Electron spectra of a self-assembled monolayer on gold: Inverse photoemission and two-photon photoemission spectroscopy

Ultraviolet photoemission spectroscopy, inverse photoemission spectroscopy, and two-photon photoemission spectroscopy are techniques commonly used to examine the electronic structure of surfaces and interfaces. We have used all three to study self-assembled monolayers of 4,4′-bis(phenylethynyl)benzenethiol on gold, a system often studied for potential application in molecular electronic junctions. We compare the results of these measurements and discuss them in relation to electronic structure calculations. The result is a better understanding of the valence electronic structure for this system, of the spectroscopic methods involved, and of previous measurements.