The behaviour of the Raman G' band of solubilized SWCNTs in aqueous solution is investigated with respect to ultrasonication time, surfactant type and centrifugation. The linewidth of the high frequency component of the G' band is shown to correlate with the degree of bundling in the solution. In particular, the linewidths of all dispersions decrease as a consequence of subsequent centrifugation, reaching values characteristic of individual SWCNTs (30 cm(-1)). These results correlate well with the observed changes of the radial breathing modes. Further, using this approach an evaluation of the extent of debundling SWCNTs using surfactant solutions (sodium dodecylbenzenesulfonate and sodium dodecyl sulfate) and deoxyribonucleic acids with respect to surfactant concentration, ultrasonication time and centrifugation was performed.

Evidence of the adsorption of sodium dodecyl sulfate (SDS) residuals on single-walled carbon nanotubes (SWNTs) is shown using x-ray photoelectron spectroscopy. The adsorption of SDS on semiconducting SWNTs (s-SWNTs) is believed to result in deposition and alignment of s-SWNTs between predefined electrode pairs using ac dielectrophoresis. However, the presence of SDS on SWNTs degrades electrical properties of the fabricated devices. Attempts at surface cleaning, aimed at removal of the SDS residuals and formation of an improved contact between the SWNTs and the metal, are described.

In spite of much work, the formation of epitaxial CoSi2 from Ti/Co on (100) Si remains something of a mystery. It has been proposed that epitaxy occurs via the formation of an intermediate phase of CoSi with a (311) preferred orientation. In the absence of sufficient information it is impossible to validate or to invalidate the specific original claim. However, one shows that the formation of preferably oriented CoSi is not a necessary condition for the subsequent growth of epitaxial CoSi2. Careful measurements of diffraction intensities reveal the probable, temporary formation of a metastable form of CoSi2, based on a diamond cubic rather than the usual CaF2 structure.

Raman scattering experiments were performed on Si(60 nm)/metal/substrate structures with and without silica microspheres (with a diameter between 0.5 and 5 mm) on top. Raman scattering from the thin Si layer exhibits enhancements (~20) due to the dielectric spheres, where the enhancement factors depend on the diameter of the spheres. The interaction between light and dielectric spheres has been simulated by finite difference time domain calculations (FDTD), wherein particularly the electric energy density (ED) distribution in the thin Si layer was of concern. For microspheres with a diameter less thañ 3 mm, the transverse ED distribution (perpendicular to the incident light direction) within the Si layer is characterised by a single peak centered on the optical axis. For larger diameters, a multimodal transverse ED distribution develops where the maximum is not centered on the optical axis. Using an ad-hoc approach for surface enhanced Raman scattering in combination with the FDTD calculations, the experimental Raman observations are well accounted for.

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