Resonant X-ray Scattering and Multiple Beam Diffraction in LaMnO3

Fig 1: The solid points give the location and shape of the (1 0 –4) resonant reflection in orthorhombic LaMnO3. Open circles display Mn Kα fluorescence from the same sample on a common energy scale. The vertical scale is arbitrary and the lines are guides to the eye. In conventional X-ray diffraction the beam scatters from all electrons in the unit cell, but in resonant diffraction at a forbidden reflection only electrons involved in the electronic transition, near an atomic absorption edge, contribute to the intensity. To get intensity at a space-group forbidden reflection, the atomic resonance must somehow distinguish scattering from otherwise identical atoms.