Molecular fluorescence from Zn TBP porphyrin
molecular layers on Cu(100) induced by tunnelling currents
X-L Guo, Z-C Dong, A S Trifonov, K Miki, S Mashiko and
T Okamoto
Abstract:
Molecular fluorescence from the surface of ZnTBP porphyrin (ZnTBPP)
molecular layers on Cu( 100) is induced with nanoprobe excitation in the
tunnelling regime. The observed well-defined molecular fluorescence is a
perfect match with the standard photoluminescence data of ZnTBPP
molecules. The decoupling of the electronic stale of the top layer ZnTBPP is
controlled by the thickness of the molecular layers. The excitation
mechanism of molecular luminescence may be attributed to the hot electron
injection into the molecules in proximity to the tip apex of a scainning
tunnelling microscope. This approach features simplicity, bipolar operation
and good reproducibility. The research provides a new way for the
integration of molecular fluorescence with a nanoprobe and the development
of a nanoscale molecular light source.