Polarization of molecular x-ray fluorescence

Polarization of Cl K x-ray fluorescence following selective excitation of gaseous CH₃CL with synchrotron radiation is reported. The degree of polarization of the fluorescence depends sensitively on the chosen incident excitation energy in the Cl K-edge region. Theoretical considerations indicate that the fluorescence-polarization measurements can provide directly absorption and emission anisotropies, molecular-orbital symmetries, and relative fluorescence transition strengths.