Surface states of a Pd monolayer formed on a Au(111) surface studied by angle-resolved photoemission spectroscopy

Abstract

Electronic states of a Pd-deposited ($l1$ ML) Au(111) surface have been studied using angle-resolved ultraviolet photoemission spectroscopy. A shoulder induced by Pd deposition was observed on a peak assigned to the Shockley surface states of the Au(111) substrate in the spectra measured around the surface normal direction. The photoemission study revealed that the Pd-induced states have parabolic energy dispersion with an effective mass identical to that of the substrate states while its binding energy is $0.17\ifmmode\pm\else\textpm\fi{}0.2\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ smaller than the substrate state. It is also found that the binding energy of the Au substrate surface states decreases with Pd deposition. The spectroscopic properties of the Pd-induced states indicate that the states originate from the Au(111) surface states and are modified by the presence of monolayer Pd islands on the substrate.