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Espectroscopía Raman de nanotubos de carbono

2007; Volume: 40; Issue: 2 Linguagem: Espanhol

2171-8814

Gonzalo Santoro, Concepción Domingo,

Knowledge Societies in the 21st Century

espanolSe presentan los conceptos basicos de la estructura geometrica, electronica y vibracional (fononica) de los nanotubos de carbono (NTCs), con la aparicion de las singularidades de van Hove en su correspondiente densidad de estados electronicos, asi como una descripcion de las principales bandas de sus espectros Raman resonantes. En particular, se examinan las bandas debidas a: 1) los modos de respiracion radial (Radial Breathing Modes, RBM) caracteristicos de los nanotubos de pared unica, de los de los que se extrae informacion sobre el diametro y quiralidad de los mismos; 2) la banda tangencial G, cuyo perfil indica el caracter metalico o semiconductor de los NTCs; y 3) las bandas D (Disorder-induced) y G' (sobretono de D). Del comportamiento dispersivo de las dos ultimas bandas se extrae informacion sobre la estructura fina de las bandas de valencia y conduccion de los NTCs. Ademas, dichas bandas actuan como sensores de tension residual en materiales compuestos basados en NTCs. Por ultimo se apuntan algunos aspectos de la espectroscopia Raman de NTCs a desarrollar en un futuro proximo. EnglishThe basic concepts of the geometrical, electronic and vibrational (phononic) structures of carbon nanotubes (CNTs), as well as the van Hove singularities appearing in their electronic Density of States are here presented, together with a description of the main bands of their Resonant Raman spectra. In particular, the following bands are reported: 1) the Radial Breathing Modes (RBM), typical of Single Wall Carbon Nanotubes, from which information about their diameter and quirality is extracted; 2) the tangencial G band, whose spectral profile reveals the semiconductor or metallic character of the nanotubes; and 3) the D (Disorder induced) and G’ (D overtone) bands. From the dispersive behaviour of the last two bands, it is possible to extract information about the fine structure of the valence and conduction bands of the CNTs. Moreover, such bands act as sensors of residual strains in composites based on CNTs. Some aspects of the Raman spectroscopy of carbon nanotubes, to be developed in the near future, are also indicated.