Department of Chemistry, University of California, Berkeley, California 94720, USA.
ACS Nano. 2012 Mar 27;6(3):2078-85. doi: 10.1021/nn203837m. Epub 2012 Mar 2.
Direct imaging of nanoparticle solutions by liquid phase transmission electron microscopy has enabled unique in situ studies of nanoparticle motion and growth. In the present work, we report on real-time formation of two-dimensional nanoparticle arrays in the very low diffusive limit, where nanoparticles are mainly driven by capillary forces and solvent fluctuations. We find that superlattice formation appears to be segregated into multiple regimes. Initially, the solvent front drags the nanoparticles, condensing them into an amorphous agglomerate. Subsequently, the nanoparticle crystallization into an array is driven by local fluctuations. Following the crystallization event, superlattice growth can also occur via the addition of individual nanoparticles drawn from outlying regions by different solvent fronts. The dragging mechanism is consistent with simulations based on a coarse-grained lattice gas model at the same limit.
液相透射电子显微镜直接成像纳米粒子溶液，使我们能够对纳米粒子的运动和生长进行独特的原位研究。在目前的工作中，我们报告了在非常低的扩散极限下二维纳米粒子阵列的实时形成，其中纳米粒子主要受到毛细管力和溶剂波动的驱动。我们发现超晶格的形成似乎被分成多个区域。最初，溶剂前沿拖动纳米粒子，将它们凝聚成无定形的团聚体。随后，纳米粒子通过局部波动结晶成阵列。结晶事件后，超晶格的生长也可以通过不同溶剂前沿从外围区域吸引单个纳米粒子来实现。这种拖动机制与基于粗粒化格子气模型在相同极限下的模拟结果一致。
