Bovio S, Podestà A, Milani P, Ballone P, Del Pópolo M G
C.I.Ma.I.Na, Università degli Studi di Milano, via Celoria 16, 20133, Milano, Italy. Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133, Milano, Italy.
J Phys Condens Matter. 2009 Oct 21;21(42):424118. doi: 10.1088/0953-8984/21/42/424118. Epub 2009 Sep 30.
Atomic force microscopy images for [bmim][Tf(2)N] films deposited at ambient conditions by drop-casting show a population of terraced islands of mesoscopic area (1-100 μ(2)) and ∼50 nm height. The regularity of terraces and steps, stiff mechanical properties and a fragile fracture mode all suggest that the islands are solid-like, even though bulk [bmim][Tf(2)N] is liquid at the temperature of the experiment. Molecular dynamics simulations for a homogeneous [bmim][Tf(2)N] film 4 nm thick on silica also display marked layering in proximity to silica of periodicity closely matching the experimental estimate of the step height. The density modulation of the simulated sample, however, decays into an approximatively homogeneous and fluid-like density distribution ∼2 nm from the solid surface. The detailed comparison of experiments and simulations is contained in the closing section of the paper.
通过滴铸法在环境条件下沉积的[bmim][Tf(2)N]薄膜的原子力显微镜图像显示，存在大量介观区域（1 - 100 μ(2)）且高度约为50 nm的梯田状岛屿。梯田和台阶的规则性、坚硬的机械性能以及易碎的断裂模式都表明，尽管在实验温度下本体[bmim][Tf(2)N]是液体，但这些岛屿类似固体。在二氧化硅上4 nm厚的均匀[bmim][Tf(2)N]薄膜的分子动力学模拟也显示，在靠近二氧化硅处有明显的分层，其周期性与台阶高度的实验估计值紧密匹配。然而，模拟样品的密度调制在距固体表面约2 nm处衰减为近似均匀且类似流体的密度分布。实验和模拟的详细比较包含在论文的结尾部分。
