Dipole Moment Measurements Research Articles

Measurement of the neutron electric dipole moment by crystal diffraction

An experiment using a prototype setup to search for the neutron electric dipole moment by measuring spin rotation in a non-centrosymmetric crystal (quartz) was carried out to investigate statistical sensitivity and systematic effects of the method. It has been demonstrated that the concept of the method works. The preliminary result of the experiment is d n = ( 2.5 ± 6.5 ) × 10 - 24 e cm . The experiment showed that an accuracy of ~ 2.5 × 10 - 26 e cm can be obtained in 100 days data taking, using available quartz crystals and neutron beams.

In situ measurements of emission transition dipole moment of individual ordered microdomain of diprotonated tetraphenylporphine aggregate formed at dodecane/aqueous H2SO4 interface

Rhombic-ordered microdomains of diprotonated 5,10,15,20-tetraphenylporphine aggregate, whose sizes were 10-200 microm, were formed at dodecane/aqueous H(2)SO(4) interfaces. The light excitation of their two absorption bands (410 and 473 nm for H- and J-bands, respectively) led to one fluorescence band at longer wavelength (723 nm). The direction of the emission transition dipole moment (mu(e)) of individual rhombic microdomains, determined with an in situ optical microscope and a linear polarizer, was almost parallel to the major axis, which was also almost parallel to the direction of the absorption transition dipole moment of their J-bands. Their absorption and emission transition scheme was proposed.

Neutron electric dipole moment measurements at the ILL

The origin of the CP violation which created the matter in the universe is one of the enduring mysteries of fundamental physics. Particle electric dipole moments provide a sensitive probe of CP violation from new physics. The article describes past and future work being done at the ILL in Grenoble to search for an electric dipole moment of the neutron.

On the Electric Dipole Moments of Asymmetric Tops: Measurement by High-Resolution Electronic Spectroscopy in the Gas Phase

Reported here are Stark-effect measurements of the permanent electric dipole moments of two structural isomers of aminobenzonitrile, 2ABN and 3ABN, using high-resolution laser molecular beam techniques. When combined with previous results on 4ABN, the data show that each structural isomer has a unique dipole moment, in both its ground (S(0)) and electronically excited (S(1)) states, thereby providing a means of distinguishing them. Possible applications of the method to other, biologically relevant molecules are discussed.

High-resolution infrared spectroscopy of Mg–HF and Mg–(HF)2 solvated in helium nanodroplets

High-resolution infrared (IR) spectroscopy is used to investigate the Mg-HF and Mg-(HF)(2) van der Waals complexes. Both complexes are formed and probed within helium nanodroplets. Rotationally resolved zero-field and Stark spectra are assigned to a linear binary complex composed of a Mg atom bound to the hydrogen end of the HF molecule. Although high level ab initio calculations predict a fluorine bonded complex, none of the observed IR bands can be assigned to this complex. The collocation method is employed to determine the bound states on the two-dimensional intermolecular Mg-HF potential energy surface. The ground and first excited state wave functions for this potential surface have zero amplitude in the well corresponding to the fluorine bonded complex, consistent with experiment. The two HF stretching bands of the Mg-(HF)(2) complex are observed and assigned using a combination of the spectral symmetry, ab initio calculations, pick-up cell pressure dependencies, and dipole moment measurements. Comparisons with the helium solvated HF dimer show large changes to the HF stretching frequencies upon the addition of a single Mg atom to the hydrogen side of (HF)(2).

Push−Pull Molecules in the Gas Phase: Stark-Effect Measurements of the Permanent Dipole Moments of p-Aminobenzoic Acid in Its Ground and Electronically Excited States

Stark effect measurements of the permanent electric dipole moments of p-aminobenzoic acid (PABA) in the gas phase are reported based on studies of its fully resolved S1<--S0 electronic spectrum in the presence of an electric field. Ground-state (S0) PABA has mu = 3.3 D, whereas excited-state (S1) PABA has mu = 4.4 D. Despite PABA's reputation as a "push-pull" molecule, the photon-induced change in both the magnitude and orientation of mu is relatively small. Possible reasons for this behavior are discussed.

Measurement of the Magnetic Properties of FeH in ItsX4Δ andF4Δ States from Sunspot Spectra

The spin-rotational levels of FeH in its F4Δ and X4Δ states are significantly perturbed by nearby electronic states. As a result, it is not possible to make reliable calculations of its magnetic dipole moments from a simple effective Hamiltonian. In this paper, we report experimental measurements of the magnetic dipole moments of FeH in several rotational levels of the two lowest spin components of the v = 0 levels of both the F4Δ and X4Δ states. The observational data are taken from the Sunspot Spectral Atlas of Wallace et al.; the local magnetic flux densities are determined from the splittings of atomic lines present in the spectrum. These results considerably extend the range of known magnetic dipole moments for FeH and provide many lines in the F4Δ–X4Δ transition at 990 nm (the Wing-Ford system) for astronomers to use for the measurement of the local magnetic fields of cool stars where suitable atomic lines are not available for this purpose.

The First 85 Years of C-Nitroso Compounds: A Survey of the Salient Features

In this account we trace the development of the structural chemistry of C-nitroso compounds from 1874, the year in which research into these compounds began. From the beginning, the colors displayed by these compounds (blue, blue-green, white) fascinated researchers, and it was soon realized that dimerization of the compounds could account for the white color of the solids. Extensive synthetic and reactive studies of the monomeric compounds resulted, and although some attention was directed to the structure of the dimers, both experimental and theoretical tools for this were limited. In the 1920s and 1930s electronic theories of valency were applied to nitroso compounds aided by dipole moment measurements. Systematic crystallographic and spectroscopic studies were employed from 1948 onwards. The early widespread belief that primary and secondary nitrosoalkanes were too unstable to isolate (due to isomerization to oximes) was overcome by successful syntheses of these compounds. The example of C-nitroso compounds illustrates the interplay of theory and experiment throughout the period 1874–1959.

Neutralino relic density from ILC measurements in theCP-violating MSSM

We discuss ILC measurements for a specific MSSM scenario with CP phases, where the lightest neutralino is a good candidate for dark matter, annihilating efficiently through t-channel exchange of light staus. These prospective (CP-even) ILC measurements are then used to fit the underlying model parameters. A collider prediction of the relic density of the neutralino from this fit gives 0.116<{omega}h{sup 2}<0.19 at 95% C.L. CP-odd observables, while being a direct signal of CP violation, do not help in further constraining {omega}h{sup 2}. The interplay with (in)direct detection of dark matter and with measurements of electric dipole moments is also discussed. Finally we comment on collider measurements at higher energies for refining the prediction of {omega}h{sup 2}.

On the Stability of the Nematic Order Observed During the Cold-crystallization of PET

The rotational isomeric state analysis of poly(ethylene terephthalate) (PET) was carried out by using parameters adjusted so as to reproduce the experimental results of 1H NMR and dipole moment measurements on ethylene glycol dibenzoate. The central OC-CO bond of the ethyleneglycol unit prefers to be in the gauche form at lower temperatures, suggesting that the PET chains should contain many kink conformations in the amorphous state. In the following part, the nematic conformation of the same C-C bond was studied by preparing a model compound which is capable of forming an enantiotropic nematic liquid crystalline (LC) phase. IR studies indicate that the trans fraction of the C-C bond increases from ∼15% in the isotropic liquid to ∼50% in the nematic LC state at the phase boundary. For this drastic change in the conformation at the transition, the C-C bond should be required to pay certain entropy penalty. These results are however compatible with the recent observations by SAXS and DPLS that the formation of nematic LC-like domains proceeds prior to the evolution of primary crystal nucleation during the cold-crystallization of PET. The PET chain is known to take the planar all-trans conformation in the crystalline state. Finally a possible mechanism leading to the nematic order in the amorphous PET is presented. Growth of the nematic LC-like domains in the amorphous phase may lead to a spinodal microphase separation, as suggested by Kaji et al.

StrongCPProblem with1032Standard Model Copies

We show that a recently proposed solution to the hierarchy problem simultaneously solves the strong CP problem, without requiring an axion or any further new physics. Consistency of black hole physics implies a nontrivial relation between the number of particle species and particle masses, so that with approximately 10(32) copies of the standard model, the TeV scale is naturally explained. At the same time, as shown here, this setup predicts a typical expected value of the strong-CP parameter in QCD of theta approximately 10(-9). This strongly motivates a more sensitive measurement of the neutron electric dipole moment.

Magnetic dipole moments ofCu58andCu59by in-source laser spectroscopy

Online measurements of the magnetic dipole moments and isotope shifts of $^{58}\mathrm{Cu}$ and $^{59}\mathrm{Cu}$ by the in-source laser spectroscopy method are reported. The results for the magnetic moments are $\ensuremath{\mu}$ ($^{58}\mathrm{Cu}$) $=+0.52(8) {\ensuremath{\mu}}_{N},\ensuremath{\mu}$($^{59}\mathrm{Cu}$) $=+1.84(3) {\ensuremath{\mu}}_{N}$ and for the isotope shifts $\ensuremath{\delta}{\ensuremath{\nu}}^{59,65}=1.72(22)$ GHz and $\ensuremath{\delta}{\ensuremath{\nu}}^{58,65}=1.99(30)$ GHz in the transition from the $3{d}^{10}4s $$^{2}\mathrm{S}$${}_{1/2}$ ground state to the $3{d}^{10}4p $$^{2}\mathrm{P}$${}_{1/2}$ state in Cu I. The magnetic moment of $^{58}\mathrm{Cu}$ is discussed in the context of the strength of the subshell closure at $^{56}\mathrm{Ni}$, additivity rules and large-scale shell model calculations.

Measurement of the Transition Dipole Moment of the First Hot Band of the ν2 Mode of the Methyl Radical by Diode Laser Spectroscopy

The line strengths of five Q-branch lines of the first hot band of the out-of-plane bending vibration (2(1)(2)) of the methyl radical, CH 3, have been measured using infrared laser absorption spectroscopy. The spectra of the radical were measured in situ in a microwave discharge using ditertiary butyl peroxide, diluted in argon as the precursor. The line strengths were used to determine the transition dipole moment of the hot band. Absolute concentrations of the radical were required for this purpose, and these were determined kinetically from the measured decays of the spectral lines after the discharge was extinguished. The translational, rotational, and vibrational temperatures were also determined spectroscopically from measured integrated line intensities and line widths. The transition dipole moment of the first hot band was determined to be 0.31(6) D. This value is in satisfactory agreement with the value of 0.27(3) D from a high-precision ab initio calculation using the self-consistent electron pairs (SCEP) method reported by Botschwina, Flesch, and Meyer [Botschwina, P.; Flesch, J.; Meyer, W. Chem. Phys. 1983, 74, 321].

Polarization and relaxation rates of radon

Polarization and relaxation of radon isotopes by spin exchange with laser optically pumped rubidium were studied in preparation for electric dipole moment measurements with octupole deformed $^{223}\mathrm{Rn}$. \ensuremath{\gamma}-ray anisotropies provided a measure of nuclear polarization produced by spin exchange with laser polarized rubidium vapor, and the temperature dependence over the range 130 to ${220}^{\ifmmode^\circ\else\textdegree\fi{}}$C was measured to parametrize the spin exchange polarization and the quadrupole-dominated wall relaxation rate. These results provide quantitative data for developing electric dipole moment measurements of octupole-deformed $^{223}\mathrm{Rn}$ and other radon isotopes.

A method to remove synchrotron frequency from the spectrum of momentum-forced radial oscillations

Using the case of a storage ring for the resonance electric dipole moment (EDM) measurement, we demonstrate how to transform the frequency of forced radial oscillations from the frequency induced by the synchrotron oscillations of momentum, into a fraction of that frequency. This transformation, achieved through exploiting non-linearity, an oscillating external field, and destructive interference, cancels many parasitic spin resonances imitating the EDM.

Dressed spin ofHe3

We report a measurement of dressed spin effects of polarized $^{3}\mathrm{He}$ atoms from a cold atomic source traversing a region of a constant magnetic field ${B}_{0}$ and a transverse oscillatory dressing field ${B}_{d}\mathrm{cos}{\ensuremath{\omega}}_{d}t$. The observed effects are compared with a numerical simulation using the Bloch equation as well as a calculation based on the dressed atom formalism. An application of the dressed spin of $^{3}\mathrm{He}$ for a proposed neutron electric dipole moment measurement is also discussed.

Taking into account the Earth’s rotation in experiments on the search of the electric dipole moment of the neutron

The problem of taking into account the Earth’s rotation in the search of the electric dipole moment of the neutron in experiments with ultracold neutrons and in the diffraction experiment is analyzed. For the precision reached up to the present moment in the diffraction experiment, the account of the Earth’s rotation yields a negligible (exactly calculated) correction. In experiments with ultracold neutrons, this correction exceeds the systematic error of measurement of the electric dipole moment of the neutron, and its exact calculation requires additional investigations. In this regard, further development of the diffraction method should considerably promote the progress in the search of the electric dipole moment of the neutron.

Survismeter Unit for Surface Tension, Viscosity, and Dipole Moment Determination for Polystyrene Interactions in Benzene

Novel instrumental set up is developed for surface tension (γ, N m−1), viscosity (η, N s m−2)) and dipole moment (μ/Debye) measurements. A new instrument is economic, viable and pollution free in use, the γ, η and μ from viscosities (η, N s m−2) and surface tension (γ, N m−1) for 0.005 to 0.125 g% polystyrene at an interval of 0.0005 g% in benzene are measured at 288.15, 293.15, and 298.15 Kelvin temperatures. The γ, η, and μ are reported stronger frictional and cohesive forces due to stronger interactions of polystyrene with benzene. The survismeter is highly accurate and mechanically operated for pulling up liquid from reservoir bulb B1 to operational bulbs B2, B3, and B4. Densities are higher than those of benzene and also infer stronger polystyrene–benzene interactions, and hydrodynamic volume (HV) calculated with intrinsic viscosity [η] is noted in 293.15 (HV) >298.15 (HV) >288.15 (HV) order with higher values at 293.15 K. Surface tension (γ) values are slightly higher than of benzene and fall in a range of 33.47 to 33.35 N m−1.

Mononuclear Rh(II) PNP-Type Complexes. Structure and Reactivity

The Rh(II) mononuclear complexes [(PNPtBu)RhCl][BF4] (2), [(PNPtBu)Rh(OC(O)CF3)][OC(O)CF3] (4), and [(PNPtBu)Rh(acetone)][BF4]2 (6) were synthesized by oxidation of the corresponding Rh(I) analogs with silver salts. On the other hand, treatment of (PNPtBu)RhCl with AgOC(O)CF3 led only to chloride abstraction, with no oxidation. 2 and 6 were characterized by X-ray diffraction, EPR, cyclic voltammetry, and dipole moment measurements. 2 and 6 react with NO gas to give the diamagnetic complexes [(PNPtBu)Rh(NO)Cl][BF4] (7) and [(PNPtBu)Rh(NO)(acetone)][BF4]2 (8) respectively. 6 is reduced to Rh(I) in the presence of phosphines, CO, or isonitriles to give the Rh(I) complexes [(PNPtBu)Rh(PR3)][BF4] (11, 12) (R = Et, Ph), [(PNPtBu)Rh(CO)][BF4] (13) and [(PNPtBu)Rh(L)][BF4] (15, 16) (L = tert-butyl isonitrile or 2,6-dimethylphenyl isonitrile), respectively. On the other hand, 2 disproportionates to Rh(I) and Rh(III) complexes in the presence of acetonitrile, isonitriles, or CO. 2 is also reduced by triethylphosphine and water to Rh(I) complexes [(PNPtBu)RhCl] (1) and [(PNPtBu)Rh(PEt3)][BF4] (11). When triphenylphosphine and water are used, the reduced Rh(I) complex reacts with a proton, which is formed in the redox reaction, to give a Rh(III) complex with a coordinated BF4, [(PNPtBu)Rh(Cl)(H)(BF4)] (9).

Dipole moment of 3-bromopentane in various solvents

Solution dipole moment measurements of 3-bromopentane in solvents of varying static permittivity are presented. The solvents used are 3-methylpentane, pentane, benzene, toluene, o-xylene, m-xylene, p-xylene, mesitylene, cyclohexane, methylcyclohexane and 1,4-dioxane. The range of concentrations shows linear behavior for the solute in all solvents used. Excluding 1,4-dioxane, there is a negative linear relationship between the permittivity of the solvent and the calculated dipole moment of 3-bromopentane.