Photoemission spectra of para-phenylene-ethynylene thiols chemisorbed on gold have been measured. Four compounds were studied: 4,4'-bis(phenylethynyl)-benzenethiol, 4 (phenylethynyl)benzenethiol, 4-ethynylbenzenethiol, and benzenethiol. The spectra were used to determine the work function of the monolayer-covered surface and energy alignment of the highest occupied p state of the monolayer relative to the Fermi level of the substrate. The vacuum level of the monolayer-covered surface is shifted relative to that of the bare substrate by about -0.9 eV. The shift is attributed to changes in the charge distribution at the interface that occur upon chemisorption.
Citation: Journal of Physical Chemistry
Pub Type: Journals
energy-level alignment, gold, monolayer, oligo(phenylene-ethynylene, photoemission, UPS