Dynamics of Graphene Nanodrums
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Dynamics of Graphene Nanodrums Gustavo Brunetto1*, Sergio B. Legoas2, Vitor R. Coluci3, Liacir S. Lucena4, and Douglas S. Galvao1 1 Departamento de Física Aplicada, Unicamp, 13083-859 Campinas, Sao Paulo, Brazil. 2 Departamento de Física, Universidade Federal de Roraima, 69304-000 Boa Vista, Roraima, Brazil. 3 Faculdade de Tecnologia, Unicamp, 13484-370 Limeira, Sao Paulo, Brazil. 4 Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970 Natal, Brazil. * Corresponding author: [email protected] ABSTRACT Recently, it was proposed that graphene sheets deposited on silicon oxide can act as impermeable atomic membranes to standard gases, such as helium, argon, and nitrogen. It is assumed that graphene membrane is clamped over the surface due only to van der Waals forces. The leakage mechanism can be experimentally addressed only indirectly. In this work we have carried out molecular dynamics simulations to study this problem. We have considered nanocontainers composed of a chamber of silicon oxide filled with gas and sealed by single and multi-layer graphene membranes. The obtained results are in good qualitative agreement with the experimental data. We observed that the graphene membranes remain attached to the substrate for pressure values up to two times the largest value experimentally investigated. We did not observe any gas leakage through the membrane/substrate interface until the critical limit is reached and then a sudden membrane detachment occurs. INTRODUCTION From its experimental realization by Novoselov et al. [1], graphene has been the subject of intense theoretical and experimental investigations. This is in part due to its exceptional mechanical [2,3] and electronic properties [4]. Graphene has demonstrated to have nonlinear elastic properties [5,6]. These properties can be exploited to create new technological applications [1-6]. An interesting graphene application is like nano-membranes. Due to its bi-dimensional, one-atom thick material, graphene is the ultimate membrane. Membranes are very important in many physical, chemical, and biological systems [7]. Membranes are perfect structures to be used to divide the space into two regions and/or to separate systems with different physical or chemical properties. Recently, Bunch et al. [7] proposed that graphene could be used as impermeable atomic membranes. They deposited graphene membranes over a cavity made of silicon oxide filled with different gases. The membrane was clamped on all sides only by van der Waals forces between the graphene and the cavity, creating a certain volume of confined gas (nano-container). In Figure 1 we present a schematic representation of the used systems. They concluded that the gas leakage is mainly through the silicon oxide cavity walls and not through the graphene membranes or through graphene-oxide interface. These conclusions were obtained indirectly, once it was not possible to directly measure the gas leakage.
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