AVS 56th International Symposium & Exhibition
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM3
Interfacial Bonding of Thiophene and Aromatic Isocyanide on Au(111)

Wednesday, November 11, 2009, 8:40 am, Room N

Session: Surface Chemistry and Dynamics
Presenter: J. Zhou, SUNY Stony Brook
Authors: J. Zhou, SUNY Stony Brook
Y. Yang, SUNY Stony Brook
P.J. Liu, Brookhaven National Laboratory
N. Camillone, Brookhaven National Laboratory
M. White, Brookhaven National Laboratory & SUNY Stony Brook
Correspondent: Click to Email
The electronic structures of thiophene and 1,4-phenylene diisocyanide (PDI) adsorbed on Au(111) are investigated by two-photon photoemission (2PPE) spectroscopy and density functional theory (DFT) calculation. The adsorption of thiophene lowers the work function by 0.88 eV for Au(111) exposed to 4.0 L thiophene, due to the electron donation from the thiophene to the substrate. With thiophene adsorbed on Au(111), a localized σ* state forms with increasing thiophene exposure on Au(111). This state is attributed to the σ* antibonding orbital of a Au-S bond and is evidence of an orientational phase transition of adsorbed thiophene. For PDI adsorbed on Au(111), a bonding state located at 0.8 eV below the Fermi level forms at the interface. The temperature dependence of work function change of PDI/Au(111) provides an evidence for molecular crystallization on the surface. Adsorption of 1 monolayer of PDI on Au(111) lowers the work function by 0.25 eV. Upon annealing to 300 K, the work function decreases by 1.45 eV due to amplified charge transfer or dipole effects which induced by the formation of a crystallized layer.