Search results for "Quadrupole splitting"
showing 10 items of 50 documents
Heat-capacity anomaly due to spin reorientation and thermodynamic functions of ErFeO3 and TmFeO3
2001
Abstract Heat capacities of orthoferrites, ErFeO 3 and TmFeO 3 , have been measured below room temperature by adiabatic calorimetry. A broad but definite anomaly due to the spin reorientation phenomenon was successfully detected in the expected temperature range (ca. 90 K). The results are compared with a vast anomaly reported for YbFeO 3 . The temperature dependence of the electric quadrupole splitting of the Fe nuclear levels was determined by Mossbauer spectroscopy through the spin reorientation. A heat capacity anomaly centered at 3.60 K due to the magnetic ordering of Er 3+ ions was clearly detected. Some Schottky anomalies were resolved and energy splittings involved were roughly esti…
The dynamics of (57)Fe nuclei in Fe(III)-DNA condensates.
2001
Abstract The dynamics of iron nuclei in the condensates obtained by interaction of Fe III with DNA, Fe III (DNA monomer) 2 , have been investigated by variable temperature 57 Fe Mossbauer spectroscopy. Studies were effected on gel and freeze-dried samples, obtaining nearly coincident values of the parameters isomer shift and nuclear quadrupole splitting in T ranges 20–260 K. Functions ln( A T / A 77.3 ) vs. T , here employed to investigate the dynamics of Fe nuclei, showed linear trends in the T ranges 20–150 and 150–260 K, respectively, the latter with larger slopes. Data coincided for gelled and freeze-dried specimens. No variation of δ or Δ E parameters occurred at the two T intervals, w…
Investigation of ultrathin iron and iron/nickel layers prepared from Langmuir-Blodgett films
1996
Oxidic and metallic iron and iron/nickel multilayers, formed after thermal and chemical treatment of Langmuir-Blodgett films, were investigated. Reduced iron-stearate multilayers were compared with evaporated films concerning their phase composition and their lateral homogeneity. The sequence of metallic and oxidic iron in the films after reduction was determined. Oxidic iron/nickel mixed layers can be prepared from Langmuir-Blodgett films, in which a magnetically non-ordered Fe3+ phase exhibiting a distribution of the quadrupole splitting is observed. After reduction of such layers, two metallic iron phases appear dependent on the nickel concentration. The hyperfine field distribution of t…
Mössbauer effect study of the electronic ground state of iron(II)in tris(2-chlorophenanthroline)iron(II) perchlorate
1976
Abstract Mossbauer spectra of [Fe(2-Cl-phen) 3 ](ClO 4 ) 2 ·H 2 O have been measured in the temperature range 293 − 5 K. The spectra indicate that the iron atom in this compound possesses a spin quintet ground state throughout the temperature range under study, in contradiction to the suggested high spin-low spin transition, which has been concluded from a magnetic susceptibility study by other authors. From a theoretical analysis of the temperature dependence of the quadrupole splitting, with trigonal distortion, spin-orbit coupling, and effects of covalency taken into account, the ground term of iron(II) in this compound has been elucidated as being 5 A 1 ( 5 T 2g ), separated from the 5 …
Nuclear Quadrupole Moment of 119Sn
2008
Second-order scalar-relativistic Douglas-Kroll-Hess density functional calculations of the electric field gradient, including an analytic correction of the picture change error, were performed for 34 tin compounds of which molecular structures and Sn-119 Mossbauer spectroscopy parameters are experimentally known. The components of the diagonalized electric field gradient tensor, V-xx,V-yy, V-zz, were used to determine the quantity V, which is proportional to the nuclear quadrupole splitting parameter Delta E. The slope of the linear correlation plot of the experimentally determined Delta E parameter versus the corresponding calculated V data allowed us to obtain an absolute value of the nuc…
Quadrupole interaction of $^{8}$Li and $^{9}$Li in LiNbO$_{3}$ and the quadrupole moment of $^{9}$Li
1988
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.
Quadrupole splitting of Fe(II) spin crossover compounds study of temperature and pressure dependence and the implication for the interaction mechanism
1989
The temperature and pressure dependence of the quadrupole splitting ΔE Q of the 3/2→1/2 nuclear Mossbauer transition of57Fe in the spin crossover compounds [Fe x Zn1−x (2-pic)3]Cl2⋆EtOH and the deuterated analog [Fe x Zn1−x (2-pic-ND2)3] Cl2⋆EtOD (2-pic=2-picolylamine) have been studied. The change of ΔE Q can be linearly related to the defomation of the lattice as observed by X-ray measurements. The dependence of ΔE Q on temperatureT, pressurep, and the fraction γ of molecules in the electronic high spin state in the pure iron (x=1) compounds is therefore interpreted as a result of the change of the lattice contribution to the electric field gradient (EFG) at the nucleus only. The intrinsi…
Optical polarization of neutron-rich sodium isotopes and β-NMR measurements of quadrupole moments
1996
The nuclear quadrupole moments of neutron-rich sodium isotopes are being investigated with the help of in-beam polarization by optical pumping in combination with $\beta$-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO$_{3}$ for the isotopes $^{26}$Na, $^{27}$Na and $^{28}$Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments, $\beta$-decay asymmetries for the sequence of isotopes up to the $N$=20 neutron shell closure, $^{26-31}$Na, have been measured.
Electric hyperfine interaction in199Hg fluorides
1985
With the current integration technique, the Mossbauer effect on the 158 keV, 5/2−→1/2− transition in199Hg was studied using the cubic HgF2 and the tetragonal Hg2F2 as absorbers; in the latter, a quadrupole splittingeQVzz=}- 9.0(2) mm/s was observed. Electron densities were calculated with the self-consistent-charge-extended-Hueckel-molecular-orbital method and δ〈r2〉=(3.26±0.11) fm2 derived. From the quadrupole splitting and the calculation, an effective antishielding factor almost twice that of the neutral Hg atom is derived.
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…