it contains nonrelativistic P-wave and relativistic P-, D-, and F-waves in its wave function. We find the individual contributions of relativistic partial waves are significant in the decay B→D2⋆(2460)ℓ+νℓ, but the overall contribution of the relativistic effect is 24.4%, which is small due to cancellation. Similarly, for the decay Bs0→Ds2⋆−(1P)ℓ+νℓ, the contribution of the relativistic effect is 28.8%. While for Bc+→χc2(1P)ℓ+νℓ, the individual contributions of relativistic partial waves and the overall relativistic correction are both small, the later of which is 22.1%. Published by the American Physical Society 2024

Stereochemically Active Lone Pair Leads to Birefringence in the Vacancy Ordered Cs3Sb2Cl9 Perovskite Single Crystals.

Stereochemically active lone pair (SCALP) cations are attractive units for realizing optical anisotropy. Antimony(III) chloride perovskites with the SCALP have remained largely unknown to date. We synthesized a new vacancy ordered Cs3Sb2Cl9 perovskite single crystals with SbCl6 octahedral linkage containing the SCALP. Remarkably, all-inorganic halide perovskite Cs3Sb2Cl9 single crystals exhibit an exceptional birefringence of 0.12 ± 0.01 at 550 nm. The SCALP brings a large local structural distortion of the SbCl6 octahedra promoting birefringence optical responses in Cs3Sb2Cl9 single crystals. Theoretical calculations reveal that the considerable hybridization of Sb 5s and 5p with Cl 3p states largely contribute to the SCALP. Furthermore, the change in the Sb-Cl-Sb bond angle creates distortion in the SbCl6 octahedral arrangement in the apical and equatorial directions within the crystal structure incorporating the required anisotropy for the birefringence. This work explores pristine inorganic halide perovskite single crystals as a potential birefringent material with prospects in integrated optical devices.

First-principles study on the effect of point defects on the magnetic new mechanism and optical properties of the GaN:Be/Mg/Ca system

The new magnetic mechanism and optical properties of Ga vacancies and Hi interstitial in the GaN: Be/Mg/Ca system have not been fully understood, and the use of first principles can solve this problem. The effect of point defects on the magnetic mechanism and optical properties of the GaN: Be/Mg/Ca system was investigated using the first nature principle of the hybridized generalized HSE06 method. Results show that all doped systems have N2− ions in addition to N3− ions, and N2− ions have the dual property of itinerant electrons in the off-domain (donor) and of local electrons (acceptor). The magnetism of magnetic doped systems is generated by the hybrid coupling of Ga4s and N2− 2p states. In comparison with the Ga34MN36 (M = Be/Ca) system, the magnetic moments of Ga34MHiN36 (M = Be/Ca) system are reduced after doping with Hi interstitial. The magnetic properties of the Ga34MgN36 system can be regulated by the presence or absence of Hi interstitial, which is advantageous as a magnetic switch. The absorption spectral distribution of the Ga34MgHiN36 system extends to the mid-infrared optical region. This material has some reference value as infrared thermophotovoltaic cells, infrared photodetectors, or infrared semiconductor lasers.

Competition of multiphoton ionization pathways in lithium

We study the three-photon ionization of atomic lithium by intense, short light pulses, via numerically solving the time-dependent Schrödinger equation. Two-photon Rabi oscillations are induced between the 2s and 4s states, which are damped due to single-photon ionization to the p continuum. Developing a minimal three-level model, we analyze the spectral features of the Autler–Townes (AT) doublet that is formed upon the resonant coupling with the laser pulse. Furthermore, we show that this 2s→→4s→p continuum pathway is the dominant process, if the duration of the laser pulse exceeds a certain value. For shorter pulses, ionization through the 2p state ( 2s→2p→4d→f continuum ) gradually becomes the dominant process, provided that the pulse is strong enough to induce several Rabi floppings. Here, we trace the competition of these ionization pathways by observing the structural changes in the shape of the AT doublet.

Promotion of oxygen evolution through the modification of Co-O bond in spinel NiCo2O4

The coordination environment of magnetic ions in transition metal oxides has a significant impact on the oxygen evolution reaction (OER) activity. Herein, we synthesized inverse spinel oxide NiCo2-xFexO4 (x = 0–1.5) on the nickel foam (NiCo2-xFexO4@NF) to explore the impact of Fe3+ ions doping in Co site on OER activity. The electrochemical results indicate that the introduction of Fe3+ ions drastically improved the OER performance for x ≤ 1.0. While the OER activity would decrease with further doping of Fe3+. The overpotential of 10 mA cm−2 decreased from 331 mV (NiCo2O4@NF) to 260 mV versus RHE (NiCoFeO4@NF) and lower Tafel slope (41.46 mV/dec) for OER in 1.0 M KOH electrolyte. Furthermore, there is a slightly decrease in overpotential after the stability test and the difference is not more than 2%. By comparing the structure of NiCoFeO4@NF and pristine NiCo2O4@NF, it was found that the doping of moderate amounts Fe3+ (x ≤ 1.0) would help to form the structure which can expose more active sites. Furthermore, XPS results indicate that transition from Co2+ to Co3+, the higher Co3+/Co2+ ratio contributes to good reducibility and oxygen mobility, and 3d state of Co3+ would generate strong hybridization with O 2p state. The EIS results imply that the incorporation of Fe can effectively improve the conductivity of materials and reduce the charge transfer resistance. Together with the magnetic properties, we found that Fe3+ ions replaced Co site in octahedral site with low spin state for x ≤ 1.0 implies beneficial effect for OER activity. While For x > 1.0, part of the Fe3+ ions locate in tetrahedron site with high spin state which show harmful effect for the OER activity.

Shedding light on charmonium

We investigate E1 radiative transitions within charmonium in a relativistic approach based on light-front QCD. In quantum field theory, two sets of processes are pure E1: χc0→J/ψγ (ψ→χc0γ) and hc→ηcγ (ηc′→hcγ), both involving the P-wave charmonia. We compute the E1 radiative decay widths as well as the corresponding transition form factors of various processes including those involving 2P states. These observables provide an access to the microscopic structures of the P-wave charmonium. We show that our parameter-free predictions are in excellent agreement with the experimental measurements as well as lattice simulations whenever available. Published by the American Physical Society 2024

A study Electronic structure of InSb: Experiment and Theory

The current study show the results related to investigating the Compton scattering(Cs) of Indium Antimonite (InSb). 241Am with 59.54 keV Gamm-radiations source Compton spectrometer is employed for the purpose of experimental measurement. The technique of linear combination of atomic orbitals (LCAO) is utilized within the framework of density functional theory (DFT),is used to assess the theoretical values of distributing the electron momentum density. A comparison was then made between the research findings and empirical data. Additionally, calculations employing the ionic model (IO) based on the 5p state of In and the 5p state of Sb atoms reveal that 0. 5 electrons of the state of 5pIn may have been transferred to the 5p state of Sb atoms in order to estimate the charge transfer in indium antimonite (InSb).

Valence shell electronically excited states of norbornadiene and quadricyclane.

The absolute photoabsorption cross sections of norbornadiene (NBD) and quadricyclane (QC), two isomers with chemical formula C7H8 that are attracting much interest for solar energy storage applications, have been measured from threshold up to 10.8eV using the Fourier transform spectrometer at the SOLEIL synchrotron radiation facility. The absorption spectrum of NBD exhibits some sharp structure associated with transitions into Rydberg states, superimposed on several broad bands attributable to valence excitations. Sharp structure, although less pronounced, also appears in the absorption spectrum of QC. Assignments have been proposed for some of the absorption bands using calculated vertical transition energies and oscillator strengths for the electronically excited states of NBD and QC. Natural transition orbitals indicate that some of the electronically excited states in NBD have a mixed Rydberg/valence character, whereas the first ten excited singlet states in QC are all predominantly Rydberg in the vertical region. In NBD, a comparison between the vibrational structure observed in the experimental 11B1-11A1 (3sa1 ← 5b1) band and that predicted by Franck-Condon and Herzberg-Teller modeling has necessitated a revision of the band origin and of the vibrational assignments proposed previously. Similar comparisons have encouraged a revision of the adiabatic first ionization energy of NBD. Simulations of the vibrational structure due to excitation from the 5b2 orbital in QC into 3p and 3d Rydberg states have allowed tentative assignments to be proposed for the complex structure observed in the absorption bands between ∼5.4 and 7.0eV.

Effects of Sr and Mg doping on elastic, mechanical, and optical properties of hydroxyapatite: A first-principles study

Hydroxyapatite (HAp), with the chemical formula Ca10(PO4)6(OH)2, is a bioactive ceramic material typically used in the treatment of bone defects owing to the excellent biocompatibility and the ability to bond with bone tissues. Mechanical properties of HAp have drawn pronounced attention because of the crucial roles in the medical applications. Based on density functional theory (DFT), this work reports the structural, formation energy, mechanical, Vickers hardness, electronic properties, and optical properties of hydroxyapatite (HAp), strontium-substituted HAp (Sr-HAp), and magnesium-substituted HAp (Mg-HAp). The results reveal that the Sr2+ and Mg2+ ions mainly replace the Ca2+ ion at the Ca-1 site in HAp. Resistance to hydrostatic compression followed the order Mg-HAp > HAp > Sr-HAp. Sr-HAp has the capability to enhance thermal shock resistance and lattice thermal conductivity. In addition, the electronic properties of HAp change upon substitutional Sr2+ and Mg2+ doping. In comparison with pristine HAp, the energy gap of Sr-doped HAp relatively increases, whereas that of Mg-doped HAp decreases. Nevertheless, both Sr-HAp and Mg-HAp remain insulators. Intriguingly, Sr-HAp possesses the improved hardness by 11.31 % owing to the hybridization of the Sr (4p) and O (2p) states, which contributed to its high shear modulus and high hardness. Beyond that, we further investigate their optical properties. The presence of Mg states at approximately 10 eV in the conduction band leads to enhanced absorption within the 14 – 20 eV for Mg-doped HAp. Similarly, the presence of a deep Sr(4p) level in Sr-HAp amplifies absorption within the 20–25 eV range. These findings have raised a potential avenue for selectively boosting the optical absorption of HAp, thus improving its photocatalytic properties.

On the Importance of Future, Precise, X-ray Measurements in Kaonic Atoms

Progress in the construction of precise X-ray detectors allows measurements of energies and widths of “upper levels” in K− mesic atoms. These can be used to determine sub-threshold Kaon-nucleon amplitudes, which are important in investigations of nuclear states of these mesons. The special case of the 2P state in Kaonic Helium is discussed and used to check the properties of the K− proton quasi-bound state. Similar attempts in other elements indicate a need for new, precise measurements.

Electronic perturbation-promoted interfacial pathway for facile C–H dissociation

Interface has often played significant role in the behavior of metal-based catalysts during various heterogeneous reactions. Herein, we reported a novel interfacial pathway for propane dehydrogenation on Pt-GaOx dual sites. The active ensemble, composing Pt particles and Ga2O3 clusters, facilitates the facile dissociation of C–H bonds (energy barrier < 0.30 eV) through H-abstraction by O sites, coupled with alkyl stabilization on the Pt surface. Notably, the electronic perturbation of the Pt slab induces higher-lying O 2p states at the interface, accompanied by a substantial density of states around fermi level. This is in stark contrast to the O species present in Ga2O3 crystals or clusters alone, leading to an exceptionally strong affinity for H and a robust ability for C–H scission. The Pt/Ga-Al2O3 catalysts prepared with Pt nanoparticles decorated by Ga oxide exhibit superior performance compared to Pt/Al2O3 and PtSn/Al2O3 catalysts. This insight into interfacial catalysis contributes to a broader understanding of the origin of the high catalytic efficiency observed in metal-based catalysts.

Carrier mobility in doped Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; based on deformation potential theory

Antimony selenide (Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt;) is an element-rich, cost-effective, and non-toxic material used as an absorber layer in solar cells. The performance of solar cells is significantly influenced by the transport characteristics of charge carriers. However, these characteristics in Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; have not been well understood. In this work, through density functional theory and deformation potential theory, we investigate the hole transport properties of pure Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; and As-, Bi-doped Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt;. The incorporation of as element and Bi element does not introduce additional impurity levels within the band gap. However, the band gaps are reduced in both As-Sb&lt;sub&gt;2&lt;/sub&gt;Se3 and Bi-Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; due to the band shifts of energy levels. This phenomenon is primarily attributed to the interactions between the unoccupied 4p and 6p states of the doping atoms and the unoccupied 4p states of Se atoms, as well as the unoccupied 5p states of Sb atoms. In this study, we calculate and analyze three key parameters affecting mobility: effective mass, deformation potential, and elastic constants. The results indicate that effective mass has the greatest influence on mobility, with Bi-Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; exhibiting the highest average mobility. The average effective mass is highest in As-Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; and lowest in Bi-Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt;. The elastic constants of the As- and Bi-doped Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; structures show minimal differences compared with that of the intrinsic Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; structure. By comparing the intrinsic, As-doped, and Bi-doped Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt;, it is evident that doping has a minor influence on deformation potential energy along various directions. The study reveals that the hole mobility in Sb&lt;sub&gt;2&lt;/sub&gt;Se&lt;sub&gt;3&lt;/sub&gt; displays significant anisotropy, with higher mobilities observed in the &lt;i&gt;x&lt;/i&gt;-direction and the &lt;i&gt;y&lt;/i&gt;-direction than in the &lt;i&gt;z&lt;/i&gt;-direction. This discrepancy is attributed to stronger covalent bonding primarily in the &lt;i&gt;x&lt;/i&gt;- and &lt;i&gt;y&lt;/i&gt;-direction, while in the &lt;i&gt;z&lt;/i&gt;-direction weaker van der Waals forces is dominant. The directions with enhanced charge carrier transport capability contribute to efficient transfer and collection of photo-generated charge carriers. Therefore, our research theoretically underscores the significance of controlling the growth of antimony selenide along specific directions.

Valence-band hybridization in sulphides.

The hybridization state in solids often defines the critical chemical and physical properties of a compound. However, it is difficult to spectroscopically detect and evaluate hybridization beyond just general fingerprint signatures. Here, the valence-band hybridization of metal d-derived bands (short: "metal d bands") in selected metal sulphides is studied with a combined spectroscopic and theoretical approach to derive deeper insights into the fundamental nature of such compounds. The valence bands of the studied sulphides are comprised of hybrid bands derived from the metal d, S 3s, and S 3p states. Employing S K and L2,3 X-ray emission spectroscopy and spectra calculations based on density functional theory, the degree of hybridization (i.e., the covalency) of these bands can be directly probed as a function of their relative energies. We find that the relative intensity of the "metal d band" features in the spectra scales with the inverse square of the energy separation to the respective sulfur-derived bands, which can be analytically derived from a simple two-orbital model. This study demonstrates that soft X-ray emission spectroscopy is a powerful tool to study valence state hybridization, in particular in combination with hard X-ray emission spectroscopy, promising a broad impact in many research fields.