Jain Sandeep K, Juričić Vladimir, Barkema Gerard T
Institute for Theoretical Physics, Universiteit Utrecht, Princetonplein 5, 3584 CC Utrecht, The Netherlands.
Nordita, Center for Quantum Materials, KTH Royal Institute of Technology and Stockholm University, Roslagstullsbacken 23, S-106 91 Stockholm, Sweden.
Phys Chem Chem Phys. 2017 Mar 15;19(11):7465-7470. doi: 10.1039/c6cp08535k.
Gas molecules trapped between graphene and various substrates in the form of bubbles are observed experimentally. The study of these bubbles is useful in determining the elastic and mechanical properties of graphene and adhesion energy between graphene and the substrate, and manipulating the electronic properties via strain engineering. In our numerical simulations, we use a simple description of the elastic potential and adhesion energy to show that for small gas bubbles (∼10 nm) the van der Waals pressure is in the order of 1 GPa. These bubbles show universal shape behavior irrespective of their size, as observed in recent experiments. With our results, the shape and volume of the trapped gas can be determined via the vibrational density of states (VDOS) using experimental techniques such as inelastic electron tunneling and inelastic neutron scattering. The elastic energy distribution in the graphene layer which traps the nanobubble is homogeneous apart from its edge, but the strain depends on the bubble size; thus variation in bubble size allows control of the electronic and optical properties.
实验观察到气体分子以气泡形式被困在石墨烯和各种衬底之间。对这些气泡的研究有助于确定石墨烯的弹性和力学性能、石墨烯与衬底之间的粘附能，并通过应变工程来调控电子性能。在我们的数值模拟中，我们使用弹性势和粘附能的简单描述来表明，对于小气泡（约10纳米），范德华压力约为1吉帕。正如最近实验中所观察到的，这些气泡无论大小如何都呈现出普遍的形状行为。根据我们的结果，利用非弹性电子隧穿和非弹性中子散射等实验技术，通过振动态密度（VDOS）可以确定被困气体的形状和体积。除了边缘外，捕获纳米气泡的石墨烯层中的弹性能量分布是均匀的，但应变取决于气泡大小；因此，气泡大小的变化可以控制电子和光学性能。
