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Titolo:
Spin dynamics and energy gap of a Fe dimer from susceptibility and H-1 nuclear magnetic resonance
Autore:
Lascialfari, A; Tabak, F; Abbati, GL; Borsa, F; Corti, M; Gatteschi, D;
Indirizzi:
Dipartimento Fis A Volta, Unita INFM Pavia, I-27100 Pavia, Italy Dipartimento Fis A Volta Pavia Italy I-27100 Pavia, I-27100 Pavia, Italy Univ Modena, Dept Chem, I-41100 Modena, Italy Univ Modena Modena Italy I-41100 odena, Dept Chem, I-41100 Modena, Italy Univ Florence, Dept Chem, I-50144 Florence, Italy Univ Florence FlorenceItaly I-50144 Dept Chem, I-50144 Florence, Italy
Titolo Testata:
JOURNAL OF APPLIED PHYSICS
fascicolo: 8, volume: 85, anno: 1999,
parte:, 2A
pagine: 4539 - 4541
SICI:
0021-8979(19990415)85:8<4539:SDAEGO>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
IRON(III) IONS; RINGS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
15
Recensione:
Indirizzi per estratti:
Indirizzo: Lascialfari, A Dipartimentolyis A Volta, Unita INFM Pavia, Via Bassi 6, I-27100 Pavia, Ita Dipartimento Fis A Volta Via Bassi 6 Pavia Italy I-27100 a
Citazione:
A. Lascialfari et al., "Spin dynamics and energy gap of a Fe dimer from susceptibility and H-1 nuclear magnetic resonance", J APPL PHYS, 85(8), 1999, pp. 4539-4541

Abstract

The iron(III) S=5/2 dimer [Fe(OMe)(dbm)(2)](2) (in short Fe2) has a nonmagnetic S=0 ground state. The separation between the singlet ground state andthe first excited (triplet) state is determined from susceptibility measurements to be about 22 K; for a dimer this value is equal to the antiferromagnetic exchange constant J. Proton nuclear magnetic resonance measurements were performed on Fe2. The nuclear spin-lattice relaxation rate (NSLR) was studied as a function of temperature at 31 and 67 MHz and as a function of the resonance frequency (10-67 MHz) at T=295 K. At room temperature the H-1NSLR is independent of frequency contrary to the strong dependence found in planar ring compounds like Fe6 and ferric wheel (Fe10). The temperature dependence of the proton NSLR shows an exponential decrease on lowering the temperature from which we estimate a gap value about double the value obtained from the uniform susceptibility, a result which is unexpected if the NSLR were simply proportional to the concentration of dimers in the triplet excited state. (C) 1999 American Institute of Physics. [S0021-8979(99)27308-2].

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Documento generato il 02/07/20 alle ore 22:28:41