Measurement of the phonon contribution to quasiparticle lifetime and of the mass enhancement parameter lambda from the sp-derived surface state on copper(111) and gold(111) by angle-resolved photoemission spectroscopy.

摘要

This thesis reports studies of the phonon contribution to hole lifetime at a metal surface by angle-resolved photoemission (ARP). The hole lifetime is determined by the electron-phonon, electron-electron, and electron-impurity interactions. Each interaction is described and the contribution of each interaction to hole lifetime is calculated. At high temperature (T) and at low energies of the hole, the T dependence of inverse hole lifetime is dominated by the electron-phonon interaction and is (2pilambdakbT)/h where 2pih is Planck's constant and kb is Boltzman's constant. lambda is a dimensionless measure of the strength of the electron-phonon interaction.;From the temperature dependence of hole lifetime, the mass enhancement parameter lambda is extracted. All previous determinations of the mass enhancement parameter are for the bulk (lambdab). This thesis describes how to measure a mass enhancement parameter at the surface (lambdas) using ARP. lambda depends on the electronic density of states (DOS), an average of a square phonon angular frequency, and an average of a squared electron-phonon matrix element. Bulk and surface differences between these quantities are expected to make lambdas different from lambda b. This thesis reports lambdas = 0.15 +/- 0.01 at Cu(111), while lambdab = 0.15 +/- 0.03. This thesis reports preliminary measurement of lambdas = 0.34 +/- 0.04 at Au (111), while lambdab = 0.17 +/- 0.05. Recent theoretical work indicates the difference between lambdas and lambda b of Au(111) is not readily attributable to bulk and surface differences in the electron DOS.;The quasiparticle picture of photoemission is verified to be a valid interpretation of ARP spectra from the sp-derived surface states of Cu(111) and Au(111). The predicted and observed lineshapes are Lorentzian. The linewidths are consistent with linewidth being determined by inverse hole lifetime.