Quadrupole interaction of $^{8}$Li and $^{9}$Li in LiNbO$_{3}$ and the quadrupole moment of $^{9}$Li
The quadrupole interaction of nuclear spin polarized8Li (I=2) and9Li (I=3/2) in LiNbO3 has been studied at room temperature. The polarization was achieved by optical pumping of a fast atomic beam with circularly polarized laser light. The atoms were implanted into a hexagonal LiNbO3 single crystal and the quadrupole splitting ofβ-NMR spectra was measured. A ratio of ¦Q(9Li)/Q(8Li)¦=0.88(4) for the nuclear quadrupole moments was deduced, yielding a new value of ¦Q(9Li)¦=25.3 (9) mb for the quadrupole moment of9Li.
Nuclear moments of strongly deformed strontium isotopes
Nuclear spins, moments and mean square charge radii of78–100Sr have been obtained by fast ion-beam collinear laserspectroscopy. The experiments performed at ISOLDE have been extended to include99Sr, measured by a non-optical detection scheme with a two-step optical pumping sequence. The results for the strongly deformed isotopes are discussed in the frame of the particle-plus-deformed core model.
Quadrupole moments of radium isotopes from the 7p 2 P 3/2 hyperfine structure in Ra II
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…
Isotope shift and hyperfine structure of stable platinum isotopes
Isotope shift (IS) and hyperfine structure (hfs) measurements have been performed on seven lines of the platinum I spectrum with interference as well as laser fluorescence spectroscopy. In the latter case a frequency-doubled single-mode cw dye laser was applied. The IS of190Pt with a natural abundance of only 0.01% was determined to beδν 190, 192=−38.65(8) mK in theλ306.47 nm transition. The IS parameters and the effective hfs integrals in the configuration (5d+6s)10 were determined in intermediate coupling by a least squares fit of the IS and hfs data with eigenvectors obtained from the platinum fine structure (fs). The results are compared with theoretical values and yield improvedδ〈r 2〉 …
Systematics of nuclear ground state properties inSr78–100by laser spectroscopy
Hyperfine structures and isotope shifts of strontium isotopes with A=78 to A=98 and A=100 were measured by collinear fast beam laser spectroscopy. Nuclear spins, moments and changes in mean square charge radii are extracted from the data. The spins and moments of most of the odd isotopes are explained in the framework of the single particle model. The changes in mean square charge radii are compared with predictions of the droplet model and of Hartree-Fock-plus-BCS calculations. For the isotopes in the transitional regions below and above the N=50 shell closure, the inclusion of quadrupole zero point motion in the Droplet model describes part of the observed shell effect. An additional chan…
Nuclear ground state spins of short-lived strontium isotopes
Nuclear ground state spins of the odd-mass strontium isotopes between A=79 and 97 were determined by measurements of the hyperfine structure in the ionic transition 5s2S1/2−5p2P3/2. The spins of93Sr and97Sr are revised to I=5/2 and I=1/2, respectively, while assignments for the remaining isotopes are confirmed.
A New Sensitive Technique for Laser Spectroscopic Studies of Radioactive Rare-Gas Isotopes
The concept of laser ionization has been widely used in spectroscopy studies and for the detection of minute samples of atoms. Being based on ion counting, it avoids the sensitivity problems of conventional fluorescence spectroscopy, which are due to low detection efficiency and large background from scattered laser light. We report the first application of an alternative ionization scheme which we have developed for collinear laser spectroscopy on fast atomic beams /1/. Here the increase in sensitivity has considerably enlarged the range of isotopes very far from stability, for which nuclear moments and radii can be investigated in hyperfine structure and isotope shift measurements.
Moments and Radii of 78–100Sr
The chain of Sr isotopes ranges from the neutron-shell closure at N = 50 into both the N = 38 and N = 60 deformation regions which represent the main topic of this workshop. For a detailed understanding of the nature of these nuclei, laser spectroscopy can provide the ground state spins and moments, as well as the the changes in the mean square charge radii as a function of the neutron number N. Recent experiments at Karlsruhe [1] and at Daresbury [2] essentially cover the neutron-deficient and stable Sr isotopes between N = 40 and N = 50. In order to complement these results, and to extend the measurements into the region of neutron-rich isotopes, we have performed an experiment at the ISO…
Very high sensitivity in collinear laser spectroscopy: resonance detection by particle counting techniques
Abstract Fast-beam collinear laser spectroscopy with resonance detection by counting of fluorescence photons provides a versatile tool for precise determinations of nuclear ground-state properties. The intrinsic high sensitivity of this method can be further increased by almost three orders of magnitude if measuring schemes based on ion or atom counting are introduced. The optical pumping from one atomic state to another at an appreciably different excitation energy is detected via state-selective collisional charge exchange processes and charge-state separated atom or ion counting. Applications of these techniques on alkaline earth, noble gas, mercury and thallium beams is examined.
Nuclear spin and magnetic moment of 11Li
Abstract Nuclear spin and magnetic moment of 11Li have been measured by optical pumping of a fast atomic beam. The angular asymmetry of the β-radiation from the polarized nuclei was used to detect the hfs of the 2s 2 S 1 2 −2 p 2 P 1 2 resonance line and the NMR signal cubic LiF crystal lattice. The results I= 3 2 and μI=3.6673(25) n.m. indicate a pure 1p 3 2 state of the valence proton.
Nuclear ground state properties of 99Sr by collinear laser spectroscopy with non-optical detection
Abstract Collinear fast-beam laser spectroscopy, with improved sensitivity for ions with hyperfine split transitions, is performed to measure the hyperfine structure and the isotope shift of the well deformed short-lived 99Sr. The new method consists in ground state depopulation by a two-step optical pumping sequence prior to state selective neutralization and fast-atom counting. A definitive nuclear spin value I = 3 2 , the change in mean square charge radius δ〈r2〉98,99 and the nuclear moments are derived. These results are compared to nuclear spectroscopy information and are interpreted in the frame of the particle plus deformed core model.