Mode-selective electron-phonon coupling in laser photoemission on Cu(110)

Abstract

By combining density functional perturbation theory (DFPT) calculations and laser photoemission spectroscopy (LPES) experiments, we have clarified the selective coupling between low-energy photoelectrons and subsurface phonon modes. A step structure resulting from the inelastic scattering of photoelectrons appeared at 14.7 meV below the Fermi level in the LPES of Cu(110). We found that the inelastic step originates from an indirect excitation in which the electron is excited by the low-energy photon near the $\overline{\mathrm{Y}}$ point and then scattered to the $\overline{\ensuremath{\Gamma}}$ point by phonon modes that are predominantly present in the subsurface region.