Materials World Network: Quantum Phenomena in Atomic Hydrogen Stabilized in Solid Molecular Hydrogen

这个材料世界网络项目将集中在两个主要重点上：(i)进一步研究分子H2膜中的H原子以及D2膜中的D原子在较低温度下，以及（ii）将杂质-氦凝析样品的工作扩展到较低温度和较高浓度。为了观察H2中H的玻色-爱因斯坦凝聚（BEC）和D和D2薄膜中的泡利顺磁性，将改进技术以获得更高浓度的H和D原子。将继续进行t1 K下H2分子薄膜和厚膜中H原子的毫米波研究，重点是在不同条件下制备的样品的磁化强度的温度依赖性测量，以确定先前在1 K以下观察到的两个最低超精细态的居群的非玻尔兹曼行为的原因。此外，石英微天平将用于测试低温下的超流体行为，这是BEC的一种表现。我们将研究与BEC相关的拉曼光谱的变化。正在进行的研究将包括进一步研究含有氢原子、氘原子或氢和D原子混合物的杂质-氦凝聚物，以及Kr和其他稀有气体的簇。X波段脉冲和连续波ESR将用于研究纳米团簇内和周围H和D原子的磁弛豫行为和分布。证实氢原子在固体氢分子晶体中运动时发生玻色-爱因斯坦凝聚将是周期性结构中玻色-爱因斯坦凝聚的一个重要例子。此外，分子基质中含有H和D原子的混合样品是通过交换量子隧穿过程研究低温化学反应的优良体系。对由纳米团簇组合而成的杂质氦凝析物的研究与对其他形式的软凝聚态物质的研究有很好的联系。杂质-氦凝聚体提供了一种储存大量化学能的方法，当原子结合形成分子时释放出化学能。这个材料世界网络项目显然跨越了物理和化学的界限，可能为实用的储能系统提供有价值的线索。为超低温磁共振而开发的毫米波技术的进一步进步将在许多其他科学领域发挥作用。合作项目将受益于合作实验室之间研究生、博士后和高级研究人员的长期访问。本项目由凝聚态物理项目和材料研究部特别项目办公室支持。

TECHNICAL SUMMARYThis Materials World Network project will be focus on two main thrusts: (i) further studies of H atoms in molecular H2 films as well as D atoms in D2 films at lower temperatures, and (ii) extension of the work on impurity-helium condensate samples to lower temperatures and higher concentrations. Techniques will be modified to attain higher concentrations of H and D atoms in an attempt to observe Bose-Einstein condensation (BEC) of H in H2 and Pauli paramagnetism in D and D2 films. The mm wave studies of H atoms at T 1 K in thin and thick films of molecular H2 will be continued, with emphasis on careful temperature dependence measurements of the magnetization for samples prepared under different conditions in order to identify the cause of the non-Boltzmann behavior of the populations of the two lowest hyperfine states previously observed below 1 K. In addition a quartz microbalance will be utilized to test for superfluid behavior at low temperatures, a manifestation of BEC. A search will be made for changes in the Raman Spectrum associated with BEC. The ongoing research will include further studies of impurity-helium condensates containing hydrogen atoms, deuterium atoms or mixtures of H and D atoms in and on clusters of Kr and other noble gases. X band pulsed and CW ESR will be employed to study the magnetic relaxation behavior and the distribution of H and D atoms in and around the nanoclusters.NON-TECHNICAL SUMMARYConfirmation of the occurrence of Bose-Einstein condensation for H atoms moving through a solid molecular hydrogen crystal would be an important example of Bose-Einstein condensation in a periodic structure. Furthermore, mixed samples of H and D atoms contained in molecular matrices are excellent systems for the study of low temperature chemical reactions through the process of exchange quantum tunneling. Studies of impurity- helium condensates composed of assemblages of nanoclusters tie in nicely with studies of other forms of soft condensed matter. The impurity-helium condensates provide a means of storing large amounts of chemical energy which is released when the atoms combine to form molecules. This Materials World Network project clearly crosses the boundary between physics and chemistry and may provide valuable clues for practical energy storage systems. Further advances in millimeter wave technology being developed for ultralow temperature magnetic resonance will be useful in many other areas of science. The collaborative programs will benefit greatly from extended visits of graduate students, post docs and senior researchers between the partner laboratories. This project is supported by the Condensed Matter Physics program and the Office of Special Programs in the Division of Materials Research.