Search results for "DIPOLE"
showing 10 items of 982 documents
Magneto-elastic oscillations and the damping of crustal shear modes in magnetars
2010
In a realistic model of magneto-elastic oscillations in magnetars, we find that crustal shear oscillations, often invoked as an explanation of quasi-periodic oscillations (QPOs) seen after giant flares in soft gamma-ray repeaters (SGRs), are damped by resonant absorption on timescales of at most 0.2s, for a lower limit on the dipole magnetic field strength of 5 10 13 G. At higher magnetic field strengths (typical in magnetars) the damping timescale is even shorter, as anticipated by earlier toy-models. We have investigated a range of equations of state and masses and if magnetars are dominated by a dipole magnetic field, our findings exclude torsional shear oscillations of the crust from ex…
Intramolecular Dipole Reorientation of Amino Compounds and their Interaction with Solvent Molecules. I
1972
Abstract The dielectric absorption of dilute solutions of aniline, methyl substituted anilines, chlorine substituted anilines, N,N,N',N'-tetramethyl-p-phenylene diamine and 4-aminobiphenyl in various sol-vents has been measured between 0.3 and 135 GHz. The measurements have been carried out at 20 °C and for some mesitylene solutions also at -30 °C and 60 °C. The absorption curves have been resolved into multiple absorption regions. A far infrared (FIR) term had to be included in each analysis. Its contribution to the total dipole reorientation depends on the solvent and on the mobility of the substituted groups in the phenyl ring. The obtained group relaxation times are longer than those re…
Gas-phase detection of HSOD and empirical equilibrium structure of oxadisulfane
2006
We present the first gas phase spectra of singly deuterated oxadisulfane, HSOD, in its vibrational ground state. More than 100 transitions have been recorded with highest frequency accuracy using the Cologne Terahertz Spectrometer. The molecular parameters derived from a least squares fit analysis proof HSOD to be an almost accidental symmetric prolate top molecule with an asymmetry parameter kZK0.9985. Spectra of c-type and weaker b-type transitions have been recorded in the range from 716 to 772 GHz. The ratio of the dipole moments mc/mbZ2.4(3) has been derived from measured line intensities. The c-type transitions are split by the tunneling motion of a hindered internal rotation, whereas…
The manifestation of dipoles clustering in paraelectric phase of disordered ferroelectrics
2001
Abstract We predict the existence of Griffiths phase in the dielectrics with concentrational crossover between dipole glass (electric analog of spin glass) and ferroelectricity. The peculiar representatives of above substances are KTaO3: Li, Nb, Na or relaxor ferroelectrics like Pb1−xLaxZr0.65Ti0.35O3. Since this phase exists above ferroelectric phase transition temperature (but below that temperature for ordered substance), we call it “para-glass phase”. We assert that the difference between paraelectric and para-glass phase of above substances is the existence of clusters (inherent to “ordinary” Griffiths phase in Ising magnets) of correlated dipoles. We show that randomness play a decisi…
Electric field control of the spin state in mixed-valence magnetic molecules.
2012
Multiferroic molecules for spintronics: In a many-electron mixed-valence dimer with dominant double exchange, as compared with antiferromagnetic superexchange, the electric field is shown to induce a spin crossover from the ferromagnetic spin state to the antiferromagnetic one. This leads to a sharp decrease in the magnetic moment of the molecule and a simultaneous stepwise increase in the electric dipole (see figure).
Ab initio study on the photoisomers of a nitro-substituted spiropyran
2000
Structural and spectroscopic properties of the photoisomers of a nitro-substituted spiropyran have been investigated by performing ab initio molecular orbital (MO) calculations both in vacuo and in hexafluoro-2-propanol solution. Full geometry optimisation of the closed form and of the transoid conformations of the open form has been carried out. Dipole moments of both photoisomers have been determined, the ratio of which agrees with recent experimental results. Net atomic charges have also been determined according to three different approaches.
Ground- and First-Excited-Singlet-State Electric Dipole Moments of Some Photochromic Spirobenzopyrans in Their Spiropyran and Merocyanine Form
2002
The dipole moments of four photochromic derivatives of indolinospirobenzopyran have been studied in their spiro and their open merocyanine form, in dioxane. Determinations have been done by electrooptical absorption measurements (EOAM). To prepare either a pure spiropyran or a pure merocyanine form solution, the experimental setup had to be modified by addition of a second light beam. In this way thermal equilibration between the spiropyran and the merocyanine form and switching from one form to the other induced by the measuring light beam could be avoided. The ground-state dipole moment of the spiro form amounts to (10−15) × 10-30 C m and increases strongly to about 60 × 10-30 C m with th…
The anomalous magnetic moment of the muon in the Standard Model
2020
We are very grateful to the Fermilab Directorate and the Fermilab Theoretical Physics Department for their financial and logistical support of the first workshop of the Muon g -2 Theory Initiative (held near Fermilab in June 2017) [123], which was crucial for its success, and indeed for the successful start of the Initiative. Financial support for this workshop was also provided by the Fermilab Distinguished Scholars program, the Universities Research Association through a URA Visiting Scholar award, the Riken Brookhaven Research Center, and the Japan Society for the Promotion of Science under Grant No. KAKEHNHI-17H02906. We thank Shoji Hashimoto, Toru Iijima, Takashi Kaneko, and Shohei Nis…
Two-dimensional dye crystals with controllable optical properties
1993
The structure, molecular ordering and optical properties of single crystals of cyanine dyes grown by adsorption from a water subphase to a positively charged lipid monolayer are discussed. These crystals are one monolayer thick, of uniform dimensions between 10 and 100μm (depending on nucleation conditions) and of rectangular shape. Single crystals were studied by transmission electron diffraction and by polarized absorption and emission spectroscopy. We show that the crystals consist of two rows of densely stacked molecules with two different orientations of the long molecular axes. This leads to two perpendicularly polarized absorption bands. The measured splitting is in accordance with r…
Wait-and-switch stochastic model of the non-Debye relaxation. Derivation of the Burr survival probability
2006
Abstract Stochastic mechanism of relaxation, in which a dipole waits until a favourable condition for reorientation exists, is discussed. Assuming that an imposed direction of a dipole moment may be changed when a migrating defect reaches the dipole, we present a mathematically rigorous scheme relating the local random characteristics of a macroscopic system to its effective relaxation behaviour. We derive a relaxation function (the Burr survival probability) that is characterized by the stretched exponential or the power-law behaviour.