POLARIZATION EFFECTS IN MOLECULAR X-RAY FLUORESCENCE

Abstract
Highly polarized x-ray fluorescence has been observed following K-shell excitation of several Cl-containing molecules. Monochromatic synchrotron radiation (SR) with a high degree of linear polarization was used to resonantly excite Cl 1s electrons in CH₃Cl, and the three Freons, CF₃Cl, CF,Cl₂, and CF₃Cl. The subsequent Cl Kβ fluorescence was found to be strongly linearly polarized. The direction of polarization of the Kβ fluorescence is determined in part by the symmetry of the valence-orbital electron involved in the fluorescence decay which fills the Cl 1s hole. Our results illustrate that the core-level resonance lifetimes are short enough to preclude substantial disorientation of the molecule prior to fluorescence decay. Measurements of this type may prove to be a sensitive probe of orbital symmetry in more complicated molecular systems, condensed matter, and adsorbates.