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

技术总结这个材料世界网络项目将集中在两个主要方面：(I)进一步研究低温下分子H2膜中的H原子和D2膜中的D原子，以及(Ii)将杂质氦冷凝物样品的工作扩展到更低的温度和更高的浓度。为了观察氢在氢中的玻色-爱因斯坦凝聚(BEC)以及在D和D2薄膜中的泡利顺磁性，将改进技术以获得更高的H和D原子浓度。氢原子在T1K的毫米波研究将继续进行，重点是仔细测量不同条件下制备的样品的磁化强度随温度的变化，以确定先前在1K以下观察到的两个最低超精细态布居的非玻尔兹曼行为的原因。此外，还将利用石英微天平测试低温下的超流体行为，这是BEC的一种表现。将搜索与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在Kr和其他惰性气体团簇中和之上含有氢原子、氚原子或H和D原子混合物的杂质氦冷凝物。X波段脉冲和连续电子自旋共振将被用来研究纳米团簇的磁弛豫行为以及H和D原子在纳米团簇及其周围的分布。非技术总结证实了H原子通过固体分子氢晶体时发生玻色-爱因斯坦凝聚，这将是周期结构中玻色-爱因斯坦凝聚的一个重要例子。此外，分子基质中含有H原子和D原子的混合样品是通过交换量子隧道过程研究低温化学反应的良好体系。对由纳米团簇组合组成的杂质氦凝聚物的研究与对其他形式的软凝聚物质的研究很好地结合在一起。杂质氦凝聚体提供了一种储存大量化学能量的方法，当原子结合形成分子时，这些能量就会释放出来。这个材料世界网络项目显然跨越了物理和化学之间的界限，可能会为实际的能量存储系统提供有价值的线索。正在开发的用于超低温磁共振的毫米波技术的进一步进展将在许多其他科学领域有用。合作项目将从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中受益匪浅。该项目得到了凝聚态物理计划和材料研究部特别计划办公室的支持。

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.