Cross luminescence of CsF excited by X-ray synchrotron radiation

Spectral and temporal properties of crossluminescence of a CsF crystal were investigated using a monochromatic X-ray beam. The cross luminescence spectrum is shown to be independent of excitation energy, whereas its amplitude exhibits a huge non-linearity near the Cs L absorption edges. The room temperature crossluminescence quantum yield of CsF drops down by a factor of 6 at the L-III-edge, by a factor of 2 at the L-II-edge and only by 20% at the L-I-edge. Various mechanisms are considered to account for the observed features in X-ray excitation spectrum. It is suggested that quenching due to the non-radiative Auger decay of the outer most core hole is at the origin of this behavior. Our tentative interpretation is supported by the excitation energy dependence of crossluminescence decay curves.