Resonant X-ray emission spectra by the electric quadrupole excitation at the MnK-edge of MnO

We study the incident, the scattering and the azimuthal angle dependences of the Mn Kbeta resonant x-ray emission spectroscopy (RXES) due to the electric quadrupole excitation by tuning the incident photon energy to the pre-edge region of the Mn K-edge for a MnO single crystal both experimentally and theoretically. RXES caused by the electric quadrupole excitation shows a strong sensitivity to these angles, and the agreement between theory and experiment is good. Different angle dependences are shown between the excitation to the T-2g orbital and that to the E-g one. It is discussed that RXES can be a powerful tool to separate the electric quadrupole and dipole contributions in the pre-edge region of the transition-metal K-edge in transition metal compounds.