Charge-mediated adsorption behavior of CO on MgO-supported Au clusters.
The CO binding behavior to gold particles supported on MgO thin films has been analyzed with scanning tunneling microscopy (STM) and infrared spectroscopy (IRAS). The ad-particles accommodate excess electrons that originate either from a charge transfer through the thin oxide film or from a local interaction with electron-rich oxide defects that act as Au nucleation centers. The enhanced electron density in the Au aggregates affects both the spatial distribution and the vibrational properties of adsorbed CO species. Whereas preferential CO attachment to the chemically unsaturated and electron-rich boundary sites of the Au islands is deduced from the STM data, a continuous downshift of the CO stretching frequency with decreasing particle size is observed in IRAS. Both results are interpreted in the light of CO adsorption to negatively charged metal aggregates and used to draw general conclusions on the interplay between charge and adsorption properties of confined metal systems.
Lin
Xiao
X
Fritz-Haber-Institut der MPG, Faradayweg 4-6, D-14195 Berlin, Germany.
Yang
Bing
B
Benia
Hadj-Mohamed
HM
Myrach
Philipp
P
Yulikov
Maxim
M
Aumer
Andreas
A
Brown
Matthew A
MA
Sterrer
Martin
M
Bondarchuk
Oleksander
O
Kieseritzky
Esther
E
Rocker
Jan
J
Risse
Thomas
T
Gao
Hong-Jun
HJ
Nilius
Niklas
N
Freund
Hans-Joachim
HJ