| Carbon nanotubes have extraordinary electrical properties. They show large sensitivity to many gases have great potential in many kinds of sensing applications. In order to quantitatively study the effects of gases on nanotubes, it is important to understand adsorption on nanotubes.;Adsorption on two dimensional graphitic surfaces and carbon nanotube bundles has been extensively studied over the last few decades. Noble gases adsorbed on graphite exhibit two-dimensional (2D) analogs of 3D phases, as well as new phases unique to the adsorption system. The properties of such 2D phases and the transitions between them have been studied experimentally using bulk adsorption isotherms, heat capacity measurements, and scattering techniques. Adsorption on carbon nanotube bundles offers possibilities for approaching the 1D limit, and is fundamental to applications in gas sensing and storage.;Suspended carbon nanotubes can act as nanoscale resonators with remarkable electromechanical properties and the ability to detect adsorption at the level of single atoms. In this thesis we show that nanotube resonators offer a powerful new means of investigating fundamental aspects of adsorption on carbon, including the collective behavior of adsorbed matter and its coupling to the substrate electrons. By monitoring the resonance frequency in the presence of gases, we observe the formation of monolayers on the cylindrical surface, phase transitions within them, and simultaneous modification of the electrical conductance of the nanotube. We also show that the adsorption can be tuned electrically and demonstrate new techniques for study adsorption arising from such unique capabilities. |
