We present yield spectra of electrons elastically backscattered from surfaces of NiO, Cr2O3, and Cu. The chromium- and nickel-oxide surfaces show fine structure above the 2p core excitation energies of the transition metals. The fine structure extends above the core threshold for at least 100 eV and is periodic in the free momentum of an excited 2p core electron at energies well above the bottom of the conduction band. We interpret the structure in terms of a model based on final-state interference of the excited electron. Accurate recovery of nearest-neighbor atomic distances may require consideration of multiple scattering. © 1979 The American Physical Society.