ANHARMONICITY ON THE CU(110)-(2X1)O SURFACE

We have studied the temperature-dependent energy shift of surface vibrations on the Cu(110)-(2x1)O reconstructed surface using high-resolution electron energy loss spectroscopy. Interatomic bonds involved in the observed vibrations were extracted from phonon slab calculations. The measured energy shifts can be directly related to the anharmonicity of the potentials between the vibrating atoms by using a simple Morse oscillator model. By comparing to bulk phonon measurements, we find that both the oxygen-copper and copper-copper bonds at the surface have bulk-like anharmonicity. This is in contrast to the clean surface where strong anharmonicity is observed.