The single-wall carbon nanotubes (SWCNs) were discovered in '93 [1] and are made of pure carbon atoms just like a single sheet of graphite wrapped around a cylindrical axis. The same material with slight variations in the geometrical arrangement yields different electronic properties, which could range from metallic to semiconducting behavior. They have fascinating chemical, mechanical and electrical properties which result remarkably different from those of any other carbon-based materials and which suggest enormous potential application in many technological areas, as catalysis, energy and gas storage, electron emitters, sensors,fast acting switches, molecular electronics, etc. [2-6]. In this contest it is very important to know and to control the electronical and chemical characteristics of the SWCNs.……
In this paper we present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. We also describe recent progress in performing geometrical fitting of the XANES (X-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach.
We present here a general overview of electron spectroscopies from a practical point of view. The most frequently used ones are described and the type of structural information they can provide on materials is explained in relation to the physical processes on which they are based. Furthermore, we explore critically and in detail various tools that have been developed to allow a systematic solving of structures by these spectroscopies.
