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Mössbauer Spectroscopy in Hungary
In the response to a general call for information on the current Mössbauer research that is taking place in Hungary, the following reports were received by the Mössbauer Effect Data Center.
Remembering
the Early Years of
Mössbauer Effect Studies in Hungary
L. Keszthelyi
Institute of Biophysics, Biological
Research Centre
Hungarian Academy of Sciences
Szeged
Science could somewhat develop in Hungary in the years 1958-60,
though we still felt the consequences of the 1956 revolution.
In the Central Research Institute for Physics, we had accelerators
of about 1 MeV energy and a nuclear reactor. We made some nuclear
physics research and published papers, but were cut off from
personal contacts with colleagues from western countries. To
compensate for this difficulty, we studied the literature that,
luckily enough, arrived without restriction. Thus, I found the
paper of Rudolf Mössbauer and became enthusiastic. I became
even more so when I read the paper of Pound and Rebka on the
57Fe Mössbauer effect. It was easy to understand that the
study of the 57Fe Mössbauer effect offered immense possibilities
to make studies in physics, chemistry, and so on. I realized
that the Mössbauer effect opened a way for poor men's physics.
I wrote a letter to Rudolf
Mössbauer expressing my views on the perspectives of this
research, which were confirmed in his answer.
It was obvious that the study of the 57Fe Mössbauer effect
should be a program in our laboratory. There were, however, two
problems. First, the apparatus to move the source or absorber
to a vibration-free place. I thought this would be easy because
we had good technicians, but it turned out to be difficult, as
I came to understand in the coming years. Second, we had to buy
57Co isotope from a "capitalist" country because our
accelerators and the reactor could not produce it. It seemed
impossible. Nevertheless, we ordered the isotope and, as a wonder,
we obtained it in October 1960. István Dézsi, a
nuclear chemist, was at hand and wanted to join the program.
The technicians fabricated a rotating cam to move the source
with one velocity in one direction. Dézsi diffused the
isotope into iron foil that was attached to the mover. I remember
that on a misty November night, Dézsi and I began to measure
the number of transmitted g-quanta through iron foil, changing
the frequency of the rotation step-by-step. We were extremely
happy seeing that we reproduced the results known to us from
literature. Our happiness culminated on the 5th of December,
when we took all our apparatus to the usual Monday night meeting
of the Roland Eötvös Physical Society and demonstrated
the 57Fe Mössbauer effect for the physics community in Budapest.
(Just to characterize the circumstances, I mention that an agent
of the Hungarian Secret Police with a cover name reported that
I delivered a lecture in the physicist's club on .. effect. I
learned that in this year, 2003, when I obtained the secretly
collected information about my activities.) In 1961, I wrote
a paper in Hungarian to show the possibilities of the Mössbauer
effect [1].
After the euphoria, we had to continue our work to do real research.
The rotating cam was not a productive apparatus; therefore, we
asked our engineers to build a machine based on oil pressure
that could produce positive and negative velocities. That was
made, but oil came out everywhere. We worked with that and reported
some not very interesting results in Hungarian [2].
Our first notable outcome was a report on the Mössbauer
effect of 159Tb nuclide. We reported preliminary measurements
at the Mössbauer meeting in Dubna [3]. A more thorough paper
was published in 1966 [4] when, due to the effort of the engineers
of the Central Research Institute of Physics, we already had
a "modern" Mössbauer apparatus with the source
attached to the coil of a loudspeaker and multichannel analyzer
for data collection. Everything, even the multichannel analyzer,
was manufactured in our workshop. The first apparatus was ready
in early 1964 and later became a product, and was sold inside
Hungary and also exported, for example, to Egypt.
It took nearly four years to reach a satisfactory level of experimentation.
Our first really interesting work was made in 1964 when, following
the suggestion of István Dézsi, we measured the
Mössbauer effect on iron salts in ice [5]. The data were
surprising, but also rewarding because this paper catalyzed an
important sub-topic inside Mössbauer effect studies.
"Poor men's physics" attracted many good people into
our group: László Cser, Dénes Nagy, and
Imre Vincze were the first to join us. Work started also at the
Eötvös Loránd University, where László
Korecz, Attila Vértes, and Kálmán Burger
dealt with the Mössbauer effect. We had long-term visitors
from East Germany (Werner Meisel, Klaus Fröhlich), from
Poland (Dominik Kulgawczuk, Jozef Bara), from Egypt (Nabil Eissa,
Ahmed Sanad), and others. The activity brought worldwide acknowledgement:
we were entrusted to organize the International Conference on
the Mössbauer Effect in 1969.
My personal carrier took another way in 1973, when I accepted
a position in the Institute of Biophysics, Biological Research
Centre of the Hungarian Academy of Sciences. My first interest
in biophysics -- the search of the origin of homochirality of
biomolecules - was not too far from my physics background. Homochirality
of biomolecules means that all living beings contain L-amino
acids and D-sugars, though by synthesis both are produced in
equal number. One of the ideas - to trace the origin of this
asymmetry was that the circularly polarized bremsstrahlung,
produced by the b-particles, could destroy the D-amino acids.
We thought with Imre Vincze to check this assumption with the
circularly polarized lines from magnetic splitting of 57Fe. We
found that the relative difference in absorption of 14 keV g-radiation
between L- and D-amino acid is less than 10-4 [6].
The development in physics led to another important application
of the Mössbauer effect in the same field. It turned out
that, due to weak neutral current, an energy difference exists
between L-and D-molecules. The difference, calculated theoretically,
is very small, but it increases with the 6th power of Z of atom
in the asymmetry center. I thought that the extremely high resolution
of the Mössbauer effect offers a method to measure this
basic phenomenon. Kálmán Burger and Attila Vértes
helped to organize L- and D- Ir complex from Denmark (F. Galsbřl
and B. Rasmussen) and measuring capacity from Germany (F. Wagner).
The isomer shift was supposed to reflect the difference of the
energy between the two complexes. An upper limit could only be
established: the difference in isomer shift is surely smaller
than 3.8x102 times the theoretical value [7]. Recently, I figured
out that the difference, if at all, could be measured in case
of 181Ta nuclide [8].
The two last paragraphs do not belong to the first years of Mössbauer
studies in Hungary. I included them only to demonstrate that
what I learned in the field of the Mössbauer effect reappeared
in my mind encountering another problem. Thus, my early enthusiasm
comes back even in these days - in my work and also in the work
of a large number of people in the Hungarian Mössbauer community.
References
1. L. Keszthelyi, "Mössbauer effect and its applications"
(in Hungarian). Magy. Fiz. Folyóirat 9, 2891 (1961).
2. I. Demeter, I. Dézsi and L. Keszthelyi, "Measurements
with the aid of Mössbauer effect" (in Hungarian). KFKI
Közl. 10, 21 (1962).
3. I. Dézsi and L. Keszthelyi, "Observation of the
Mössbauer effect in Tb159." In Proc. Dubna Conf. on
Mössbauer Effect (in Russian), 857 (1963).
4. T. Czibók, I. Dézsi and L. Keszthelyi, "Mössbauer-effect
in Tb159." Acta Phys. Hung. 20, 3791 (1966).
5. I. Dézsi, L. Keszthelyi, L. Pócs and L. Korecz,
"Mössbauer-effect on some iron salt in ice." Phys.
Letters 14, 1411 (1965).
6. L. Keszthelyi and I. Vincze, "Absorption of circularly
polarized g-radiation in L- and D- amino acids." Rad. Environm.
Biophys. 12, 181 (1975).
7. L. Keszthelyi, J. Biol. Phys. 20, 241 (1994).
8. L. Keszthelyi, Mendeleev Journal (2003), in press.
Mössbauer
Groups of the
KFKI Research Institute for
Particle and Nuclear Physics
(KFKI RMKI)
Budapest
I. Dézsi and
D.L. Nagy
Department of Nuclear Physics
KFKI Research Institute for Particle and Nuclear Physics
Budapest
Mössbauer studies in Hungary were started by L. Keszthelyi
and I. Dézsi in 1960. In November of this year, the effect
on 57Fe was observed and presented. We intended to discover a
new Mössbauer nucleus by choosing 159Tb. Using a 159Gd source
prepared in the research reactor of the predecessor institute
KFKI, the effort was successful. We observed first the Mössbauer
transition on this nucleus [1]. After developing a reliable driving
system, a series of studies was commenced on frozen solutions,
alloys, and on transitional metal oxides. For frozen solutions,
the studies yielded the first evidence of a glass transition,
melting, recrystallization of the amorphous frozen solute-solvent
system [2]. Detailed studies of the paramagnetic relaxation phenomena
of Fe3+-containing solutions were carried out. Furthermore, systematic
studies were performed on iron oxides, on a-FeOOH, d-FeOOH, and
(FeRh)2O3, as well as on perovskites. During the 1960s, successful
international collaborations were begun and new colleagues --
physicists L. Cser (1963), L. Korecz (1963), T. Czibók
(1965), D.L. Nagy (in 1966 he became a member of our research
group), I. Vincze (1967), and the chemist Attila Vértes
(1966) joined us to learn the Mössbauer effect. Together
with Attila Vértes, we first showed the possible application
of the Mössbauer effect for corrosion studies. Later on,
intensive studies were made on high-spin ferrous hydrates and
on organometallic complexes. Amongst the results obtained, the
first Mössbauer evidence on the spin-crossover transition
in Fe2+ compounds [3] and of an orbital ground state inversion
in Fe2+ crystalline hydrates were discovered. The research reactor
made it possible to perform Mössbauer experiments on various
nuclides, such as 161Dy and 191Au. In 1969, we organized the
first Mössbauer Conference where scientists both from the
"eastern" and "western" countries participated
[4].
In the early 1970s we continued studies, mostly in international
collaboration (University of Louisville, Kentucky, USA, with
P.J. Ouseph; Universität Erlangen, with H. Wegener
and G. Ritter), on frozen solutions and crystalline hydrates.
There was a successful collaboration between J.M.D. Coey
and I. Dézsi in the studies of crystalline hydrates
and magnetic oxides. Magnetic phase transitions in oxides, nitrides,
and carbides were also studied, both with 57Fe and 119Sn resonance,
the latter revealing a series of magnetic phase transitions in
Mn3SnN and Mn3SnC. Soon thereafter, L. Keszthelyi's interest
turned to biophysics and Mössbauer spectroscopy no longer
belonged to his applied methods. The research was extended by
four new topics: the determination of texture parameters in Mössbauer
absorbers, paramagnetic relaxation phenomena in crystalline systems
containing high-spin Fe3+, catalysts containing Fe and LiNbO3
with Co and Fe impurity. The latter topic was studied in collaboration
mostly with W. Keune and U. Gonser.
The investigation of ion-implanted systems began in the Instituut
voor Kern- en Stralingsfysika of the Katholieke Universiteit
Leuven with R. Coussement, G. Langouche, and M. Van
Rossum in 1976. These studies resulted in the proof of the formation
of amorphous regions in Si, Ge, substrates around the implanted
57Co, 57Fe, 125Te, 129I. It was also pointed out that CoSi2 forms
in Co implanted and annealed Si. This silicide became one of
the most important materials in semiconductor technology. The
studies were also extended to the 133Cs nucleus in collaboration
with H. Pattyn.
Starting with the mid-1980s, two new groups were gradually formed
from the old one: one group around I. Dézsi, with
a main interest in materials science, and another group around
D.L. Nagy, with a main interest in solid-state physics.
Although these groups have been sharing the same laboratories
since then and are intensively cooperating in the methodology,
the development of their research activity became rather independent.
The interest of the members of the materials science group turned
to the study of the fundamental physical processes of ion implantation,
the formation of various transitional metal silicides, and the
investigation of the formation and structure of very thin layers.
For comparison of the phases formed after ion implantation of
Te in Si and Ge to the amorphous systems, amorphous SixTe(1-x),
GexTe(1-x), and single crystalline tellurides were studied. Ion
implantation made it possible to incorporate atoms into target
substrates in which the solubility of iron is extremely low.
By measuring the isomer shift values in lattice sites, it was
possible to present a new systematic of isomer shift of 57Fe
in elements and pointed out the effects of d-d hybridization
on the atomic charge density [5].
The ion-implantation studies were extended to metals and insulators,
in the latter case to a-Al2O3, a-Fe2O3 [6], and to LiNbO3. In
order to identify the annealing products in these target substrates,
detailed studies were performed on spinels containing Co and
Fe. A series of studies were performed on the formation processes
of epitaxial CoSi2 on Si and SixGe(1-x) with the participation
of A. Vantomme, G. Petô, and other collaborators.
It was possible to successfully grow epitaxial CoSi2 layers of
excellent quality on the surface of these substrates. Ternary
silicide phases were also investigated [7]. It is worthwhile
to mention here that we grew successfully 57Co doped b-FeSi2
crystals in a special furnace of gradual temperature and proved
that the Co atoms populate both the two different crystal sites
in the orthorhombic b-FeSi2.
Very thin (0.15-10 ML) 57Fe on Ag surfaces were grown in MBE
in Leuven and investigated by using STM and Conversion Electron
Mössbauer Spectroscopy. It was found that Fe deposits in
clusters on the Ag single crystal surfaces and gradually the
clusters cover the surfaces up to 10 ML thickness. The layers
are paramagnetic up to 5 ML. For 57Co deposition, electroplating
was applied. Very similar behavior to Fe was observed, but the
sensitivity of the measurement increased significantly because
of the radioactive tracing effect and by using a special resonance
counter. The latter measurement was performed first by our group.
The Mössbauer studies at low temperature are in progress.
Presently, the materials science group performs measurements
on very low nanosized metal oxides, e.g., magnetite.
The main interest of the solid-state physics group in the 1980s
was a topic stemming from cooperation with H. Spiering (Universität
Erlangen and Universität Mainz before and after 1978, respectively)
- the interpretation of the hyperfine interaction of high-spin
Fe2+ ions in terms of ligand field theory utilizing Mössbauer
measurements performed at low temperature in external magnetic
field. In the 1970s, this method was successfully applied to
a series of crystalline hydrates containing the Fe2+(H2O)6 coordination
ion. A study of Fe(ClO4)2 frozen solution showed that, even in
the amorphous environment, the same normal distortions, i.e.,
the bond-bending ones, are present as in the crystalline hydrates
and also the local symmetry around the Fe2+ ion is the same [8].
A new kind of after-effect of the electron capture of 57Co
long-lived low-energy electronic excitations of nucleogenic high-spin
Fe3+ -- was found in cooperation with G. Ritter's group
(Erlangen) in various systems, including 57Co:LiNbO3. The effect
made it possible to investigate for the first time the ligand
field in short-lived excited terms of the nucleogenic ion [9].
More recently, a systematic study of the nucleogenic valence
states lead to revisiting the model of competing acceptors [10].
L. Bottyán joined the solid-state physics group in
1986. With the appearance of the high-TC superconductors, he
initiated Mössbauer studies on YBa2Cu3O7 and related systems.
Probably the first Mössbauer emission study on a high-TC
superconductor (57Co:YBa2Cu3O7) was done by the group. A scheme
of the valance state of Fe and its coordination in YBa2Cu3O7-y
was established [11].
Starting in 1992, the interest of the solid-state physics group
gradually shifted to thin film magnetism as investigated with
grazing-incidence nuclear resonant scattering of synchrotron
radiation, a method that we prefer calling "Synchrotron
Mössbauer Reflectometry" (SMR). The key phenomenon
of this method is the so-called "total reflection peak"
first predicted by L. Deák in 1994. A general anisotropic
optical theory of SMR was developed 1996 in cooperation with
H. Spiering (Universität Mainz) [12]. More recently,
we demonstrated that the same formalism can be used for polarized
neutron reflectometry (PNR) [13]. Since then, we successfully
applied SMR to nanometer-resolution phase analysis of iron oxide
films, to identifying finite-size effects in the magnetic structure
of coupled multilayers, to demonstrating the bulk-spin-flop phenomenon
in a coupled superlattice, etc.
Recently, SMR has been extended to off-specular scattering, thereby
allowing for the study of antiferromagnetic domains in coupled
multilayers. A new kind of domain transformation, the spin-flop-induced
coarsening, has been discovered in a wide international cooperation
by off-specular SMR and confirmed by PNR [14].
Structural and magnetic properties of molecular magnets were
studied in the late 1990s by a cooperation of L. Bottyán
with the Institute for Chemical Physics in Chernogolovka. Low-temperature
high-field Mössbauer studies made possible, among other
techniques, the interpretation of the negative magnetization
in terms of the giant magnetocrystalline anisotropy in a 2D molecular
ferrimagnet.
Considerable efforts have been invested into developing data
reduction codes. SIRIUS, the standard fitting program of the
group, stems in its original form from the late 1960s and the
early 1970s. This program was the first realization of the "transformation
matrix concept" of L. Pócs and is now widely
used in many other Mössbauer codes. The first application
of SIRIUS was the evaluation of lunar samples in 1971. Several
mainframe versions of SIRIUS were used in the 1970s-1980s all
over the world. In the late 1980s, a PC-DOS version of SIRIUS
became the standard tool of many Mössbauer laboratories.
Recently, we have been very much involved in developing the general
simultaneous fitting environment EFFI of H. Spiering, Universität
Mainz.
As for our teaching activity, we offer laboratory classes for
undergraduate students. Diploma and Ph.D. students are often
part of our groups. Two courses on nuclear solid-state physics
are held at the Eötvös Loránd University (D.L.
Nagy is affiliated part-time with the Department of Atomic Physics
of the University).
The main technological background of both groups has been, since
1963, the laboratory of chemical technology and nuclear chemistry
lead by B. Molnár. Besides standard chemical facilities,
the laboratory is equipped with various vacuum furnaces, evaporation
and electrolysis facilities, and all allowing handling of radioactive
materials. Beginning at October 2003, molecular beam epitaxy
(MBE) equipment will become operational.
Our groups are presently comprised of 13 people, some of them
doing Mössbauer spectroscopy on a part-time basis only.
These are (in the order of the cover photo, from the left to
the right): L. Bottyán, M. Major, I.S. Szucs,
I. Dézsi, B. Molnár, F. Tancziko,
Zs. Kajcsos, D.L. Nagy, Cs. Fetzer, D. Merkel,
L. Deák, E. Szilágyi, and J. Fenyves.
Cs. Fetzer and I.S. Szucs are involved in materials
science studies with I. Dézsi. Two Ph.D. students
(M. Major and F. Tanczikó) as well as the diploma
student D. Merkel are working on thin-film magnetism with
L. Bottyán and D.L. Nagy. L. Deák
is developing the theory of SMR and related methods. E. Szilágyi
is mainly doing ion-beam analysis and, in part time, thin-film
magnetism with SMR. Zs. Kajcsos' primary method is positron
annihilation, but he is also involved, in cooperation with K. Lázár
(Institute of Isotope and Surface Chemistry), in Mössbauer
studies on highly porous systems. In the 1980s, in Jülich
and in Mainz, Zs. Kajcsos had significant contributions
to Mössbauer spectroscopy, including time-differential emission
Mössbauer spectroscopy and the investigation of surface
magnetism with the depth-selective conversion electron Mössbauer
spectroscopy (DCEMS). B. Molnár is running the laboratory
of chemical technology and nuclear chemistry. Finally, J. Fenyves
is technically assisting both research groups.
References
1. I. Dézsi, L. Keszthelyi, "The observation
of the Mössbauer Effect of 159Tb." In Proceedings of
the Conference on the Mössbauer Effect in Dubna, 64/17-1
(1962).
2. I. Dézsi, L. Keszthelyi, L. Pócs,
L. Korecz, "Mössbauer Effect on Some Iron Salts
in Ice." Phys. Lett. 14, 14 (1965).
3. I. Dézsi, B. Molnár, T. Tarnóczy,
K. Tompa, "On the Magnetic Behaviour of Iron (II)-bis-(1,10
Phenantroline) - Thiocynate between -190° and 30°."
J. Inorg. and Nucl. Chem. 29, 2486 (1967).
4. I. Dézsi. Proc. Conf. Appl. Mössbauer Effect,
Tihany, 1969. Akadémiai Kiadó, Budapest (1971).
5. I. Dézsi, U. Gonser, and G. Langouche, "Systematics
of the Isomer Shifts of 57Fe in various Hosts." Phys. Rev.
Lett. 62, 1659 (1989).
6. I. Dézsi, I. Szucs, Cs. Fetzer, H. Pattyn, G. Langouche,
H.-D. Phannes, R. Magalhăes-Paniago. "Local interactions
of 57Fe after electron capture of 57Co implanted in a-Al2O3 and
in a-Fe2O3." J. Phys.: Cond. Matter 12, 2291-2296 (2000).
7. Cs. Fetzer, I. Dézsi, A. Vantomme, M. F. Wu, S. Jin,
H. Bender. "Ternary CoxFe(1-x)Si2 and NixFe(1-x)Si2 formed
by ion implantation in silicon." J. Appl. Phys. 92, 3688
(2002).
8. H. Domes, O. Leupold, D.L. Nagy, G. Ritter,
H. Spiering, B. Molnár, I.S. Szucs. "Mössbauer
study of short range order in frozen aqueous solutions of Fe(ClO4)2."
J. Chem. Phys. 85, 7294 (1986).
9. R. Doerfler, W. Gruber, P. Gütlich, K.M. Hasselbach,
O. Leupold, B. Molnár, D.L. Nagy, G. Ritter,
H. Spiering, F. Tuczek. "Mössbauer spectroscopic
evidence of angle-dependent inter-system crossing in LiNbO3:Fe3+."
Phys. Rev. Lett. 57, 2849 (1986).
10. T. Becze-Deák, L. Bottyán, G. Corradi,
L. Korecz, D.L. Nagy, K. Polgár, S. Sayed,
H. Spiering. "Electron trapping centres and cross sections
in LiNbO3 studied by 57Co Mössbauer emission spectroscopy."
J Phys.: Cond. Matter 11, 6239 (1999).
11. L. Bottyan, B. Molnar, D.L. Nagy, I.S. Szucs,
J. Toth, J. Dengler, G. Ritter, J. Schober.
"Evidence for Fe4+ in YBa2(Cu1-xMx)3O7-y (M=57Co,57Fe) by
absorption and emission Mössbauer spectroscopy." Phys.
Rev. B 38, 11373 (1988).
12. L. Deák, L. Bottyán, D.L. Nagy,
H. Spiering. "The coherent forward scattering amplitude
in transmission and grazing incidence Mössbauer spectroscopy."
Phys. Rev. B 53, 6158 (1996).
13. L. Deák, L. Bottyán, D.L. Nagy,
H. Spiering. "A common optical algorithm for the evaluation
of specular spin polarized neutron and Mössbauer reflectivities."
Physica B 297, 113 (2001).
14. D.L. Nagy, L. Bottyán, B. Croonenborghs,
L. Deák, B. Degroote, J. Dekoster, H.J. Lauter,
V. Lauter-Pasyuk, O. Leupold, M. Major, J. Meersschaut,
O. Nikonov, A. Petrenko, R. Rüffer, H. Spiering,
E. Szilágyi. "Coarsening of Antiferromagnetic
Domains in Multilayers: The Key Role of Magnetocrystalline Anisotropy."
Phys. Rev. Lett. 88, 157202 (2002).
Mössbauer
Laboratory at the
Institute of Isotope and Surface
Chemistry, Chemical Research Centre Hungarian Academy of Sciences
Budapest
Károly Lázár
Institute of Isotope and Surface
Chemistry
Chemical Research Centre
Hungarian Academy of Sciences
Budapest
The Mössbauer Laboratory at the Institute of Isotope
and Surface Chemistry was established in 1979 as a part of the
Catalysis Department (headed at that time by László
Guczi). The Department of Catalysis and Tracer Studies was formed
in 1992, and the Laboratory is one of the constituting groups
of that Department since that time.
The main activity of the Laboratory is studying catalysts by
in-situ Mössbauer spectroscopy. Mostly the conventional
measuring technique, transmission 57Fe spectroscopy, is applied.
During the early period, iron-base Fischer-Tropsch catalysts
were studied. Then a slightly broader field -- bimetallic supported
catalysts (Fe-Ru, Fe-Pd) for CO + H2 conversion reactions --
were investigated. These catalysts were prepared by decomposing
bimetallic carbonyls. In a short series, amorphous quenched metal
catalysts were also studied. From the 1990s, the study of various
zeolitic systems commenced as well. As one possibility
utilizing the spatial confinement provided inside the zeolite
cages - small metallic particles can be formed. In this field,
successful preparation of PdFe nanoparticles was achieved in
Y zeolite. In another preparation method, metallic iron was formed
in the cages of Y zeolite by reduction of iron ions with sodium-azide.
The other aspect originates from the strictly determined structure
of zeolites. The symmetries are determined; thus, iron sites
can be identified. In this way steps of solid-state ion exchange
were monitored (e.g., in the process of FeCl2 + NH4-Zeol Ć
Fe-Zeol + NH3 + HCl .) Furthermore, a variety of isomorphously
substituted Fe zeolites (BEA, FER, MFI, MWW, TON) have also been
studied. The framework and extra-framework types of iron can
be distinguished by evacuation or by studying their reducubility.
Presence of dinuclear Feframework-O- Feextra-framework species
is also suggested from their respective spectra. 119mSn measurements
have also been carried out, on Pt-Sn/SiO2 and PtSn/Al2O3 systems
the formation of variuos PtXSny alloys was monitored --
and on stannisilicate zeolite analogs (MFI, MEL, MTW). Recently,
mesoporous systems (MCM-41 and SBA-15) are studied both by 57Fe
and 119mSn spectroscopies. Coordination and states of iron and
tin are distinctly different in comparison to those found in
zeolites under similar conditions.
Approximately 80 papers have been published based, at least in
part, on the work performed in the Mössbauer Laboratory.
A more detailed description can be found on the Laboratory's
home page: <www.iki.kfki.hu/catrace/Mosba.html>.
The staff at present consists of Károly Lázár
(head) and research fellows János Megyeri, Annamária
Murányi-Szeleczky (part-time), and László
Szirtes (part-time). Several students have also contributed to
the work of the Laboratory, by performing measurements for Ph.D.
or MS theses.
In the near future, we would like to construct an in-beam Mössbauer
facility in which the generation and excitation of the Mössbauer
source nuclei would be provided by continuous irradiation with
neutrons. The project has already commenced in cooperation with
the Department of Nuclear Research -- the respective beam line
at the Budapest Neutron Centre is under development.
Department
of Nuclear Chemistry
Eötvös Loránd University
Budapest
Zoltán Homonnay
and Attila Vértes
Department of Nuclear Chemistry
Eötvös Loránd University
Budapest
The first Mössbauer spectrometer was put into operation
at the Department of Physical Chemistry and Radiology in the
Institute of Chemistry of Eötvös Loránd University
in 1967. This device was a Hungarian-made spectrometer, designed
and built with the help of an electrical engineer János
Soós, as well as that of Lajos Keszthelyi and István
Dézsi who worked at the Central Research Institute for
Physics (KFKI) and had already achieved substantial experience
in the application of the Mössbauer effect by that time.
The subject of the first measurements carried out together with
István Dézsi was Mössbauer analysis of the
corrosion products of iron. The results were published in 1967,
first in Hungarian with an English version released in 1969 [1].
This was the first paper that showed that Mössbauer spectroscopy
is a unique tool to study the corrosion of iron.
Mössbauer investigation of frozen solutions began in the
mid-1960s by Lajos Keszthelyi and István Dézsi.
The special experimental quenching technique developed by them
was used later by Attila Vértes in order to explore the
chemical structure of solutions [2].
The mean time of the paramagnetic spin relaxation (t) could be
raised by applying dilute (< 0,05 M) iron(III) solutions at
low temperature (< 80 K) so that magnetic hyperfine splitting
showed up in the Mössbauer spectra. From the measured value
of the magnetic hyperfine field, the chemical effect of the ligands
on the central Fe3+ ion could also be deduced [3]. Dimerization
of Fe3+ species in the solution was shown by the observation
of magnetic to paramagnetic transition (due to accelerated spin-spin
relaxation) [4]. If polymerization or coalescence of Fe3+ species
occurs in the solution, the size distribution of the resultant
superparamagnetic particles can be determined from the temperature
dependence of the Mössbauer spectra [5].
Our group showed first that the Mössbauer effect can occur
in the liquid phase at room temperature in the microporous "thirsty
glass" (micropore diameter ~4 nm) [6].
A respected cooperation partner of the group in the application
of Mössbauer spectroscopy on solution and coordination chemistry
was Kálmán Burger, professor of the University
of Szeged, who died in 2000.
The group, in cooperation with researchers of Lehigh University,
Bethlehem, PA (Professors Leidheiser and Simmons), did pioneering
work in the application of Mössbauer spectroscopy in electrochemistry,
publishing dozens of papers in the field.
More recent activity of the group included Mössbauer studies
of aluminum alloys, electrodeposits, amorphous systems, superconductors,
and colossal magnetoresistant materials [7-12]. In addition to
these fields, the group is active in numerous other applications
(e.g., minerals, coordination chemistry).
The group loosened its ties with the Department of Physical Chemistry
and Radiology in 1983 when the Laboratory of Nuclear Chemistry
was established, which in a few years was declared as the Department
of Nuclear Chemistry headed by Prof. Attila Vértes. (The
Department's other important research activity is positron annihilation
spectroscopy.)
In the mid-1990s, the Research Group for the Application of Nuclear
Methods in Structural Chemistry headed by Prof. Attila Vértes
was created. This Research Group is sponsored by the Hungarian
Academy of Sciences. In 1999, Prof. Vértes resigned as
Department Head due to age limitation rules. His follower is
Prof. Zoltán Homonnay, former student of Prof. Vértes.
Thus the Mössbauer "crew" at the Chemistry Institute
of Eötvös University is now composed of colleagues
affiliated to the Department (Zoltán Homonnay, Professor,
Head; Sándor Nagy, Associate Professor; Attila Vértes,
Professor; and Zoltán Németh, Ph.D. student) and
to the Research Group of the Hungarian Academy of Sciences (Attila
Vértes, Head; Ernô Kuzmann, Research Professor;
Zoltán Klencsár, Research Associate Professor).
Former member of the Department Ilona Nagyné-Czakó
retired in 1995. György Vankó, former member of the
Research Group, left in 2001. About 40 Masters and 30 Ph.D. students
prepared their theses in our Laboratory in the past two to three
decades.
The Department of Nuclear Chemistry has the privilege of offering
Nuclear Chemistry as an obligatory course to all chemistry major
students. Since Mössbauer spectroscopy is part of this course,
there is a large pool from which to select future Mössbauer
spectroscopists. Currently, two Ph.D. students, two Masters (finishing
their diploma), three 4th-year students (starting their diploma
work next year), and another 3rd-year student (doing undergraduate
research) are directly involved in Mössbauer research in
various fields. The Department and the Research Group currently
have seven Mössbauer spectrometers, all in constant operation,
normally with three to four 57Co, one to two 119mSn, and one
151Eu sources available.
Three monographs and several book chapters dealing with Mössbauer
spectroscopy were published by our group.
There is hope that the application of Mössbauer spectroscopy
will continue for a long time in the Chemistry Institute of Eötvös
University, Budapest.
References
1. I. Dézsi, A. Vértes, L. Kiss, "Mössbauer
study of the corrosion products of iron." Magyar Kémiai
Folyóirat 73, 412 (1967); J. Radioanal. Chem. 2, 183 (1969).
2. A. Vértes, S. Nagy, I. Nagy-Czakó, É.
Csákvári, "Mössbauer study of equilibrium
constants of solvates. I. Determination of equilibrium constants
of tetraiodotin-trimethyl-isopropoxylane and tetrabromotin-acetic
anhydride solvates." J. Phys. Chem. 79, 149 (1975) and A.
Vértes, I. Nagy-Czakó, K. Burger, "Mössbauer
study of equilibrium constants of solvates. 2. Determination
of some solvation parameters of tin tetrahalides." J. Phys.
Chem. 80, 1314 (1976).
3. A. Vértes, F. Parak, "A study of the relationship
between the spin relaxation and certain chemical properties of
paramagnetic iron(III)-salt solutions by Mössbauer spectroscopy."
J. Chem. Soc. Dalton Trans., 2062 (1972).
4. A. Vértes, I. Nagy-Czakó, K. Burger, "Mössbauer
study of equilibrium constants of solvates. Solvent-solute interactions
in non-aqueous solutions of iron(III) chloride." J. Phys.
Chem. 82, 1469 (1978).
5. A. Vértes, L. Korecz, K. Burger. Mössbauer-spectroscopy.
Elsevier: Lausanne (1979), pp. 331-334.
6. K. Burger, A. Vértes, "Capillary Mössbauer
spectroscopy for solution chemistry." Nature 306, 353 (1983).
7. L. Murgás, Z. Homonnay, S. Nagy, and A. Vértes,
"Investigation of Phase Transformation in an Al-0.58 Wt
Pct Alloy by Mössbauer Spectroscopy." Metallurgical
Transactions 19A, 259-264 (1988).
8. E. Kuzmann, Z. Homonnay, A. Vértes, M. Gál,
K. Torkos, B. Csákvári, K. Sólymos, G. Horváth,
J. Bánkuti, I. Kirschner, and L. Korecz, "Metastability
in EuBa2(Cu1-xSnx)3O7-y Studied by 119Sn and 151Eu Mössbauer
Spectroscopy." Phys. Rev. B 39, 328-333 (1989).
9. Gy. Vankó, Z. Homonnay, S. Nagy, A. Vértes,
G. Pál-Borbély, H.K. Beyer, "On the synthesis
and steric distortion of the tris(2,2'-bipyridine)iron(II) complex
ion in zeolite-Y." JCS Chemical Communications, 785-786
(1996).
10. Z. Homonnay, Z. Klencsár, V. Chechersky, Gy. Vankó,
M. Gál, E. Kuzmann, S. Tyagi, J.-L. Peng, R.L. Greene,
A. Vértes and A. Nath: "The Effect of Praseodymium
on the Lattice Dynamics and Electronic Structure of the Cu(1)-O(4)
chain in Y1-xPrxBa2Cu3O7-d. Phys. Rev. B 59, 11596-11604 (1999).
11. Z. Homonnay, K. Nomura, G. Juhász, M.Gál, K.
Sólymos, S. Hamakawa, T. Hayakawa, and A. Vértes,
"Simultaneous probing of the Fe- and Co-sites in the CO2-absorber
perovskite Sr0.95Ca0.05Co0.5Fe0.5O3-d: a Mössbauer study."
Chemistry of Materials 14, 1127-1135 (2002).
12. Z. Klencsár, E. Kuzmann, Z. Homonnay,
A. Vértes, A. Simopoulos, E. Devlin, G. Kallias,
"Interplay between magnetic order and the vibrational state
of Fe in FeCr2S4." Journal of Physics and Chemistry of Solids
64, 325.
Research
Institute for
Solid-State Physics
Hungarian Academy of Sciences
Budapest
Imre Vincze
Research Institute for Solid-State
Physics
Hungarian Academy of Sciences
Budapest
Our Non-Equilibrium Alloys research group is a branch of the
Mössbauer group founded by L. Keszthelyi. Technical improvements
made by L. Keszthelyi, I. Dézsi, L. Cser, and the engineering
corps of the Central Research Institute for Physics, Budapest
(KFKI), resulted in high-quality equipment around 1970. This
equipment was suitable for studying the subtle alloying effects
of iron, which manifested mainly in changes of the line shape.
Until about 1974, the temperature and composition dependent studies
of the impurity effects in iron were our main research objects,
and they were performed in close cooperation with I.A. Campbell
(Orsay). Information on the conduction electron polarization
contribution of the iron hyperfine field and on the anomalous
temperature dependence of certain impurity magnetic moments (Mn,
Ru, Os, Ni, Pd, Pt) was obtained. Later, correlations between
the iron hyperfine fields and the magnetic moments in concentrated
binary, pseudo-binary alloys and intermetallic compounds were
studied together with A.J. Meyer's group in Strasbourg. Thanks
to the invitation of I. Vincze by M.G. Kalvius (1975-76),
a collaboration with F.E. Wagner in Munich was also established.
The research on metallic glasses started shortly after the discovery
of this new family of materials, and an important result in this
field the similarity of the short-range order of amorphous
alloys and certain intermetallic compounds was achieved
in works performed in Budapest and in Groningen (1979-87) together
with the group of F. van der Woude. In the early 1990s, the effect
of large external magnetic field on the spinglass-like behavior
in amorphous Fe-Zr and related alloys was investigated.
Recent research programs aim to study different nanostructured
materials prepared by ball milling (e.g., Fe, Fe-B, Fe-Al), magnetic
multilayers (e.g., Fe-B, Fe-Ag) evaporated in high vacuum, and
nanocrystallized amorphous ribbons (e.g., Fe-Zr-B-Cu and related
alloys). In a comparative study of these systems, it was found
that nonequilibrium alloying in nanostructures play an overwhelming
role in the deviation of the hyperfine fields from the bulk value
and the grain boundary effects cannot be separated. Nonequilibrium
mixing in nanostructures takes place even in cases when the elements
are unsolvable in the bulk state (e.g., Fe-Ag). With diminishing
grain size, superparamagnetic relaxation of the grains becomes
dominant. In the case of soft magnetic nanocrystalline alloys,
this may result in magnetic decoupling of the bcc grains from
the ferromagnetic residual amorphous matrix. At present, investigations
on the external magnetic field dependence of the superparamagnetic
relaxation of nanometer size particles and the possibility of
field induced collective behavior in concentrated small particle
system is in progress.
Another line of Mössbauer effect-related research started
at the end of the 1980s. Experiments based on the resonant scattering
of Mössbauer quanta were initiated by G. Faigel. These included
various measurements using laboratory and synchrotron sources:
The possibility of laboratory source-based diffraction experiments
on powdered samples was demonstrated. A monochromator was made
for the 151Eu resonance and the technique of the nuclear resonant
scattering of synchrotron radiation was extended to this isotope.
Quantum beats on Eu2O3 and EuS powder mixture were measured.
Theoretical works on inside source gamma holography based on
the interference of recoil free scattered photons were done.
The setting up of an experimental station for gamma holography
is underway.
Dr. Göstar Klingelhöfer
Johannes Gutenberg-Universität Mainz
Institut für Anorganische und Analytische Chemie
Staudinger Weg 9,
D-55099 Mainz
Tel.: +49-6131-39-23282 (Sekr.:-25333);
Fax: +49-6131-39-26263
email: klingel@mail.uni-mainz.de
Mainz, 2.6.2003
Hi All,
Yesterday evening (2. June 2003) at 7:45 pm MEZ (6:45 pm GMT) we had a very successful launch of Mars-Express and Beagle 2 with our spectrometer MIMOS II at Baikonur, Kasachstan. After one interim orbit around Earth and 1 hour 32 min after launch the spacecraft was injected to the interplanetary trajectory towards Mars. Solar panels are deployed already and the spacecraft is oriented correctly.
For about 12 hours now, for the very first time a Mössbauer spectrometer left Earth and is on its way to Mars with a speed of 30 km/sec (3 km/sec relative to Earth). The actual distance to Earth currently is already more than 400 000 km which is more than the average distance Earth-Moon.
That's a great day for ESA, Europe, our MIMOS II team, and the Mössbauer community.
There is still a long way to go until landing on Mars, but finally it's on its way to Mars.
Cheers,
Göstar
Mainz, 11.6.2003
Hi All,
Yesterday evening (10. June 2003) at 7:58:47 pm MEZ we had again a very successful launch. The first out of two of the NASA Mars-Exploration-Rovers, with our spectrometer MIMOS II on board, was launched from the Kennedy Space Center in Florida, USA, for Mars. About 36 minutes after launch the MER spacecraft separated from the third stage of the Delta II rocket, and was injected successfully to the interplanetary trajectory towards Mars. Solar panels are deployed, batteries are coming up, and the spacecraft is oriented correctly.
For about 22 hours now, the second (out of three hopefully) Mössbauer spectrometer left Earth and is on its way to Mars. By now everything is working nominal.
The launch of the second NASA MER, having the third MIMOS on board, is scheduled for 25.June (first opportunity) at about 6 am MEZ.
If everything goes well we will have a Mössbauer Network on Mars the beginning of 2004.
There is still a long way to go until landing on Mars, but finally we are on our way to Mars.
Cross your fingers!
Cheers,
Göstar
Professor Philipp Gütlich Honored by Eötvös Loránd University
On 9 May 2003, Professor Philipp Gütlich was honored
by the award of "Doctor et Professor Honoris Causa"
by Eötvös Loránd University in Budapest,
Hungary. Congratulations, Professor Gütlich!(Contributed
by Attila Vértes, Eötvös Loránd University,
Budapest.)
The
Third Nassau Mossbauer Conference
Garden City, New York,
United States
10 January 2003
Conference Report
This one-day symposium on the further development and novel
application of the Mössbauer technique to science was held
on Friday, January 10, 2003. The Conference was jointly organized
by Clive Wynter of Nassau Community College and E. Ercan Alp
of Argonne National Laboratory.
Conference day was blessed with good weather and a group of approximately
35 scientists assembled at 8:30 A.M. to have a light continental
breakfast followed by a welcome address by Dr. John Ostling,
Academic Vice President of Nassau Community College.
The actual meeting started on a bright note as Dr. Wolfgang Sturhahn
of Argonne National laboratory explained in some detail nuclear
resonant inelastic x-ray scattering (NRIXS), and the study of
magnetic properties with synchrotron Mössbauer (SMS). Isotopes
discussed were 57Fe, 119Sn, and 161Dy. This was followed by Dr.
Viktor V. Struzhkin's talk on density of states and elastic properties
of Fe and FeO; highlights of this talk included geophysical implications
resulting from the elastic and magnetoelastic properties of these
and related materials under compression.
The next three presentations were focused on rare earth Mössbauer
spectroscopy. Professor Dennis Brown from Northern Illinois University
interpreted NRIXS studies of dysprosium compounds, such as the
enriched metal, the metal oxides, and intermetallic dysprosium
materials. Professor John "Sean" Cadogan of the University
of New South Wales presented some useful rules-of-thumb for the
analysis of 166Er, 169Tm, and 170Yb Mössbauer spectra by
first generation Mössbauer spectrometer. This was followed
by an equally interesting study of 166E and 170Yb magnetic ordering
and valence by Professor Dominic Ryan of McGill University.
Just prior to lunch, Professor Fred Oliver of Morgan State elaborated
on 57Fe used to characterize pulse-laser-deposited (PLD) films.
Lunch break was followed by a Poster Session Review from 1:30-2:00
P.M. Poster papers included 119Sn halides by Professor Georges
Denes, anthracene as a non-hygroscopic diluting agent for Mössbauer
spectroscopy, a historical Mössbauer spectroscopy calender
by Professor Leopold May, 151Eu and 57Fe study by Professor Dereje
Seifu, and the ranking of coal using 57Fe by Professor Clive
Wynter.
Professor Desmond Cook of Old Dominion University gave an enlightening
talk about the application of 57Fe Mössbauer spectroscopy
to corrosion of bridges, Audria Stubna of Carnegie Mellon University
reported characterization of high-valence, non-heme iron complexes,
while Dr. Ravi K. Kukkadapu engaged us in microbial reduction
of crystalline Fe3+- oxides in Oak Ridge sediment. Professor
Sat Taneja discussed Mössbauer and x-ray studies of thermal
plant coal and fly ash. Professor Georges Denes of Concordia
University discussed bonding in the doubly disordered barium
tin mixed halides. This was followed by Professor B.J. Evans
of the University of Michigan, who discussed the controversy
in the 57Fe coordination member of the sites for the ferrous
ion and the ferrous-to-ferrous ratio in highly reduced glasses.
Finally, Professor John Stevens reviewed the past and the present
Mössbauer community, and the expectations of a future Mössbauer
community.
All in all, it was an exciting, enlightening meeting; the informational
diet was just right.
(Submitted by Conference Co-Organizer Dr. Clive I. Wynter, Nassau Community College, Nassau, New York, USA.)
Future
Conferences,
Symposia, and Workshops
May 25-30, 2003
7th International Conference on Materials and Mechanisms of Superconductivity
and High Temperature Superconductors (M2S-HTSC-VII); Rio de Janeiro,
Brazil (for more information see Vol. 26, No. 1 Newsletter).
June 4, 2003
Symposium: Nuclear Techniques for the Characterization of Modern
Materials; Ličge, Belgium (for more information see
Vol. 26, No. 2 Newsletter).
June 5-6, 2003
Groupe Francophone de Spectrométrie Mössbauer Meeting:
Mineralogy and New Technical Developments; Ličge, Belgium
(for more information see Vol. 26, No. 2 Newsletter).
July 22-25, 2003
XVIII International Colloquium on Magnetic Films and Surfaces
(ICMFS-2003); Madrid, Spain (for more information see Vol.
26, No. 1 Newsletter).
August 24-28, 2003
10th International Symposium on Metastable, Mechanically Alloyed
and Nanocrystalline Materials (ISMANAM 2003); Foz do Iguaçu,
Brazil (for more information see Vol. 25, No. 9 Newsletter).
September 4, 2003
44th UK Mössbauer Discussion Group Meeting (MDG-44); London,
England (for more information see Vol. 26, No. 3 Newsletter).
September 7-11, 2003
4th International Conference on Mechanochemistry and Mechanical
Alloying (4th INCOME); Braunschweig, Germany (for more information
see Vol. 26, No. 3 Newsletter).
September 21-25, 2003
International Conference on the Applications of the Mössbauer
Effect (ICAME 2003); Muscat, Sultanate of Oman (for more information
see Vol. 26, No. 3 Newsletter).
June 21-25, 2004
IX International Conference on Mössbauer Spectroscopy and
Its Applications (IX ICMSA); Ekaterinburg, Russia (for more
information see Vol. 26, No. 2 Newsletter).
June 27 - July 1, 2004
Second Seeheim Conference on Magnetism (SCM2004); Seeheim, Germany
(for more information see Vol. 26, No. 2 Newsletter).
October 4-8, 2004
International Symposium on the Industrial Applications of the
Mössbauer Effect (ISIAME 2004); Madrid, Spain (for more
information see Vol. 24, No. 8 Newsletter).
The following is a selected list of important dates relating to upcoming conferences. Please mark your calendars accordingly!
April 2003
10: Deadline for Receipt
of Abstracts
XVIII International Colloquium on Magnetic Films and Surfaces
(ICMFS-2003)
15: Deadline for Receipt
of Abstracts
10th International Symposium on Metastable, Mechanically Alloyed
and Nanocrystalline Materials (ISMANAM-2003)
May 2003
4: Deadline for Receipt
of Abstracts
Fourth International Conference on Mechanochemistry and Mechanical
Alloying (4th INCOME)
23: Deadline for Reduced-Rate
Registration
XVIII International Colloquium on Magnetic Films and Surfaces
(ICMFS-2003)
30: Requested Date for Attendance
and Title Information
44th UK Mössbauer Discussion Group Meeting (MDG-44)
June 2003
15: Deadline for Early Registration
10th International Symposium on Metastable, Mechanically Alloyed
and Nanocrystalline Materials (ISMANAM-2003)
July 2003
1: Deadline for Receipt
of Abstracts and Registration Information
International Conference on the Applications of the Mössbauer
Effect (ICAME 2003)
15: Deadline for Hotel Reservations
10th International Symposium on Metastable, Mechanically Alloyed
and Nanocrystalline Materials (ISMANAM-2003)
August 2003
1: Deadline for Fees and
Visa Request; Hotel Reservations
International Conference on the Applications of the Mössbauer
Effect (ICAME 2003)
1: Deadline for Early Registration
Fourth International Conference on Mechanochemistry and Mechanical
Alloying (4th INCOME)
24: Deadline for Receipt
of Manuscripts
10th International Symposium on Metastable, Mechanically Alloyed
and Nanocrystalline Materials (ISMANAM-2003)
September 2003
7: Deadline for Receipt
of Manuscripts
Fourth International Conference on Mechanochemistry and Mechanical
Alloying (4th INCOME)
10: Deadline for Receipt
of Manuscripts
International Conference on the Applications of the Mössbauer
Effect (ICAME 2003)
March 2004
1: Deadline for Receipt
of Abstracts
Second Seeheim Conference on Magnetism (SCM2004)
20: Deadline for Receipt
of Manuscripts
Second Seeheim Conference on Magnetism (SCM2004)
25: Deadline for Registration
Second Seeheim Conference on Magnetism (SCM2004)
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Newsletter Notes
If you have information that you would like to share with
the Mössbauer scientific community in our Newsletter, please
contact:
Mössbauer Effect Data Center
University of North Carolina
206 Rhoades Hall, CPO 2311
Asheville, NC 28804-8511 USA
Email: MEDC@UNCA.EDU
Fax: 828-232-5179