Manifestations of electronic correlations in the diffraction of electron pairs from crystals

The energy-sharing spectra of correlated electron pairs ejected from Cu(001) and Fe(110) surfaces reveal characteristic structures associated with diffraction of the pair from the lattice. It is demonstrated theoretically and experimentally that (1) the momentum-space positions of these new features are determined by the change of the center-of-mass wave vector of the pairs as compared to the reciprocal lattice vector, and (2) the relative intensities of the peaks and the shapes of the individual peaks are dependent on the internal correlation of the pairs. Possible pathways for the pair creation are envisaged at various diffracted beams.