Orbital-Symmetry-Dependent Electron Transfer through Molecules Assembled on Metal Substrates.
Femtosecond charge-transfer dynamics in self-assembled monolayers of cyano-terminated ethane-thiolate on gold substrates was investigated with the core hole clock method. By exploiting symmetry selection rules rather than energetic selection, electrons from the nitrogen K-shell are state-selectively excited into the two symmetry-split π* orbitals of the cyano end group with X-ray photons of well-defined polarization. The charge-transfer times from these temporarily occupied orbitals to the metal substrate differ significantly. Theoretical calculations show that these two π* orbitals extend differently onto the alkane backbone and the anchoring sulfur atom, thus causing the observed dependence of the electron-transfer dynamics on the symmetry of the orbital.
Florian
F
Blobner
‡Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Pedro B
PB
Coto
Francesco
F
Allegretti
‡Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Michel
M
Bockstedte
‡Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Oscar
O
Rubio-Pons
§Department of Chemistry and Biochemistry, MSC 3C, New Mexico State University, Las Cruces, New Mexico 88003, United States.
Haobin
H
Wang
∥Departments of Chemistry and Material Science, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
David L
DL
Allara
⊥Angewandte Physikalische Chemie, Universität Heidelberg, 69120 Heidelberg, Germany.
Michael
M
Zharnikov
‡Institut für Theoretische Physik und Interdisziplinäres Zentrum für Molekulare Materialien, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91058 Erlangen, Germany.
Michael
M
Thoss
Peter
P
Feulner
charge transfer; core hole clock; femtosecond time scale; orbital symmetry; self-assembled monolayers