The effect of core electrons on the spin transfer parameters

1982 ◽  
Vol 60 (5) ◽  
pp. 636-639 ◽  
Author(s):  
M. E. Ziaei
Keyword(s):  
Hyperfine Interaction ◽  
Electron Distribution ◽  
Spin Transfer ◽  
Unpaired Spin ◽  
Core Electrons ◽  
Transfer Parameters

ENDOR measurements and covalency arguments have been used to investigate the electron distribution in CsCdF3 crystals containing Mn2+ and Ni2+. The bond structure is of the form M—F−—Cd2+ (M = Mn2+ or Ni2+) and the measured isotropic supertransferred hyperfine interaction (sthfi) at the Cd site is related to the unpaired spin fraction fσ in the 2pσ orbital of F− by three different theoretical approximations. In these three methods it is assumed that [Formula: see text] orbital of the 3d ion, and the 2pz orbital of the F− ion make eovalent bonds with the (4s), (3s,4s,5s), and (1s,2s,3s,4s,5s) sets of orbitals of the Cd2+ ion respectively. The results show that cadmium core s electrons make important contributions to the isotropic sthfi. However, it seems that fσ values obtained are fairly insensitive to the approximations used.

Estimation of spin transfer parameters through the anisotropic supertransferred hyperfine interaction

1985 ◽  
Vol 63 (5) ◽  
pp. 557-559
Author(s):  
M. E. Ziaei
Keyword(s):  
Hyperfine Interaction ◽  
Neutron Scattering ◽  
Configuration Interaction ◽  
Reasonable Agreement ◽  
Hyperfine Interactions ◽  
Interaction Model ◽  
Covalent Bonding ◽  
Spin Transfer ◽  
Scattering Data ◽  
Transfer Parameters

Using the experimental transferred and anisotropic supertransferred hyperfine interactions, with the configuration interaction model of covalent bonding for the linear bonds of M2+(3dσ)–F−(2pσ)–Cd2+(4pσ) and M2+(3dπ)–F−(2pπ)–Cd2+(4pπ) existing in crystals of CsCdF3: M2+ (where M = Mn or Ni), suggests that fσ, the σ-type spin transfer parameter for the Mn2+–F− bond, is about 3.1%. This value is much larger than estimates from neutron scattering data, although it is in reasonable agreement with the works of Ziaei and Owen, and Rinneberg and Shirley.

Measurement of the () inclusive spin transfer parameters K0nn0C and K0k″k0C on carbon with 590 MeV protons

1989 ◽  
Vol 231 (3) ◽  
pp. 323-327 ◽  
Author(s):  
R. Binz ◽  
R. Büchle ◽  
M. Daum ◽  
J. Franz ◽  
G. Gaillard ◽  
...  
Keyword(s):  
Spin Transfer ◽  
Transfer Parameters ◽  
Mev Protons

General solution of the spin Hamiltonian for complex electron nuclear double resonance spectra

1981 ◽  
Vol 59 (2) ◽  
pp. 298-304 ◽  
Author(s):  
M. E. Ziaei
Keyword(s):  
Double Resonance ◽  
Spin Transfer ◽  
Nearest Neighbour ◽  
Spin Hamiltonian ◽  
Electron Nuclear Double Resonance ◽  
Order Of Magnitude ◽  
Transfer Parameters ◽  
Fluorine Ions ◽  
Host Lattices ◽  
The Magnetic Field

An electron nuclear double resonance investigation of CsCdF3:M (M = Mn2+, Ni2+, Cr3+, and Co2+) has been carried out to measure the transferred hyperfine interaction (thfi) between M and nearest neighbour fluorine ions. A general spin Hamiltonian which takes account of the multiplicity of the interacting nuclei, is solved for a general orientation of the magnetic field. An example is given to show that theory agrees well with experiment. Spin transfer parameters obtained are of similar order of magnitude for the same ions in similar host lattices.

NMR investigation of spin transfer to H in K2CuCl4∙2H2O

1983 ◽  
Vol 61 (12) ◽  
pp. 1627-1632 ◽  
Author(s):  
Tae Jong Han ◽  
Sung Ho Choh
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Hyperfine Interaction ◽  
Temperature Dependence ◽  
Exchange Interaction ◽  
Room Temperature ◽  
Copper Ion ◽  
Spin Transfer ◽  
Temperature Dependent ◽  
Super Exchange Interaction

Nuclear magnetic resonance of 1H in K2CuCl4∙2H2O has been measured with frequencies of 3 to 35 MHz at room temperature, 163, and 77 K. The fractional spin transfer from the copper ion to hydrogen due to the transferred hyperfine interaction is analyzed: 0.19 ± 0.03% at 300 K, 0.23 ± 0.02% at 163 K, and 0.27 ± 0.02% at 77 K, showing that the spin transfer is temperature dependent. This temperature dependence is closely associated with the unusually strong temperature dependent super-exchange interaction between Cu2+ ions in this crystal.

Study of charge transfer in FeTi

1983 ◽  
Vol 41 ◽  
pp. 296-297
Author(s):  
J. Taft∅
Keyword(s):  
Charge Transfer ◽  
Charge Distribution ◽  
Electron Scattering ◽  
Periodic System ◽  
Electron Distribution ◽  
Scattering Amplitude ◽  
Transition Elements ◽  
Hartree Fock ◽  
Cscl Structure ◽  
The Right

It is well known that for reflections corresponding to large interplanar spacings (i.e., sin θ/λ small), the electron scattering amplitude, f, is sensitive to the ionicity and to the charge distribution around the atoms. We have used this in order to obtain information about the charge distribution in FeTi, which is a candidate for storage of hydrogen. Our goal is to study the changes in electron distribution in the presence of hydrogen, and also the ionicity of hydrogen in metals, but so far our study has been limited to pure FeTi. FeTi has the CsCl structure and thus Fe and Ti scatter with a phase difference of π into the 100-ref lections. Because Fe (Z = 26) is higher in the periodic system than Ti (Z = 22), an immediate “guess” would be that Fe has a larger scattering amplitude than Ti. However, relativistic Hartree-Fock calculations show that the opposite is the case for the 100-reflection. An explanation for this may be sought in the stronger localization of the d-electrons of the first row transition elements when moving to the right in the periodic table. The tabulated difference between fTi (100) and ffe (100) is small, however, and based on the values of the scattering amplitude for isolated atoms, the kinematical intensity of the 100-reflection is only 5.10-4 of the intensity of the 200-reflection.

Extended Core Edge Fine Structure in the E.M.

1980 ◽  
Vol 38 ◽  
pp. 120-121
Author(s):  
R.D. Leapman
Keyword(s):  
Fine Structure ◽  
Electron Scattering ◽  
Inelastic Electron ◽  
High Resolution Imaging ◽  
X Ray ◽  
Analytical Electron ◽  
Analytical Electron Microscope ◽  
Core Electrons ◽  
Resolution Imaging ◽  
X Ray Absorption

Extended X-ray Absorption Fine Structure (EXAFS) analysis makes use of synchrotron radiaion to measure modulations in the absorption coefficient above core edges and hence to obtain information about local atomic environments. EXAFS arises when ejected core electrons are backscattered by surrounding atoms and interfere with the outgoing waves. Recently, interest has also been shown in using inelastic electron scattering1-4. Some advantages of Extended X-ray-edge Energy Loss Fine Structure (EXELFS) are: a) small probes formed by the analytical electron microscope give spectra from μm to nm sized areas, compared with mm diameter areas for the X-ray technique, b) EXELFS can be combined with other techniques such as electron diffraction or high resolution imaging, and c) EXELFS is sensitive to low Z elements with K edges from ˜200 eV to ˜ 3000 eV (B to Cl).

Electron distribution change of small nickel particles encaged in X zeolite in presence of Ce3+ ions, related to their catalytic properties

1986 ◽  
Vol 83 ◽  
pp. 619-621 ◽  
Author(s):  
F. Vergand ◽  
B. Iraqi ◽  
C. Bonnelle ◽  
E. Ramaroson ◽  
M.F. Guilleux ◽  
...  
Keyword(s):  
Electron Distribution ◽  
Catalytic Properties ◽  
Distribution Change ◽  
Nickel Particles ◽  
X Zeolite
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