Optical phonons in CdS nanocrystals: Effects of size, shape and packing density

• Tipo: Artigo em Revista Científica Internacional
• Data: 1999

Autores

Rolo, AG (Autor) Outra; Vasilevskiy, MI (Autor) Outra; Gomes, MJM (Autor) Outra; Vikhrova, OV (Autor) Outra; Rakovich, YP (Autor) Outra; Artemyev, MV (Autor) Outra

Revista

A Revista está pendente de validação pelos Serviços Administrativos.

Título: MRS Proceedings

Vol. 571

Páginas: 217-222

ISSN: 0272-9172

Indexação

Scopus - 1 Citação

Outras Informações

ID Authenticus: P-007-90F

Abstract (EN): Optical vibrations confined in CdS nanocrystals (embedded in a glass film or forming a close-packed film with some organic-molecule links between them) have been studied experimentally, by means of FIR and Roman spectroscopies, and theoretically. The asymmetric Raman lineshape can be modelled considering resonant and non-resonant scattering on spherical modes with l=0 (those with n>1 are responsible for the low-frequency wing). A phonon-related dielectric response of the nanocrystal composites has been studied by measuring FIR reflectivity and transmission spectra. The theoretical consideration consists of the (i) calculation of the single-particle polarisability due to the confined l=1 modes and (ii) including the dipole-dipole interaction between the particles. We show that, for the smallest particles, the FIR response has a bimodal structure, which disappears as the nanocrystal size increases. However, the experimentally observed bulk-CdS-like reflection band at 230-300 cm-1 is too broad and can not be explained by the model. Only making further assumptions, namely, of a fractal structure of the nanocrystal composites, enables us to fit well the experimental FIR spectra. © 2000 Materials Research Society.

Idioma: Inglês

Tipo (Avaliação Docente): Científica