Energy Level Shifts Research Articles

Ab initio study on the dynamics and spectroscopy of collective rovibrational polaritons.

Accurate rovibrational molecular models are employed to gain insight in high-resolution into the collective effects and intermolecular processes arising when molecules in the gas phase interact with a resonant infrared (IR) radiation mode. An efficient theoretical approach is detailed, and numerical results are presented for the HCl, H2O, and CH4 molecules confined in an IR cavity. It is shown that by employing a rotationally resolved model for the molecules, revealing the various cavity-mediated interactions between the field-free molecular eigenstates, it is possible to obtain a detailed understanding of the physical processes governing the energy level structure, absorption spectra, and dynamic behavior of the confined systems. Collective effects, arising due to the cavity-mediated interaction between molecules, are identified in energy level shifts, in intensity borrowing effects in the absorption spectra, and in the intermolecular energy transfer occurring during Hermitian or non-Hermitian time propagation.

Suppressing Polaronic Defect-Photocarrier Interaction in Halide Perovskites by Pre-distorting Its Lattice.

In halide perovskites, photocarriers can have strong polaronic interactions with point defects. For iodide-deficient MAPbI3, we found that the Fermi level can shift significantly by 0.6-0.7 eV upon light illumination. This energy level shift is accompanied by the formation of deep electron traps. These experimental observations are consistent with the formation of a Pb-Pb dimer when photoexcited electrons are trapped at an iodide vacancy. Interestingly, we found that this polaronic interaction is suppressed when a portion of MA+ cations is replaced by smaller Cs+ ions. Density functional theory calculations reveal that Cs-doping can reduce the distance between two Pb atoms across an iodide vacancy, even without electron trapping. The predistortion of the lattice induced by cation replacement resembles the Pb-Pb dimer formed by electron trapping at the defect site, which explains the suppression of light-induced effects observed in the experiment. Our finding unveils a counterintuitive strategy to enhance the photostability of halide perovskites by preintroducing distortions into its lattice.

Blackbody-radiation-induced energy-level shifts for a uniformly moving atom in a dielectric medium

Blackbody-radiation-induced energy-level shifts for a uniformly moving atom in a dielectric medium

Topological states in finite graphene nanoribbons tuned by electric fields

In this comprehensive study, we conduct a theoretical investigation into the Stark shift of topological states (TSs) in finite armchair graphene nanoribbons (AGNRs) and heterostructures under transverse electric fields. Our focus centers on the multiple end zigzag edge states of AGNRs and the interface states of9--7--9AGNR heterostructures. For the formal TSs, we observe a distinctive blue Stark shift in energy levels relative to the electric field within a range where the energy levels of TSs do not merge into the energy levels of bulk states. Conversely, for the latter TSs, we identify an oscillatory Stark shift in energy levels around the Fermi level. Simultaneously, we reveal the impact of the Stark effect on the transmission coefficients for both types of TSs. Notably, we uncover intriguing spectra in the multiple end zigzag edge states. In the case of finite9--7--9AGNR heterostructures, the spectra of transmission coefficient reveal that the coupling strength between the topological interface states can be well controlled by the transverse electric fields. The outcomes of this research not only contribute to a deeper understanding of the electronic property in graphene-based materials but also pave the way for innovations in next-generation electronic devices and quantum technologies.

Anisotropy in Carbon Dioxide Adsorption on Forsterite.

In this study, density functional theory (DFT) method were used to investigate the adsorption behavior and binding mechanism of CO2 molecules on six crystallographic surfaces of forsterite (Mg2SiO4). The influence of surface crystallographic orientation on CO2 adsorption efficiency was examined at the atomic level. Results showed stable binding of CO2 on all surfaces. The interaction strength decreases in the order: (001) > (101) > (120) > (111) > (010) > (110), with the (001) surface exhibiting the highest binding capacity due to accessible magnesium cations interacting with CO2. Detailed electronic property analysis revealed significant charge transfer between CO2 oxygen atoms and surface magnesium atoms, driven by hybridization of oxygen 2p and magnesium 2s orbitals, leading to the formation of ionic and covalent bonds. These interactions stabilize the adsorbed CO2 and are accompanied by changes in the electronic structure, such as energy level shifts and modifications in the partial density of states (PDOS). The computational analysis provides a theoretical foundation for understanding CO2 binding mechanisms by forsterite. The findings highlight the importance of crystallographic orientation and electronic properties of the mineral surface in adsorption efficiency, contributing to a deeper understanding of CO2 interactions with mineral surfaces.

Enhancing catalytic efficiency: InSe quantum dots’ role in hydrogen evolution reaction

This study investigates the structural, electronic, and adsorption properties of InSe quantum dots. We focus on hydrogen atom adsorption and its implications on quantum stability chemical parameters and the hydrogen evolution reaction (HER). Optimized structures reveal distinct atomic interactions post-H adsorption, affecting bond lengths, dihedral angles, and bond angles. Adsorption energies confirm spontaneous H-adsorption across various sites, highlighting preferences for specific interactions. Electronic properties analysis showcases significant shifts in energy levels, energy gaps, and chemical parameters following H-atom adsorption, indicating a transition towards more insulating states. The catalytic performance for HER is assessed through calculated free energy changes (ΔG), demonstrating superior catalytic activity. Comparison with a Pt catalyst underscores the potential of these quantum dots as efficient HER catalysts. For instance, the ΔG value decreases to 0.005 eV in InSe-quantum dots passivated with F- and H-atoms at the edges. These findings contribute to understanding the role of InSe quantum dots in enhancing the HER reaction, offering insights for potential application in electrocatalysis and energy conversion.

Polymer Based on Asymmetrically Halogenated Benzotriazole Enables High Performance Organic Solar Cells Prepared in Nonhalogenated Solvent.

Halogenation on the A unit of the D-π-A-type polymer donor has been proven as an effective strategy to improve the performance of organic solar cells (OSCs). Compared with fluorination, chlorination usually increases the open-circuit voltage because of the downward shift of energy levels, but decreases the charge transport ability due to the large steric hindrance of the chlorine atom. We reported herein a method to balance the energy loss and charge transport through asymmetric halogenation on the benzotriazole (BTA) unit of the polymer. The designed PE3-FCl based on the BTA unit containing fluorine and chlorine atoms rendered the highest power conversion efficiency (PCE) of 17.83% when eC9-2Cl-γ and o-xylene were used as the electron acceptor and solvent, respectively. The performance is obviously higher than that of the polymer PE3 containing a difluorinated BTA unit (16.65%) and polymer PE3-2Cl with dichlorinated BTA (14.65%) due to the manipulated morphology by preaggregation, improved and more balanced charge carrier transport, and reduced recombination loss. Notably, this PCE is a breakthrough for the BTA-based polymers processed by nonhalogenated solvent. This work gives deep insight into the asymmetric halogenation of polymer donors for high-performance green solvent-processed OSCs.

Strong noninertial radiative shifts in atomic spectra at low accelerations

Despite numerous proposals investigating various properties of accelerated detectors in different settings, detecting the Unruh effect remains challenging due to the typically weak signal at achievable accelerations. For an atom with frequency gap ω0, accelerated in free space, significant acceleration-induced modification of properties like transition rates and radiative energy shifts requires accelerations of the order of ω0c. In this paper, we make the case for a suitably modified density of field states to be complemented by a judicious selection of the system property to be monitored. We study the radiative energy-level shift in inertial and uniformly accelerated atoms coupled to a massless quantum scalar field inside a cylindrical cavity. Uniformly accelerated atoms experience thermal correlations in the inertial vacuum, and the radiative shifts are expected to respond accordingly. We show that the noninertial contribution to the energy shift can be isolated and significantly enhanced relative to the inertial contribution by suitably modifying the density of field modes inside a cylindrical cavity. Moreover, we demonstrate that monitoring the radiative energy shift, as compared to transition rates, allows us to reap a stronger purely noninertial signal. We find that a purely noninertial radiative shift as large as 50 times the inertial energy shift can be obtained at small, experimentally achievable accelerations (a∼10−9ω0c) if the cavity’s radius R is specified with a relative precision of δR/R0∼10−7. Given that radiative shifts for inertial atoms have already been measured with high accuracy, we argue that the radiative energy-level shift is a promising observable for detecting Unruh thermality with current technology. Published by the American Physical Society 2024

In silico analysis predicts mutational consequences of CITED2, NUDT4, and Ar18B in patients with bipolar disorder

Bipolar disorder is a mood-related disorder, which can be portrayed as extreme shifts in energy, mood, and activity levels which can also be characterized by manic highs and depressive lows that can be often misdiagnosed as unipolar disorder due to primitive diagnostics techniques based on clinical assessments as well as diagnostic complexities arising due to its heterogeneous nature and overlapping symptoms with conditions like schizophrenia. leading to delays in treatment Strong evidence in support of genetic and epigenetic aspects of bipolar disorder, including mechanisms such as compromised hypothalamic-pituitary-adrenal axis, immune-inflammatory imbalances, oxidative stress, and mitochondrial dysfunction are found. Moreover, some previous research has already stated the role of genes like CITED2, NUDT4, and Arl8B in these processes. The primary goal of this study is to investigate the involvement of the genes in exploring and validating their potential as biomarkers for bipolar disorder. In silico tools like MutationTaster, PolyPhen2, SIFT, GTEx, PhenoScanner, and RegulomeDB were used to perform mutational and gene expression analyses. Results revealed potentially dangerous mutations caused in CITED2, NUDT4, and Arl8B, those which can have diverse outcomes. RegulomeDB, GTEx, and PhenoScanner reveal the involvement of these genes in various brain regions highlighting their relevance to bipolar disorder. This analysis suggests the potential utility of CITED2, NUDT4, and Arl8B as diagnostic markers hence shedding light on their roles to elaborate the molecular range of bipolar disorder. The study also contributes to providing valuable insights into the genetic and molecular basis of bipolar disorders.

Impact of the Interruption Duration on Photoluminescence Properties of MOCVD-Grown GaAsP/InAlGaAs Quantum Well Structures.

The growth interruption technology is introduced to the growth of GaAsP/InAlGaAs quantum well (QW) structure using metal-organic chemical vapor deposition (MOCVD). The effect of growth interruption time (GIT) on the crystalline quality and optical properties are investigated. The two distinctive emission peaks are the transition recombination between the electron level of conduction band and the light and heavy hole level of valence band in the photoluminescence (PL) at room temperature. The PL peaks present a redshift and merge together with the increasing GIT, which is attributed to the QW energy level shift caused by the increase in arsenic concentrations in GaAsP QW, the diversified thickness of QW and the variations of indium components in the InAlGaAs barrier layer. The Gaussian deconvolution parameters in temperature-dependent PL (TDPL) show that the GaAsP/InAlGaAs QW with a GIT of 6 s has a 565.74 meV activation energy, enhancing the carrier confinement in QW and the PL intensity, while the 6 s-GIT GaAsP QW has the increasing interface roughness and the non-radiative centers at the InGaAsP intermediate layer, leading to a spectral broadening. The QW with 10 s-GIT exhibits a small full width at half maximum (FWHM) with the various temperature, indicating reduced interface roughness and excellent crystal quality. An increase in GIT may be suitable for optimizing the optical properties of GaAsP/InAlGaAs QW.

Polarizable Continuum Models and Green's Function GW Formalism: On the Dynamics of the Solvent Electrons.

The many-body GW formalism, for the calculation of ionization potentials or electronic affinities, relies on the frequency-dependent dielectric function built from the electronic degrees of freedom. Considering the case of water as a solvent treated within the polarizable continuum model, we explore the impact of restricting the full frequency-dependence of the solvent electronic dielectric response to a frequency-independent (ϵ∞) optical dielectric constant. For solutes presenting small to large highest-occupied to lowest-unoccupied molecular orbital energy gaps, we show that such a restriction induces errors no larger than a few percent on the energy level shifts from the gas to the solvated phase. We further introduce a remarkably accurate single-pole model for mimicking the effect of the full frequency dependence of the water dielectric function in the visible-UV range. This allows a fully dynamical embedded GW calculation with the only knowledge of the cavity reaction field calculated for the ϵ∞ optical dielectric constant.

Bose–Einstein distribution temperature features of quasiparticles around magnetopolaron in Gaussian quantum wells of alkali halogen ions

Abstract We have applied strong coupling unitary transformation method combined with Bose–Einstein statistical law to investigate magnetopolaron energy level temperature effects in halogen ion crystal quantum wells. The obtained results showed that under magnetic field effect, magnetopolaron quasiparticle was formed through the interaction of electrons and surrounding phonons. At the same time, magnetopolaron was influenced by phonon temperature statistical law and important energy level shifts down and binding energy increases. This revealed that lattice temperature and magnetic field could easily affect magnetopolaron and the above results could play key roles in exploring thermoelectric conversion and conductivity of crystal materials.

A DFT study on catalytic cracking mechanism of tar by Ni or Fe doped CaO during biomass steam gasification

The presence of byproduct tar seriously reduces the efficiency and syngas quality in the biomass gasification process. The current understanding of CaO-catalyzed tar cracking mainly depends on experimental findings and conjecture about CaO properties. However, there is a significant lack of simulation studies that explore the conversion mechanism at the molecular level. In this work, the reaction mechanism of tar catalytic cracking on Ni or Fe doped CaO was studied using density functional theory simulation. The benzene, phenol and toluene were chosen as the tar model compounds to determine the influences of Ni and Fe on the adsorption characteristics of CaO surface. CaO doped with Ni and Fe increases its electron affinity and electron conductivity from 4.99 to 9.21/5.58 eV-1. It also enhances the interactions between the d-orbitals of Ni/Fe atoms and the p-orbitals of O atoms. The C-H activation of ·CH3 is the most kinetically and energetically feasible first step. The Ni-doped CaO and Fe-doped CaO decrease the energy barriers by 15.7 % and 21.7 %, respectively, compared with undoped CaO. Ni enhances the surface adsorption capacity for ·H radicals to form OH* at the O top site, whereas Fe promotes the stabilization of ·H radicals at the Ca-O vacancy. Through the enhancement of chemical adsorption capacity, improvement of electronic properties, introduction of electron reorganization and orbital hybridization, low-energy shift of energy levels, and generation of new energy states (from -0.85 to -1.64/-3.05 eV), the surfaces of Ni-doped CaO and Fe-doped CaO provide a favorable electronic environment for the tar catalytic cracking, which improves the reaction efficiency and selectivity.

Cation Occupation Engineering Realizes Valence Modulation of Manganese-Activated ZnGa2O4.

Herein, a series of Mn-activated ZnGa2O4 (ZGO) phosphors have been developed for multifunctional applications. The characteristic green and red emission at 503 and 668 nm of Mn-activated ZGO phosphors can be observed under excitation of 247 and 375 nm, respectively, attributed to the partial oxidation of Mn2+ ions resulting in the coexistence of Mn2+ and Mn4+ ions in the host lattice. The valence modulation of Mn content not only realizes the adjustment of red and green luminescence intensity but also achieves the management of persistent luminescence time and thermo-luminescence time. Further, the codoping of Mg2+ could transform the position occupancy preference of Mn and effectively facilitate the conversion of Mn2+ to Mn4+, leading to the regulation of the valence state of manganese ions. Surprisingly, the existence of Mg2+ ions broadens the emission band of Mn4+ and enhances the photoluminescence intensity to 3.8 times, which can be ascribed to the weakened crystal field leading to the downward shift of the 4T2 energy level and the increase of Mn4+ concentration. For this valence modulation behavior, two different hypotheses about the occupancy of Mg2+ have been proposed to explain the corresponding phenomenon. Finally, the potential applications of the synthesized phosphors have been explored in advanced anticounterfeiting strategies, information storage, and plant lighting field.

Environment-Driven Variability in Absolute Band Edge Positions and Work Functions of Reduced Ceria.

The absolute band edge positions and work function (Φ) are the key electronic properties of metal oxides that determine their performance in electronic devices and photocatalysis. However, experimental measurements of these properties often show notable variations, and the mechanisms underlying these discrepancies remain inadequately understood. In this work, we focus on ceria (CeO2), a material renowned for its outstanding oxygen storage capacity, and combine theoretical and experimental techniques to demonstrate environmental modifications of its ionization potential (IP) and Φ. Under O-deficient conditions, reduced ceria exhibits a decreased IP and Φ with significant sensitivity to defect distributions. In contrast, the IP and Φ are elevated in O-rich conditions due to the formation of surface peroxide species. Surface adsorbates and impurities can further augment these variabilities under realistic conditions. We rationalize the shifts in energy levels by separating the individual contributions from bulk and surface factors, using hybrid quantum mechanical/molecular mechanical (QM/MM) embedded-cluster and periodic density functional theory (DFT) calculations supported by interatomic-potential-based electrostatic analyses. Our results highlight the critical role of on-site electrostatic potentials in determining the absolute energy levels in metal oxides, implying a dynamic evolution of band edges under catalytic conditions.

High rectification effects of heterojunctions based on C3N4 nanoribbons

Two heterojunctions based on zigzag graphitic carbon nitride nanoribbons (ZCNNRs), namely, BnAn and CnAn, are considered and their electronic transport properties are studied using the nonequilibrium Green's function (NEGF) in combination with the density functional theory (DFT). The BnAn is formed by the joining of bare and partially hydrogenated ZCNNRs. The CnAn is created by the attachment of bare and fully hydrogenated ZCNNRs which leads to a Schottky barrier. The results show that current–voltage characteristics (I–V) can be significantly tuned by the length variation of heterojunctions. Furthermore, it is found that both heterojunctions have a remarkable nonlinear behavior in the whole bias range. The B4A4, B3A4, and B4A3 have forward rectifier performance whereas B2A2, B3A3, C2A2, C3A3, C4A4, C3A4, C4A3, C5A3, and C6A3 show the reverse rectification behavior. In the case of BnAn, the maximum rectification ratio (RR) of B4A4 is boosted up to 3.97 × 107 at 0.4 V. Additionally, for CnAn, the maximum RR of C4A3 can reach 1.37 × 105 at 1.0 V. Our investigation reveals that the BnAn heterojunction has negative differential resistance (NDR) under positive bias.The peculiar transport behaviors of B4A4 and C4A3 are explained due to the energy level shifts of electrodes with applied bias voltage and great alterations in the transmission spectrum. Furthermore, the Molecular projected self-consistent Hamiltonian (MPSH) and projected local density of states (PLDOS) are analyzed for these devices. The findings of this work reveal unique opportunities to design the ZCNNRs nanoelectronic devices.

Sensing at the Nanoscale Using Nitrogen-Vacancy Centers in Diamond: A Model for a Quantum Pressure Sensor.

The sensing of stress under harsh environmental conditions with high resolution has critical importance for a range of applications including earth's subsurface scanning, geological CO2 storage monitoring, and mineral and resource recovery. Using a first-principles density functional theory (DFT) approach combined with the theoretical modelling of the low-energy Hamiltonian, here, we investigate a novel approach to detect unprecedented levels of pressure by taking advantage of the solid-state electronic spin of nitrogen-vacancy (NV) centers in diamond. We computationally explore the effect of strain on the defect band edges and band gaps by varying the lattice parameters of a diamond supercell hosting a single NV center. A low-energy Hamiltonian is developed that includes the effect of stress on the energy level of a ±1 spin manifold at the ground state. By quantifying the energy level shift and split, we predict pressure sensing of up to 0.3 MPa/Hz using the experimentally measured spin dephasing time. We show the superiority of the quantum sensing approach over traditional optical sensing techniques by discussing our results from DFT and theoretical modelling for the frequency shift per unit pressure. Importantly, we propose a quantum manometer that could be useful to measure earth's subsurface vibrations as well as for pressure detection and monitoring in high-temperature superconductivity studies and in material sciences. Our results open avenues for the development of a sensing technology with high sensitivity and resolution under extreme pressure limits that potentially has a wider applicability than the existing pressure sensing technologies.

First measurement of kaonic helium-4 M-series transitions

In this paper we present the results of a new kaonic helium-4 measurement with a 1.37 g l−1 gaseous target by the SIDDHARTA-2 experiment at the DAΦNE collider. We measured, for the first time, the energies and yields of three transitions belonging to the M-series. Moreover, we improved by a factor about three, the statistical precision of the 2p level energy shift and width induced by the strong interaction, obtaining the most precise measurement for gaseous kaonic helium, and measured the yield of the L α transition at the employed density, providing a new experimental input to investigate the density dependence of kaonic atoms transitions yield.

Centering prayer in the treatment of bipolar disorder

Bipolar Disorder (BD), formerly manic-depressive illness or manic depression, is a lifelong mood disorder and mental health condition that causes intense shifts in mood, energy levels, thinking patterns, and behavior. These shifts can last for hours, days, weeks, or months, interrupting the ability to carry out daily tasks. The condition is manageable with medications, talk therapy, lifestyle changes, and other treatments, but the therapy results are unreliable in many patients. Most faith traditions have two forms of prayer: discursive and contemplative. Most believers practice discursive prayer. Medical research has shown the statistical healing effects of discursive prayer, but there is considerably less research on contemplative prayer. Hesse reports a method of teaching CP by asking a volunteer to help demonstrate the analogy between human and Divine relationships in the following quoted phases., Therefore, we hypothesize that CP might produce a significant depression improvement in BP patients. Two neurologists double-blind diagnosed five patients complaining of BD and five normal subjects. All cases expressed their belief in God, so CP is prayer, not non-theistic meditation. Patients will be free of medication and selected during depressive episodes. Among the trait markers are frontal alpha asymmetry,55,56, and changes in frontal qEEG cordance. A very stable QEEG pattern, consisting of frontal alpha asymmetry, was observed in all five patients. Hence, this pattern was used to compare QEEG before and after CP. Our main result showed that the focal left frontal Alpha increment disappeared after CP. Conclusion: CP is a promising tool for treating depression, organizing the function interplay among brain networks that subserve Cognition-emotion interactions in the prefrontal cortex.

Enhanced visible-light photocatalytic activity of Fe3O4@MoS2@Au nanocomposites for methylene blue degradation through Plasmon-Induced charge transfer

In this study, we synthesized Fe3O4@MoS2@Au nanoparticles as a photocatalyst for the degradation of methylene blue (MB). The presence of gold nanoparticles induced Localized Surface Plasmon Resonance (LSPR), extending the absorption range into the visible light spectrum. Under green light exposure (540 nm, 8 W), the Fe3O4@MoS2@Au photocatalyst exhibited remarkable performance, achieving a degradation efficiency of 98.95%, outperforming Fe3O4@MoS2, which reached 72.46%. The pseudo-first-order reaction rate constant for Fe3O4@MoS2@Au was 3.8 × 10−3 min−1, surpassing Fe3O4@MoS2 by 2.7 times. Additionally, Fe3O4@MoS2@Au demonstrated superior degradation efficiency under natural light, reaching 78% after 3 h compared to 70.2% for Fe3O4@MoS2. To elucidate the degradation mechanism, density functional theory (DFT) based computational simulations were employed to analyze the electron charge density at each step of the degradation process. The density of state simulation revealed a shift in electron energy levels towards higher energies in Fe3O4@MoS2@Au compared to Fe3O4@MoS2, thereby promoting electron transfer and enhancing the efficiency of photodegradation.