Photoemission Study of Thiol-Capped Gold Nanoparticles

Abstract

A photoemission study of dodecanethiol (DT)-capped Au nanoparticles on the highly oriented pyrolytic graphite (HOPG) substrates has been carried out in order to investigate in detail the electronic structures of metallic nanoparticles supported on the substrates. The present DT-capped Au nanoparticles show that the leading edge in the photoemission spectra near the Fermi level is not the Fermi edge, with the midpoint of the steep slope being away from the Fermi level. From these results, we discuss the electronic structures of DT-capped Au nanoparticles, especially nanoparticle-HOPG substrate interaction.

Chemical states of dodecanethiolate-passivated Au nanoparticles: synchrotron-radiation photoelectron spectroscopy

“…From the static viewpoint, the kinetic energy shift of photoelectrons due to the photohole left behind in the nanoparticle is give by ∆E=e 2 /2C, where C=4πε 0 R N is the self-capacitance of the nanoparticle with a radius of R N . An exact calculation shows that this energy-shift is given by ∆E=αe 2 /4πε 0 R N with α=0.41 for Au nanoparticle [17]. The higher-energy shifts with decreasing the nanoparticle diameter also can be qualitatively explained by this final-state effect.…”

“…The higher-energy shifts with decreasing the nanoparticle diameter also can be qualitatively explained by this final-state effect. However, from the previous works [12,13,17,18], the experimental photoemission spectra have been well characterized by a dynamic final-state effect model that takes into account the Coulomb interaction between the photoelectron and photohole with a finite tunneling time during the photoemission process. This discussion is described in detail elsewhere [12,13,17,18].…”