  A scanning tunneling microscope is used to generate the electroluminescence
of phthalocyanine molecules deposited on NaCl/Ag(111). Photon spectra reveal an
intense emission line at 1.9 eV that corresponds to the fluorescence of the
molecules, and a series of weaker red-shifted lines. Based on a comparison with
Raman spectra acquired on macroscopic molecular crystals, these spectroscopic
features can be associated to the vibrational modes of the molecules and
provide a detailed chemical fingerprint of the probed species. Maps of the
vibronic features reveal sub- molecularly-resolved structures whose patterns
are related to the symmetry of the probed vibrational modes.
