Search results for "Relaxation process"

showing 5 items of 5 documents

A new MHD-assisted Stokes inversion technique

2016

©2017 The American Astronomical Society. All rights reserved. We present a new method of Stokes inversion of spectropolarimetric data and evaluate it by taking the example of a Sunrise/IMaX observation. An archive of synthetic Stokes profiles is obtained by the spectral synthesis of state-of-the-art magnetohydrodynamics (MHD) simulations and a realistic degradation to the level of the observed data. The definition of a merit function allows the archive to be searched for the synthetic Stokes profiles that best match the observed profiles. In contrast to traditional Stokes inversion codes, which solve the Unno–Rachkovsky equations for the polarized radiative transfer numerically and fit the …

Magnetohydrodynamics (MHD)010504 meteorology & atmospheric sciencesphotosphere [Sun]FOS: Physical sciencesTechniques: spectroscopicAstrophysicspolarimetric [Techniques]01 natural sciencesspectroscopic [Techniques]0103 physical sciencesMerit functionRadiative transferInitial value problemAstrophysics::Solar and Stellar Astrophysics010303 astronomy & astrophysicsSun: magnetic fieldsSolar and Stellar Astrophysics (astro-ph.SR)0105 earth and related environmental sciencesPhysicsRelaxation processTechniques: polarimetricSun: photosphereAstronomy and AstrophysicsInversion (meteorology)Computational physicsmagnetic fields [Sun]Astrophysics - Solar and Stellar AstrophysicsSpace and Planetary ScienceSolar timeMagnetohydrodynamics
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Evidence for a glassy dynamics in (Rb-NH 4 ) 2 SO 4 mixed compounds

1996

An orientational glass behavior is evidenced in a [Rb0.7(NH4)0.3]2SO4 mixed crystal. Dielectric experiments (1 kHz–250 MHz) performed along the c-axis evidenced a polydispersive relaxation process. Its temperature dependence follows a Vogel-Fulcher law with a freezing temperature of 12 K.

Materials scienceMixed crystalCondensed matter physicsDynamics (mechanics)Relaxation processGeneral Physics and AstronomyDielectricOrientational glassEurophysics Letters (EPL)
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Relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds

2008

We studied ultrafast relaxation of localized excited states at Ge-related oxygen deficient centers in silica using femtosecond transient-absorption spectroscopy. The relaxation dynamics exhibits a biexponential decay, which we ascribe to the departure from the Frank-Condon region of the first excited singlet state in 240 fs, followed by cooling in ∼10 ps. At later times, a nonexponential relaxation spanning up to 40 ns occurs, which is fitted with an inhomogeneous distribution of nonradiative relaxation rates, following a chi-square distribution with one degree of freedom. This reveals several analogies with phenomena such as neutron reactions, quantum dot blinking, or intramolecular vibrat…

Physics and Astronomy (miscellaneous)Chemistrypoint defectSilicaNanosecondExcited state (localized; relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds); Excited singlet state; Localized electronic state; Point defects; Vibrational relaxation (relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds); Optical absorption (transient; relaxation processes of point defects in vitreous silica from femtosecond to nanoseconds)Crystallographic defectSettore FIS/07 - Fisica Applicata(Beni Culturali Ambientali Biol.e Medicin)ultrafast spectroscopyNuclear magnetic resonanceQuantum dotExcited stateFemtosecondVibrational energy relaxationNeutronrelaxation point defect vitreous silica nanosecondPhysics::Chemical PhysicsAtomic physicsSpectroscopyApplied Physics Letters
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Theory of the dynamical behaviour of inverted spins linearly coupled to a lattice

1971

Abstract The relaxation process of a system of paramagnetic spins linearly interacting with a phonon field is studied in the region of inverted population of the levels. The peculiar dynamical behaviour of the present model in that region is shown to be in agreement with some recent experimental results.

Physicseducation.field_of_studyCondensed matter physicsSpinsPhononPopulationRelaxation processGeneral ChemistryCondensed Matter PhysicsParamagnetismLattice (order)Materials ChemistryCondensed Matter::Strongly Correlated ElectronseducationSolid State Communications
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Hexanuclear NiII4LnIII2 Complexes with SMM Behavior at Zero Field for Ln = Tb, Dy, Ho

2020

A mononuclear Ni(II) complex, [NiL2]·2H2O, was prepared by the reaction of a N2O2 donor monocondensed Schiff base ligand, 2-((3-aminopropylimino)methyl)-6-methoxyphenol (HL), with NiCl2·6H2O. The reaction of this complex with NiCl2·6H2O and LnCl3·6H2O (Ln = Gd, Tb, Dy, Ho) in a 1:1:1 molar ratio leads to four hexanuclear Ni4Ln2 complexes formulated as [{(NiL)2Gd}2(μ2-Cl)2(μ3-OH)4(OH2)4]Cl4·CH3CN·H2O (1), [{(NiL)2Tb}2(μ2-Cl)2Cl2(μ3-OH)4(OH2)2]Cl2·12H2O (2), [{(NiL)2Dy}2(μ2-Cl)2Cl2(μ3-OH)4(OH2)2]Cl2·16H2O (3), and [{(NiL)2Ho}2(μ2-Cl)2(μ3-OH)4(OH2)4]Cl4·CH3CN·1.8H2O (4). The Ln(III) centers are octacoordinated with a triangular-dodecahedral geometry, and the geometries around the Ni(II) center…

Schiff baseMaterials science010405 organic chemistryLigandRelaxation (NMR)Relaxation processGeneral Chemistry010402 general chemistryCondensed Matter Physics01 natural sciences0104 chemical scienceschemistry.chemical_compoundCrystallographychemistryFerromagnetismOctahedronZero fieldMolar ratioGeneral Materials ScienceCrystal Growth & Design
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