Eur. Phys. J. D 45, 477-483 (2007)
https://doi.org/10.1140/epjd/e2007-00257-7

Mass-selected Ag₃ clusters soft-landed onto MgO/Mo(100): femtosecond photoemission and first-principles simulations

¹ Institut für Oberflächenchemie und Katalyse, Universität Ulm, 89069 Ulm, Germany
² Institut für Chemie, Humboldt Universität zu Berlin, Brook-Taylor-Strae 2, 12489 Berlin, Germany

Corresponding author: ^a thorsten.bernhardt@uni-ulm.de

Received: 31 January 2007
Revised: 18 May 2007
Published online: 5 September 2007

Abstract

The electronic structure of supported mass-selected Ag₃ clusters is analyzed by joint femtosecond photoemission spectroscopy and ab initio theoretical investigations. A wide band gap insulating magnesia ultra-thin film on Mo(100) has been chosen as substrate in order to minimize the electronic interaction between metal clusters and support. After magnesia ultra-thin film preparation no photoemission from the molybdenum substrate is observed anymore, instead very weak two photon photoemission is detected possibly originating from surface or subsurface oxide defect states. Soft-landing deposition of 2 of atomic monolayer equivalents of Ag₃ clusters results in the disappearance also of the MgO two photon photoemission signal, while a strong single photon photoemission signal is detected from states located directly below the Fermi level. The theoretical study of structural, electronic and optical properties of Ag₃ at two model sites of MgO (100), the stoichiometric MgO(100) and an F_S-center defect, based on the DFT method and the embedded cluster model provides insight into the interactions between the cluster and the support which are responsible for the characteristic spectroscopic features.