Nanoparticle lattices and surfaces The challenge of resolving the details of the surfaces or assemblies of colloidal semiconductor nanoparticles can be overcome if several characterization methods are used (see the Perspective by Boles and Talapin). Boneschanscher et al. examined honeycomb superlattices of lead selenide nanocrystals formed by the bonding of crystal faces using several methods, including high-resolution electron microscopy and tomography. The structure had octahedral symmetry with the nanocrystals distorted through “necking”: the expansion of the contact points between the nanocrystals. Zherebetskyy et al. used a combination of theoretical calculations and spectroscopic methods to study the surface layer of lead sulfide nanocrystals synthesized in water. In addition to the oleic acid groups that capped the nanocrystals, hydroxyl groups were present as well. Science , this issue p. 1377 , p. 1380 ; see also p. 1340