Local-plasmon-enhanced up-conversion fluorescence from copper phthalocyanine

Luminescence experiments on supported molecules with the scanning tunneling microscope

“…Although the object of many STM-LE investigations [36,37], molecular luminescence in these systems is prevented by the direct contact between molecules and metal leading to quenching of the optical transition (non-radiative de-excitation of the molecule) caused by conduction electron screening. Only very recently the luminescence spectra from supported molecules, at the submolecular scale [38], has been observed by successfully decoupling the molecules from the metallic substrate, using either a thin dielectric film [38][39][40][41] or molecular films with a thickness of several monolayers [42][43][44][45][46]. These experiments paved the way towards unambiguous chemical identification of individual molecules via their luminescence induced by tunneling electrons.…”

“…We address the current state-of-the-art of this approach by presenting a specifically illustrative example, nano-islands consisting of a mixture of C 60 and C 70 molecules on a dielectric NaCl spacer layer. 1 The successful LE experiments on molecules supported on ultrathin dielectric films or on molecular multilayers reveal the decisive role of the substrate and/or tip material in the enhancement of the molecular fluorescence [38,44,51,45,40,52].…”

Hot electron cascades in the scanning tunneling microscope

“…While the present work focuses on a metallic model system it should be noted that fluorescence at hν > eV has also been reported from molecular films. [19][20][21] The thermalization of electrons in metals has been investigated with pulsed-laser excitation. Electron-electron interaction leads to thermalization of the electron system on a sub-ps timescale over which the distribution evolves from a nonthermal to a hot Fermi-Dirac shape.…”

Nonequilibrium Green's Function Theory of Scanning Tunneling Microscope-Induced Light Emission from Molecule Covered Metal Surfaces: Effects of Coupling between Exciton and Plasmon Modes

“…When a molecule is placed near the tip-substrate gap region, optical processes of molecules and interface plasmons can strongly influence each other. Enhancement of molecular luminescence intensity using intense electromagnetic fields generated by interface plasmons have been investigated in previous theoretical [25][26][27][28][29] and experimental studies [30][31][32][33][34][35] that the dynamics of molecule (e.g. energy absorption and emission of molecules) affect a luminescence spectral profile of interface plasmons [36].…”