Search results for "Fine structure"
showing 10 items of 656 documents
Implementation of a double-scanning technique for studies of the Hanle effect in rubidium vapor
2007
We have studied the resonance fluorescence of a room-temperature rubidium vapor exited to the atomic 5P3/2 state (D2 line) by powerful single-frequency cw laser radiation (1.25 W/cm^2) in the presence of a magnetic field. In these studies, the slow, linear scanning of the laser frequency across the hyperfine transitions of the D2 line is combined with a fast linear scanning of the applied magnetic field, which allows us to record frequency-dependent Hanle resonances from all the groups of hyperfine transitions including V- and Lambda - type systems. Rate equations were used to simulate fluorescence signals for 85Rb due to circularly polarized exciting laser radiation with different mean fre…
The Hanle effect and level crossing spectroscopy in Rb vapour under strong laser excitation
2003
We measure and simulate numerically the Hanle effect and non-zero field level crossing signals in 85 Rb and 87 Rb atoms in a magnetic field at room temperature. Diode laser radiation from 4 mW cm −2 to 3. 3W cm −2 tuned to the D2 absorption line of each isotope excites atoms into all the excited-state hyperfine levels simultaneously inside the unresolved Doppler profile. Polarization fluorescence detection is used to observe dark and bright resonances, as well as non-zero field level crossing resonances, for several excitation lines. A broad spectral line excitation model is applied to analyse the measured signals. The non-linear Zeeman effect is included in the model for both ground and ex…
Iodine hyperfine structure and absolute frequency measurements at 565, 576, and 585nm
2006
Abstract The hyperfine structure splittings of the P(10)14-1, R(15)14-1, and R(99)15-1 transitions at 585 nm, P(62)17-1 at 576 nm, and P(80)21-1 at 565 nm in 127 I 2 are measured by heterodyne spectroscopy using two dye lasers. In addition, the absolute frequencies of the hyperfine components P(10)14-1 a 15 and P(80)21-1 a 10 are determined using a self-referenced frequency comb. These frequencies are used in an experiment testing relativistic time dilation by laser spectroscopy on a fast ion beam.
Disappearance of correlations in the atom motion upon hydrogen intercalation into ReO3lattice
2016
The influence of hydrogen intercalation on the local structure of rhenium trioxide is studied in-situ by the Re L3-edge EXAFS spectroscopy and analysed using a novel approach, based on the use of evolutionary algorithm and wavelet transform. The proposed method allows us to perform accurate EXAFS analysis within the multiple-scattering approach taking into account contributions from outer coordination shells and to access the information on correlations in atomic thermal motion.
Interpretation of EXAFS in scheelite-type AWO4(A = Ca, Sr, Ba) compounds using molecular dynamics simulations
2013
In this work we successfully interpret the W L3-edge EXAFS spectra in scheelite-type AWO4 (A = Ca, Sr, Ba) compounds using a combination of classical NVT molecular dynamics (MD) and ab initio multiple-scattering (MS) theory. The configuration-averaged EXAFS spectra show good agreement with our room temperature experimental data supporting the reliability of the developed force-field models. The contributions from all coordination shells up to 6 A are elucidated. The contribution of the MS effects into the total EXAFS signal in AWO4 compounds is small, being around 10%.
Laser spectroscopy of gallium isotopes beyond N = 50
2012
The installation of an ion-beam cooler-buncher at the ISOLDE, CERN facility has provided increased sensitivity for collinear laser spectroscopy experiments. A migration of single-particle states in gallium and in copper isotopes has been investigated through extensive measurements of ground state and isomeric state hyperfine structures. Lying beyond the N = 50 shell closure, 82Ga is the most exotic nucleus in the region to have been studied by optical methods, and is reported here for the first time. ispartof: pages:012071-6 ispartof: Journal of Physics: Conference Series vol:381 issue:1 pages:012071-6 ispartof: Rutherford Centennial Conference on Nuclear Physics location:Manchester, UK dat…
Mössbauer Spectroscopy: Elegance and versatility in chemical diagnostics
2010
Dedicated to Professor Rudolf Ludwig Mossbauer on the occasion of his 80th birthday . Soon after the discovery of the recoilless nuclear resonance fluorescence by Rudolf L. Mossbauer some fifty years ago a new spectroscopic technique developed quickly on the basis of this resonance phenomenon as an excellent tool for the investigation of materials through electric and magnetic hyperfine interactions between electrons and suitable Mo uml ssbauer nu-clides. Many disciplines of solid state research have benefited from applications of the new tool for non-destructive phase analysis. Chemists in particular have recognized the information that can be derived from Mo uml ssbauer spectra regarding …
Effect of the capping agents on cobalt nanoparticles
2009
The achievement of high information density and fast recording rate in memory devices crucially depends on the structure of magnetic domains. In this paper cobalt nanoparticles are synthesised using two capping agents (TOA, ODA) and two different preparation routes: thermal decomposition (TD) and Solvated Metal Atom Dispersion (SMAD). The interaction of capping agents with free metal clusters and their influence on Co nanoparticles size, atomic structure and oxidation state is investigated by means of X-ray diffraction and X-ray absorption spectroscopy.
Interpretation of the U L3-edge EXAFS in uranium dioxide using molecular dynamics and density functional theory simulations
2016
X-ray absorption spectroscopy is employed to study the local structure of pure and Cr-doped UO2 at 300 K. The U L3-edge EXAFS spectrum is interpreted within the multiplescattering (MS) theory using the results of the classical and ab initio molecular dynamics simulations, allowing us to validate the accuracy of theoretical models. The Cr K-edge XANES is simulated within the full-multiple-scattering formalism considering a substitutional model (Cr at U site). It is shown that both unrelaxed and relaxed structures, produced by ab initio density functional theory (DFT) calculations, fail to describe the experiment.
Ab initio molecular dynamics simulations of the Sc K-edge EXAFS of scandium trifluoride
2016
Scandium fluoride ScF3 has a simple cubic structure and attracts attention due to its large negative thermal expansion (NTE) over a wide range of temperatures (0-1100 K). In this study we present ab initio molecular dynamics (AIMD) simulations of ScF3 and their validation using the Sc K-edge EXAFS spectra in the temperature range from 300 K to 1000 K measured at the XAFS beamline of ELETTRA. The obtained results allow an assessement of the employed AIMD model and provide insight into the local structure and the lattice dynamics of ScF3 beyond the harmonic approximation. A strong anisotropy of the fluorine atom vibrations in the direction orthogonal to the -Sc-F-Sc- chain is observed. An exp…