Search results for "HYPERFINE STRUCTURE"
showing 10 items of 423 documents
Luminescence and EPR spectroscopy of neutron-irradiated single crystals of magnesium aluminium spinel
2016
Abstract Neutron irradiated single crystals of stoichiometric MgAl 2 O 4 and MgAl 2 O 4 :Mn 2+ (0.15 wt. %) were studied using the methods of luminescence spectroscopy and versions of electron paramagnetic resonance. In stoichiometric MgAl 2 O 4 :Mn 2+ single crystals, the transition of a part of manganese impurity ions from tetrahedral to octahedral coordination, caused by irradiation with fast fission neutrons, is detected using photoluminescence spectra. This fact confirms the partial inversion of a normal spinel due to neutron-irradiation. Using pulse EPR technique it is shown that an electron in the field of oxygen vacancy (i.e. from neutron-irradiation induced F + centres, which are s…
The effect of less additives on magnetic properties and microstructure of sintered Nd–(Fe,Ti,Al)–B magnets
2001
Abstract The effect of the addition of 0.5 at.% Cu, Ga, Hf, V, Mo, Nb, Co, Ni, Cr, Dy or Tb on the magnetic properties and the microstructure of sintered Nd 16 Fe 75.22 Ti 1.26 Al 0.32 B 7.2 magnets has been studied. It is shown that these additives cause a small decrease in remanence and in intrinsic coercivity, with the exception of Cu, Dy and Tb additives, which lead to an increase in the intrinsic coercivity. The correlation between the hyperfine magnetic field and the magnetic properties of the investigated magnets is discussed.
Laser and radiofrequency spectroscopy of the 5d 4 6s 6 D multiplet in Ta I
1993
The hyperfine structure (hfs) of181Ta has been investigated using laser radio-frequency double resonance and high resolution laser spectroscopy on collimated atomic beams. The magnetic dipole and electric quadrupole hyperfine structure coupling constants of the 5d46s 6D3/2, 5/2, 7/2, 9/2 metastable states have been determined using radio-frequency spectroscopy. In the 5d4 6s6D1/2 metastable state and the excited 5d3 6s 6p4D3/2,6D5/2, 9/2 as well as the unidentified 28 182.6 cm−1 and 30 021.2 cm−1 states, hfs constants have been obtained from high resolution laser spectroscopy. A radio-frequency converter has been developed in order to reach the frequency region 2.7–10 GHz.
Delocalized Nature of theEδ′Center in Amorphous Silicon Dioxide
2005
We report an experimental study by electron paramagnetic resonance (EPR) of E(')(delta) point defect induced by gamma-ray irradiation in amorphous SiO2. We obtained an estimation of the intensity of the 10 mT doublet characterizing the EPR spectrum of such a defect arising from hyperfine interaction of the unpaired electron with a 29Si (I=1/2) nucleus. Moreover, determining the intensity ratio between this hyperfine doublet and the main resonance line of E(')(delta) center, we pointed out that the unpaired electron wave function of this center is actually delocalized over four nearly equivalent silicon atoms.
Hyperfine transition in209Bi80+—one step forward
2015
The hyperfine transitions in lithium-like and hydrogen-like bismuth were remeasured by direct laser spectroscopy at the experimental storage ring. For this we have now employed a voltage divider which enabled us to monitor the electron cooler voltage in situ. This will improve the experimental accuracy by about one order of magnitude with respect to our previous measurement using the same technique.
High-Spatial-Resolution Monitoring of Strong Magnetic Field using Rb vapor Nanometric-Thin Cell
2011
We have implemented the so-called $\lambda$-Zeeman technique (LZT) to investigate individual hyperfine transitions between Zeeman sublevels of the Rb atoms in a strong external magnetic field $B$ in the range of $2500 - 5000$ G (recently it was established that LZT is very convenient for the range of $10 - 2500$ G). Atoms are confined in a nanometric thin cell (NTC) with the thickness $L = \lambda$, where $\lambda$ is the resonant wavelength 794 nm for Rb $D_1$ line. Narrow velocity selective optical pumping (VSOP) resonances in the transmission spectrum of the NTC are split into several components in a magnetic field with the frequency positions and transition probabilities depending on th…
EPR, ENDOR and TRIPLE Resonance and MO Studies on Ubiquinones (Q-n): Comparison of Radical Anions and Cations of Coenzymes Q-10 and Q-6 with the Mode…
1997
Radical anions and cations of the biologically important coenzymes Q-6 and Q-10, which have 6 and 10 unsaturated isoprene units in their side chains, respectively, have been generated in various solvents, and the results compared with those obtained for Q-0, a ubiquinone with no isoprene units, and for decylubiquinone Q-2 which has a saturated side chain. Hyperfine splitting constants (hfsc) of methyl and methoxy protons of the substituents in the quinone ring, and beta and gamma protons of the side chain were measured by EPR and ENDOR spectroscopy for both the radical anions and cations of Q-0, Q-6 and Q-10, and for the radical anion of Q-2. The relative signs of the hfsc were determined b…
The first unpaired electron placed inside a C3-symmetry P-chirogenic cluster
2010
The Pd(3)(dppm*)(3)(CO)(n+) enantiomers (n = 2 (2), 1 (3)) were prepared either from (R,R)- or (S,S)-P-chirogenic bis(phenyl-m-xylylphosphino)methane (dppm*; 1) and Pd(OAc)(2) in the presence of CF(3)CO(2)H, CO and water (n = 2), and then by reductive electrolysis (n = 1). The stable enantiomeric [Pd(3)((S,S)-dppm*)(3)(CO)](+)˙ (3), is the first C(3)-symmetry radical-cation M-M bonded cluster, therefore the odd electron is delocalized onto the Pd(3) frame within this symmetry. The novel chiral species have been characterized by circular dichroism (CD) of both enantiomers of the Pd(3)(dppm*)(3)(CO)(2+) clusters (2) and by EPR spectroscopy for the Pd(3)((S,S)-dppm*)(3)(CO)(+)˙ paramagnetic co…
High-precision measurements of the hyperfine structure of cobalt ions in the deep ultraviolet range
2023
Scientific reports 13(1), 4783 (2023). doi:10.1038/s41598-023-31378-1
NQR/NMR and Mössbauer spectroscopy of sulfides: potential and versatility
2013
Nuclear quadrupole resonance (NQR), nuclear magnetic resonance (NMR) and nuclear gamma-resonance (NGR or Mossbauer Effect) methods are generally described as highly sensitive tools in studies of local electronic structure and symmetry in solid-state materials. This is due to high informativity in electronic structure investigations, high resolution in phase-structural diagnostics (down to nano-scale), possibility to study polycrystalline and complex compounds, and to the non-destructive character of these methods. As applied to Earth sciences, both NQR/NMR and Mossbauer spectroscopy methods contribute to mineralogical material science and mineral physics. Another important aspect is the fac…