Relazione su invito

X-ray spectroscopy of element specific channels in photo excitation of $TiO_{2}$ nanostructures.

Rossi G., Calizzi M., Amidani L., Pasquini L., Boscherini F.
  Giovedì 14/09   09:00 - 11:30   Aula A224   II - Fisica della materia
Refined X-ray spectroscopies can become a powerful tool to elucidate charge transfer phenomena, which play a key-role in photocatalysis and other processes relevant for clean energy. We have developed a differential illumination RIXS and HERFD-XAS method on ID26 @ ESRF to investigate charge transfer phenomena with chemical sensitivity. We have studied two materials systems in which $TiO_{2}$ nanostructures are modified to extend light absorption to the sub band gap spectral region: in one case by loading with Au nanoparticles and in the other by V-doping. In the first case, we have shown that light-induced excitation of the surface plasmon resonance in Au gives rise to hot electron transfer to the $TiO_{2}$ matrix; in the second, that visible light absorption is predominantly due to excitation of electrons from states centered on substitutional V ions. In both cases, the electrons are trapped in charge transfer induced, low-coordination defective Ti sites, where they have a long (ms) lifetime.