Relaxation in phase-modulated Moessbauer spectroscopy

The authors study the transmission of phase-modulated radiation from a Moessbauer source through an absorber, assuming that the transition frequencies of the absorber nuclei fluctuate according to a dichotomic Markov process. The relaxation affects the transmission characteristics strongly both for a thin and a thick absorber. In the latter case the phases of the Fourier components of the transmitted intensity allow for a a direct access to the relaxation mechanism of the absorber. (Auth.)