Temperature dependence of surface plasmons on Ag(001)

We report on high-resolution electron-energy-loss measurements of surface-plasmon losses on Ag(001) performed for crystal temperatures T in the range 100–400 K. Both the surface-plasmon frequency and linewidth are found to depend on T. The surface-plasmon frequency decreases with increasing T, nearly independently of wave vector; the linewidth increases by 7×${10}^{\mathrm{-}5}$ eV/K. The shift in energy is explained by the thermal expansion of the crystal, while the linewidth is influenced by the surface-plasmon–phonon interaction.