Search results for "Hyperfine structure"
showing 10 items of 423 documents
Laser spectroscopy of cooled zirconium fission fragments
2002
The first on-line laser spectroscopy of cooled fission fragments is reported. The $^{\mathrm{96}\mathrm{--}\mathrm{102}}\mathrm{Z}\mathrm{r}$ ions, produced in uranium fission, were extracted and separated using an ion guide isotope separator. The ions were cooled and bunched for collinear laser spectroscopy by a gas-filled linear Paul trap. New results for nuclear mean-square charge radii, dipole, and quadrupole moments are reported across the $N=60$ shape change. The mean-square charge radii are found to be almost identical to those of the Sr isotones and previously offered modeling of the radial changes is critically reviewed.
On the sensitivity of ion traps for spectroscopic applications
1979
Ba+ ions, created by surface ionization near one endcap of an rf quadrupole trap were slowed down by collisions with the background gas. At He pressures of 10−6 mbar or more 2% of the primary ions could be trapped. The sensitivity of ion detection by fluorescence radiation allows spectroscopic experiments, starting from less than 107 particles. The observation of the ground-state hyperfine splitting of137Ba+ is given as an example.
Collinear Laser Spectroscopy on Fast Atomic Beams
1978
In collinear geometry we have observed laser-excited, narrow resonances in fast beams of Na and Cs atoms obtained from ion beams by charge transfer collisions. Being very sensitive, the method is suited for measuring isotope shifts and hyperfine structure of isotopes far from stability provided by on-line mass separators. It may be used furthermore to study inelastic charge transfer from the energy-loss spectrum of the Doppler-shifted lines.
Isotope shifts and hyperfine structure in the transitions of gadolinium
2000
High-resolution resonance ionization mass spectrometry has been used to measure isotope shifts and hyperfine structure in all (J = 2-6) and the transitions of gadolinium (Gd I). Gadolinium atoms in an atomic beam were excited with a tunable single-frequency laser in the wavelength range of 422-429 nm. Resonant excitation was followed by photoionization with the 363.8 nm line of an argon ion laser and resulting ions were mass separated and detected with a quadrupole mass spectrometer. Isotope shifts for all stable gadolinium isotopes in these transitions have been measured for the first time. Additionally, the hyperfine structure constants of the upper states have been derived for the isotop…
A New Sensitive Technique for Laser Spectroscopic Studies of Radioactive Rare-Gas Isotopes
1987
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.
Charge trapping processes and energy transfer studied in lead molybdate by EPR and TSL
2019
Abstract Charge trapping and energy transfer processes are investigated in PbMoO4 single crystals by electron paramagnetic resonance (EPR) and wavelength-resolved thermally stimulated luminescence (TSL) in a correlated manner. New signals produced by two differently perturbed Mo5+ centers (Mo2 and Mo3) were observed in EPR spectra measured in the crystals after 420 nm light irradiation. Two sets of spin-Hamiltonian parameters, g tensor and the 95,97Mo, 207Pb (super) hyperfine tensors, have been determined and analyzed in terms of crystal field and LCAO-MO theories. A significant overlap of the Mo 5d1 and 6s6p ligand Pb orbitals was deduced for the Mo3 whereas the Mo2 center seemed to be not…
Peculiarities of Forming of Magnetic Hardening in Sintered Nd15Fe76.2Ti1.0Al0.8B7 Permanent Magnet by Ageing
1999
Variations of the intrinsic coercivity ( i H c ) with ageing (at 293 to 1173 K for 0.45 to 57.6 ks) of sintered Nd 15 Fe 76.2 Ti 1.0 Al 0.8 B 7 have been investigated. The tests indicated minimum and maximum of intrinsic coercivity ( i H min c and i H max c ) at temperatures 725 K and 1025 K, respectively. The observed behaviour of i H c has been compared with microhardness measurements and microstructure observations (SEM, EDAX, domain structure (DS) and room temperature Mossbauer spectroscopy). SEM and DS investigations gave hints to a change in microstructure. Fitting of the Mossbauer spectra of permanent magnets for different i H c has shown that the magnetic hyperfine field Bhf of 8j2 …
An unambiguous procedure for discovering relaxation influence on M�ssbauer spectra
1994
A mathematical procedure which gives an opportunity to distinguish between relaxation and distribution mechanisms of the Mossbauer line broadening is proposed. It is based on the method of Mossbauer line sharpening developed recently [1] and allows one to answer unambiguously the question whether or not relaxation manifests itself in Mossbauer measurements by examining the wings of the spectrum. The procedure is applied to the spectra of high spin ferric metmyoglobin and (Fe0.65Ni0.35)1−xMnx alloys. Analysis of the metmyoglobin spectra manifests the presence of the relaxation influence in the temperature range 10 K≦T≦100 K. Analysis of the alloy spectra shows that for the temperatures 4 K≦T…
Ni61Mössbauer study of the hyperfine magnetic field near the Ni surface
1987
$^{61}\mathrm{Ni}$ M\"ossbauer measurements have been performed at 4.2 K on spherical Ni particles covered with a protective layer of SiO, with average diameter of 500 and 50 \AA{}. The hyperfine magnetic field at $^{61}\mathrm{Ni}$ nuclei for 500-\AA{} particles has been found to be 78.3(4) kOe, compared with the field for Ni foil of 75.0(2) kOe. The small difference is due to the demagnetization and dipolar fields in 500-\AA{} particles. The spectrum of 50-\AA{} particles has a surface component with the corresponding value of the hyperfine magnetic field of 40.3(5.4) kOe. This strongly indicates that, in accordance with recent theoretical studies, there is a decrease of the hyperfine mag…
The role of impurities in the irradiation induced densification of amorphous SiO(2).
2011
In a recent work (Buscarino et al 2009 Phys. Rev. B 80 094202), by studying the properties of the (29)Si hyperfine structure of the E'(γ) point defect, we have proposed a model able to describe quantitatively the densification process taking place upon electron irradiation in amorphous SiO(2) (a-SiO(2)). In particular, we have shown that it proceeds heterogeneously, through the nucleation of confined densified regions statistically dispersed into the whole volume of the material. In the present experimental investigation, by using a similar approach on a wider set of materials, we explore how this process is influenced by impurities, such as OH and Cl, typically involved in relevant concent…