The Open Condensed Matter Physics Journal
2010, 2 : 15-18Published online 2009 April 28. DOI: 10.2174/1874186X00902010015
Publisher ID: TOCMPJ-2-15
RESEARCH ARTICLE
Effective Linewidth in Raman Spectra of Titanium Dioxide Nanocrystals
2 LIMINA Laboratory, University of Cagliari, s.p. 8 Km 0.7, 09042 - Monserrato, Cagliari, Italy
* Address correspondence to this author at the Department of Physics, University of Cagliari, s.p. 8 Km 0.7, 09042 - Monserrato, Cagliari, Italy; E-mail: carlo.ricci@dsf.unica.it
ABSTRACT
Raman spectra of nanocrystals titanium dioxide are discussed and the correlation between the band shape of the allowed A1g Raman mode and the crystals dimensions is discussed. Data on Raman spectra are reconsidered in the framework of a modified "hard confinement" model (MHC). The proposed model is based on the idea of using an effective linewidth parameter, which is a function of the effective dimension of the nanostructure, in spite of the intrinsic Raman band linewidth.
The comparison with standard hard confinement model reveals better agreement with the experimental results for the MHC model up to 6 nm. Moreover, the analysis permits to improve the knowledge of the phonon dispersion curve as well as the intrinsic Raman bulk parameters. An analytical form of the size-dependent peak-position in nanocrystals, useful for an approximated size estimation, has been explicated. The general structure of the model permits to extended the MHC to other nano-sized materials.