Low Temperature Nuclear Spin Relaxation and the Structure and Dynamics of Defects in Materials

9305344诺伯格这个项目将为量子固体和薄膜以及材料中的缺陷的联合理论和低温实验研究提供支持。理论和脉冲核磁共振研究将在氧化镁、氮化硼和硅上物理吸附成薄膜的氢分子、氢气和稀有气体原子。这些分子和原子也将作为基质隔离物种在非磁性主体中进行研究，并在低温核磁共振(NMR)金刚石顶压室中进行高压研究。吸附物种特有的多个自旋回波将被用来研究高密度和受限维度下的动力学和相变。一项密切相关的工作将在光致材料电子性质发生亚稳态变化的条件下研究非晶态半导体薄膜中的氢和氢。理论工作将包括对含有各种掺杂的非晶硅大型超级电池进行第一性原理分子动力学模拟。这个项目将为量子固体和薄膜以及材料中缺陷的联合理论和低温实验研究提供支持。理论和脉冲核磁共振研究将在氧化镁、氮化硼和硅上物理吸附成薄膜的氢分子、氢气和稀有气体原子。这些材料也将在高压下进行检查。这项研究涉及与材料中的缺陷以及这些缺陷在决定材料性能中所起的作用有关的基本主题和技术上的重要主题。例如，我们将研究掺杂各种原子的非晶态半导体，以更多地了解用于光导太阳能电池的这些材料的性能。这项研究将有助于揭示目前光电池的亚稳态特性，以及它们的效率和实用价值。***

9305344 Norberg This project will provide support for a joint theoretical and low temperature experimental study of quantum solids and films and of defects in materials. Theoretical and pulsed nuclear magnetic resonance investigations will be carried out on molecular hydrogen and deuterium and rare gas atoms physisorbed as thin films on magnesium oxide, boron nitride, and silicon. These molecules and atoms will also be studied as matrix-isolated species in non- magnetic hosts and at high pressures in a cryogenic nuclear magnetic resonance (NMR) diamond anvil cell. Multiple spin echoes unique to adsorbed species will be used to examine dynamics and phase transitions at high densities and under restricted dimensionality. A closely related effort will examine hydrogen and deuterium in amorphous semiconducting films under conditions where light-induced metastable changes in the electronic properties of the materials occur. The theoretical effort will include first principles molecular dynamics simulations on large supercells of amorphous silicon containing various dopants. %%% This project will provide support for a joint theoretical and low temperature experimental study of quantum solids and films and of defects in materials. Theoretical and pulsed nuclear magnetic resonance investigations will be carried out on molecular hydrogen and deuterium and rare gas atoms physisorbed as thin films on magnesium oxide, boron nitride, and silicon. These materials will also be examined at high pressures. The research involves fundamental topics as well as technologically important subjects related to defects in materials and the role these defects play in determining materials properties. For example, amorphous semiconductors doped with various atoms will be investigated to learn more about the properties of these materials which are used in photoconducting solar cells. The research should shed light on the metastable properties of the photocells which at present li mit their efficiency and practical utility. ***