Acquisition of a Variable Temperature Scanning Tunnelling Microscope

小行星9307734 该项目是为了获得一个变温扫描隧道显微镜/光谱系统，将在25 K-1500 K范围内工作。 这个包的基本组成部分将是JEOL JSTM-4500 VT扫描隧道显微镜。 这种商用STM已经证明了从室温到1475 K的原子分辨率。 此外，JEOL正在设计一个低温样品台，与JSTM-4500 VT兼容，能够在低至25 K的样品上进行原子分辨率成像。 本提案的参与者将与JEOL合作，探索低温阶段的能力。 一个广泛的材料问题将与变温STM研究，利用其能力，做原子尺度的显微镜和光谱。 在薄膜非金属-金属转变中原子和电子结构之间的相互作用将被研究。 莫特，威尔逊，和佩尔斯-类跃迁的详细性质，可以探测在原子细节作为吸附物密度和衬底温度的函数。 低温STM将用于监测高Tc超导薄膜的脉冲激光烧蚀外延生长的生长条件，直接测量孤立生长步骤中超导性能的调制，并识别与表面形态相关的磁通钉扎位点;为了研究氢与简单、贵金属和碳表面和薄膜的相互作用，专注于结构和键合的温度依赖性变化;并研究合金表面在高温下的物理和化学性质，结合STM的短程实空间能力和X射线散射的长程有序能力。 最后，实验将针对纳米纤维，其中选定的有机金属络合物将被物理吸附，随后通过来自非金属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". ***