Program package CONFIT enables a complex processing of 57Fe and 119mSn Mossbauer spectra. The mouse drag-and-drop technique is used to set up the background and parameters of the individual spectral components according to the structural model supposed. An original method has been applied: a nonlinear least-squares procedure with the Fast Fourier Transform (FFT) technique. A combination with improved matrix formalism can create various physical models to analyze the measured experimental data in a proper way. The hyperfine field distribution(s) and also quadrupole splitting distribution(s) with Gaussian profile can be applied, besides discrete components. The finite sample thickness can be included in terms of transmission integral and a dependence of the spectral line-width on its position with respect to the spectrum center is described by an additional parameter. This fitting procedure is suitable for Mossbauer spectra taken in the transmission and in the back-scattering geometry (including γ-ray and conversion electrons) and it can be successfully applied for analyzing the emission Mossbauer spectra. The transmission Mossbauer spectra yield information concerning the bulk microstructure, the back-scattering geometry is used for surface studies and the emission Mossbauer spectra yield information from grain boundaries or interface regions. The CONFIT is user friendly, fast and applicable for complicated Mossbauer spectra. Copyright © 2006 John Wiley & Sons, Ltd.

CONFIT: Mössbauer spectra fitting program

A promising approach by which to gain information about the spin distributions in different sample layers using depth-sensitive angle-dependent conversion electron Mossbauer spectroscopy is presented in combination with magneto-optical Kerr effect, Rutherford backscattering spectrometry and x-ray diffraction investigations. Three 77 nm thick Fe films containing a 15 nm 57Fe marker layer at different depths were deposited on Si(100) substrates and irradiated under well defined mechanical stress with 200 keV Xe ions. The distribution of the spins in the sample plane was analyzed by Mossbauer spectroscopy and by tilting the sample toward the incident γ beam and observing the variation in angle-dependent relative intensity of the sextet lines. For the sample with the sensitive marker layer in the middle of the ferromagnetic film, all spins were found to be oriented exactly along the mechanical stress axis. This agrees with the angular properties of the macroscopic hysteresis curves measured by the magneto-opt...

Determination of spin distributions in ion-beam magnetic textured iron films by magnetic orientation Mössbauer spectroscopy

A new coat was given to the well-tried software for the fitting of Mossbauer spectra. The program is based on the Veslý’s idea of convolution [1–3] and on the optimization package of Kuicera et al. [4]. It enables the use of transmission integral and of distribution of magnetic splitting and/or isomer shift allowing to fit precisely overlapped spectra of amorphous, microcrystalline or multiphase materials. The process of fitting can be checked and stopped or continued after the parameter change using on-screen controls. The newly implemented dialogues simplify the man-machine interface of this 32 bit Windows® 95 application. Internally, the computation was speed-up by omitting all obsolete parts and program desegmentation, the numerical stability was improved by the 8 byte representation for the substantial part of variables. Finally, some pieces of information concerning current and future extension of the described software package are added.

Confit for Windows® 95

Mossbauer spectroscopy is a useful analytical tool in earth sciences. It is applicable to elements having Mossbauer-active isotopes like iron, tin and gold, etc. It gives information about the oxidation and magnetic state of these elements and about the short-range crystal chemistry of crystalline and amorphous materials containing Mossbauer active nuclides.

Geological and Mineralogical Applications of Mössbauer Spectroscopy

Mossbauer (nuclear γ-resonance) spectroscopy is a powerful technique which is actively used in various fields from physics and chemistry to biology and medicine. Rudolf L. Mossbauer, who observed nuclear γ-resonance and published his results in 1958, got a Nobel Prize in physics in 1961 for this discovery. 57Fe is the most widely used nucleus in Mossbauer spectroscopy. Therefore, a large variety of compounds containing iron can be studied by Mossbauer spectroscopy. It is well known that planetary matter contains various iron-bearing phases and minerals. Therefore, the extraterrestrial material from different meteorites, asteroids, and planets can be studied using 57Fe Mossbauer spectroscopy as an additional powerful technique. Two parts of this review consider the results of more than 50 years of experience of Mossbauer spectroscopy applied for the studies of various meteorites, soils and rocks from the Moon and a recent investigation of the Martian surface using two rovers equipped with miniaturized Mossbauer spectrometers. Part I considered the results of Mossbauer spectroscopy of undifferentiated meteorites. Part II discusses the results of Mossbauer spectroscopy of differentiated meteorites formed in asteroids and protoplanets due to matter differentiation, as well as Lunar and Martian matter.

Applications of Mössbauer Spectroscopy in Meteoritical and Planetary Science, Part II: Differentiated Meteorites, Moon, and Mars

A new method for least-squares processing of Mossbauer spectra is presented applicable not only to the common spectra with superposition of bound Lorentzians or to a simple model of hyperfine field distribution, but allowing to use the transmission integral as well. A FORTRAN IV implementation comprises, among others, a computer-aided matrix model design and extensive postprocessing involving velocity scale calibration and area analysis. As an illustration, fitting of spectra of partially crystallized amorphous alloys having both crystalline and amorphous contributions is presented.

Universal FFT/matrix method for processing Mössbauer spectra

To produce magnetic anisotropy in amorphous alloys, stress-annealing above the Curie temperature was substituted for the common thermomagnetic treatment. A tilting three-angle Mossbauer method was applied to see the changes of the57Fe hyperfine field directions and intensities due to this procedure. The resulting pictures of the domain orientations distribution in the Fe80Cr2B14Si4 and Fe40Ni40B20 amorphous alloys are compared with the measured magnetic anisotropies and domain structures.

Mössbauer spectroscopy of creep-annealed soft magnetic amorphous alloys

In a previous work [1], a large magnetic anisotropy was found as a preliminary result of the formation of electrochemically deposited Fe93P7 alloy. Mossbauer spectroscopy was used in order to get information about the magnetic anisotropy of electrochemically prepared Fe−P and Fe−Ni−P amorphous alloys. The Mossbauer spectra and the hyperfine field distributions of the samples show that Fe−Ni−P and Fe−P electrodeposited amorphous materials can be prepared in a reproducible way from a point of view of short range ordering which is strongly dependent on the chemical composition determined by preparation conditions. The average magnetization directions in the samples were determined from the transmission spectra measured in a normal and two tilted geometries by two types of evaluation methods [2,3]. We have found that the small spread model of the domain structure better describes the experimental results. The obtained data reflect the prevailing anomalous magnetization orientation in these electrodeposited amorphous alloys.

Mössbauer study of magnetic anisotropy in electrochemically deposited Fe−Ni−P amorphous alloys

Long term stability of the coercivity and57Fe Mossbauer parameters (magnitude and average orientation of hyperfine induction) at ca 150 °C was tested at three TM-M type amorphous alloys (Fe83B17, Fe40Ni40B20 and Co66Fe5Cr7Si8B14) up to 5000 hrs. Correlations between the Mossbauer and magnetic quantities were found and their possible causes are discussed.

Long-term low-temperature ageing of amorphous alloys

A systematic increase of the average hyperfine magnetic induction at57Fe measured at room temperature during interrupted isothermal annealing was found to be inherent to the irreversible relaxation processes in the Fe−B based soft magnetic alloys at moderately elevated temperatures. Assuming superimposed asymptotic exponential field vs. time dependences. several processes can be distinguished, their relaxation times determined and from the Arrhenius-like log τ vs. 1/T plots average activation enthalpies estimated. Results on the Fe70Co10B20 and Fe85−x
Co
 x
 B15 (x=17, 19 and 21 at. % Co) amorphous ribbons between 100 and 200°C are compared and discussed in terms of possible stress relief, free volume annihilation and short range ordering mechanisms.

T. Zemčík

Papers

Universal FFT/matrix method for processing Mössbauer spectra

Mössbauer spectroscopy of creep-annealed soft magnetic amorphous alloys

Mössbauer study of magnetic anisotropy in electrochemically deposited Fe−Ni−P amorphous alloys

Long-term low-temperature ageing of amorphous alloys

Hyperfine field relaxations in the Fe−Co−B amorphous alloys