Adatom dipole moments on metals and their interactions

An expression is derived for the dipole moment μ, associated with an arbitrary adatom on an arbitrary metal surface, in terms of the differential work done in moving the adatom from the interior of the metal to its actual position in the presence and absence, respectively, of small, asymptotically uniform electric field on the exterior of the metal. With the aid of this expression it is shown that the non-oscillatory part of the interaction energy of two dipoles μ_A and μ_B, situated on the surface and separated by a large distance v, is given by U_AB = 2μ_Aμ_Bv^?3. This exceeds by a factor of 2 the interaction energy of two dipoles in the same relative configuration but in a vacuum.     

Electric dipole moments as probes of new physics

We review several aspects of flavour-diagonal CP-violation, focussing on the role played by the electric dipole moments (EDMs) of leptons, nucleons, atoms, and molecules, which constitute the source of several stringent constraints on new CP-violating physics. We dwell specifically on the calculational aspects of applying the hadronic EDM constraints, reviewing in detail the application of QCD sum-rules to the calculation of nucleon EDMs and CP-odd pion-nucleon couplings. We also consider the current status of EDMs in the Standard Model, and on the ensuing constraints on the underlying sources of CP-violation in physics beyond the Standard Model, focussing on weak-scale supersymmetry.     

Influence of local excitation of octupolar Oligophenylenevinylenes on their dipole moments

Absorption and fluorescence spectra of octupolar centrosymmetric oligophenylenevinylene dyes (E,E)-bis[2-(4-hexyloxyphenyl)ethenyl]-(E,E)-3,6-bis-[2-(4-N,N-dipropylaminophenyl)ethenyl]pyrazine and (E,E,E,E)-2,3,5,6- tetra-[2-(4-hexyloxyphenyl)ethenyl]pyrazine were measured in various solvents. An electro-optical absorption method was used to determine their dipole moments as μ _g  = 6.1∙10^–30 and 3.4∙10^–30 C∙m in the equilibrium ground state and the increased values ∆ ^a μ = 11.9∙10^–30 and 8.2∙10^–30 C∙m upon excitation into a Franck–Condon state. Quantum-chemical calculations showed that the molecules had non-planar configurations. The π,π-conjugated system was localized on the most planar part of the molecule that was responsible for light absorption in the range 300–450 nm due to a change in the geometry of the molecules in the ground state. Localized excitation of the molecules caused their dipole moments ∆ ^a μ to change significantly.     

Photophysical characteristics of three novel benzanthrone derivatives: Experimental and theoretical estimation of dipole moments

The effect of solvents on absorption and fluorescence spectra and dipole moments of novel benzanthrone derivatives such as 3-N-(N′,N′-Dimethylformamidino) benzanthrone (1), 3-N-(N′,N′-Diethylacetamidino) benzanthrone (2) and 3-morpholinobenzanthrone (3) have been studied in various solvents. The fluorescence lifetime of the dyes (1-3) in chloroform were also recorded. Bathochromic shift observed in the absorption and fluorescence spectra of these molecules with increasing solvent polarity indicates that the transitions involved are π→π^?. Using the theory of solvatochromism, the difference in the excited-state (μ_e) and the ground-state (μ_e) dipole moments was estimated from Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet, and McRae equations by using the variation of Stokes shift with the solvent’s relative permittivity and refractive index. AM1 and PM6 semiempirical molecular calculations using MOPAC and ab-initio calculations at B3LYP/6-31 G^? level of theory using Gaussian 03 software were carried out to estimate the ground-state dipole moments and some other physicochemical properties. Further, the change in dipole moment value (Δμ) was also calculated by using the variation of Stokes shift with the molecular-microscopic empirical solvent polarity parameter (E_T^N). The excited-state dipole moments observed are larger than their ground-state counterparts, indicating a substantial redistribution of the π-electron densities in a more polar excited state for all the systems investigated.     

A new type of trapping center for molecules with dipole moments in insulators

An analysis of the mechanism underlying the sensitivity of metal-insulator-semiconductor sensors to the concentration of a variety of gases, as well as of a number of experiments, suggests the formation of electrically charged trapping centers for molecules with dipole electric moments in thin insulating layers doped by catalytic metals. It is assumed that these traps are essentially nanoclusters consisting of atoms of the insulator and atoms of the catalytic metal. Trapping centers of this type may be involved in other physical phenomena as well.     

Coherent excitons at different orientation arrangements of local transition dipole moments in circular light-harvesting complexes

The coherent exciton plays an important role in the photosynthetic primary process, and its functions are deeply dependent on the orientation arrangements of local transition dipole moments (TDMs). We theoretically and systematically study the physical property of the coherent exciton at different orientation arrangements of the local TDMs in circular light-harvesting (LH) complexes. Especially, if the orientation arrangements are different, the delocalized TDMs of the coherent excitons and the energy locations of the optically active coherent excitons (OACEs) can be obviously different, and then there are more manners to capture, store and transfer light energy in and between LH complexes. Similarly, if the orientation arrangements are altered, light absorption and radiative intensities can be converted fully between the OACEs in the upper and lower coherent exciton bands, and then the blue and red shifts of the absorption and radiative bands of the pigment molecules can occur simultaneously at some orientation arrangements. If the systems are in the vicinities of the critical orientation arrangements, the weak static disorder or small thermal excitation can destroy the coherent electronic excitations, and then the coherent exciton cannot exist any more.     

Electric dipole moments and conformations of isolated peptides

The electric dipole moments of the isolated amino acid tryptophan and small glycine-based peptides (WG_n, n = 1-5, W = tryptophan, G = glycine) have been measured by deflection of a molecular beam in an inhomogeneous electric field. The measurements are compared to the results of ab initio calculations and Monte-Carlo simulations. The conformation and the flexibility of the peptides, at different temperatures, are discussed. The WG_n peptides are much more floppy than an isolated tryptophan, even a single glycine is enough to make the peptide floppy on the timescale of the electric deflection measurements. Received 4 January 2002 Published online 13 September 2002     

Neutrino dipole moments and charge radii in non-commutative space-time

In this paper we obtain a bound TeV on the scale of space-time non-commutativity considering photon-neutrino interactions. We compute *-dipole moments and *-charge radii originating from space-time non-commutativity and compare them with the dipole moments calculated in the neutrino-mass extended standard model (SM). The computation depends on the nature of the neutrinos, Dirac versus Majorana, their mass and the energy scale. We focus on Majorana neutrinos. The *-charge radius is found to be at TeV.Received: 17 June 2004, Published online: 18 August 2004     

Electric dipole moments in the limit of heavy superpartners

Supersymmetric loop corrections induce potentially large CP-violating couplings of the Higgs bosons to nucleons and electrons that do not vanish in the limit of heavy superpartners. The Higgs-mediated CP-odd four-fermion operators are enhanced by tan((3)beta and induce electric dipole moments of heavy atoms which exceed the current experimental bounds for the electroweak scale Higgs masses and tan(beta greater, similar 10. If only the first two sfermion generations are heavy, the Higgs-mediated contributions typically dominate over the Barr-Zee type two-loop diagrams at tan(beta>30.     

Electric dipole moments of lithium atoms in Rydberg states

Recently, the diverse properties of Rydberg atoms, which probably arise from its large electric dipole moment(EDM),have been explored. In this paper, we report electric dipole moments along with Stark energies and charge densities of lithium Rydberg states in the presence of electric fields, calculated by matrix diagonalization. Huge electric dipole moments are discovered. In order to check the validity of the EDMs, we also use these electric dipole moments to calculate the Stark energies by numerical integration. The results agree with those calculated by matrix diagonalization.     

The microwave spectra and dipole moments of the cyanopyridines

Rotational transitions of 4-cyanopyridine, 3-cyanopyridine and 2-cyanopyridine have been observed and assigned. The values of the rotational constants for these three molecules are (in MHz):

$\text{4-cyanopyridine}\text{A=6000.}\text{B=1541.19}\text{C=1226.00}\text{3-cyanopyridine}\text{A=5823.01}\text{B=1571.34}\text{=1237.17}\text{2-cyanopyridine}\text{A=5835.756}\text{1598.219}\text{1254.460}$

The dipole moment components were also measured and are (in Debye):

$\text{4-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=1.96}\text{μ}{}_{\mathrm{b}}\text{=0}\text{μ}{}_{\mathrm{total}}\text{=1.96}\text{3-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=3.13}\text{μ}{}_{\mathrm{b}}\text{=1.90}\text{μ}{}_{\mathrm{total}}\text{=3.66}\text{2-cyanopyridine}\text{μ}{}_{\mathrm{a}}\text{=5.47}\text{μ}{}_{\mathrm{b}}\text{=1.87}\text{μ}{}_{\mathrm{total}}\text{=5.78}$

     

The relative electric dipole moments of singlets and triplets

A sensitivity analysis formalism is constructed for collinear reactive systems with multiple electronic potential energy surfaces. The work extends the sphere of application of sensitivity theory into the reactive domain. Expressions are obtained for the first order elementary sensitivity coefficients (i.e. partial derivatives) of both the reactive and non-reactive component elements of the scattering matrix with respect to an arbitrary system parameter. In the case of the non-reactive elements, the sensitivity coefficients involve essentially the piecewise integration of a function matrix containing the available solution of the scattering problem. The reactive sensitivity coefficients draw on both forward and backward propagated solutions. The paper concludes with a discussion of the scope and applicability of reactive sensitivity analysis.     

Formation of dipole nanoclusters in blood serum protein solutions containing europium and potassium ions

Aqueous solutions of major serum proteins (albumin and g-globulin) with small concentrations of potassium and europium ions were investigated with the use of photon-correlation spectroscopy and atomicforce microscopy. The coefficients of translation diffusion, as well as the effective radiuses of the scattering particles in the solutions as a function of pH and salt concentration, were obtained. It was found that protein dipole nanoclusters form in these solutions, which was confirmed by AFM methods as well.     

A new generalized spectral luminescent method for determining dipole moments of molecules in the ground and excited states

An original spectral luminescent method for determining dipole moments of molecules in the ground and excited states was proposed, and its preliminarily tests were made. It is based on a combined quantitative analysis of experimental data on the linear (solvation) and nonlinear (complex formation) components of the orientation shift of electronic and vibrational spectra of molecules in two-and three-component solutions. To realize the method in practice, one should make a series of standard measurements of the position of absorption bands or the stationary luminescence of diluted solutions of a substance under study in several rationally chosen liquid individual and binary solvents at the room temperature. The distinctive feature of the method is that it is based on the use of spectroscopic data only and does not require that the equilibrium value of the effective radius of the intermolecular interaction (Onsager radius of a molecule of a diluted substance) be specified and the angles between the moments of ground and excited states be known.     

Pair production and vacuum polarization of vector particles with electric dipole moments and anomalous magnetic moments

The matrix 8-component Dirac-like form of the P-odd equations for boson fields of spin 1 and 0 are obtained and the symmetry group of the equations is derived. We found exact solutions of the field equation for vector particles with arbitrary electric and magnetic moments in external constant and uniform electromagnetic fields. The differential probability of pair production of vector particles with electric dipole moments and anomalous magnetic moments by an external constant and uniform electromagnetic field has been found using exact solutions. We have calculated the imaginary and real parts of the electromagnetic field Lagrangian that takes into account the vacuum polarization of vector particles. Received: 14 April 2001 / Revised version: 13 July 2001 / Published online: 19 September 2001