Acquisition of a Variable Temperature Scanning Tunnelling Microscope

9307734 Plummer该项目是为了购买一个变温扫描隧道显微镜/光谱系统，该系统将在25K-~1500K的范围内运行。该组件的基本组件将是JEOL JSTM-4500VT扫描隧道显微镜。这种商用扫描隧道显微镜已经展示了从室温到1475K的原子分辨率。此外，JEOL正在设计一种与JSTM-4500VT兼容的低温样品台，能够在低至25K的样品上进行原子分辨率成像。这项提议的参与者将与JEOL合作，探索低温阶段的能力。变温扫描隧道显微镜将利用其进行原子尺度显微镜和光谱分析的能力，研究广泛的材料问题。我们将研究薄膜非金属到金属转变过程中原子结构和电子结构之间的相互作用。Mott、Wilson和Peierls类跃迁的详细性质可以作为吸附密度和衬底温度的函数在原子细节上进行探索。低温STM将用于监测脉冲激光烧蚀外延生长高T_c超导薄膜的生长条件，直接测量孤立生长步骤中超导性能的调制，并确定与表面形貌相关的磁通钉扎位置；研究氢与简单、贵金属和碳表面和薄膜的相互作用，重点关注结构和成键随温度的变化；以及结合STM的短程真实空间能力和X射线散射的长程有序能力，研究高温下合金表面的物理和化学性质。最后，实验将以纳米制造为目标，其中选定的有机金属络合物将被物理吸附，然后被来自隧道电流的电子撞击分解，形成“金属线”。***

9307734 Plummer The project is for the acquisition of a variable-temperature scanning tunneling microscopy/spectroscopy system that will operate in the range of 25K-~1500K. The essential component of this package will be the JEOL JSTM-4500VT Scanning Tunneling Microscope. This commercial STM has demonstrated atomic resolution from room temperature up to 1475K. Also, JEOL is in the process of engineering a low-temperature sample stage, compatible with JSTM- 4500VT, and capable of allowing atomic resolution imaging on samples as low as 25K. The participants in this proposal will be working with JEOL to explore the capabilities of the low- temperature stage. A broad range of materials problems will be investigated with the variable-temperature STM, utilizing its ability to do atomic scale microscopy and spectroscopy. The interplay between atomic and electronic structure in thin film nommetal-to-metal transitions will be studied. The detailed nature of Mott, Wilson, and Peierls- like transitions can be probed in atomic detail as a function of adsorbate density and substrate temperature. The low temperature STM will be used to monitor growth conditions for pulsed-laser ablation epitaxial growth of high Tc superconducting films, to directly measure the modulation of superconducting properties at isolated growth steps, and to identify flux pinning sites associated with surface morphology; to investigate the interaction of hydrogen with simple, noble, and carbon surfaces and thin films, concentrating on temperature-dependent changes in the structure and bonding; and to investigate the physical and chemical properties of alloy surfaces at elevated temperatures, combining the short-range real-space capabilities of the STM with the long-range-order capabilities of x-ray scattering. Finally, experiments will be aimed at nanofabrication, where selected organometallic complexes will be physisorbed and subsequently decomposed by the electron impact from the t unneling current to form "metal wires". ***