Understanding the Hopping Mechanism of Molecule Cascades at Very Low Temperatures
Understanding the Hopping Mechanism of Molecule Cascades at Very Low Temperatures
复制标题
了解极低温度下分子级联的跳跃机制
DOI：
10.1063/1.1639683
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发表时间：
2003
期刊：
影响因子：
--
通讯作者：
D. Eigler
中科院分区：
文献类型：
--
作者：
A. Heinrich;C. Lutz;J. Gupta;D. Eigler
我们使用新型低温扫描隧道显微镜来研究铜 (111) 表面分子级联中单个 CO 分子的运动。该显微镜的基础温度为1K，单次模式下连续循环3He和0.5K，保持时间约为10小时。 3He 的初始液化是通过利用 3He 气体的焦耳-汤姆逊膨胀来实现的，这消除了对泵送 4He 储层的需要。可以在超高真空下制备样品并将其转移到显微镜中。我们发现跳跃率对碳同位素有很强的依赖性，这使我们得出这样的结论：CO 分子在低于 6K 的温度下从初始状态隧道到最终状态。在较高温度下，热激活过程有助于提高跳跃率，并且讨论了该过程的几种模型。
We use a novel low‐temperature scanning tunneling microscope to study the motion of individual CO molecules in molecule cascades on a copper (111) surface. The microscope has a base temperature of 1K in continuous circulation of 3He and 0.5K in a single shot mode with a hold time of about 10 hours. The initial liquefaction of 3He is achieved by utilizing Joule‐Thomson expansion of 3He gas which eliminates the need for a pumped 4He reservoir. Samples can be prepared and transferred into the microscope in ultra high vacuum. We found a strong dependence of the hopping rate on the carbon isotope, which leads us to the conclusion that CO molecules tunnel from initial to final state at temperatures below 6K. At higher temperatures a thermally activated process contributes to the hopping rate and several models for this process are discussed.