HAL Id: jpa-00216722
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Submitted on 1 Jan 1976
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HYPERFINE INTERACTION AND LIFETIME OF
ANOMALOUS SPIN STATES OF IRON (II) IN [57
Co(phen)3] (ClO4)2.2H2O BY TIME-DEPENDENT
MÖSSBAUER EMISSION SPECTROSCOPY
R. Grimm, P. Gütlich, R. Link, E. Kankeleit
To cite this version:
JOURNAL DE PHYSIQUE Colloque C6, supplkment au no 12, Tome 37, Ddcembve 1976, page C6-917
HYPERFINE INTERACTION AND LIFETIME OF
ANOMALOUS SPIN STATES OF IRON (11)
IN
[ 5'C~(phen)~]
(C104)2
.2
H,
0
BY TIME-DEPENDENT
MOSSBAUER
EMISSION SPECTROSCOPY
R. GRIMM, P. GUTLICH, R. LINK
Institut fur Anorganische Chemie und Analytische Chemie der Unversitat, D 6500 Mainz/BRD
E. KANKELEIT
Institut fur Kernphysik der Technischen Hochschule Darmstadt, D 6100 DarmstadtIBRD
Abstract.
-
Using the time-differential Mossbauer coincidence technique we have measured emission-spectra of [57Co(phen)3] (C104)~. 2 H20 (phen = 1, l0 -phenanthroline) as the source in the temperature range 4.2-80 K. The lifetimes of the anomalous high spin states of 57Fe(II) originating from the EC process of 57Co in the source matrix have been derived. The two spin quintet (S = 2) states of iron (11) decay into the singlet (S = 0 ) state of[57Fe(phen) 3 ] (C10 4) 2.2 H 2 0
,
which is the only observable species in the corresponding absorption experiment at any temperature. Using the computer code of Hoy et al. [l] we have evaluated the intensities of the high spin (ZES) and low spin (ZLS) quadrupole doublets by a least squares fitting procedure, taking into account the effect of time filtering, absorber thickness and source broadening as well as the cosine smearing effect.
The intensity ratio of the high spin to IOW spin states ZHS/ILS is derived as a function of time after the decay of the 57C0 nucleus. Evaluating the intensity ratio
by means of a least squares fitting procedure we obtain the lifetimes r of the excited states as a function of temperature (TA, TE : time window ; P O , y : initial population probability and decay constant of the unstable state respectively ; 2 ro : experimental time resolution ; f : Debye-Waller
factor). For the ratio of the DW factors we obtained the value ~ H S ~ ~ L S = 1. The results are dis- cussed on the basis of the recombination of a positive charge hole at the ligands-formed by radiolysis with an electron. At lower temperatures long range tunneling should be the dominant process.
References [l] HOY, G. R. HAMILL, D. W., WINTERSTEINER, P. P. MB-
Effect Meth. 6 (1970).
