Time-dependent polarization in Mössbauer experiments with synchrotron radiation: Suppression of electronic scattering

The resonant forward scattering of x-rays from $^{57}\mathrm{Fe}$ nuclei is strongly polarization dependent. The broad-band excitation provided by synchrotron radiation (SR) results in an interesting time-dependent polarization mixing, which we will discuss. Further we demonstrate that by selecting only the component of the transmitted radiation which has a 90\ifmmode^\circ\else\textdegree\fi{} rotated plane of polarization, the nonresonant (nonrotated) transmitted intensity can be substantially reduced. This new technique will allow full utilization of new powerful SR sources currently under construction.