L105
Femtosecond electron transfer from adsorbed molecules to empty electronic states of a solid
B. Burfeindt,
C. Zimmermann,
S. Ramakrishna,
T. Hannappel,
B. Meissner,
W. Storck,
F. Willig
Hahn-Meitner-Institut
Recently, considerable interest has arisen in photo-induced electron transfer from adsorbed molecules
into empty electronic states of solids. This type of heterogeneous photo-reaction is the fundamental step
in AgBr photography. It has been postulated to represent the fundamental step in low yield photodissociation
on metal surfaces. A new type of electrochemical solar cell is based on this primary charge separating photo-
reaction. We report on time-resolved experiments of such ultra-fast surface reactions. Electron transfer times
of a few ten femtoseconds were measured employing transient absorption and fluorescence up-conversion.
Two signals probed the disappearance of the excited donor state and two other signals the generation
of the product state. The experiments were carried out in ultra-high-vacuum. Basic features of the
experimental results were captured with a quantum theoretical model.
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