The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Nano Lett. 2012 Mar 14;12(3):1295-9. doi: 10.1021/nl203776n. Epub 2012 Feb 24.
Transmission electron microscopy was used to determine the structure of molecular films of self-assembled monolayers of pentathiophene derivatives supported on various electron transparent substrates. Despite the extreme beam sensitivity of the monolayers, structural crystallographic maps were obtained that revealed the nanoscale structure of the film. The image resolution is determined by the minimum beam diameter that the radiation hardness of the monolayer can support, which in our case is about 90 nm for a beam current of 5 × 10(6) e(-)/s. Electron diffraction patterns were collected while scanning a parallel electron beam over the film. These maps contain uncompromised information of the size, symmetry and orientation of the unit cell, orientation and structure of the domains, degree of crystallinity, and their variation on the micrometer scale, which are crucial to understand the electrical transport properties of the organic films. This information allowed us to track small changes in the unit cell size driven by the chemical modification of the support film.
透射电子显微镜用于确定各种电子透明衬底支撑的五噻吩衍生物自组装单分子层的分子膜的结构。尽管单层对电子束极为敏感，但仍获得了结构晶体学图谱，揭示了薄膜的纳米级结构。图像分辨率由单层的辐射硬度所能支持的最小光束直径决定，在我们的情况下，对于 5×10(6)e(-)/s 的束流，其约为 90nm。在平行电子束扫描薄膜的同时收集电子衍射图谱。这些图谱包含了单元晶胞的大小、对称性和取向、畴的取向和结构、结晶度及其在微米尺度上的变化等未受损的信息，这些信息对于理解有机薄膜的电输运性质至关重要。这些信息使我们能够跟踪由支撑膜的化学修饰引起的单元晶胞尺寸的微小变化。
