Mössbauer spectroscopy
The Mössbauer spectroscopy is a non-destructive, physical fine analytical method , for example, in Biochemistry , solid state physics and geology is used.
description
v. l. Right: Mössbauer drive, gamma ray source, collimator , material sample, detector
In Mößbauer spectroscopy , the Doppler effect is used in addition to the Mößbauer effect . A hyperfine modulation of a gamma emitter is generated by moving it mechanically during the measurement. In this way, gamma quanta with different energies can be generated in a hyperfine spectrum.
If the sample of a material whose atomic nuclei can absorb gamma quanta is transilluminated with appropriately modulated gamma radiation, a high-resolution transmission spectrum typical for the material can be recorded using appropriate detectors and computer-aided evaluation .
This enables qualitative and quantitative statements about the elements contained in the sample . About the high-resolution hyperfine structure , which results from electron-nucleus interactions, one can not only make statements about the nuclei themselves, but also about properties of their electronic environment, such as: B. oxidation state , spin states, magnetic behavior, electronegativity of ligands and other properties of chemical bonds such as the degree of covalency .
application
The main area of application of Mössbauer spectroscopy is the distinction between divalent and trivalent iron . It can also be used to detect the elements tin , antimony and tellurium . In the 1980s, portable Mössbauer spectrometers were used to explore the tin deposits in the Ore Mountains .
Miniaturized Mössbauer spectrometer, developed as "MIMOS II" at the University of Mainz and built in the NASA - Mars probes of the missions Spirit and Opportunity in use and analyze the Martian rocks . In addition to clear evidence of water, they also found evidence of a phase in Martian history when there was much more oxygen in the atmosphere than today.
Another example, only the size of a fist, was supposed to land on the Martian moon Phobos in 2013 with the Russian probe ' Fobos-Grunt ' . After the probe was stranded in a park orbit , it entered the earth's atmosphere on January 15, 2012 and burned up over the Eastern Pacific.
See also
literature
- Christian Meier: Mössbauer spectroscopy on biomimetic model complexes and non-heme iron proteins. Shaker, Aachen 2001, ISBN 3-8265-8381-7 .
- Stefan Lauterbach: The degree of oxidation of the iron in the lower mantle: a study of the Fe 3+ content of the silicate perovskite as a function of its Al content with Mössbauer spectroscopy and electron energy loss spectroscopy (EELS). Dissertation, University of Bayreuth, 2000.
- Horst Wegener: The Mössbauer effect and its application to physics and chemistry . University paperback publishing house, Mannheim, 1965.
Individual evidence
- ^ Philipp Gütlich: Physical methods in chemistry: Mössbauer spectroscopy I. In: Chemistry in our time . No. 4, 1970, pp. 133-144 (review article, doi: 10.1002 / ciuz.19700040502 ).
- ↑ Distinct Reaction Pathways followed Upon Reduction of Oxy-Heme Oxygenase and Oxy-Myoglobin as Characterized by Mössbauer Spectroscopy; J. Am. Chem. Soc. 2007 February 7; 129 (5): 1402-1412. doi: 10.1021 / ja067209i , PMC 2519892 (free full text)
- ↑ Mars-Mößbauer-Group: Structure of the MIMOS II ( Memento of the original from June 27, 2009 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. .
- ^ Spiegel Online
- ^ William Harwood: Russians now preparing for re-entry of failed Mars probe , in Spaceflight Now, Date: December 17, 2011, Accessed: December 18, 2011
- ↑ Bernd Leitenberger: Phobos-Grunt , accessed: December 18, 2011
