Selected by David J. Sellmyer
George Holmes University Professor of Physics
Director, Nebraska Center for Materials and Nanoscience
Director, Nebraska Nanoscale Facility: National Nanotechnology Coordinated Infrastructure

I was intrigued by the Alan Cohen photograph because it has interesting structural aspects that are similar to those encountered in various types of nanostructured materials. The length scale of features in nanoscale materials is the nanometer, which is one billionth of a meter, or the length of about four iron atoms lined up in a row. The photo has regions that could be called “grains,” within which there are “building blocks” that are arranged in regular arrays. The several grains in the photo are separated by straight-line boundaries or interfaces. 

All of these features are of great interest to those of us engaged in materials and nanoscience research. In this field we are creating new materials to solve many of the most pressing challenges facing mankind. Among these are renewable energy sources, new methods for information processing and storage, environmental and health protection, and economic and defense security. In the case of nanostructured materials, the properties of the individual building blocks, the grains and the grain boundaries or interfaces all are crucial in understanding the behavior of the material, whether it is a magnet in a hybrid car or a structural material in an airplane wing. The control of all of these structural features is at the heart of many modern technologies. 

The photo is stimulating because it invites us to ponder the spatial relationships and how the pieces fit together. It also is thought provoking because it makes us wonder about the optical techniques that were used in its production.