Mössbauer effect is based on the recoilless nuclear emission and resonant absorption of gamma-rays in the sample. The record of the Mössbauer spectrum employs a measurement of the intensity of gamma-ray in accordance with precise controlled movement of the radioactive source.
Mössbauer spectroscopy allows to determine and quantify the phase composition of solids (amorphous, nano-crystalized); in addition it enables to determine valence and spin states of atoms under investigation, to distinguish the structural positions of atoms, to determine the magnetic states and local configuration of magnetic atomic moments and determine magnetic characteristics including temperature and magnetic transitions of the matter; to study the mechanisms and kinetics of reactions in solid phases and phase transformations.
There is also a possibility to measure temperature and field dependencies of the mentioned features. Mössbauer spectroscopy represents an analytical tool for material research bearing specific nuclei (mostly Fe and Sn, Au, Ni, Zn, Au …) by the form of local probe in their nearest surrounding. Mössbauer spectroscopy is highly element selective and allows identifying certain species and compounds, even if they appear in the material quite rarely.
Utilizing the cryostats or high temperature furnaces, one can analyze samples at various conditions, at low temperature (from 1,5 to 300 K, i.e.) and at high temperatures (up to 600 °C, or higher i.e., with the choice of reactions or inert atmosphere, or vacuum), or to apply an external magnetic field (up to 7 T, in the regime of low temperatures, below room temperature).
Samples can be in the forms of powders, thin layers, foils, and plates. If there is a need to analyze larger samples with nondestructive approach, it is advised to apply Mössbauer method in backscattering geometry.
Transmission Mössbauer spectrometer, 5–300 K, RT–600 °C (low-room-high temperatures)
Transmission Mössbauer spectroscopy (TMS) is used for analysis of samples by the penetration of radiation, hence in the direct geometry, where the source, sample, and the detector lie in the axis. Sample should not absorb the radiation γ of given energy. There is an effort to set the thickness of the sample as optimal, since it should not be so thick to not increase the resonance line width affected by the multi resonance absorption/emission processes and concurrently the absorption should be as high as possible.
Mössbauer spectrometer in the backscattering regime, RT
Mössbauer spectrometer in the backscattering regime / geometry (BMS) is used for studying thin and thick films, large specimens and phase composition of surfaces. While there is an energy loss during the absorption of rays in the material under investigation, the analysis deepness is about 10 μm.
As a commercial contract we provide:
- structural, phase, and magnetic characterization of iron containing samples
- element selective (Fe, Sn) determination and quantification of phase composition of samples including amorphous and nanocrystalline (detection limit of approx. 2%)
- determination of valent and spin states of iron atoms, recognition of structural positions of iron atoms, stoichiometry evaluation, and cations substitutions
- determination of magnetic states and local arrangement of atom moments
- measurement of spectra temperature dependence
- determination of magnetic features, including temperature induced magnetic transitions and superparamagnetism
- study of mechanism and kinetic of reactions in solid phase, phase transformations
- elements – isotopes:
- iron 57Fe,
- alternatively tin 119Sn
- temperature range:
- from 5 to 300 K,
- room temperature
- high temperatures (in situ)
- thin sheets, films on support, foils
- special modes after discussion – i.e. backscattering geometry for (corrosion) study of surfaces of large specimens, the analysis of deepness from 1-10-100 µm, measurement in the inert or reactive atmosphere, etc.