Novel 1- and 2-Dimensional Systems

本项目将研究沉积（吸附）在单壁碳纳米管（SWNT）束和其他表面的原子和分子的新的热力学和结构性质。纳米尺寸的低维系统是研究物质新状态的前沿。单壁碳纳米管束和其他均匀的衬底通过在其表面吸附原子/分子，使得制造一维和二维（1d, 2d）形式的物质成为可能。吸附热,热容和x射线散射测量是用来研究多个系统:(a) 1 d氦,会保持在一个流体相绝对零度,(b)一维氢分子,这可能保持流体温度很低,(c) 1 d和2 d晶体形成的基于“增大化现实”技术,基米-雷克南,Xe, (d) 1 d和2 d氧气将显示交叉从二维到一维磁性,和(e)量子效应的2 d阶段氦同位素混合物。SWNT束显示了储氢的前景，这是该计划中高度技术重要性的问题。参与的研究生和本科生学习广泛的现代实验技术，为他们未来的就业做好准备。纳米尺寸、低维系统是研究新型流体和固体状态物质的前沿。这项实验工作的重点是测量沉积（吸附）在单壁碳纳米管（SWNT）束上的简单气体和分子的一维和二维（1d, 2d）性质，以及吸附在非常小的平面上的氦同位素混合物的二维性质。热和x射线测量表征了被吸附物质的相和相变化作为温度和密度的函数。引人入胜的新系统有：一维氦在任何温度下都应保持单一流体相，一维氢分子在极低温度下可能保持流体状态，一维和二维Ar、Kr和Xe在束上形成固体结构，一维和二维氧可能从二维到一维磁性交叉，以及氦同位素混合物的二维特性及其明显的量子效应。束状结构显示了氢储存的前景，这是一个相当重要的技术问题。参与的研究生和本科生将获得一系列现代实验技能，为他们未来在任何部门的就业做好准备。

This project will investigate novel thermodynamic and structural properties of atoms and molecules deposited (adsorbed) on single-wall carbon nanotube (SWNT) bundles and other surfaces. Nanometer-size, low dimensionality systems are at the forefront of research on new states of matter. SWNT bundles and other uniform substrates have made possible the fabrication of one- and two-dimensional (1d, 2d) forms of matter by adsorption of atoms/molecules on their surface. Heat of adsorption, heat capacity and X-ray scattering measurements are used to study several systems: (a) 1d helium, expected to remain in a single fluid phase down to absolute zero, (b) 1d molecular hydrogen, which may remain fluid to very low temperatures, (c) 1d and 2d crystals formed by Ar, Kr, and Xe, (d) 1d and 2d oxygen expected to show a crossover from 2d to 1d magnetic properties, and (e) quantum effects on the 2d phases of helium isotopic mixtures. SWNT bundles show promise for hydrogen storage, a matter of high technological importance addressed in this program. Participating graduate and undergraduate students learn a broad range of modern experimental techniques that position them well for future employment. Nanometer size, low dimensionality systems are at the forefront of research on novel fluid and solid states of matter. This experimental work focuses on measurements of the one- and two-dimensional (1d, 2d) properties of simple gases and molecules deposited (adsorbed) on single-wall carbon nanotube (SWNT) bundles, and the 2d properties of helium isotopic mixtures adsorbed on very small flat surfaces. Thermal and X-ray measurements characterize the phases and phase changes of the adsorbed substances as a function of temperature and density. Fascinating novel systems are: 1d helium which should remain in a single fluid phase at all temperatures, 1d molecular hydrogen which may remain fluid to very low temperatures, 1d and 2d Ar, Kr, and Xe which show solid structures being formed on the bundles, 1d and 2d oxygen with possible crossover from 2d to 1d magnetic properties, and the 2d properties of helium isotopic mixtures and their pronounced quantum effects. Bundles show promise for hydrogen storage, a matter of considerable technological importance. Participating graduate and undergraduate students acquire an array of modern experimental skills that position them well for future employment in any sector.