Search results for "HYPERFINE"
showing 10 items of 428 documents
Hyperfine shifts for cesium in Argon at high density
1974
An optical pumping experiment was performed to obtain precise hfs shifts for Cs in Argon. The shifts measured include a term quadratic in the densityρ and a large temperature coefficient. The coefficients of the expansionδv/v0=a ρ+bρ2 area(80 °C)=−29.8(6)x10−9(Torr−1(0°C))b(80 °C)=+11(2)x10−14(Torr−2(0 °C)).
Precision spectroscopy at heavy ion ring accelerator SIS300
2007
Unique spectroscopic possibilities open up if a laser beam interacts with relativistic lithium-like ions stored in the heavy ion ring accelerator SIS300 at the future Facility for Antiproton and Ion Research FAIR in Darmstadt, Germany. At a relativistic factor gamma = 36 the 2P 1/2 level can be excited from the 2S 1/2 ground state for any element with frequency doubled dye-lasers in collinear geometry. Precise transition energy measurements can be performed if the fluorescence photons, boosted in forward direction into the X-ray region, are energetically analyzed with a single crystal monochromator. The hyperfine structure can be investigated at the 2P 1/2 - 2S 1/2 transition for all elemen…
Mössbauer Spectral Study of Two Layered Honeycomb Molecular Magnets: PPh4FeIIFeIII(ox)3 and NBu4FeIIFeIII(ox)3
2002
The Mossbauer spectra of the layer ferrimagnets PPh4FeIIFeIII(ox)3 and NBu4FeIIFeIII(ox)3 have been measured between 1.9 and 315 K. The paramagnetic spectra exhibit both high-spin iron(II) and iron(III) doublets. The iron(II) quadrupole splittings are negative and decrease substantially upon cooling as a result of a low-symmetry crystal field splitting. In contrast, the iron(III) splittings are small, positive, and virtually independent of temperature. The respective magnetic ordering temperatures of 30 and 42.5 K agree well with the phase observed by bulk magnetometry and the magnetic sextets yield hyperfine fields of ca. 60 kOe for iron(II) and 540 kOe for iron(III). The unusually low iro…
Importance of Spin-Orbit Interaction for the Electron Spin Relaxation in Organic Semiconductors
2013
Despite the great interest organic spintronics has recently attracted, there is only a partial understanding of the fundamental physics behind electron spin relaxation in organic semiconductors. Mechanisms based on hyperfine interaction have been demonstrated, but the role of the spin-orbit interaction remains elusive. Here, we report muon spin spectroscopy and time-resolved photoluminescence measurements on two series of molecular semiconductors in which the strength of the spin-orbit interaction has been systematically modified with a targeted chemical substitution of different atoms at a particular molecular site. We find that the spin-orbit interaction is a significant source of electro…
57Fe,61Ni, and121Sb M�ssbauer study of oxidic spinel ferrites CoxNi5/3?xFeSb1/3O4
1987
Antimony substituted nickel ferrites Co x Ni5/3−xFeSb1/3O4 withx=0,1/3,1,4/3, and 5/3 were prepared by the common ceramic technique, and the single-phase structure was confirmed by x-ray powder diffraction.57Fe Mossbauer spectra were recorded at 4.2 K with and without an applied magnetic fieldHlong=60 kOe in order to determine the cation distribution and the spin structure. Utilizing the cation distributions and the Yafet-Kittel spin structures for B-site Fe3+ ions, derived from Mossbauer experiments the calculated magnetic moments are in excellent agreement with the experimental values at 4.2 K. The existence of Ni2+ ions in crystallographic A-sites was confirmed by61Ni Mossbauer spectrosc…
New Nuclear Magnetic Moment of Bi209 : Resolving the Bismuth Hyperfine Puzzle
2018
A recent measurement of the hyperfine splitting in the ground state of Li-like ${^{208}\mathrm{Bi}}^{80+}$ has established a ``hyperfine puzzle''---the experimental result exhibits a $7\ensuremath{\sigma}$ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017); J. P. Karr, Nat. Phys. 13, 533 (2017)]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (${\ensuremath{\mu}}_{I}$) of $^{209}\mathrm{Bi}$. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of ${\ensuremath{\mu}}_{I}(^{209…
Limits on gravitational Einstein Equivalence Principle violation from monitoring atomic clock frequencies during a year
2016
Sun's gravitation potential at earth varies during a year due to varying Earth-Sun distance. Comparing the results of very accurate measurements of atomic clock transitions performed at different time in the year allows us to study the dependence of the atomic frequencies on the gravitational potential. We examine the measurement data for the ratio of the frequencies in Hg$^+$ and Al$^+$ clock transitions and absolute frequency measurements (with respect to caesium frequency standard) for Dy, Sr, H, hyperfine transitions in Rb and H, and obtain significantly improved limits on the values of the gravity related parameter of the Einstein Equivalence Principle violating term in the Standard Mo…
Observation of the Bottomonium Ground State in the Decay Υ(3S)→γηb
2008
The authors report the results of a search for the bottomonium ground state {eta}{sub b}(1S) in the photon energy spectrum with a sample of (109 {+-} 1) million of {Upsilon}(3S) recorded at the {Upsilon}(3S) recorded at the {Upsilon}(3S) energy with the BABAR detector at the PEP-II B factory at SLAC. They observe a peak in the photon energy spectrum at E{sub {gamma}} = 921.2{sub -2.8}{sup +2.1}(stat) {+-} 2.4(syst) MeV with a significance of 10 standard deviations. They interpret the observed peak as being due to monochromatic photons from the radiative transition {Upsilon}(3S) {yields} {gamma} {eta}{sub b}(1S). This photon energy corresponds to an {eta}{sub b}(1S) mass of 9388.9{sub -2.3}{…
Measurement of the quadrupole moment of Re185 and Re187 from the hyperfine structure of muonic X rays
2020
The hyperfine splitting of the 5g→4f transitions in muonic Re185,187 has been measured using high resolution high purity germanium detectors and compared to state-of-the-art atomic theoretical predictions. The spectroscopic quadrupole moment has been extracted using modern fitting procedures and compared to the values available in literature obtained from muonic x rays of natural rhenium. The extracted values of the nuclear spectroscopic quadrupole moment are 2.07(5) b and 1.94(5) b, respectively for Re185 and Re187.
Quadrupole moments of radium isotopes from the 7p 2 P 3/2 hyperfine structure in Ra II
1988
The hyperfine structure and isotope shift of221–226Ra and212,214Ra have been measured in the ionic (Ra II) transition 7s 2 S 1/2–7p 2 P 3/2 (λ=381.4 nm). The method of on-line collinear fast-beam laser spectroscopy has been applied using frequency-doubling of cw dye laser radiation in an external ring cavity. The magnetic hyperfine fields are compared with semi-empirical and ab initio calculations. The analysis of the quadrupole splitting by the same method yields the following, improved values of spectroscopic quadrupole moments:Q s (221Ra)=1.978(7)b,Q s (223Ra)=1.254(3)b and the reanalyzed valuesQ s (209Ra)=0.40(2)b,Q s (211Ra)=0.48(2)b,Q s (227Ra)=1.58(3)b,Q s (229Ra)=3.09(4)b with an ad…