Direct determination of molecular orbital symmetry ofH2S using polarized x-ray emission

X-ray emission from the molecule ${\mathrm{H}}_2$S is strongly polarized following excitation of a sulfur K-shell electron to an unoccupied subthreshold molecular orbital with a polarized x-ray beam. Changes in the polarization of the emission spectrum are observed as the incident beam’s energy is swept across the subthreshold absorption resonance. The previously unresolved absorption resonance is shown experimentally to be primarily associated with a molecular orbital of ${\mathit{b}}_2$ symmetry, but with a high-excitation-energy component due to an orbital with ${\mathit{a}}_1$ symmetry. Satellite emission intensity is shown to depend on the primary photon energy and is therefore associated with multivacancy effects and not with contamination, as previously suggested.