Mössbauer gamma echo

By applying stepwise phase modulation of recoilless gamma radiation in a coincidence experiment, constructive interference is produced in transmission geometry between the source and the absorber fields. The resulting regenerated decay signal is called a gamma echo. Here it is demonstrated that during the decay of the 14.4 keV state of⁵⁷Fe multiple echo signals can be generated.     

Gravitational redshift experiments with the high-resolution Mössbauer resonance in67Zn

A gravitational tedshift (GRS) experiment using the high-resolution Mössbauer resonance in⁶⁷Zn is described. The tiny Doppler motion of the source can be checked by a dc-SQUID based displacement sensor. The results on the GRS strongly indicate that solid-state effects, which are difficult to control experimentally, finally limit the accuracy that Mössbauer measurements can provide in determining the GRS. We argue that for this reason conventional Mössbauer experiments most probably will not be able to compete with other methods in future GRS measurements of very high precision.     

Preparative and Mössbauer studies of Bi2Sr2Ca n-1Cu n O y compounds withn=2 or 3

The influence of sintering temperatures and nominal starting compositions on the phase contents of polycrystalline Bi₂Sr₂Ca _n-1Cu _n O_4+2n samples are reported. After every sintering the samples were characterized with X-ray diffraction and magnetic AC susceptibility measurements. For Mössbauer studies, in each case also a corresponding specimen containing⁵⁷Fe was synthetized. The identification of various superconducting Bi₂Sr₂Ca _n-1Cu _n O_4+2n phases on the basis of Mössbauer spectra consisting usually of three quadrupole doublets is discussed.     

Studies of hyperfine interactions inRBa2(Cu1-x 57Fex)3O7-δ high-T c superconductors

Both⁵⁷Fe and¹⁵¹Eu Mössbauer resonances were used to study polycrystallineRBa₂Cu₃O_7-δ samples. The dependence of hyperfine interaction parameters on the oxygen deficiency δ is studied in detail with¹⁵¹Eu. For⁵⁷Fe spectra, a site assignment is proposed.     

Influence of high-frequency magnetic fields on Mössbauer resonance

The influence of high-frequency magnetic modulation on Mössbauer resonance is investigated using the⁶⁷Zn resonance. A phase-modulation theory theory explaining the experimental results is presented. Implications to magnetic modulation experiments with the⁵⁷Fe resonance are also discussed.     

Double resonance experiments in57Fe Mössbauer spectroscopy

Splitting of Mössbauer lines has been observed in conventional energy domain spectra of Permalloy samples when an external radio frequency (rf) magnetic field was tuned to be in resonance with the separation of Zeeman sublevels of either the ground or the excited state of the⁵⁷Fe nucleus. Time domain measurements were performed with the frequency of the rf field close to the natural linewidth of the 14.4 keV Mössbauer state. A nonmagnetostrictive magnetically soft Permalloy sample was used in the experiments.