Inside Front Cover: Line Defects Embedded in Three‐Dimensional Photonic Crystals (Adv. Mater. 15/2005)

The inside cover illustrates an approach to creating line defects embedded in the interior of a self‐assembled photonic crystal, as reported by Zhao and co‐workers on p. 1917. Photoresist patterns are first constructed on the surface of a silica opal film by conventional optical photolithography. After regrowth of the silica colloidal crystal, photoresist line defects are successfully introduced into the self‐assembled silica colloidal crystal. Further processing results in an inverse opal with air‐core line defects embedded in its interior, which provides a prototype for future optical waveguide devices based on self‐assembled three‐dimensional photonic crystals.     

Inside Front Cover: Curling Colloidal Photonic Crystals (Adv. Mater. 18/2006)

The inside cover features a schematic illustration (right) and three representative electron microscopy images (left) of photonic‐crystal strips with controlled curvature. As reported by Kitaev and co‐workers on p. 2481, the curvature is induced by infiltration of polymer opal with alkoxide precursors to attain an overlayer that experiences controllable shrinkage upon hydrolysis. Both continuity and high structural order are perfectly preserved throughout precursor infiltration and polymer microsphere removal.     

Inside Front Cover: Experimental Evidence for Superprism Effects in Three‐Dimensional Polymer Photonic Crystals (Adv. Mater. 2/2006)

The inside cover illustrates the highly dispersive propagation of light in a three‐dimensional polymer photonic crystal. White light is coupled into a woodpile structure and split into its wavelength components due to the frequency‐dependent dispersion properties of the structure. This superprism effect is orders of magnitudes higher than in a conventional glass prism and is caused by the strong anisotropy of the dispersion surface at frequencies slightly above the photonic bandgap. In work reported on p. 221, Serbin and Gu fabricated these woodpile structures operating in the near‐infrared wavelength range by means of two‐photon polymerization and give theoretical and experimental evidence for the superprism effect in these low‐index photonic‐crystal structures.     

Cover Picture: Colloidal Crystal Capillary Columns—Towards Optical Chromatography (Adv. Mater. 4/2005)

The cover illustration, designed by Ludovico Cademartiri, is an artistic rendering of novel micro‐ and nanobore chromatographic columns, as reported by Ozin and co‐workers on p. 438. The three‐dimensional periodic arrangement of the building blocks, solid spheres or air‐spheres, constituting the chromatographic stationary phase allows wavelength‐selective interaction of electromagnetic radiation with the stationary phase. The photonic stop band responsible for the structural color of the column is monitored spectroscopically and shifts of its wavelength, generated by minute refractive index changes within a mobile phase (here represented by alkane homologues), can be immediately detected at any point along and around the column due to the exceptional structural uniformity.     

Perfecting Imperfection—Designer Defects in Colloidal Photonic Crystals

Current progress in the exciting and burgeoning field of functional defects in colloidal photonic crystals (CPCs) is reported. After a brief introduction into the importance and nature of defects in CPCs the state‐of‐the‐art in fabricating point, line, and planar defects is described. Measurement and characterization techniques as well as the corresponding theory are discussed. Besides normal, passive defects, the recent development of reversibly tunable defects adds important functionality. In particular, the addition of chemical functionality is demonstrated to open a path to a wide range of color readout devices for ultrasensitive optical detection of biomolecules and pharmaceuticals.     

Cover Picture: Functionalization of Crystalline Colloidal Arrays through Click Chemistry (Adv. Mater. 21/2007)

Photonic crystals based on electrostatically‐stabilized colloidal arrays dispersed in a liquid medium are of interest to materials scientists partly because of the optical tuning afforded to theses systems with a variation in interparticle distance. On p. 3507, Stephen Foulger and co‐workers from Clemson University, USA report on a general strategy for the preparation of well‐defined and regioselectively functionalized ordered colloidal particles through the exploitation of “click” chemistry. Click transformations have found utility in the synthesis and/or functionalization of a range of systems. In addition, the solvochromic tuning of the ordered arrays is employed to modify the emission spectra of the surface‐attached photoluminescent dyes.     

Inside Front Cover: Photonic Crystal Structures as a Basis for a Three‐Dimensionally Interpenetrating Electrochemical‐Cell System (Adv. Mater. 13/2006)

The inside cover shows an SEM image of a 3D‐interpenetrating electrochemical cell with submicrometer features, as reported by Stein and coworkers on p. 1750. The pores of an inverse‐opal carbon electrode are coated with a conformal layer of a polymer separator and infiltrated with vanadia to form the opposite electrode after lithiation. The idealized scheme illustrates lithium‐ion transport between the electrodes through the polymer membrane.     

Cover Picture: Partially Oxidized Macroporous Silicon: A Three‐Dimensional Photonic Matrix for Microarray Applications (Adv. Mater. 23/2006)

Partial oxidation of macroporous silicon membranes with different pore wall thicknesses results in a regular compartmentalized structure of SiO₂ domains separated by opaque silicon, as shown on the cover. Dertinger and co‐workers report on p. 3135 that control of the experimental conditions ensures the flatness of the partially oxidized macroporous silicon. Fluorescence crossover is minimized within the photonic crystal, enabling its use as a microarray support for sensitive bioanalytic applications, such as DNA hybridization.