Contribution Of Dipole Moment Research Articles

Polymorphism of Niobium Phosphate Bronze Na4Nb8P4O32 Deduced by the Packings of Structural Units: A Centrosymmetric Phase.

Herein, a new centrosymmetric phase Na4Nb8P4O32 (referred to as CS-Na4Nb8P4O32) was obtained by a molten salt method, which is a polymorph of niobium phosphate bronze Na4Nb8P4O32. CS-Na4Nb8P4O32 displays high structural similarity to the noncentrosymmetric Na4Nb8P4O32 phase (referred to as NCS-Na4Nb8P4O32): Distorted NbO6 octahedra are corner-coordinated to form ReO3-type layers, which are further joined together by isolated PO4 tetrahedra. However, two polymorphous phases adopt different packings of structural units, resulting in distinct symmetries. NbO3 layers and PO4 tetrahedra are reversely arranged along the crystallographic a direction in CS-Na4Nb8P4O32, thereby producing a centrosymmetric structure. The reverse packing cancels out all contributions of dipole moments originating from the distorted NbO6 octahedra; NCS-Na4Nb8P4O32 exhibits the C2-rotation distribution of NbO3 layers and PO4 tetrahedra, thus generating a noncentrosymmetric and polar structure. The C2-rotation packing of structural units brings a constructive addition of the dipole moments, further obtaining large calculated independent second harmonic generation susceptibilities. The study of structural evolution deduced by the packings of structural units in polymorphous Na4Nb8P4O32 might provide valuable insights into polymorphism and structural regulation.

All-Optical Valley Polarization Switch via Controlling Spin-Triplet and Spin-Singlet Interlayer Exciton Emission in WS2/WSe2 Heterostructure.

Although selective singlet and triplet interlayer exciton (IX) emission of transition metal dichalcogenides (TMD) heterostructures can be achieved by applying an electric or magnetic field, the device structure is complex and a low temperature is usually required. Here, we demonstrate a simple all-optical approach to selectively enhance the emission of singlet and triplet IX by selectively coupling singlet or triplet IX of a WS2/WSe2 heterostructure to a SiO2 microsphere cavity. Angle-resolved photoluminescene reveals that the transition dipole of triplet IX is almost along the out-of-plane direction, while singlet IX only has 69% out-of-plane dipole moment contribution. Since the out-of-plane dipole presents a higher Purcell factor within the cavity, we can simultaneously enhance the emission intensity of IX and control the emissive IX species at room temperature in an all-optical route. Importantly, we demonstrate an all-optical valley polarization switch with a record high on/off ratio of 35.

Role of neutrino form factors in the energy loss rates of the pair annihilation process

The stellar energy loss rates due to the production of neutrino pairs are calculated using the minimal extension of the Standard Model with the electromagnetic properties of the Dirac neutrinos, which takes the contributions of the neutrino charge radius, anapole moment, and dipole moments into account. We show that the contribution of the electron neutrino's dipole moment is small compared with that of the charge radius. The obtained results are also compared with the results obtained using the Standard Model.

Double electric dipole moment contribution model of the Verdet constant of paramagnetic magneto-optical materials

Besides considering the influence of the transition dipole moment, the impact of the external magnetic field and photoelectric field on the electron’s movement is also taken into account by using forced vibration to correct the electric dipole moment, and a unique double electric dipole moment contribution model of the Verdet constant of paramagnetic magneto-optic materials is deduced. Using terbium gallium garnet (TGG) crystal as an example, various microscopic effects and energy levels splitting inside the paramagnetic magneto-optic materials are analyzed in detail. Then, the Verdet constant of TGG crystal under different theoretical models is quantitatively solved. Compared with current theories, the results calculated using the double electric dipole moment contribution model are more consistent with the experimental data, indicating that the model has certain advantages.

Neutrino energy-loss rate in 331β model

We evaluate the stellar energy-loss rates [Formula: see text] due to the production of neutrino pair in 3-3-1 models. The energy loss rate [Formula: see text] is evaluated for different values of [Formula: see text] in which [Formula: see text] is a parameter used to define the charge operator in the 331 models. We show that the contribution of dipole moment to the energy loss rate is small compared to the contribution of new natural gauge boson [Formula: see text]. The correction [Formula: see text] compared with that of Standard Model is evaluated and do not exceed 14% and is highest with [Formula: see text]. Of all the evaluated models, model with [Formula: see text] give a relative large [Formula: see text] correction for the mass of [Formula: see text][Formula: see text] GeV. This mass range is within the searching range for [Formula: see text] boson at LHC.

Estimation of the relative contributions to the electronic energy transfer rates based on Förster theory: The case of C-phycocyanin chromophores.

In the present study, we provide a reformulation of the theory originally proposed by Förster which allows for simple and convenient formulas useful to estimate the relative contributions of transition dipole moments of a donor and acceptor (chemical factors), their orientation factors (intermolecular structural factors), intermolecular center-to-center distances (intermolecular structural factors), spectral overlaps of absorption and emission spectra (photophysical factors), and refractive index (material factor) to the excitation energy transfer (EET) rate constant. To benchmark their validity, we focused on the EET occurring in C-phycocyanin (C-PC) chromophores. To this aim, we resorted to quantum chemistry calculations to get optimized molecular structures of the C-PC chromophores within the density functional theory (DFT) framework. The absorption and emission spectra, as well as transition dipole moments, were computed by using the time-dependent DFT (TDDFT). Our method was applied to several types of C-PCs showing that the EET rates are determined by an interplay of their specific physical, chemical, and geometrical features. These results show that our formulas can become a useful tool for a reliable estimation of the relative contributions of the factors regulating the EET transfer rate.

Atomic charge and atomic dipole modeling of gas-phase infrared intensities of fundamental bands for out-of-plane CH and CF bending vibrations

Out-of-plane CH group bending vibrational bands have long been known to be more intense than those for CF groups in similar molecular environments. This contrasts with expectations derived from charge models for which equilibrium atomic charge displacements are considered dominant contributions to dipole moment change on vibration. For this reason, the Charge, Charge Transfer, Dipolar Polarization (CCTDP) model based on the Quantum Theory for Atoms in Molecules (QTAIM) has been applied to the ethylene, tetrafluoroethylene and difluoro- and dichloroethylene molecules. Atomic charges and atomic dipoles from QTAIM and infrared intensities were calculated at the M06-2X/aug-cc-pVTZ level. The CH out-of-plane bending vibrations with relatively high intensities between 48.0 and 82.1 km/mol are characterized by small atomic charge and large polarization contributions having the same sign resulting in large net dipole moment contributions. Large charge and polarization dipole moment derivative contributions with opposite signs cancel each other producing very small intensities between 0.3 and 12.7 km/mol for the CF bends. Intensity variations can be successfully modeled by only their carbon atomic contributions with smaller contributions from the terminal atoms. Both CH and CF bending vibrations have large polarization contributions. Their charge contributions are usually small except for carbon atoms bonded to two fluorine atoms. The terminal atoms as well as the carbons have charge and polarization contributions of opposite sign. Comparison to benzene and hexafluorobenzene reveals that changes in these molecules’ electronic densities caused by the out-of-plane atomic displacements are characteristic for each bond. In conclusion, successful modeling of the ethylene intensities must include atomic dipole parameters.Models based only on charges are doomed to failure.

Bianisotropy for light trapping in all-dielectric metasurfaces

Magnetoelectric dipole coupling effects in all-dielectric metasurfaces composed of particles with bianisotropic electromagnetic response are investigated. This bianisotropic response is associated with the trapped mode excitation. Maintaining the trapped mode resonant conditions allows one to sufficiently increase the quality factor and reduce radiation losses in all-dielectric nanostructures (metasurfaces). An analytical model accounting for the contributions of both electric and magnetic dipole moments induced in particles by external electromagnetic fields is proposed. We show how bianisotropy can lead to the excitation of the trapped mode in metasurfaces. This mode corresponds to the electromagnetic coupling between the out-of-plane particle dipole moments, which do not radiate collectively from the metasurface plane resulting in the enhanced storage of electromagnetic energy. Our approach reveals a physical mechanism of the trapped mode excitation and demonstrates that the specially initiated bianisotropy of particles enables the energy flow between external electromagnetic waves and the trapped mode. Due to this bianisotropy, one can control the process of light-matter interaction and energy storage in all-dielectric metasurfaces via excitation of trapped modes.

Towards an algebraic method of solar cycle prediction

An algebraic method for the reconstruction and potentially prediction of the solar dipole moment value at sunspot minimum (known to be a good predictor of the amplitude of the next solar cycle) was suggested in the first paper in this series. The method sums up the ultimate dipole moment contributions of individual active regions in a solar cycle: for this, detailed and reliable input data would in principle be needed for thousands of active regions in a solar cycle. To reduce the need for detailed input data, here we propose a new active region descriptor called ARDoR (Active Region Degree of Rogueness). In a detailed statistical analysis of a large number of activity cycles simulated with the 2 × 2D dynamo model we demonstrate that ranking active regions by decreasing ARDoR, for a good reproduction of the solar dipole moment at the end of the cycle it is sufficient to consider the top N regions on this list explicitly, where N is a relatively low number, while for the other regions the ARDoR value may be set to zero. For example, with N = 5 the fraction of cycles where the dipole moment is reproduced with an error exceeding ±30% is only 12%, significantly reduced with respect to the case N = 0, i.e. ARDoR set to zero for all active regions, where this fraction is 26%. This indicates that stochastic effects on the intercycle variations of solar activity are dominated by the effect of a low number of large “rogue” active regions, rather than the combined effect of numerous small ARs. The method has a potential for future use in solar cycle prediction.

Towards an algebraic method of solar cycle prediction

We discuss the potential use of an algebraic method to compute the value of the solar axial dipole moment at solar minimum, widely considered to be the most reliable precursor of the activity level in the next solar cycle. The method consists of summing up the ultimate contributions of individual active regions to the solar axial dipole moment at the end of the cycle. A potential limitation of the approach is its dependence on the underlying surface flux transport (SFT) model details. We demonstrate by both analytical and numerical methods that the factor relating the initial and ultimate dipole moment contributions of an active region displays a Gaussian dependence on latitude with parameters that only depend on details of the SFT model through the parameter η/Δu where η is supergranular diffusivity and Δu is the divergence of the meridional flow on the equator. In a comparison with cycles simulated in the 2 × 2D dynamo model we further demonstrate that the inaccuracies associated with the algebraic method are minor and the method may be able to reproduce the dipole moment values in a large majority of cycles.

Exclusive Magnetic Excitation Enabled by Structured Light Illumination in a Nanoscale Mie Resonator.

Recent work has shown that optical magnetism, generally considered a challenging light-matter interaction, can be significant at the nanoscale. In particular, the dielectric nanostructures that support magnetic Mie resonances are low-loss and versatile optical magnetic elements that can effectively manipulate the magnetic field of light. However, the narrow magnetic resonance band of dielectric Mie resonators is often overshadowed by the electric response, which prohibits the use of such nanoresonators as efficient magnetic nanoantennas. Here, we design and fabricate a silicon (Si) truncated cone magnetic Mie resonator at visible frequencies and excite the magnetic mode exclusively by a tightly focused azimuthally polarized beam. We use photoinduced force microscopy to experimentally characterize the local electric near-field distribution in the immediate vicinity of the Si truncated cone at the nanoscale and then create an analytical model of such structure that exhibits a matching electric field distribution. We use this model to interpret the PiFM measurement that visualizes the electric near-field profile of the Si truncated cone with a superior signal-to-noise ratio and infer the magnetic response of the Si truncated cone at the beam singularity. Finally, we perform a multipole analysis to quantitatively present the dominance of the magnetic dipole moment contribution compared to other multipole contributions into the total scattered power of the proposed structure. This work demonstrates the excellent efficiency and simplicity of our method of using Si truncated cone structure under APB illumination compared to other approaches to achieve dominant magnetic excitations.

Electric dipole moment of the neutron from a flavor changing Higgs-boson

I consider neutron electric dipole moment contributions induced by flavor changing Standard Model Higgs boson couplings to quarks. Such couplings might stem from non-renormalizable SU(2)_L times U(1)_Y invariant Lagrange terms of dimension six, containing a product of three Higgs doublets. We extend previous one loop analysis to two loops. The divergent loops, due to non-renormalisabillity, are parametrized in terms of an ultraviolet cut-off Lambda . I also consider QCD corrections. Using the current experimental bound on the neutron electric dipole moment, then for cut offs from one to seven TeV, I find a constraint of order 10^{-3} for the imaginary part of the product of the Higgs flavor changing coupling for (d rightarrow b)-transition and the CKM element V_{td}. Assuming that the previous bound of the absolute value of the Higgs flavor changing coupling for (d rightarrow b)-transition obtained from B_d - bar{B_d}-mixing is saturated, the experimental bound on the neutron electric dipole moment would be reached for the bare result, if the cut off were extended up to about ca 20 TeV. However, QCD corrections suppress this result by a factor of order ten, and keep the nEDM below the experimental bound.

Radiative heat transfer between core-shell nanoparticles

Radiative heat transfer in systems with core-shell nanoparticles may exhibit not only a combination of disparate physical properties of its components but also further enhanced properties that arise from the synergistic properties of the core and shell components. We study the thermal conductance between two core-shell nanoparticles (CSNPs). The contribution of electric and magnetic dipole moments to the thermal conductance depend sensitively on the core and shell materials, and adjustable by core size and shell thickness. We predict that the radiative heat transfer in a dimer of Au@SiO2 CSNPs (i.e., silica-coated gold nanoparticles) could be enhanced several order of magnitude compared to bare Au nanoparticles. However, the reduction of several orders of magnitude in the heat transfer is possible between SiO2@Au CSNPs (i.e., silica as a core and gold as a shell) than that of uncoated SiO2 nanoparticles.

How Many Active Regions Are Necessary to Predict the Solar Dipole Moment?

Abstract We test recent claims that the polar field at the end of Cycle 23 was weakened by a small number of large, abnormally oriented regions, and investigate what this means for solar cycle prediction. We isolate the contribution of individual regions from magnetograms for Cycles 21, 22, and 23 using a 2D surface flux transport model, and find that although the top ∼10% of contributors tend to define sudden large variations in the axial dipole moment, the cumulative contribution of many weaker regions cannot be ignored. To recreate the axial dipole moment to a reasonable degree, many more regions are required in Cycle 23 than in Cycles 21 and 22 when ordered by contribution. We suggest that the negative contribution of the most significant regions of Cycle 23 could indeed be a cause of the weak polar field at the following cycle minimum and the low-amplitude Cycle 24. We also examine the relationship between a region’s axial dipole moment contribution and its emergence latitude, flux, and initial axial dipole moment. We find that once the initial dipole moment of a given region has been measured, we can predict the long-term dipole moment contribution using emergence latitude alone.

Variation of the Intersection Point of the Potential Surface Crossing Induced by the Laser Phase Along the Reaction Path in Ion-Molecule Reactions: Application To Li+ + CH4

A laser ion-molecule reaction interaction through both polarizability and dipole moment contribution leads to variation in the intersection point in potential energy surface crossings along the reaction path; the polarizability is maximum and the dipole changes its sign at s = 4 a.u., defining a virtual transition state. Using the gauge representation (electric field gauge) for a wave length λ = 20.6 μm, intensity I = 5×1012 W/cm2, I = 1×1013 W/cm2, I = 3×1013 W/cm2, we show here that we can create a laser-induced potential energy surface crossing along the reaction path (s = 7-8 a.u.). We illustrate such effects for the Li H + CH 3 + ↔ Li+ + CH4 reaction which takes the form of inverted Morse (without a barrier) using ab initio methods for calculating the reaction path and electric properties of the ion-molecule reaction.

Simultaneous dipole and quadrupole moment contribution in the Bogoliubov spectrum: Application of the non-integral Gross–Pitaevskii equation

We present the Gross–Pitaevskii equation for Bose–Einstein condensates (BECs) possessing the electric dipole and the electric quadrupole moments in a non-integral form. These equations are coupled with the Maxwell equations. The model under consideration includes the dipole–dipole, the dipole–quadrupole, and the quadrupole–quadrupole interactions in terms of the electric field created by the dipoles and quadrupoles. We apply this model to obtain the Bogoliubov spectrum for three-dimensional BECs with a repulsive short-range interaction. We obtain an extra term in the Bogoliubov spectrum in comparison with the dipolar BECs. We show that the quadrupole–quadrupole interaction gives a positive contribution in the Bogoliubov spectrum. Hence, this spectrum is stable.

Variation of potential energy surface height and bound state depth induced by laser phase along the reaction path in atom-molecule reactions: Application to Li + CH4 → LiH + CH3

Laser atom-molecule reaction interaction through polarizability and dipole moment contribution leads to potential energy surface barrier reshaping and bound states along the reaction path. The polarizability is maximum in the transition state. We will show here by using gauge representation (electric field gauge) for wave length λ = 20.6 μm, intensity I = 1 × 1012 W/cm2, I = 5 × 1012 W/cm2, I = 1 × 1013 W/cm2, I = 3 × 1013 W/cm2, that we can create laser induced potential energy surface barrier reshaping in the transition state region (–1–0.5 a. u.). We illustrate such effects for the LiH + CH3 ↔ Li + CH4 reaction with a barrier using ab-initio methods for calculating the reaction path, polarizability and dipole moment contribution of the atom-molecule reaction.

Surface properties of polyene glycol phospholipid monolayers

We studied the surface properties of monolayers composed of polyunsaturated conjugated ethylene glycol phospholipids (carotenoid lipids), compared the data with monolayers of dipalmitoylphosphatidylcholine (DPPC) to which carotenoids were added and evaluated the impact of the unsaturated glycol lipids on monolayers with the glycerolipid DPPC. The carotenoid based glycol lipids formed monolayers at the air/water interface. Using the Langmuir method we obtained series of pressure-area (π-A) isotherms and determined the limiting area A per molecule of three glycol lipids, C30:9-C0A=42.6±1.4Å2, C30:9-C2A=76.1±2.5Ǻ2 and C30:9-C12A=354.0±12.0Å2 and their mixtures with DPPC at various mole fraction X. C30:9-C0 and C30:9-C2 did not affect significantly the shape of the isotherm, but caused their slight shift toward a lower and larger molecular area, respectively. C30:9-C12 at mole fractions X>0.02 affected the shape of isotherm. The compressibility modulus Cs−1 of monolayers depended on the surface pressure. Cs−1 value was substantially higher for DPPC monolayers in comparison with those of pure glycol lipids. At low surface pressure π=5–10mN/m and low mole fractions X<0.02 the glycol lipids formed complexes with DPPC; at higher surface pressure the separation of pure components took place. The dipole potential of the monolayers composed of cationic glycol lipids C30:9-C2 and C30:9-C12 was higher in comparison with those of zwitterionic DPPC and C30:9-C0. This may be connected with various contributions of dipole moments of the molecules and their orientation in the monolayer.

Axial, scalar, and tensor charges of the nucleon from2+1+1-flavor Lattice QCD

We present results for the isovector axial, scalar and tensor charges $g^{u-d}_A$, $g^{u-d}_S$ and $g^{u-d}_T$ of the nucleon needed to probe the Standard Model and novel physics. The axial charge is a fundamental parameter describing the weak interactions of nucleons. The scalar and tensor charges probe novel interactions at the TeV scale in neutron and nuclear $\beta$-decays, and the flavor-diagonal tensor charges $g^{u}_T$, $g^{d}_T$ and $g^{s}_T$ are needed to quantify the contribution of the quark electric dipole moment (EDM) to the neutron EDM. The 9 ensembles, generated by the MILC Collaboration using the HISQ action with 2+1+1 dynamical flavors, span three lattice spacings $a \approx 0.06, 0.09$ and 0.12 fm and light-quark masses corresponding to the pion masses $M_\pi \approx 135, 225$ and 315 MeV. High-statistics estimates on five ensembles using the all-mode-averaging method allow us to quantify all systematic uncertainties and perform a simultaneous extrapolation in the lattice spacing, lattice volume and light-quark masses for the connected contributions. Our final estimates, in the $\overline{\text{MS}}$ scheme at 2 GeV, of the isovector charges are $g_A^{u-d} = 1.195(33)(20)$, $g_S^{u-d} = 0.97(12)(6) $ and $g_T^{u-d} = 0.987(51)(20)$. The first error includes statistical and all systematic uncertainties except that due to the extrapolation Ansatz, which is given by the second error estimate. Combining our estimate for $g_S^{u-d}$ with the difference of light quarks masses $(m_d-m_u)^{\rm QCD}=2.67(35)$ MeV given by FLAG, we obtain $(M_N-M_P)^{\rm QCD} = 2.59(49)$ MeV. Estimates of the connected part of the flavor-diagonal tensor charges of the proton are $g^{u}_T=0.792(42)$ and $g^{d}_T=-0.194(14)$. Combining our new estimates with precision low-energy experiments, we update constraints on novel scalar and tensor interactions, $\epsilon_{S,T}$, at the TeV scale.

Synthesis and Conformational Analysis of 2,11‐Disila[3.3]metacyclophanes

Silyl‐tethered [3.3]metacyclophanes were prepared and subjected to conformational analysis. The results show that these compounds exist in unprecedented anti‐rich metacyclophane forms. In the case of 2,2,11,11‐tetrasubstituted 2,11‐disila[3.3]metacyclophanes, anti conformers are lower in energy than their syn counterparts. Evidence for this assignment comes from the results of 1H NMR spectroscopic and X‐ray crystallographic analyses, along with molecular orbital calculations. However, the 2,2,11,11‐tetrahydro derivative displays the opposite behavior, which means that the syn conformer is thermodynamically most stable. The syn/anti ratios of these compounds in solution are governed by temperature and solvent polarity in a manner that can be explained by considering the mixed contributions of ΔΔG and dipole moments.