Techniques for fitting Mossbauer spectra

How much does this affect the resultant Fe /EFe ratios An example from Rancourt (1994a) serves to illustrate the effects. Spectra of three micas (two biotites and an annite) were fit with either multiple Lorentzian doublets or a Voigt-based quadrupole splitting distribution (QSD) of peaks. The Lorentzian fits yielded Fe /EFe ratios of 8.62, 22.17, and 18.79, while the QSD fits gave values of 10.60, 25.44, and 17.52 respectively, for the three samples. Based upon this author s considerable recent experience in fitting mica spectra both ways, these differences are typical. 

These papers have serious implications for interpreting all of the previous work on Mossbauer in micas. Most importantly, they demonstrate the futility of attempting to extract ordering information about micas from the areas of and [ Fe doublets. 

However, they do not necessarily negate the efforts of the majority of previous workers whose main interest has been characterization of Fe /EFe ratios. For those studies, the critical but now informed reader should be aware that a small amount of additional error is imposed by use of the Lorentzian rather than QSD model. In many cases, quoted error bars on Fe VEFe ratios are already sufficiently large to accommodate this additional error. 

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