One-Dimensional and Two-Dimensional Adsorbate Systems on Single-Walled Carbon Nanotubes

University Of Washington, Seattle WA

Investigators

Abstract

Non-Technical Abstract. This project will address many applied and fundamental issues surrounding how matter behaves when deposited on the surface of nanometer-scale objects (carbon nanotubes), and how the electronic and elastic properties of those objects are affected. Matter in one- and two-dimensions (1D and 2D) has different properties than in our 3D world, with classical and quantum modifications of phases and transitions between those phases, many of which are observable only at low temperatures. As the world enters the nano-age, the development of sensors with capability to detect a small fraction of a single layer of atoms or molecules deposited on them has potential for use in various applications. Students at all levels will acquire the expertise needed to build devices containing suspended Nanotubes. It should be possible to measure the minutest amount of matter deposited on the Nanotubes, from a very small fraction of a single layer of atoms or molecules up to one or more complete layers, and to carry out measurements of the influence of the deposited matter on the electrical properties of the devices. Additional thermodynamic measurements will be carried out, at X-ray and/or neutron scattering facilities in the USA or France, to help understand the behavior of matter on bundles formed by multiple nanotubes. Technical Abstract. This project will combine novel electrical measurements developed for individual single-walled carbon nanotubes with established thermodynamic and structure measurements on surface-deposited atomic and molecular monolayers, to gain fundamental insight into the behavior of one- and two-dimensional phases of matter (1D and 2D). The crossover from 2D to 1D and the influence of adsorbed matter on the nanotube electronic properties will be quantified. Specifically, predictions of 1D gaseous, fluid and/or solid phases with no phase transitions as a function of temperature will be tested using (a) lines of atoms formed in the grooves of nanotube bundles and (b) cylindrical monolayers on the surface of isolated nanotubes, from the low-mass weakly interacting quantum case (such as He) to the high-mass strongly interacting classical case (such as Xe). Undergraduate and graduate students involved in this project will become knowledgeable in nanodevice fabrication and in measurements of conductance, vibrations, adsorption isotherms, heat capacity, and neutron and X-ray diffraction on nanotubes. Results will impact our understanding of gas/surface interactions, dimensionality, the formation of commensurate phases on curved surfaces, and the elasticity of a single layer of atoms/molecules.