Search results for "Hyperfine structure"

Ground-state hyperfine-structure measurements of unstableEu+isotopes in a Paul ion trap

1997

Hyperfine separations in unstable ${\mathrm{Eu}}^{+}$ ions of mass 148, 149, and 150 have been measured in laser-microwave double-resonance experiments in a Paul ion trap. In spite of the small available quantities of the isotopes, the experimental uncertainties are of the order of ${10}^{\ensuremath{-}8}$ or below, which is of the same order as in earlier measurements on stable isotopes of ${\mathrm{Eu}}^{+}.$ Extensive second-order perturbation calculation is required to obtain coupling constants for magnetic-dipole $(A)$ and electric-quadrupole $(B)$ interactions. The uncertainties are a few times ${10}^{\ensuremath{-}7}$ for $A$ and ${10}^{\ensuremath{-}3}$ for $B.$ The experiments are …

Analytic energy gradients in closed-shell coupled-cluster theory with spin-orbit coupling

2008

Gradients in closed-shell coupled-cluster (CC) theory with spin-orbit coupling included in the post Hartree-Fock treatment have been implemented at the CC singles and doubles (CCSD) level and at the CCSD level augmented by a perturbative treatment of triple excitations [CCSD(T)]. The additional computational effort required in analytic energy-gradient calculations is roughly the same as that for ground-state energy calculations in the case of CCSD, and it is about twice in the case of CCSD(T) calculations. The structures, harmonic frequencies, and dipole moments of some heavy-element compounds have been calculated using the present analytic energy-gradient techniques including spin-orbit co…

The rare isotopomers of HCN: HC15N and DC15N. Rotational spectrum and resolved nuclear hyperfine structures due to 15N and D.

2005

In the present work the J + 1 ← J rotational transitions, with J = 0-7, of HC15N and the J + 1 ← J rotational transitions, with J = 0-7, 9, of DC15N have been investigated. The Lamb-dip technique has been employed in order to resolve the hyperfine structure due to deuterium and 15N. For HC15N, the hyperfine parameters have been determined for the first time. With respect to DC15N, only the spin rotation of 15N have been determined for the first time but a more reliable spin rotation of D has been obtained. The experimental evaluation of the hyperfine constants has been aided by highly accurate ab initio computations. Furthermore, the rotational transitions observed allowed us to provide the…

Si29Hyperfine Structure of theE′αCenter in Amorphous Silicon Dioxide

2006

We report a study by electron paramagnetic resonance on the $E^{\ensuremath{'}}{}_{\ensuremath{\alpha}}$ point defect in amorphous silicon dioxide ($a\mathrm{\text{\ensuremath{-}}}{\mathrm{SiO}}_{2}$). Our experiments were performed on $\ensuremath{\gamma}$-ray irradiated oxygen-deficient materials and pointed out that the $^{29}\mathrm{Si}$ hyperfine structure of the $E^{\ensuremath{'}}{}_{\ensuremath{\alpha}}$ consists of a pair of lines split by $\ensuremath{\sim}49\text{ }\text{ }\mathrm{mT}$. On the basis of the experimental results, a microscopic model is proposed for the $E^{\ensuremath{'}}{}_{\ensuremath{\alpha}}$ center, consisting of a hole trapped in an oxygen vacancy with the un…

Spectroscopic data, spin-orbit functions, and revised analysis of strong perturbative interactions for theA 1Σ+andb 3Πstates of RbCs

2010

The current interest in producing ultracold RbCs molecules by optical excitation from weakly bound Feshbach resonances and stimulated decay to the absolute ground state requires detailed analyses of the intermediate excited states. In this study, we present two sets of experimental Fourier-transform spectroscopic data of the $A{ }^{1}{\ensuremath{\Sigma}}^{+}$-$b{ }^{3}\ensuremath{\Pi}$ complex. The $A$-$b$ mixed vibrational levels are the most likely candidates to be intermediates in the molecular formation. The more recent and more accurate data set is from mixed $A$-$b\ensuremath{\rightarrow}X$ transitions, while the second is derived in large part from $(4){ }^{1}{\ensuremath{\Sigma}}^{…

Laser Resonance Chromatography of Superheavy Elements.

2020

Optical spectroscopy constitutes the historical path to accumulate basic knowledge on the atom and its structure. Former work based on fluorescence and resonance ionization spectroscopy enabled identifying optical spectral lines up to element 102, nobelium. The new challenges faced in this research field are the refractory nature of the heavier elements and the decreasing production yields. A new concept of ion-mobility-assisted laser spectroscopy is proposed to overcome the sensitivity limits of atomic structure investigations persisting in the region of the superheavy elements. The concept offers capabilities of both broadband-level searches and high-resolution hyperfine spectroscopy of s…

Hyperfine structure in the rotational spectra of trans-formic acid: Lamb-dip measurements and quantum-chemical calculations

2010

Context. Formic acid, HCOOH, is the simplest organic acid and the first that has been identified in the interstellar medium. Its astrophysical relevance has motivated this spectroscopic study. Aims. The aim of this investigation is to provide very accurate rest frequencies for the trans isomer of HCOOH as well as to improve the spectroscopic and hyperfine parameters available in the literature for this molecule. Methods. The Lamb-dip technique has been exploited in order to record the rotational spectrum of trans-HCOOH at sub-Doppler resolution in the millimeter- and submillimeter-wave frequency ranges and, when possible, to resolve the hyperfine structure due to the hydrogen nuclei. THz me…

Hyperfine structure measurements of neutral niobium with Fourier transform spectroscopy

2010

Aims. We report on experimental studies of hyperfine structure splitting of neutral niobium.Methods. We used high-resolution Fourier transform spectroscopy to record a spectrum of niobium produced with a hollow cathode discharge lamp in the range of wavenumbers from 10 000 cm-1 to 30 000 cm-1 .Results. The magnetic dipole hyperfine structure constants A were determined for the 109 levels of odd parity by analyzing the profiles of 224 spectral lines. The A  values of 57 of these level are reported for the first time.

PRECISE DETERMINATION OF 135Ba+ AND 137Ba+ HYPERFINE STRUCTURE

1981

Sudden change in the nuclear charge distribution of very light gold isotopes

1987

4 pages, 3 tables, 2 figures.-- PACS nrs.: 21.10.Ft, 21.10.Ky, 27.70.+q.