Invited paper: Temperature dependence of surface state lifetimes, dephasing rates and Binding energies on Cu(111) studied with time-resolved photoemission

摘要

The ultrafast electron dynamics of surface states on(111) is investigated as a function of temperature between 25 K and 460 K employing time-resolved two-photon photoemission (2PPE) spectroscopy. Analysis of the thermally-induced energy shift of the unoccupied n=1 image potential state based on a multiple reflection model allows a precise determination of the position of the upper edge(L_6+) of the sp-gap in the (111)-direction (E_L6+(T)-E_F=4.15eV-(0.26meV/K)T). We find that the lifetime of the n=1 image state decreases from 22 ± 3 fs at 25 K to 14 ± 3 fs at 350K.