CHEMISORPTION AND PHYSISORPTION OF ALKANETHIOLS ON Cu(111). A QUANTUM MECHANICAL INVESTIGATION

FERRAL, A; PAREDES OLIVERA, P; MACAGNO, V; PATRITO, E. M.

Elsevier

Año: 2003 vol. 525 p. 85 - 85

he adsorption of n-alkanethiols on the 1 1 1 surface of copper was studied by means of quantum mechanical calculations. Charge transfer processes between the adsorbates and the metal were investigated in order to elucidate the nature of the adsorbed species. The electronic structure of the adsorbates in the proximity of the Fermi level was also investigated to obtain a better understanding of the electronic states which contribute to scanning tunneling microscopy (STM) images. We found that the bonding of the n-alkanethiols is independent of the chain length when the adsorbates are perpendicular to the surface. This bonding mainly involved the sulfur p-orbitals and, to a lesser extent, the orbitals of the first methyl group. From the analysis of dipole moment curves and Mulliken populations, a charge transfer of 0.6 electrons from the metal towards the adsorbate was obtained, thus confirming the anionic nature of the adsorbate. A depletion of electron density was observed in the metal