Mossbauer spectroscopy fields

Mossbauer spectroscopy is a specialist characterization tool in catalysis. Nevertheless, it has yielded essential information on a number of important catalysts, such as the iron catalyst for ammonia and Fischer-Tropsch synthesis, as well as the CoMoS hydrotreating catalyst. Mossbauer spectroscopy provides the oxidation state, the internal magnetic field, and the lattice symmetry of a limited number of elements such as iron, cobalt, tin, iridium, ruthenium, antimony, platinum and gold, and can be applied in situ. 

Relativistic effects in core properties like electric field gradients can be extremely large [103]. As the isotope 197-Au is widely used is Mossbauer spectroscopy [104], an... 

Spiering, H. The Electric Field Gradient and Quadmpole Interaction. In Long, G. (ed.) Mossbauer Spectroscopy Applied to Inorganic Chemistry, p. 79. Plenum, New York (1984)... 

However, useful as it is, ligand field theory is not a predictive first principles theory. Thus, it cannot be used to predict a priori the Mossbauer parameters of a given compound. Yet, the need to do so arises fi equently in Mossbauer spectroscopy. For example, if a reaction intermediate or some other unstable chemical species has been characterized by freeze quench Mossbauer spectroscopy and its SH parameters become available, then the question arises as to the structure of the unstable species. Mossbauer spectroscopy in itself does not provide enough information to answer this question in a deductive way. However, the more modest question which structures are compatible with the observed Mossbauer parameters can be answered if one is able to reliably predict Mossbauer parameters... 

The third prominent interaction in iron Mossbauer spectroscopy is the magnetic hyperfine interaction of the Fe nucleus with a local magnetic field. As explained in detail in Chap. 4, it can be probed by performing the Mossbauer experiment in the presence of an applied external magnetic field. 

Since Mossbauer spectroscopy is sensitive to all terms in the SH, it is also sensitive to the ZFS and the g-tensor. The theory of both interactions can be approached along the same lines as explained in some detail in Appendix 1 (Part III, 3 of CD-ROM) [89, 90]. This becomes somewhat elaborate for the ZFS while the g-tensor is more readily approached. Both quantities have been previously treated in some detail and a protracted discussion would be inappropriate here [9, 79, 89-93]. In general, the accuracy with which both quantities can be calculated from DFT is rather moderate and a combination of ligand field theory and DFT or some... 

Spin-canting is conveniently studied by Mossbauer spectroscopy with large magnetic fields applied parallel to the y-ray direction. The relative areas of the six lines are given by 3 p l l p 3, where... 

The previous chapters are exclusively devoted to the measurements and interpretation of Fe spectra of various iron-containing systems. Iron is, by far, the most extensively explored element in the field of chemistry compared with all other Mdssbauer-active elements because the Mossbauer effect of Fe is very easy to observe and the spectra are, in general, well resolved and they reflect important information about bonding and structural properties. Besides iron, there are a good number of other transition metals suitable for Mossbauer spectroscopy which is, however, less extensively studied because of technical and/or spectral resolution problems. In recent years, many of these difficulties have been overcome, and we shall see in the following sections a good deal of successful Mossbauer spectroscopy that has been performed on compounds of... 

McCammon et al. have studied fine nickel particles using Ni Mossbauer spectroscopy [22]. The measured average hyperfine field of 10 nm particles at 4.2 K was 7.7 T for nickel foil, it was found to be 7.5 T. Application of an external magnetic field of 6 T caused a reduction of the hyperfine splitting to 1.5 T as a consequence of the negative hyperfine field at Ni nuclei. 

Ta foil Nuclear forward scattering of synchrotron radiation (NFS) at Ta resonance in Ta foil without and with applied magnetic field, point out advantages over conventional Ta Mossbauer spectroscopy... 

Because of the limited scope of this monograph, it is impossible to give a rigorous account of the work that has been accomplished in these fields. By the end of 2008, about 60,000 publications dealing with the use of Mossbauer spectroscopy had been documented in the literature. Excellent review articles on Mossbauer Spectroscopy Applied to Inorganic Chemistry (3 volumes) are given in [30, 34-35] in Chap. 1 and on Mossbauer Spectroscopy Applied to Magnetism and Materials Science (2 volumes) in [38, 40] in Chap. 1. 

The authors of this book consider it appropriate to include in this section two contributions from their own laboratories, one on Mossbauer spectroscopy of spin crossover (SCO) phenomena in iron(II) compounds and the other on applications to biological systems. Both chapters will demonstrate the effectiveness of Mossbauer spectroscopy in these particular fields. 

By far the most utilized Mossbauer isotope is Fe, particularly in (bio)inorganic chemistry. Most iron compounds are found in the oxidation states iron(ll) and iron (III), either with low-spin or high-spin electron configuration. The literature on the application of Fe Mossbauer spectroscopy in this field of research has been reviewed in several textbooks, which are referenced in Chap. 1. The present chapter is intended as a survey of the Mossbauer studies on iron compounds with less common, nevertheless increasingly interesting, valence and spin states. 

Four-coordinate, planar iron(II)-dithiolate complexes also exhibit intermediate spin. The first example described was the tetraphenylarsonium salt of the square-planar bis(benzene-l,2-dithiolate)iron(II) dianion, (AsPh4)2[Fe(II)bdt2], which showed 5 = 0.44 mm s and AEq = 1.16 mm s at 4.2 K [157]. The electronic structure of a different salt was explored in depth by DFT calculations, magnetic susceptibility, MCD measurements, far-infra red spectroscopy and applied-field Mossbauer spectroscopy [158]. 

The miniaturized Mossbauer spectrometer MIMOS II has been used already in several terrestrial applications which would not have been possible before. A number of other possible terrestrial applications, for example, in the field, in industry, and fundamental research, are under consideration. With the new generation of the Mossbauer spectrometer MIMOS 11, the method itself can be applied to numerous new fields in research, environmental science, planetary science, and many other fields. Because of this reason, Mossbauer spectroscopy may become a more widely used method than it is today. 

A CD-ROM is attached containing a teaching course of Mossbauer spectroscopy (ca. 300 ppt frames), a selection of examples of applications of Mossbauer spectroscopy in various fields (ca. 500 ppt frames), review articles on computation and interpretation of Mossbauer parameters using modem quantum-mechanical methods, list of properties of isotopes relevant to Mossbauer spectroscopy, appendices refering to book chapters, and the first edition of this book which appeared in 1978. In subsequent printmns files are available via springer.extra.com (see imprint page). 

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