Electron Transition of Eu^(2+) and Energy Transfer in Crystals BaFX:Eu^(2+),Eu^(3+) (X=Cl,Br)

In crystals BaFX:Eu^(2+)(X=Cl,Br).there exists configuration interaction between 4f^65d and 4f^65s ex- cited state of Eu^(2+)ion.and it results in the change of relative intensities of d-f and f-f transition.The transition ~S_-_2→4f^65d-6s is observed.The variation of F/X atomic ratio between 110/90 and 90/110 does not obvi- ously influence the luminescence of BaFX:Eu^(2-).There is energy transfer between Eu^(2+)(f-f)and Eu^(3+)which coexists in the matrices.

Effect and Mechanism Analysis of Solvent on the Electron Transition of Fluoroquinolones Based on Quantum Chemical Calculation

Ciprofloxacin（CIP）, moxifoxacin（MOX） and enrofloxacin（ENR） were selected as typical fluoroquinolones（FQs） to analyze the excitation-enhancing effect and mechanism of solvents on FQs＇ electron transition based on quantum chemical calculations. The UV spectra of three FQs in gas and five different solvents（water, cyclohexane, dimethylsulfoxide, methanol, acetone） were calculated using Gaussian 09 software. The transition mechanisms of FQs＇ main electron transitions were analyzed by natural bond orbital（NBO） theory, and the solvent effect on each electron transition was assessed qualitatively and quantitatively by sensitivity analysis and an established index system. The excitation enhancing mechanism of solvent on electron transitions of FQs was analyzed from the view of photo-induced reactions between solvent and FQs molecules. The results show that there are two main transitions located in the spectrum ranges of 300~380 and 240~300 nm for each FQ in any medium, which are assigned as n →π＊ and π→π＊ electron transitions, respectively. By comparison, the n →π＊ transition is more sensitive to solvent because of the energy transfer between solvent molecules and FQs, but the solvent effect on the π→π＊ transition is stronger than on the n →π＊ transition. The sequence of affected extent of solvent effect on electron transition was CIP 〉 MOX 〉 ENR, and the sequence of solvent effect was water 〉 DMSO 〉 methanol 〉 acetone 〉 cyclohexane（stronger solvent effect with increasing the dielectric constant of solvent）. From the view of photo-induced reactions, the reaction between FQs＊T1 and solvent＊T1 has the decisive regulatory effect on the n →π＊ transition of FQs in solvent, and the reaction between FQsS0 and solvent＊TI has an enhancing effect on the π→π＊ transition.

Emission Intensity in the Hydrogen Atom Calculated from a Non-Probabilistic Approach to the Electron Transitions

Quantum aspects of the Joule-Lenz law for the transmission of energy allowed us to calculate the time rate of energy transitions between the quantum states of the hydrogen atom in a fully non-probabilistic way. The calculation has been extended to all transitions between p and s states having main quantum numbers not exceeding 6. An evident similarity between the intensity pattern obtained from the Joule-Lenz law and the corresponding quantum-mechanical transition pro-babilities has been shown.

Time Intervals of the Electron Transitions between the Energy States in the Hydrogen Atom Calculated in a Non-Probabilistic Way

Definitions of the mechanical parameters entering the Bohr model of the hydrogen atom allowed us to calculate the time intervals connected with the electron transitions between the nearest-neighbouring energy levels in the atom. This is done in a strictly non-probabilistic way. The time results are compared with those derived earlier on the basis of the classical Joule-Lenz law for the energy emission adapted to the case of the electron transfer in the quantum systems. A similar formalism has been next applied to the harmonic oscillator and a particle moving in the one-dimensional potential box.

ABSORPTION SPECTRA OF 4f ELECTRON TRANSITIONS IN THE SYSTEM OF NEODYMIUMSEMIXYLENOL ORANGE-CETYLPYRIDINIUM CHLORIDE

In this paper the absorption spectra of Nd-SXO-CPC complex by 4f electron transitions have been studied by zero-order and fourth-order derivative spectrophotome-try. The molar absorptivity is 2.6×10~3 1.mol^(-1).cm^(-1) at 585 nm, the fourth-order derivative molar absorptivity is 1.4×10~4 1.mol^(-1).cm^(-1) at 584.5(-) and 587(+) nm. They are 300 times and 1600 times greater than those of the chloride, respectively.

ABSORPTION SPECTRA OF 4f ELECTRON TRANSITIONS OF NEODYMIUM COMPLEX WITH 8-HYDROXYQUINOLINE AND OCTYLPHENOL POLY(ETHYLENEGLYCOL)ETHER

In this paper the absorption spectra of 4f electron transitions of the neodymlum complex with 8-hydroxyquinoline and octylphenol poly(ethyleneglycol)ether have been studied. The marked intensification of the band at low octylphenol poly(ethyleneglycol)ether concentration is found normally at 575 nm, and its resolution into three sharp bands centering at 572, 580 and 584 nm. The absorbances of the absorption maxima are 3.5 (at 572 nm), 7.2 (at 580 nm) and 10.2 (at 584 nm) times greater than that of the chloride.

Quanta of the Phase-Space Areas Given by Intervals of Energy and Time Associated with Electron Transitions

The paper examines the energy of electron transitions in an emission process and the time intervals necessary for that process. For simple quantum systems, the both parameters—that of energy and time—depend on the difference Δn of the quantum numbers n labelling the beginning and end state of emission. It is shown that the phase-space areas formed by products of energy and time involved in the emission can be represented as a quadratic function of Δn multiplied by the Planck constant h.

Relativistic Reduction of the Electron-Nucleus Force in Bohr’s Hydrogen Atom and the Time of Electron Transition between the Neighbouring Quantum Energy Levels

The aim of the paper is to get an insight into the time interval of electron emission done between two neighbouring energy levels of the hydrogen atom. To this purpose, in the first step, the formulae of the special relativity are applied to demonstrate the conditions which can annihilate the electrostatic force acting between the nucleus and electron in the atom. This result is obtained when a suitable electron speed entering the Lorentz transformation is combined with the strength of the magnetic field acting normally to the electron orbit in the atom. In the next step, the Maxwell equation characterizing the electromotive force is applied to calculate the time interval connected with the change of the magnetic field necessary to produce the force. It is shown that the time interval obtained from the Maxwell equation, multiplied by the energy change of two neighbouring energy levels considered in the atom, does satisfy the Joule-Lenz formula associated with the quantum electron energy emission rate between the levels.

Joule-Lenz Energy of Quantum Electron Transitions Compared with the Electromagnetic Emission of Energy

In the first step, the Joule-Lenz dissipation energy specified for the electron transitions between two neighbouring quantum levels in the hydrogen atom has been compared with the electromagnetic energy of emission from a single level. Both the electric and magnetic vectors entering the Pointing vector of the electromagnetic field are referred to the one-electron motion performed along an orbit in the atom. In the next step, a similar comparison of emission rates is performed for the harmonic oscillator. Formally a full agreement of the Joule-Lenz and electromagnetic expressions for the energy emission rates has been attained.

Electron transition manipulation under graphene-mediated plasmonic engineering nanostructure

Monolayer graphene has attracted enormous attention owing to its unique electronic and optical properties.However,achieving an effective approach without applying electrical bias for manipulating the charge transfer based on graphene is elusive to date.Herein,we realized the manipulation of excitons’transition from emitter to the graphene surface with plasmonic engineering nanostructures and firstly obtained large enhancements for photon emission on the graphene surface.The localized plasmons generated from the plasmonic nanostructures of shell-isolated nanoparticle coupling to ultra-flat Au substrate would dictate a consistent junction geometry while enhancing the optical field and dominating the electron transition pathways,which may cause obvious perturbations for molecular radiation behaviors.Additionally,the three-dimensional finite-difference time-domain and time-dependent density functional theory were also carried out to simulate the distributions of electromagnetic field and energy levels of hybrid nanostructure respectively and the results agreed well with the experimental data.Therefore,this work paves a novel approach for tunning graphene charge/energy transfer processes,which may hold great potential for applications in photonic devices based on graphene.

Unveiling the pressure-driven metal–semiconductor–metal transition in the doped TiS_(2)

Conventional theories expect that materials under pressure exhibit expanded valence and conduction bands,leading to increased electrical conductivity.Here,we report the electrical properties of the doped 1T-TiS_(2) under high pressure by electrical resistance investigations,synchrotron x-ray diffraction,Raman scattering and theoretical calculations.Up to 70 GPa,an unusual metal-semiconductor-metal transition occurs.Our first-principles calculations suggest that the observed anti-Wilson transition from metal to semiconductor at 17 GPa is due to the electron localization induced by the intercalated Ti atoms.This electron localization is attributed to the strengthened coupling between the doped Ti atoms and S atoms,and the Anderson localization arising from the disordered intercalation.At pressures exceeding 30.5 GPa,the doped TiS_(2) undergoes a re-metallization transition initiated by a crystal structure phase transition.We assign the most probable space group as P2_(1)2_(1)2_(1).Our findings suggest that materials probably will eventually undergo the Wilson transition when subjected to sufficient pressure.

Cascaded electron transition in CuWO4/CdS/CDs heterostructure accelerating charge separation towards enhanced photocatalytic activity

CuWO4,as an n-type oxide semiconductor with a bandgap of 2.2 eV,has stimulated enormous interest as a potential broad-spectrum-active photocatalyst for environmental pollution remediations.However,rapid charge recombination greatly hinders its practical applications.Herein,we present a cascaded electron transition pathway in a ternary heterostructure consisting of CdS quantum dots,carbon dots(CDs)and CuWO4 hollow spheres,which proves to greatly facilitate the photogenerated electron-hole separation,and eventually boosts the degradation efficiency of phenol and congo red by 100%and 46%compared to bare CuWO4.The enhanced performance of the CuWO4/CdS/CDs heterostructure mainly originates from the unidirectional electron migration from CdS to CuWO4 and then to the organics through CDs.This work elucidates the electron transfer kinetics in multi-phase system and provides a new design paradigm for optimizing the properties of CuWO4 based photocatalysts.

Giant Volume Magnetostriction Caused by Itinerant Electron Metamagnetic Transition and Pronounced Invar Effects in La(Fe_xSi_(1-x))_(13) Compounds

A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.

A Precise Description of the Electronic Structures and Spin-Allowed Transition Properties of PF and Its Cation:All-Electron Configuration-Interaction Investigations Including Relativistic Effect

The electronic structures of PF and PF＋ are calculated with the high-level configuration interaction method. To improve the precision of calculations, the spin-orbit coupling effect, the scalar relativistic effect, and the Davidson correction（q-Q） are also considered. The spectroscopic parameters of bound states are derived by the electronic structures of PF and PF＋, which are in good accordance with the measurements. The transition dipole moments of spin-allowed transitions are evaluated, and the radiative lifetimes of several A S states of PF and PF＋ are obtained.

Scheme for the excitation of thorium-229 nuclei based on electronic bridge excitation

Thorium-229 possesses the lowest first nuclear excited state,with an energy of approximately 8 eV.The extremely narrow linewidth of the first nuclear excited state,with an uncertainty of 53 THz,prevents direct laser excitation and realization of the nuclear clock.We present a proposal using the Coulomb crystal of a linear chain formed by229Th^(3+)ions,where the nuclei of229Th3+ions in the ion trap are excited by the electronic bridge(EB)process.The 7 P1∕2state of the thorium-229 nuclear ground state is chosen for EB excitation.Using the two-level optical Bloch equation under experimental conditions,we calculate that 2 out of 36 prepared thorium ions in the Coulomb crystal can be excited to the first nuclear excited state,and it takes approximately 2 h to scan over an uncertainty of 0.22 eV.Taking advantage of the transition enhancement of EB and the long stability of the Coulomb crystal,the energy uncertainty of the first excited state can be limited to the order of 1 GHz.

Microwave awakening the n-π^(*) electronic transition in highly crystalline polymeric carbon nitride nanosheets for photocatalytic hydrogen generation

The n-π^(*) electronic transition in polymeric carbon nitride(PCN)can remarkably harvest visible light,which thus potentially promotes the photocatalytic hydrogen H2 generation.However,awaking the n-π^(*) lectronic transition has proven to be a grand challenge.Herein,we reported on the awakening of n-π^(*) electronic transition by microwave thermolysis of urea pellet,which yielded the PCN with absorption edge of 600 nm,near 140 nm red-shift from 460 nm of pristine PCN.The n-π^(*) electronic transition endows PCN with an increased photocata lytic H_(2) generation,with a highest H_(2) rate of 61.7μmol h^(-1) under visible light exposure,which is near 6 times higher than that by using the PCN from the thermolysis of urea pellets in an electric furnace(10.6μmol h^(-1)).Furthermore,the n-π^(*) transition in PCN leads to the longest wavelength of 535 nm that can initiate H2 generation,remarkably longer than the absorption edge of pristine PCN(460 nm).This work manifests the advantages of microwave sintering route to awaken the n-π^(*) electronic transition in PCN for an increased photocata lytic performance.

THE LINEAR CORRELATIONS BETWEEN ELECTRONIC TRANSITION ENERGY AND HAMMETT CONSTANTS FOR THE SUBSTITUTED PORPHYRIN-LIKE MACROCYCLE

The properties of absorption spectra are presented and the linear correlations of Hammett constants with the 0-0 transition energy(E_(o,o))of S_←S_o, and the ratios of oscillator strength(f/f)are used to probe the interactions betwee π-electron of aromatic maerocycles or metal ion of complexes with the sub- stituents on β-position of benzene ring for porphyrin-like maerocyclic compounds.

Electronic Structure Reconstruction across the Antiferromagnetic Transition in TaFe1.23Te3 Spin Ladder

Employing the angle-resolved photoemission spectroscopy, we study the electronic structure of TaFe1.23Te3, a two-leg spin ladder compound with a novel antiferromagnetic ground state. Quasi-two-dimensional （2D） Fermi surface is observed, with sizable inter-ladder hopping. Moreover, instead of observing an energy gap at the Fermi surface in the antiferromagnetic state, we observe the shifts of various bands. Combining these observations with density-functional-theory calculations, we propose that the large scale reconstruction of the electronic structure, caused by the interactions between the coexisting itinerant electrons and local moments, is most likely the driving force of the magnetic transition. Thus TaFe1.23Te3 serves as a simpler platform that contains similar ingredients to the parent compounds of iron-based superconductors.

In situ electronic structural study of VO_2 thin film across the metal–insulator transition

The in situ valence band photoemission spectrum （PES） and X-ray absorption spectrum （XAS） at V LⅡ-LⅢ edges of the VO2 thin film, which is prepared by pulsed laser deposition, are measured across the metal–insulator transition （MIT） temperature （TMIT=67 ℃）. The spectra show evidence for changes in the electronic structure depending on temperature. Across the TMIT, pure V 3d characteristic d‖ and O 2p-V 3d hybridization characteristic πpd, σpd bands vary in binding energy position and density of state distributions. The XAS reveals a temperature-dependent reversible energy shift at the V LⅢ-edge. The PES and XAS results imply a synergetic energy position shift of occupied valence bands and unoccupied conduction band states across the phase transition. A joint inspection of the PES and XAS results shows that the MIT is not a one-step process, instead it is a process in which a semiconductor phase appears as an intermediate state. The final metallic phase from insulating state is reached through insulator–semiconductor, semiconductor–metal processes, and vice versa. The conventional MIT at around the TMIT=67 ℃ is actually a semiconductor–insulator transformation point.

Structural Phase Transition and a Mutation of Electron Mobility in Zn_xCd_(1-x)O Alloys

We investigate the electronic structures and phase stability of ZnO, CdO and the related alloys in rocksalt（B1）and wurzite（B4） crystal, using the first-principle density functional theory within the hybrid functional approximation. By varying the concentration of Zn components from 0% to 100%, we find that the Zn_xCd（1-x）O alloy undergoes a phase transition from octahedron to tetrahedron at x = 0.32, in agreement with the recent experimental findings. The phase transition leads to a mutation of the electron mobility originated from the changes of the effective mass. Our results qualify Zn O/Cd O alloy as an attractive candidate for photo-electrochemical and solar cell power applications.