论文标题
超薄绝缘膜上单分子的电荷状态寿命
Charge-state lifetimes of single molecules on ultrathin insulating films
论文作者
论文摘要
在扫描隧道显微镜（STM）在绝缘膜上的分子实验中，通过分子共振进行隧穿意味着暂时为分子充电。通过通过绝缘膜进行隧穿回到电荷基态至关重要，例如，对于理解STM诱导的电致发光至关重要。在这里，我们使用STM报告了在Cu（111）和Au（111）上吸附在不同厚度的NaCl膜上的单个分子的电荷寿命。为此，我们在共振隧道条件下接近了分子的尖端，直到通过通过NACL膜进行隧道限制电荷传输的状态。隧道电流的饱和度是对分子电荷状态寿命的直接度量，从而提供了一种研究电荷动力学的方法，从而提供了激子动力学。在不同底物上的阴离子和阳离子寿命的比较揭示了水平比对与绝缘体的传导和价带的关键作用，以及金属 - 绝缘体界面状态。
In scanning tunneling microscopy (STM) experiments of molecules on insulating films, tunneling through molecular resonances implies transiently charging the molecule. The transition back to the charge ground state by tunneling through the insulating film is crucial, for example, for understanding STM-induced electroluminescence. Here, using STM, we report on the charge-state lifetimes of individual molecules adsorbed on NaCl films of different thicknesses on Cu(111) and Au(111). To that end, we approached the tip to the molecule at resonant tunnel conditions up to a regime where charge transport was limited by tunneling through the NaCl film. The resulting saturation of tunnel current is a direct measure of the molecule's charge-state lifetime, thus providing a means to study charge dynamics and, thereby, exciton dynamics. Comparison of anion and cation lifetimes on different substrates reveals the critical role of the level alignment with the insulator's conduction and valence band, and the metal-insulator interface state.
