  We study the influence of a scanning nano-electrode on fluorescence
excitation spectra of single terrylene molecules embedded in thin p-terphenyl
films at cryogenic temperatures. We show that applied voltages less than 10 V
can result in reversible Stark shifts of up to 100 times and linewidth increase
greater than 10 times the natural linewidth. We discuss the potential of our
experimental scheme for direct imaging of individual two-level systems (TLS) in
the nanometer vicinity of single molecules.
