Time-gated Zn-67 Mössbauer spectra of phase switching transients

Time-gated Zn-67 spectra measured during phase switching transients are presented. Novel line shapes appear in time-gated measurements in good agreement with theoretical calculations based on the assumption of coherent phase modulation with well-defined amplitude.     

Relaxation in phase-modulated Mössbauer spectroscopy

We study the transmission of phase-modulated radiation from a Mössbauer 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 direct access to the relaxation mechanism of the absorber.     

High-frequency magnetic modulation of recoilless gamma radiation of57Fe

Radio-frequency (rf) magnetic modulation has been used to generate sidebands in⁵⁷Fe Mössbauer spectra of Fe_0.18Ni_0.82 Permalloy foils which have the smallest constant of magnetostriction among Fe?Ni alloys. Sidebands in Mössbauer spectra were observed at 30 MHz and 55 MHz. In addition to the generation of sidebands, the external rf magnetic field was found to alter the line positions of the original six line spectrum. An attempt was made to study acoustic vibrations in the foil by means of X-ray diffraction. The rf magnetic field caused changes in diffraction peak intensities and positions. It was found that X-ray diffraction can be used to study the amplitude of acoustic vibrations in Permalloy foils.     

67Zn Mössbauer spectroscopy

Investigations on⁶⁷Zn Mössbauer spectroscopy are reviewed In the theoretical part, mainly phenomena to be observed due to the long nuclear lifetime of the Mössbauer state are discussed. Such phenomena include e. g. transient effects due to the phase modulation, the exceptionally large relative contribution of the second order Doppler shift and the narrowest line width observable today. Finally, a historical review of the⁶⁷Zn Mössbauer measurements is presented. Results of the experimental investigations of various research groups are given in chronological order.     

Limits of applicability of the classical field concept in Mössbauer spectroscopy

We show that the classical model widely employed for the field radiated by an excited Mössbauer nucleus predicts an enhanced rate of coincidences for two detectors. This contradicts our experiment. We discuss the limits of applicability of the classical field concept for various experimental conditions.