Valence electron orbitals of an oligo(p-phenylene-ethynylene)thiol on gold.
This communication reports measurement of one-photon (21.2 eV) and one-color, two-photon (3.2-4.5 eV) photoemission spectra of 4,4'-bis-(phenylethynyl)benzenethiol chemisorbed on gold. Four features are observed in these spectra: two occupied, predominantly molecular levels below the Fermi level and two unoccupied, predominantly molecular levels above the Fermi level. The occupied and unoccupied bands closest to the Fermi level are assigned to delocalized pi-bands, and the other occupied and unoccupied bands, to localized pi-bands. With this assignment, the hole- and electron-injection barriers and the transport gap for those levels are deduced.
Zangmeister
Christopher D
CD
National Institute of Standards & Technology, Gaithersburg, Maryland 20899, USA. christopher.zangmeister@nist.gov
Robey
Steven W
SW
van Zee
Roger D
RD
Yao
Yuxing
Y
Tour
James M
JM