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

非技术摘要。该项目将解决有关物质沉积在纳米级物体(碳纳米管)表面时的行为，以及这些物体的电子和弹性性质如何受到影响的许多应用和基本问题。一维和二维(一维和二维)的物质与我们三维世界中的物质具有不同的性质，具有经典和量子相修改以及这些相之间的转变，其中许多只有在低温下才能观察到。随着世界进入纳米时代，能够探测沉积在其上的单层原子或分子的一小部分的传感器的开发具有在各种应用中的潜力。所有级别的学生都将获得制造含有悬浮纳米管的设备所需的专业知识。应该可以测量沉积在纳米管上的最微小的物质的量，从单层原子或分子的很小一部分到一个或多个完整的层，并测量沉积物质对器件电学性质的影响。将在美国或法国的X射线和/或中子散射设施中进行额外的热力学测量，以帮助了解物质在由多个纳米管形成的束上的行为。该项目将把为单个单壁碳纳米管开发的新的电学测量与表面沉积的原子和分子单分子层的现有热力学和结构测量相结合，以获得对物质的一维和二维相(一维和二维)行为的基本见解。从二维到一维的交叉以及吸附物质对纳米管电子性质的影响将被量化。具体地说，从低质量弱相互作用量子情形(如He)到高质量强相互作用经典情形(如Xe)，将使用(A)在纳米管束沟槽中形成的原子线和(B)孤立纳米管表面的圆柱形单分子膜来测试没有相变的一维气态、流体和/或固体相作为温度的函数的预测。参与该项目的本科生和研究生将掌握纳米器件制造以及纳米管上的电导、振动、吸附等温线、热容、中子和X射线衍射的测量方面的知识。结果将影响我们对气体/表面相互作用、维度、曲面上公度相的形成以及单层原子/分子弹性的理解。

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.