We report high-resolution results from the well-known “Shockley”-type surface state localized around the $\overline{Y}$ point of the Cu(110) surface Brillouin zone. Along $\overline{\Gamma Y}$ the effective mass is $m^{*}/m=0.26\mathrm{}\pm 0.03$ and the bottom of the dispersion parabola at $\overline{Y}$ shifts linearly with sample temperature T as $E_0=-(510\mathrm{}\pm 15)\mathrm{meV}+(0.26\mathrm{}\pm 0.02$ $\mathrm{m}\mathrm{e}\mathrm{V}/\mathrm{K})T.\mathrm{}$ We have also analyzed the photoemission linewidth ${\Gamma }_h$ of this surface state. Our analysis results in an upper limit for the imaginary part of the self-energy $\mathrm{Im}\Sigma ={\Gamma }_h/2\mathrm{}<~(16\mathrm{}\pm 3)\mathrm{meV},$ which corresponds to a photohole lifetime $\tau >~(21\mathrm{}\pm 5)\mathrm{fs}$ at $\overline{Y}$ and $\overrightarrow{T}0.$ On the basis of recent calculations of ${\Gamma }_h$ for Cu(111) at $\overline{\Gamma }$ [Chulkov et al., Surf. Sci. (to be published)] we interpret ${\Gamma }_h$ of Cu(110) at $\overline{Y}$ by inelastic hole-electron interactions, with about 50% contribution each from surface band (in-plane) and from three-dimensional (coupling to substrate) decay channels. Finally we discuss the contribution of the $\overline{Y}$ surface state to the surface optical properties as observed in both second harmonic generation and (one-photon) reflection anisotropy spectroscopy from Cu(110).

• Received 21 December 1999

DOI:https://doi.org/10.1103/PhysRevB.61.14072