The Lone Pair Electrons in Post-Transition Metal and Their Contribution to Optical Response

The stereochemically active lone pairs around post-transition metal atoms play an important role in determining distorted lattice structure and optical response.The lone pair electrons are characterized by crystal orbitals,electron localization function(ELF)and partial density of states(PDOS).Birefringence is evaluated by means of a Born effective charge approach based on modern polarization theory.The origin of the different responses of birefringence and second-harmonic generation(SHG)is explored,as well as the effect of spin-orbit coupling(SOC)on the band structure and optical properties is explored.The study of this paper can help to deeply understand the lone pairs and their contribution to optical property.

Surprising New Bohr Models for H2and H2+

Niels Bohr constructed the first version of quantum mechanics. It has been called “old quantum mechanics” with a connotation of being obsolete. It is logically consistent, however, and deserves the name of simple quantum mechanics (SQM). It differs only from the semiclassical approximation by assuming that the average position and average velocity of an electron can be sharply defined on closed orbits. This assumption does not contradict Heisenberg’s uncertainty relations, since the quantization rule means that the electron can be anywhere on this orbit when it allows for stationary waves. This approach was remarkably efficient for one electron in hydrogen atoms and even for the electron pair in hydrogen molecules. However, dissociation of H2 and determination of the orbit of the single electron in H2+led to problems that remained unsolved for more than 100 years. Their solution, presented here, yields more physical insight and reveals, for instance, that mutual polarization of two hydrogen atoms can yield a metastable state.

Enhancement of electron–positron pairs in combined potential wells with linear chirp frequency

Effect of linear chirp frequency on the process of electron–positron pairs production from vacuum is investigated by the computational quantum field theory.With appropriate chirp parameters,the number of electrons created under combined potential wells can be increased by two or three times.In the low frequency region,frequency modulation excites interference effect and multiphoton processes,which promotes the generation of electron–positron pairs.In the high frequency region,high frequency suppression inhibits the generation of electron–positron pairs.In addition,for a single potential well,the number of created electron–positron pairs can be enhanced by several orders of magnitude in the low frequency region.

Synthesis,characterization and application of BiVO_4 photoanode for photoelectrochemical oxidation of chlorate

A high‐quality polycrystalline bismuth vanadate(BiVO4)film was prepared on a fluorine‐doped tinoxide substrate via a facile two‐step strategy involving electrodeposition and annealing processes.The morphology and structural characterization of the resulting film were investigated by differentmethods including scanning electron microscopy,transmission electron microscopy,X‐ray diffraction(XRD),and Fourier transform infrared,ultraviolet‐visible(UV‐vis)absorption,and Ramanspectroscopies.XRD patterns as well as optical measurements revealed that BiVO4film crystallizedwith a pure monoclinic scheelite structure.The prepared BiVO4film was used for heterogeneousoxidation of chlorate ions in aqueous solution via electrochemical(EC),photochemical(PC),andphotoelectrochemical(PEC)processes.The decrease in concentration of chlorate was monitoredusing UV‐vis absorption spectroscopy.The results revealed that BiVO4could effectively performchlorate oxidation under light irradiation through a PEC method.The kinetics of chlorate oxidationwas consistent with a first‐order reaction,and the rate constant for the PEC process was found to bemuch higher than those of EC and PC.Furthermore,a possible photocatalytic oxidation mechanismfor chlorate mainly based on the formation of perchlorate ions is proposed.

Delocalizedπ_(3)^(6) Bond in OX_(2) (X=Halogen) Molecules

OX_(2)(X=halogen)molecules was studied theoretically.Calculation results show that delocalizedπ_(3)^(6) bonds exist in their electronic structures and O atoms adopt the sp^(2) type of hybridization,which violates the prediction of the valence shell electron pair repulsion theory of sp^(3) type.Delocalization stabilization energy is proposed to measure the contribution of delocalizedπ_(3)^(6) bond to energy decrease and proves to bring extra-stability to the molecule.These phenomena can be summarized as a kind of coordinating effect.

Appearance of Spatial-Temporal Noise in Super-conducting Junction and Its Effect on Transport of Electron Pairs

Transport of electron pairs in super-conducting junction with spatial-temporal noise is investigated. We show that the spatial-temporal noise can produce the current of the electron pairs, which stems from a symmetry breaking of the system induced by the correlation of the spatial-temporal noise with the phase difference. It is found that there is a positive current for the electron pairs, exhibiting a peak with increasing the values of some parameters of the noises. The results provide a theoretical foundation for the further investigation of the super-conducting junction.

Transport of Electron Pairs in a Superconducting Junction Device： Underdamped Case

Transport of electron pairs in a superconducting junction device in the underdamped case is investigated. It is shown that the capacitance of the junctions can slow the movement of the electron pairs and reduce the net voltage. It is also shown that, for the underdamped case and the overdamped case, the movement of the electron pairs in this superconducting junctions device has some similar features. By controlling the correlation between the additive and multiplicative noise, the flux can be reversed. In addition, if the additive noise strength （or the temperature T） is large enough, a reversal can also be induced.

Giant-Resonance for a Four-Dimensionally Coupled System with Dichotomous Noise

In this paper, we investigate a four-dimensionally coupled system driven by dichotomous noise. A new kind of stochastic resonance is found, for which the response of the system to the input signal can be hugely intensified.

Net Voltage and Phenomenon of Resonance Induced by Chaotic Signal for a Superconducting Junctions Device

The effects of a quenched chaotic signal on the over-damped motion of the electron pairs of a superconducting junctions device are studied. It is shown that the chaotic signal can induce the net voltage and the phenomenon of resonance.

Changing Rules of Bonding Electron Pair Correlation Energies of CH_3X (X=F,OH,NH_2) Systems

The pair correlation energy of bonding electrons is used and analyzed in the cal- culation of CH and CY (Y = F, O, N) bonding electron pairs in CH3X (X = F, OH, NH2) isoelec- tronic systems based on intra- and interpair correlation energy results at both MP2-OPT2/6- 311++G(d) and MP2-OPT2/cc-pVtz levels with MELD program. Comparison of two set results shows that cc-pVtz and 6-311++G(d) give more correlation energy of valence electrons and innermost core electron pairs, respectively in these systems, resulting that the total correlation energy with cc-pVtz basis of each system is larger than that with 6-311++G(d). Investigations of pair correlation energy show that with the decrease of electronegativity of X atom and the increase of H atoms in these CH3X (X = F, OH, NH2) systems, the pair correlation energy of 1sC2 of the C atoms is transferable, and the correlation energy of CH bonding electron pair with little changes is of approximate transferability, while those of CY (CF, CO, CN) bonding electron pair decrease in a large extent from CH3F through CH3OH to CH3NH2 molecules. It is suggested that the study of pair correlation energy of bonding electrons will further deepen the understanding of electron corre- lation effect from traditional chemical bonding concept.

Nonequilibrium reservoir engineering of a biased coherent conductor for hybrid energy transport in nanojunctions

We show that a current-carrying coherent electron conductor can be treated as an effective bosonic energy reservoir involving different types of electron–hole pair excitations.For weak electron–boson coupling,hybrid energy transport between nonequilibrium electrons and bosons can be described by a Landauer-like formula.This allows for unified account of a variety of heat transport problems in hybrid electron–boson systems.As applications,we study the non-reciprocal heat transport between electrons and bosons,thermoelectric current from a cold-spot,and electronic cooling of the bosons.Our unified framework provides an intuitive way of understanding hybrid energy transport between electrons and bosons in their weak coupling limit.It opens the way of nonequilibrium reservoir engineering for efficient energy control between different quasi-particles at the nanoscale.

INTRA-ION PAIR ELECTRON TRANSFER OF PHOTOEXCITED METHYLENE BLUE BORATE

The photochemical reaction of methylene blue (n-butyltriphenyl) borate, MBRBPh3 was examined. The ultrafast quenching rate and large negative value of Delta G indicated that the intra-ion pair ET plays an important role in photoreaction of MBRBPh3. The sequent boron- carbon bond cleavage of butyltriphenylboranyl radical intermediate was found by GC-MS and photo-CIDNP studies.

Structural Probing on the Sn-C(C5 ring)Bond of the Sn(Ⅱ)Metallocenes in Both the Solid State and the Temperature-dependent Solution Relaxation State

Various bond modes of the M-C（C5 ring） exist in metallocene compounds of group 14 heavier elements,mostly due to an intricate interaction between the lone electron pairs at the M center and the 6 p-electrons of the C5 ring.The tin（Ⅱ） metallocene complexes LSn R（L = HC[CMe（N-2,6-iPr2C6H3）]2,R = cyclopentadienyl,C5H5（1）; indenyl,C9H7（2）; fluorenyl,C（13）H9（3）） stabilized by the β-diketiminato ligand were prepared and utilized in the study on their solid and solution state structures.X-ray single-crystal diffraction data revealed an η~1-mode of the Sn-C（C5 ring） bond in each 1~3.However,the room temperature ~1H NMR spectral studies disclosed such a fluxional bonding mode in solution.The 119 Sn NMR studies suggested a quadruple coordination nature of the Sn center in 1 while the triple coordination manner was for the Sn atom in both 2 and 3.Then the variable-temperature（25~–75 ℃） ~1H NMR spectral studies for each 1~3 were performed,which detected the relaxation state structures of 1~3 at lower temperature.All of these results indicate a stereochemical activity of the lone electron pairs at the tin（Ⅱ） atom that definitely has an electronic interaction with the 6 p-electrons of the C5 ring.The observed Sn-C（C5 ring） bond modes appear influenced by either the metallocene size or the compound state existed.

Coulomb Interaction between Electrons and a New Concept of Atom

It is shown that the approximation of a strong Coulomb interaction between electrons results in a new model of the atom with a spatial quantization of electrons accompanied by their quantization in energy. This model implies that electrons rotate in circular orbits centered outside the atomic nucleus and only orbit axes pass through it. The Coulomb interaction between electrons leads to a spherically symmetric distribution of their orbits on the surfaces of equipotential spheres of a spherically symmetric electrostatic field of the nucleus. The distribution is similar to “inscribing” electron orbits into faces of regular nucleus-centered polyhedra so each polyhedron corresponds to a certain electron state (s, p, d, f), and a certain set of polyhedra corresponds to a certain period of the Mendeleev Table. It is shown that a spherically symmetric distribution of electron orbits gives rise to the formation of electron pairs in which electron orbits with a common axis are located symmetrically with respect to the nucleus and the orbital magnetic moments of the electrons are oppositely directed. The physical meaning of the electron spin concept becomes clear. The spin turns out to be related to the orbital magnetic moment of an electron and reflects the fact that two electrons of a pair rotate in opposite directions relative to their common axis. So the spin is one of characteristics of the electron state in the atom associated with electron rotation in the orbit centered outside the nucleus. The atomic model gives an insight into the periodicity of changes in the atomic properties with increasing nuclear charge and the reasons for an electron double energy quantization associated with different states and periods. The model shows that the atomic structure and properties can be explained by using concepts of classical mechanics and classical electrodynamics which regard the electron as a particle.

In-situ transformed Mott-Schottky heterointerface in silver/manganese oxide nanorods boosting oxygen reduction,oxygen evolution,and hydrogen evolution reactions

The development of non-platinum group metal(non-PGM)and efficient multifunctional electrocatalysts for oxygen reduction reaction(ORR),oxygen evolution reaction(OER),and hydrogen evolution reaction(HER)with high activity and stability remains a great challenge.Herein,by in-situ transforming silver manganese composite oxide heterointerface into boosted Mott-Schottky heterointerface through a facile carbon reduction strategy,a nanorod-like silver/manganese oxide with superior multifunctional catalytic activities for ORR,OER and HER and stability was obtained.The nanorod-like silver/manganese oxide with Mott-Schottky heterointerface(designated as Ag/Mn_(3)O_(4))exhibits an ORR half-wave potential of 0.831 V(vs.RHE)in 0.1 M KOH,an OER overpotential of 338 mV and a HER overpotential of 177 mV at the current density of 10 mA·cm^(-2)in 1 M KOH,contributing to its noble-metal benchmarks comparable performance in aqueous aluminum-air(Al-air)battery and laboratorial overall water splitting electrolytic cell.Moreover,in-situ electrochemical Raman and synchrotron radiation spectroscopic measurements were conducted to further illustrate the catalytic mechanism of Ag/Mn_(3)O_(4)Mott-Schottky heterointerface towards various electrocatalytic reactions.At the heterointerface,the Ag phase serves as the electron donor and the active phase for ORR and HER,while the Mn_(3)O_(4)phase serves as the electron acceptor and the active phase for OER,respectively.This work deepens the understanding of the Mott-Schottky effect on electrocatalysis and fills in the gap in fundamental physical principles that are behind measured electrocatalytic activity,which offers substantial implications for the rational design of cost-effective multifunctional electrocatalysts with Mott-Schottky effect.

Bioinspired Noncyclic Transfer Pathway Electron Donors for Unprecedented Hydrogen Production

Electron donors are widely exploited in visible-light photocatalytic hydrogen production.As a typical electron donor pair and often the first choice for hydrogen production,the sodium sulfide-sodium sulfite pair has been extensively used.However,the resultant thiosulfate ions consume the photogenerated electrons to form an undesirable pseudocyclic electron transfer pathway during the photocatalytic process,strongly limiting the solar energy conversion efficiency.Here,we report novel and bioinspired electron donor pairs offering a noncyclic electron transfer pathway that provides more electrons without the consumption of the photogenerated electrons.Compared to the state-of-the-art electron donor pair Na_(2)S-Na_(2)SO_(3),these novel Na_(2)S-NaH_(2)PO_(2)and Na_(2)S-NaNO_(2)electron donor pairs enable an unprecedented enhancement of up to 370%and 140%for average photocatalytic H_(2)production over commercial CdS nanoparticles,and they are versatile for a large series of photocatalysts for visible-light water splitting.The discovery of these novel electron donor pairs can lead to a revolution in photocatalysis and is of great significance for industrial visible-light-driven H_(2)production.

Unusually high electron density in an intermolecular non-bonding region:Role of metal substrate

It has been demonstrated that intermolecular interaction,crucial in a plenty of chemical and physical processes,may vary in the presence of metal surface.However,such modification is yet to be quantitatively revealed.Here,we present a systematical density functional theory study on adsorbed bis（para-pyridyl）acetylene（BPPA） tetramer on Au（111） surface.We observed unusually high electron density between two head-to-head N atoms,an intermolecular ＂non-bonded＂ region,in adsorbed BPPA tetramer.This exceptional electron density originates from the wavefunction hybridization of the two compressed N lone-electron-pair states of two BPPA,as squeezed by a newly revealed N-Au-N threecenter bonding.This bond,together with the minor contribution from N...H-C intermolecular hydrogen bonding,shortens the N-N distance from over 4 A to 3.30 A and offers an attractive lateral interacting energy of 0.60 eV,effectively to a surface-confined in-plane pressure.The overlapped non-bonding vvavefunction hybridization arising from the effective pressure induced by the N-Au-N three-center bonding,as not been fully recognized in earlier studies,was manifested in non-contact Atomic Force Microscopy.

Modulating Room Temperature Phosphorescence by Oxidation of Thianthrene to Achieve Pure Organic Single-Molecule White-Light Emission

In order to develop pure organic single-molecule white-light emitters(SMWLE),the oxidation of thianthrene(TA)was performed on sulfur atoms at different degrees to tune room temperature phosphorescence(RTP)emission.With increasing degrees of oxidation from 1OTA,2OTA,3OTA,to 4OTA,monomeric and aggregative RTP emission was gradually suppressed,due to the gradual disappearance of lone pair electrons on sulfur atoms.Among these compounds,monomers and aggregates of 1OTA demonstrated a better intensity match between fluorescence and RTP.

Electron vortices in photoionization by a pair of elliptically polarized attosecond pulses

The photoionization by two elliptically polarized, time delayed attosecond pulses is investigated to display a momentum distribution having the helical vortex or ring structuresi The results are obtained by the strong field approximation method and analyzed by the pulse decomposition. The ellipticities and time delay of the two attosecond pulses are found to determine the rotational symmetry and the number of vortex arms. For observing these vortex patterns, the energy bandwidth and temnoral duration of the attosecond pulses are ideal.

Can electrons attract one another?

Electrons are believed to avoid one another in space(correlation) due to the Coulomb repulsion and/or the Pauli exclusion principle.It is shown, using examples of two-electron systems, that indeed the mean electron-electron distance increases in case of the ground electronic state as compared to the independent electron model. It is demonstrated however that there exist excited states, often of low energy, in which the electrons, while having a lot of free physical space(with nuclei being absent), choose to be close to each other in their motion("anticorrelation"), as if they mutually attracted one another. The source of this effect, quantummechanical in nature, is the orthogonality of the eigenfunctions, that forces the electronic wave functions to differ widely, even at the price of short electron-electron distances. There are also excited states with a mixed behaviour, with complex and often intriguing correlation-anticorrelation patterns.