Photo-induced charge transfer in molecular materials based on Prussian blue analogs: A photoacoustic study

Photoacoustic spectra of molecular materials based on the assembling of the [Fe(CN)₆] molecular block were recorded and evaluated. An intense absorption band around 600 nm was observed for compounds where the valence of the involved metals allows charge transfer through the CN ligand (inner photo-induced redox reactions). In the absence of this transition, only the signal corresponding to d-d transitions within the metal was observed, which falls below 450 nm, This suggests that photoacoustic spectroscopy provides a fast and reliable method to explore the existence of tunable photo-induced charge transfer in molecular materials.