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Submitted on 1 Jan 1985
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Influence of the hyperfine structure on the time-dependence of Mössbauer transmission
D.L. Balabanski, E.I. Vapirev, P.S. Kamenov
To cite this version:
D.L. Balabanski, E.I. Vapirev, P.S. Kamenov. Influence of the hyperfine structure on the time-dependence of Mössbauer transmission. Journal de Physique, 1985, 46 (8), pp.1387-1393.
�10.1051/jphys:019850046080138700�. �jpa-00210082�
Influence of the hyperfine structure on the time-dependence
of Mössbauer transmission
D. L. Balabanski, E. I. Vapirev and P. S. Kamenov
Sofia University « Clement Okhridsky », Faculty of Physics, 1126 Sofia, Bulgaria (Reçu le 23 juillet 1984, révisé le 4 février 1985, accepté le 18 avril 1985)
Résumé. 2014 La distribution en temps de la radiation Mössbauer traversant un absorbeur avec une structure
hyperfine est étudiée théoriquement et expérimentalement. Les expérienees sont réalisées avec une source de
(Ba119mSnO3 (raie singulet) et un absorbeur SnO2 (doublet quadrupolaire). Les résultats obtenus sont en assez bon accord quantitatif avec la théorie proposée.
Abstract.
2014The problem of the influence of the hyperfine structure on the time-dependence of resonant gamma- transmission is investigated both theoretically and experimentally in the present work. The experiments are carried
out with a source Ba119mSnO3 and an absorber SnO2 with a line split by the quadrupole interaction. A theoretical model is derived in the framework of the classical dispersion theory and it appears to be in reasonable agreement with experiment.
Classification Physics Abstracts
76.80
1. Introduction.
Following the classical experiment of Lynch et al. [1],
a series of investigations on the time-dependence of gamma-resonant interactions was carried out by
different groups under different experimental condi-
tions [2-8]. The results were interpreted with the help
of classical dispersion theory [1, 2] or of the quantum
theory of radiation [9] and the calculations are in a
good agreement with the experiment.
All these investigations are related to the simplest possible case
-source and absorber with single lines
with energies COo and coo’
-but the first experiment
was carried out with a source and absorber of 57 Fe having a hyperfine structure of six lines. The results
were interpreted with the assumption that each com- ponent of the hyperfine structure is absorbed by the corresponding transition in the absorber, because the distance between the components is great in compa- rison with the natural linewidth-y. Of course, the question exists
-what is the influence of the hyper-
fine structure on the time-dependence of gamma- resonant transmission ?
In the present work a classical model is applied to
the time-dependence of Mossbauer transmission
through a resonant absorber with a hyperfine structure
and calculations are made for the case of two compo- nents. The results are compared with measurements with Sno2, a compound which is very suitable for this
purpose, because its two lines are near to one another.
This allows the influence of the hyperfine structure on
the time-dependence to be observed. It is also shown that Mitin and Polyakov [10] have used rather crude
approximations to evaluate this influence and their model cannot be applied to all cases. In our calcula- tions, interference terms appear in the formula for the transmission intensity. The conditions are investigated
when those terms vanish, i.e. the approximations of
reference [10] are correct. The results are compared
with a model in which the interference is neglected as
done by Lynch et al. [1]. The discrepancy of those
calculations with the experiment is shown. Thus the influence of the hyperfine structure on the time- dependence of gamma-resonant transmission is demonstrated.
2. Theory.
The resonant properties of the absorbing medium,
which is considered as consisting of random damped
harmonic oscillators with natural frequencies coi, i = 1, 2,... and damping factor y, are described with the
complex index of refraction n(w) [11].
r is a constant depending on the bulk density of
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphys:019850046080138700
1388
resonant nuclei and p;, i = 1, 2,
...are the weight
factors corresponding to the resonant frequencies
The incident radiation is represented
as a damped electric wave with frequency coo.
Using the Fourier transform it is decomposed into
monochromatic components with frequency distri-
bution A(co, 0).
Each of the components is altered by a frequency dependent phase change when passing a distance x in
-