Lee Hyunsoo, Ko Jae-Hyeon, Choi Jin Sik, Hwang Jin Heui, Kim Yong-Hyun, Salmeron Miquel, Park Jeong Young
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon 34141, South Korea.
Graduate School of Nanoscience and Technology, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 34141, South Korea.
J Phys Chem Lett. 2017 Aug 3;8(15):3482-3487. doi: 10.1021/acs.jpclett.7b01377. Epub 2017 Jul 14.
Common experience shows that friction converts mechanical energy into heat. The first part of this process is vibrational excitation of atoms at the interface between rubbing bodies. The second part is the removal of the vibration energy by transferring it from the interface to the substrate. However, it is difficult to disentangle the excitation and energy transfer processes. We solved this by using a system consisting of a SiO-terminated tip sliding over graphene deposited on mica with intercalated water between them. The intercalated water was found to increase friction by a factor of ∼3 relative to dry mica. Density functional theory calculations show that water broadens the spectral range of graphene vibrations-particularly the low-frequency flexural modes-thus providing new excitation channels and also by increasing the overlap with the atomic vibrations of the mica substrate, which facilitates coupling and energy transfer.
常见经验表明，摩擦会将机械能转化为热能。这个过程的第一部分是摩擦物体界面处原子的振动激发。第二部分是通过将振动能量从界面转移到基底来去除振动能量。然而，很难区分激发和能量转移过程。我们通过使用一个系统解决了这个问题，该系统由一个SiO端接的尖端在沉积在云母上的石墨烯上滑动组成，它们之间夹有水。发现插入的水相对于干燥云母使摩擦力增加了约3倍。密度泛函理论计算表明，水拓宽了石墨烯振动的光谱范围，特别是低频弯曲模式，从而提供了新的激发通道，并且还通过增加与云母基底原子振动的重叠，这有利于耦合和能量转移。
