NUCLEAR BRAGG-DIFFRACTION OF SYNCHROTRON RADIATION IN THE PRESENCE OF ACOUSTIC VIBRATIONS

The time evolution of nuclear Bragg diffraction of 14.4 keV synchrotron radiation in a (FeBO3)-Fe-57 crystal was studied when the crystal was excited to magnetoelastic vibrations by a rf. field of 2.93 MHz. The vibrations did not modify the time evolution of the diffraction. This result is due to the fact that after the excitation by the SR pulse the nuclear vibrations cause only a phase modulation of the re-emitted radiation. Energy spectra, by contrast, are extremely sensitive to vibrations. Thus the present case is an instructive example of complementarity between energy and time domain Mossbauer spectroscopy. Time domain spectroscopy, in particular, will allow to reveal phenomena, which are blurred in the energy spectra by vibrations.