Interference between resonant and nonresonant inelastic x-ray scattering.

A detailed study of inelastic x-ray scattering from the ground state to the 3Σg(3σ(g)(-1)3s(g)1) state of the O2 molecule is presented. The observed angular anisotropy shows that the vibrational excitations within this final state are strongly dependent on the polarization of the incident radiation. The analysis demonstrates that this is a manifestation of interference between resonant and direct nonresonant inelastic x-ray scattering. This interference provides a new tool to monitor nuclear dynamics by relative rotation of the polarization vectors of the incident and scattered photons.