Search results for "SSBA"

The Electric Field Gradient and the Quadrupole Interaction

1984

The Mossbauer effect has become a popular method in analytical chemistry. In contrast to other techniques such as x-ray spectroscopy, NMR, EPR, and MCD where highly sophisticated evaluation procedures are applied to obtain reliable information on the chemical compound, the Mossbauer effect is generally used on a low level concerning the evaluation of quadrupole split spectra. This procedure on a low level is favored by the structure of the spectra especially the simple doublet of the 3/2 → 1/2 nuclear transitions in paramagnetic and diamagnetic compounds. The separation of the two absorption lines, the quadrupole splitting ΔE Q and the center of the two lines, the isomer shift, are easily d…

Density of Phonon States in Superconducting FeSe as a Function of Temperature and Pressure

2010

The temperature and pressure dependence of the partial density of phonon states (phonon-DOS) of iron atoms in superconducting ${\text{Fe}}_{1.01}\text{Se}$ was studied by $^{57}\text{F}\text{e}$ nuclear inelastic scattering. The high-energy resolution allows for a detailed observation of spectral properties. A sharpening of the optical phonon modes and shift of all spectral features toward higher energies by $\ensuremath{\sim}4\mathrm{%}$ with decreasing temperature from 296 to 10 K was found. However, no detectable change at the tetragonal--orthorhombic phase transition around 100 K was observed. Application of a pressure of 6.7 GPa, connected with an increase in the superconducting temper…

Basic Physical Concepts

2010

Mossbauer spectroscopy is based on recoilless emission and resonant absorption of γ-radiation by atomic nuclei. The aim of this chapter is to familiarize the reader with the concepts of nuclear γ-resonance and the Mossbauer effect, before we describe the experiments and relevant electric and magnetic hyperfine interactions in Chaps. 3 and 4. We prefer doing this by collecting formulae without deriving them; comprehensive and instructive descriptions have already been given at length in a number of introductory books ([7–39] in Chap. 1). Readers who are primarily interested in understanding their Mossbauer spectra without too much physical ballast may skip this chapter at first reading and p…

The average over a sphere

1980

Abstract The N points ri and the N segments ΔΩi of the unit sphere used in the numerical approximation of the average over the sphere are optimized to approximate the average of the set of spherical harmonics {;Yl,m;l = 0, 1, 2, …, L}; up to L = 18. The symmetry of f( r ) can be taken into acount by using only a distinct subquantity of the N point {; r i , ΔΩ i }; . Sets for N = 48n (n = 1, 2, …, 6) are tabulated. The advantage of the method is shown by the calculation of a powder Mossbauer spectrum including electric and magnetic hyperfine interactions.

Some Special Applications

2010

We have learned from the preceding chapters that the chemical and physical state of a Mossbauer atom in any kind of solid material can be characterized by way of the hyperfine interactions which manifest themselves in the Mossbauer spectrum by the isomer shift and, where relevant, electric quadrupole and/or magnetic dipole splitting of the resonance lines. On the basis of all the parameters obtainable from a Mossbauer spectrum, it is, in most cases, possible to identify unambiguously one or more chemical species of a given Mossbauer atom occurring in the same material.

A reduction of protein specific motions in co-ligated myoglobin embedded in a trehalose glass

2000

Organometallic complexes with biological molecules. I. Diorganotin(IV)chloro protoporphyrin IX complexes: Solid-state and solution-phase characteriza…

1993

Protoporphyrin IX (H4PPIX) complexes of diorganotin(IV)chloro moieties with formula (R2SnCl)2H2PPIX (RMe, Bu and Ph) have been obtained and their solid-state and solution-phase configurations have been studied through spectroscopic investigations. Coordination of the side-chain carboxylates of H4PPIX to R2Sn(IV)Cl moieties, with bridging carboxylate (COO−) has been inferred by comparison of the free and coordinated H4PPIX IR spectra, while the occurrence of a five-coordinated tin(IV) atom in a cis-R2 trigonal bipyramidal structure has been deduced, for all of the synthesized complexes, by rationalization of the nuclear quadrupole splitting parameters, according to the point-charge model for…

Synthesis, spectroscopic (Mössbauer, IR and NMR) and X-ray structural studies of diorganotin complexes of 2,2′-bipyrimidine and further NMR studies o…

1996

Abstract The ligand 2,2′-bipyrimidine (bipym) was reacted with diorganotins R 2 SnCl 2 (R = methyl, ethyl) and complexes of the types R 2 SnCl 2 bipym, R 2 SnCl 2 bipym · bipym and (R 2 SnCl 2 ) 2 bipym were synthesized and studied by 1 H and 13 C NMR spectroscopy in solution, and by IR and Mossbauer spectroscopy in the solid state and frozen solutions. The complexes Et 2 SnCl 2 bipym · bipym and (Et 2 SnCl 2 ) 2 bipym were characterized by X-ray diffraction methods. In both complexes the tin environment is octahedral with chloro atoms in a cis disposition, the ethyl groups in a trans disposition and two N atoms from the ligand bipym. the second complex is a centrosymmetric binuclear specie…

Complexes of organometallic compounds. XLVIII. Mössbauer and other studies on pyrazine derivatives of tin(IV) compounds. A relationship between isome…

1978

Abstract Adducts RSnCl 3 ·pyz (R = Me, Bu n , Oct n , Ph; pyz = pyrazine) have been synthesized and characterized in the solid state. It has been determined that RSnCl 3 ·pyz are polymeric compounds, where the ligand acts as bridging bis-monodentate and the tin atoms attain the coordination number six. This has been duduced from: i) temperature dependent Mossbauer spectroscopy; ii) the correlation between Mossbauer isomer shift, δ, and electrical charge on tin, Q Sn , concerning pyrazine adducts of RSnCl 3 and others; iii) an infrared study of the coordinated ligand in RSnCl 3 ·pyz. Other implications of the Mossbauer T dependent study ( e.g. , the decrease of the Debye temperature in RSnCl…

Mössbauer investigations of the hexachlorantimonate salt of the phenyliron 2,3,7,8,l2,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrinate, [Fe(oetp…

2002

Abstract The phenyliron derivative, [Fe(oetpp)C6H5)]SbCl6 (2) generated in dichloromethane by oxidation of the phenyliron(III) complex, Fe(III) (oetpp)C6H5 (1) of the 2,3,7,8,12,13,17,18-octaethyl-5,10,15,20-tetraphenylporphyrin with 1 equiv. of phenoxathiinylium hexachloroantimonate, [C12H8OS]SbCl6, was studied by Mossbauer spectroscopy. This compound exhibits an isomer shift δ of 0.13 mm s−1 and a quadrupole splitting ΔEQ of 3.23 mm s−1. The measured magnetic hyperfine pattern obtained in the temperature range 4.2–40 K in a field of 3.5 and 7 T, applied perpendicular to the γ-beam, has been consistently analyzed in the spin Hamiltonian approximation assuming an iron(IV) S=1 electronic con…