HYPERFINE INTERACTION PARAMETERS AT IODINE IN VANADIUM (II) IODIDE FROM 129I MÖSSBAUER SPECTROSCOPY

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Submitted on 1 Jan 1976

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HYPERFINE INTERACTION PARAMETERS AT

IODINE IN VANADIUM (II) IODIDE FROM 129I

MÖSSBAUER SPECTROSCOPY

J. Friedt, J. Sanchez

To cite this version:

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JOURNAL DE PHYSIQUE Colloque C6, supplkment au no 12, Tome 37, Dkcembre 1976, page C6-651

HYPERFINE INTERACTION PARAMETERS AT IODINE

IN VANADIUM (11) IODIDE FROM lZ9I

MOSSBAUER

SPECTROSCOPY

J. M. FRIEDT and J. P. SANCHEZ

Laboratoire de Chimie Nuclbaire, Centre de Recherches NuclCaires, 67037 Strasbourg Cedex, France

RksumB.

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On a obtenu les densites de charge et de spin au site de l'iode dans le diiodure de vanadium a partir des mesures de spectroscopie Mossbauer sur 1291. On deduit aussi l'orientation des moments des ions vanadium proches voisins.

Abstract.

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The charge and spin densities at iodine in vanadium diiodide are obtained from the 1 2 9 1 Mossbauer measurements. The orientation of the nearest neighbor vanadium moments is also deduced.

We have measured in both the paramagnetic and phase (160 K), the spectra are fitted as a quadrupole antiferromagnetic phases of V12 the 27.8 keV Moss- pattern using the transmission integral formalism. bauer resonance of 12'1 (Fig. 1). In the paramagnetic In the ordered phase (4.2 K), the data have been fitted using the full interaction Hamiltonian to compute the spectral component intensities and energies.

The isomer shift, quadrupole interaction parameters and transferred magnetic hyperfine interaction at the iodine site were deduced from a careful computer analysis of the experimental data (Table I). In agree- ment with structural data, all iodine ligands are chemically equivalent. The interpretation of isomer shift and quadrupole coupling constant within Townes and Dailey approach delivers the charge densities in the 5s and 5p valence orbitals of iodine (Table 11).

w 2

+

4: TABLE I1 A W

m Charge and spin densities at '''1 in VI,. N, and Np,

represent the charge densities in the 5s and 5pi valence orbitals of iodine.

f,

represents the spin density in the 5s orbital. Ns Npz N p x = N p y

fs

fo, fn - - - - - 1.94 1.83 1.76 - 0.154 x 10-2 undetermined - - 6 - 4 -2 0 2 4 6

VELOCITY (MM/S) The negative sign off, and the reduced value of

FIG. 1.

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Mossbauer spectra of 1291 in V12 at 160 K, figure la spin transfer

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as compared to the transferred and 4.2 K, figure l b . The full line represents the best computer charge density (2

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N s ) Rflect the indirect polarization

fit to the experimental data (circles). mechanism of the 5s orbital via a bonding. TABLE I

2 9 I Mossbauer parameters in VI,

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C6-652 J. M. FRIEDT AND J. P. SANCHEZ