Structure Mdssbauer spectroscopic studies

The existence of a proper y-ray transition is an outcome of nuclear structure. Therefore, a Mdssbauer transition is coupled to a certain isotope of the atom of interest. A low isotopic abundance of the resonant isotope may be a serious restriction. Next, if the excited state is rather short lived then F becomes wide and the resolution for hyperfine spectroscopy (see section 2.3) becomes too limited. The same effect can be caused by unfortunate values of nuclear moments of the two states involved in the Mdssbauer transition. Finally, difficulties to produce the source activity may hinder a wider application of measurements with that particular isotope. Difficulties in source preparation and poor resolution are, for example, present in and have prevented Mdssbauer spectroscopic studies of compounds of this most interesting actinide. 

Since 1980, newer physical techniques such as Mdssbauer spectroscopy, X-ray absorption spectroscopy and iron-sulfur-core extrusion have been used to address the question of the structure of FeS-X. The initial Mossbauer spectroscopic study by (EH) Evans, Rush, Johnson and (MC W) Evans2o indicated... 

Finally, others and us calculated Mdssbauer parameters of TauD and P4H in comparison with experiment (58,59). Although the agreement for these types of calculations is not perfect, generally the correct trend is reproduced. Recent quantum mechan-ics/molecular mechanics studies on a doubly reduced form of structure B in the catalytic cycle of P450 were performed and focused on the possible low-lying electronic states (60). In particular, the relative energy difference and spectroscopic parameters (EPR) of an Fe -porphyrin versus Fe -porphyrin anion radical were compared. 

---