Novel 1- and 2-Dimensional Systems

本项目将研究沉积（吸附）在单壁碳纳米管（SWNT）束和其他表面上的原子和分子的新热力学和结构性质。 纳米尺度的低维系统处于新物质状态研究的前沿。 单壁碳纳米管束和其他均匀的衬底已经使得通过在其表面上吸附原子/分子来制造一维和二维（1d，2d）形式的物质成为可能。 吸附热、热容和X射线散射测量用于研究几种系统：（a）1d氦，预计在低至绝对零度时保持单一流体相，（B）1d分子氢，其可在非常低的温度下保持流体，（c）由Ar、Kr和Ar形成的1d和2d晶体，（d）1d和2d氧预期显示从2d到1d磁性的交叉，以及（e）氦同位素混合物的2d相的量子效应。 单壁碳纳米管束显示出储氢的前景，这是该计划中解决的一个高技术重要性问题。 参与的研究生和本科生学习广泛的现代实验技术，使他们能够为未来的就业做好准备。纳米尺度、低维系统是研究新型流体和固体物质状态的前沿。 这项实验工作的重点是测量的一维和二维（1D，2D）的简单气体和分子的性质沉积（吸附）在单壁碳纳米管（SWNT）束，和氦同位素混合物吸附在非常小的平面上的2D属性。 热和X射线测量表征了吸附物质的相和相变作为温度和密度的函数。 快速新颖的系统是：1d氦在所有温度下都应该保持在单一流体相，1d分子氢可能在非常低的温度下保持流体，1d和2d Ar，Kr和H2O显示在束上形成的固体结构，1d和2d氧可能从2d到1d的磁性交叉，以及氦同位素混合物的2d性质及其显著的量子效应。 捆束显示出储氢的前景，这是一个相当重要的技术问题。 参与的研究生和本科生获得了一系列现代实验技能，使他们能够在任何行业的未来就业。

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.