Vibrationally resolved fluorescence from organic molecules near metal surfaces in a scanning tunneling microscope

Phys Rev Lett. 2004 Feb 27;92(8):086801. doi: 10.1103/PhysRevLett.92.086801. Epub 2004 Feb 24.


Intrinsic molecular fluorescence from porphyrin molecules on Au(100) has been realized by using a nanoscale multimonolayer decoupling approach with nanoprobe excitation in the tunneling regime. The molecular origin of luminescence is established by the observed well-defined vibrationally resolved fluorescence spectra. The molecules fluoresce at low "turn-on" voltages for both bias polarities, suggesting an excitation mechanism via hot electron injection from either tip or substrate. The excited molecules decay radiatively through Franck-Condon pi(*)-pi transitions.