Abstract
A microscopy that can offer three-dimensional (3D) images of nanometer-scale has been developed. The methodology, called transmission electron microtomography (TEMT), is a combination of the conventional transmission electron microscopy (TEM) and computerized tomography (CT). A series of TEM images of an object taken at different tilting angles ranged from 60° to the other side of 60° with an increment of a couple of degrees is subjected to CT in order to reconstruct 3D images of the object.
TEMT was used to investigate a self-organized nano-scale structure of a block copolymer. Under the conventional TEM, the structure appeared to be too complicated to characterize, while a periodic double-network structure consisting of one of the block constituents was clearly observed by TEMT. A 3D image analysis, i.e. 3D thinning, was used to estimate geometry of the network structure, which revealed that the coordination number at junctions were mainly 3. Combining this experimental result with crystallographic analysis of the network structure undoubtedly demonstrated that it has Ia3d symmetry and hence is based on one of the periodic minimal surfaces, Gyroid. Moreover, it is worth noting that the structures so far unexplored due to the lack of dimensionality, e.g., defects and grain boundary in crystals, will be able to be studied only by TEMT.
