论文标题
石墨烯上物理分子层的结构和非平衡热转移
Structure and Non-Equilibrium Heat-Transfer of a Physisorbed Molecular Layer on Graphene
论文作者
论文摘要
通过低能电子衍射和扫描隧道显微镜研究了外延石墨烯上1,2-双（4-吡啶基）乙烯（BPE）的物理次 - 单层的结构。另外，通过超快低能电子衍射研究BPE和表面之间的非平衡热转移。 BPE在与底物不相称的斜单元中排列。六个不同的旋转和/或镜像结构域，其中分子单位细胞相对于石墨烯表面旋转28 {\ pm} 0.1°。分子被弱物理，这是事实证明，它们在室温下很容易解吸。但是，在液氮温度下，层稳定，可以进行时间分辨的实验。分子和表面的温度变化可以通过其各个衍射特征的Debye-Waller因子独立测量。因此，BPE和表面之间的热流可以在皮秒时间尺度上监测。时间分辨的测量与模型模拟结合使用，显示了不同层之间存在三个相关的热屏障。发现分子层和石墨烯之间的热边界电阻为2 {\ pm} 1 {\ cdot} 10-8 k m2 w-1。
The structure of a physisorbed sub-monolayer of 1,2-bis(4-pyridyl)ethylene (bpe) on epitaxial graphene is investigated by Low-Energy Electron Diffraction and Scanning Tunneling Microscopy. Additionally, non-equilibrium heat-transfer between bpe and the surface is studied by Ultrafast Low-Energy Electron Diffraction. Bpe arranges in an oblique unit cell which is not commensurate with the substrate. Six different rotational and/or mirror domains, in which the molecular unit cell is rotated by 28{\pm}0.1° with respect to the graphene surface, are identified. The molecules are weakly physisorbed, as evidenced by the fact that they readily desorb at room temperature. At liquid nitrogen temperature, however, the layers are stable and time-resolved experiments can be performed. The temperature changes of the molecules and the surface can be measured independently through the Debye-Waller factor of their individual diffraction features. Thus, the heat flow between bpe and the surface can be monitored on a picosecond timescale. The time-resolved measurements, in combination with model simulations, show the existence of three relevant thermal barriers between the different layers. The thermal boundary resistance between the molecular layer and graphene was found to be 2{\pm}1{\cdot}10-8 K m2 W-1.
