Polarization of molecular x-ray fluorescence.

Polarization of Cl K\ensuremath{\beta} x-ray fluorescence following selective excitation of gaseous ${\mathrm{CH}}_{3}$CL 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.