Quantum Size Effects and Nature of Photoprocesses in Nanoparticles of Ag2S

Nanoparticles of silver sulfide with quantum size effects have been prepared. Photoexcitation of the nanoparticles causes direct or indirect interband electron transitions depending on the wavelength of the exciting light. The energies of these transitions have been determined for nanoparticles prepared in different ways and stabilized under various conditions.     

Photocatalytic synthesis of ZnO/Ag nanostructure sensitized by methylene blue

The possibility of photochemical synthesis of ZnO/Ag nanoheterostructures by the action of visible light absorbed by methylene blue as sensitizer was established. It was shown that sensitization of the ZnO nanoparticles results from electron transfer from the singlet-excited molecules of the dye to the conduction band of the ZnO nanoparticles. A scheme for the mechanism of the photoprocesses that occur is proposed.__________Translated from Teoreticheskaya i Éksperimentalnaya Khimiya, Vol. 41, No. 1, pp. 12–16, January–February, 2005.     

Vibrational Raman spectra of CdSx Se1‐x magic‐size nanocrystals

Resonant Raman scattering spectra of ultrasmall (<2 nm) magic‐size nanocrystals (NCs) are reported. The spectra of CdS and CdS_x Se_1‐x NCs, resonantly excited with 325 nm and 442 nm laser lines, correspondingly, reveal broad features in the range of bulk optical phonons. The relatively large width, ～50 cm^‐1, and downward shift, ～20 cm^‐1, of the Raman bands with respect to the longitudinal optical phonon in bulk crystals and large NCs are discussed based on the breaking of the translational symmetry and bond distortion in these ultrasmall NCs. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)