Role of the intermediate state in the photoinduced process of Co-Fe cyanide

The dynamics of the photoinduced phase transition has been investigated for the Co-Fe cyanide film, Na0.35Co[Fe(CN)(6)](0.79)center dot 3.7H(2)O, by means of the transient absorption spectroscopy. We observed two characteristic transient bands: short-lived intermediate band (I band) at similar to 1.9 eV and long-lived photoinduced band (PI band) at similar to 2.5 eV. We have found that the intensity of the I band transfers to the PI band as time exceeds, and interpreted the behavior in terms of the intersystem crossing from the photocreated low-spin Co2+ species to the high-spin species. We further have found that the excitation spectra of these bands are qualitatively different.