Some recent aspects of relaxation line shapes in Moessbauer spectroscopy

Theoretical development in the line shape calculation of Mossbauer resonance spectra involving spin relaxation effects is introduced. The ''eigenvalue'' procedure of calculating line shapes saves computational times by two orders of magnitude compared to traditional methods. This was illustrated by calculating the relaxation spectra of hemoglobin cyanide and a GAMMA8 quartet electronic state. The ''white noise approximation'' involved in all the relaxation theory is discussed, and its limitations are pointed out. The theory without such an approximation is used to analyze the data for Cs2NaYbCl6