Abstract
The time-resolved absorption spectra of opaque semiconductor powders have been typically studied by diffuse reflectance techniques. Herein, we show that time-resolved transmission spectroscopy of suspended nanoparticles is a suitable way to detect electrons and holes generated photochemically in these solids. Ultrasound dispersion of nanoparticulate metal oxide semiconductors, including TiO2, ZnO, NiO, and α-Fe2O3, in acetonitrile or water leads to the formation of indefinitely persistent suspensions in which metal oxide nanoparticles are dispersed in the liquid phase. Dynamic laser scattering reveals the presence of these nanoparticles of dynamic dimensions ranging from about 30 to 200 nm. Time-resolved transmission absorption spectroscopy of these suspensions allows detecting transients decaying in the microsecond time scale that are characterized by a broad absorption spanning the whole visible range and almost coincident temporal profiles in every wavelength that have been assigned to the state of cha...
Published Version
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