Search results for "hyperfine structure"
showing 10 items of 423 documents
Analytical evaluation of first-order electrical properties based on the spin-free Dirac-Coulomb Hamiltonian.
2011
We report an analytical scheme for the calculation of first-order electrical properties using the spin-free Dirac-Coulomb (SFDC) Hamiltonian, thereby exploiting the well-developed density-matrix formulations in nonrelativistic coupled-cluster (CC) derivative theory. Orbital relaxation effects are fully accounted for by including the relaxation of the correlated orbitals with respect to orbitals of all types, viz., frozen-core, occupied, virtual, and negative energy state orbitals. To demonstrate the applicability of the presented scheme, we report benchmark calculations for first-order electrical properties of the hydrogen halides, HX with X = F, Cl, Br, I, At, and a first application to th…
Deuterium hyperfine splittings in the rotational spectrum of NH2D as revealed by Lamb-dip spectroscopy
2020
Abstract In the context of radio-astronomical observations, laboratory experiments constitute a cornerstone in the interpretation of rich line surveys due to the concomitant presence of numerous emitting molecules. Here, we report the investigation of three different rotational transitions of mono-deuterated ammonia (NH2D), a species of astrophysical interest, for which the contribution of the deuterium nuclear spin to the rotational spectrum has been resolved for the first time in the millimeter- and submillimeter-wave domain. The effect of hyperfine interactions on the rotational spectrum has been unveiled by a combined theoretical and experimental approach. Quantum-chemical calculations …
Probing Sizes and Shapes of Nobelium Isotopes by Laser Spectroscopy
2018
Until recently, ground-state nuclear moments of the heaviest nuclei could only be inferred from nuclear spectroscopy, where model assumptions are required. Laser spectroscopy in combination with modern atomic structure calculations is now able to probe these moments directly, in a comprehensive and nuclear-model-independent way. Here we report on unique access to the differential mean-square charge radii of ^{252,253,254}No, and therefore to changes in nuclear size and shape. State-of-the-art nuclear density functional calculations describe well the changes in nuclear charge radii in the region of the heavy actinides, indicating an appreciable central depression in the deformed proton densi…
Lifetimes and g-factors of the HFS states in H-like and Li-like bismuth
2018
The LIBELLE experiment performed at the experimental storage ring (ESR) at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, Germany, has successfully determined the ground state hyperfine (HFS) splittings in hydrogen-like ($^{209}\rm{Bi}^{82+}$) and lithium-like ($^{209}\rm{Bi}^{80+}$) bismuth. The study of HFS transitions in highly charged ions enables precision tests of QED in extreme electric and magnetic fields otherwise not attainable in laboratory experiments. Besides the transition wavelengths the time resolved detection of fluorescence photons following the excitation of the ions by a pulsed laser system also allows to extract lifetimes of the upper HFS levels and g-fac…
Laser spectroscopy measurement of the 2s-hyperfine splitting in lithium-like bismuth
2017
We have recently reported on the first direct measurement of the $2s$ hyperfine transition in lithium-like bismuth (209Bi80+) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany. Combined with a new measurement of the $1s$ hyperfine splitting (HFS) in hydrogen-like (209Bi82+) the so-called specific difference ${\rm{\Delta }}^{\prime} E=-61.37(36)$ meV could be determined and was found to be in good agreement with its prediction from strong-field bound-state quantum electrodynamics. Here we report on additional investigations performed to estimate systematic uncertainties of these results and on details of the experimental setup. We show that the dominating uncertainty a…
Microwave, High-Resolution Infrared, and Quantum Chemical Investigations of CHBrF2: Ground and v4 = 1 States
2011
A combined microwave, infrared, and computational investigation of CHBrF(2) is reported. For the vibrational ground state, measurements in the millimeter- and sub-millimeter-wave regions for CH(79)BrF(2) and CH(81)BrF(2) provided rotational and centrifugal-distortion constants up to the sextic terms as well as the hyperfine parameters (quadrupole-coupling and spin-rotation interaction constants) of the bromine nucleus. The determination of the latter was made possible by recording of spectra at sub-Doppler resolution, achieved by means of the Lamb-dip technique, and supporting the spectra analysis by high-level quantum chemical calculations at the coupled-cluster level. In this context, the…
Towards Molecular Conductors with a Spin‐Crossover Phenomenon:Crystal Structures, Magnetic Properties and Mössbauer Spectra of[Fe(salten)Mepepy][M(dm…
2005
Three new iron(III) compounds of formula [Fe(salten)Mepepy][M(dmit)2]·CH3CN (M = Ni, Pd, Pt; H2salten = 4-azaheptamethylene-1,7-bis(salicylideneiminate); Mepepy = 1-(pyridin-4-yl)-2-(N-methylpyrrol-2-yl) ethane; dmit2– = 1,3-dithiole-2-thione-4,5-dithiolato) have been synthesised and the crystal structure of each compound has been solved at different temperatures. The structures consist of alternating layers of [M(dmit)2]– units and [Fe(salten)Mepepy] cations. In the Ni compound photo-isomerisation of the Mepepy ligand can be observed in dichloromethane solution. The temperature dependence of the magnetic susceptibility of the compounds reveals a gradual S = 5/2 blabla S = 1/2 spin crossove…
Fifty Years of Mössbauer Spectroscopy in Solid State Research - Remarkable Achievements, Future Perspectives
2011
Mossbauer spectroscopy was founded more than fifty years ago based on an outstanding discovery by the young German physicist Rudolf Ludwig Mossbauer while working on his Ph.D. thesis. He discovered the recoilless nuclear resonance fluorescence of gamma radiation and was awarded the Nobel Prize in Physics in 1961 as one of the youngest recipients of this most prestigious award. His discovery led to the development of a new technique for measurements of hyperfine interactions between nuclear moments and electromagnetic fields. This method, with highest sharpness of tuning of 10–13, yields information on valence state, symmetry, magnetic behavior, phase transition, lattice dynamics and other s…
CRIS: A new method in isomeric beam production
2013
The Collinear Resonance Ionization Spectroscopy (CRIS) experiment at ISOLDE, CERN, uses laser radiation to stepwise excite and ionize an atomic beam for the purpose of ultra-sensitive detection of rare isotopes, and hyperfine-structure measurements. The technique also offers the ability to purify an ion beam that is heavily contaminated with radioactive isobars, including the ground state of an isotope from its isomer, allowing decay spectroscopy on nuclear isomeric states to be performed. The isomeric ion beam is selected by resonantly exciting one of its hyperfine structure levels, and subsequently ionizing it. This selectively ionized beam is deflected to a decay spectroscopy station (DS…
Lambda-doublet specificity in the low-temperature capture of NO(X Π21/2) in low rotational states by C+ ions
2009
Following our general approach to Lambda-doubling specificity in the capture of dipolar molecules by ions [M. Auzinsh et al., J. Chem. Phys. 128, 184304 (2008)], we calculate the rate coefficients for the title process in the temperature range 10(-4)<T<10(2) K. Three regimes considered are as follows: (i) nonadiabatic capture in the regime of high-field Stark effect with respect to the Lambda-doubling components, (10(-1)<T<10(2) K), (ii) adiabatic capture in the regime of intermediate Stark effect (10(-3)<T<10(-1) K), and (iii) adiabatic capture in the limit of very low temperatures (T<<10(-3) K) in the regime of quadratic Stark effect with respect to the Lambda-doubling and hyperfine compo…