title: Colloidal crystals with diamond symmetry at optical lengthscales.
abstract: Future optical materials promise to do for photonics what semiconductors did for electronics, but the challenge has long been in creating the structure they require-a regular, three-dimensional array of transparent microspheres arranged like the atoms in a diamond crystal. Here we demonstrate a simple approach for spontaneously growing double-diamond (or B32) crystals that contain a suitable diamond structure, using DNA to direct the self-assembly process. While diamond symmetry crystals have been grown from much smaller nanoparticles, none of those previous methods suffice for the larger particles needed for photonic applications, whose size must be comparable to the wavelength of visible light. Intriguingly, the crystals we observe do not readily form in previously validated simulations; nor have they been predicted theoretically. This finding suggests that other unexpected microstructures may be accessible using this approach and bodes well for future efforts to inexpensively mass-produce metamaterials for an array of photonic applications.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Yifan
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Ian C
authors.initials: IC
authors.lastname: Jenkins
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: James T
authors.initials: JT
authors.lastname: McGinley
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Talid
authors.identifier: 0000-0003-2489-1613
authors.initials: T
authors.lastname: Sinno
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of Pennsylvania, 220 S. 33rd Street, Philadelphia, Pennsylvania 19104, USA.
authors.forename: John C
authors.identifier: 0000-0001-6239-6010
authors.initials: JC
authors.lastname: Crocker