face consisting of {100} faces possesses three-fold axes at the apexes. The four-fold symmetry at the center of the {100} faces may not be obvious when the cubes form interfaces with the Au surface using {110} or {111} faces. In summary, we have demonstrated a methodological approach for utilizing the preferential adsorption of amphi- philes during the electrodeposition process to precisely con- trol the shapes of Cu 2 O crystals. The pH dependence of pref- erential adsorption made it possible to selectively tune the growth rate of Cu 2 O crystals along the <111> directions and therefore, their final morphology. The detailed nature of the preferential adsorption of SDS on the {111} Cu 2 O faces and its pH-dependence are currently under investigation. The resulting electrodes will be useful to elucidate any depen- dence of the catalytic, electrochemical, and photoelectro- chemical properties on different crystallographic planes of Cu 2 O particles (e.g., {100} versus {111}). [18±22] Experimental Preparation of Electrodes: For the counter electrode, 100  of tita- nium followed by 500  of platinum were deposited on clean glass slides by sputter coating. For the working electrode, 100  of chro- mium followed by 500  of gold were deposited on clean glass slides by thermal evaporation. SEM images of the resulting Au electrodes showed a smooth and featureless surface (grain size < 50 nm) and the XRD measurement revealed a strong preferential orientation of Au {111} planes parallel to the substrate. Electrodeposition of Cu 2 O: Cu 2 O crystals were prepared by cathod- ic deposition from aqueous solutions of 0.02 M Cu(NO 3 ) 2 ´ 6H 2 O. SDS (5 wt.-% = 0.17 M) or sodium sulfate (0.17 M) was introduced as additives to produce the results shown in Figures 1b,c, Figure 2, and Figure 4b. The pH of the solutions was adjusted by adding HCl and NaOH when required. The pH of the solutions containing SDS was adjusted and measured before SDS was added because the presence of SDS in the solution complicates reliable pH readings. All the crys- tals shown in Figures 1,2 were deposited galvanostatically (0.7 A m ±2 ) at 60 C for 20 min without stirring except for the octahedral crystals shown in Figure 1b, which were produced by pulsed deposition com- posed of current pulses of 1.8 A m ±2 for 0.1 s followed by a resting time of 0.9 s. The net deposition time was 3 min (total deposition time was 30 min). Octahedral crystals deposited using continuous galvano- static deposition showed less-uniform crystal sizes. Received: February 7, 2004 Final version: March 30, 2004 ± [1] S. Mann, Angew. Chem. Int. Ed. 2000, 39, 3392. [2] J. H. Adair, E. Suvaci, Curr. Opin. Colloid Interface Sci. 2000, 5, 160. [3] Y. Sun, Y. Xia, Science 2002, 298, 2176. [4] C. A. Orme, A. Noy, A. Wierzbicki, M. T. McBride, M. Grantham, H. H. Teng,P. M. Dove, J. J. 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[15] J.-F. Liu, W. A. Ducker, J. Phys. Chem. B 1999, 103, 8558. [16] Cu 2 O crystallizes in the space group Pn-3m (S. G.# 224). For this space group (h00) reflections with h ¹ 2n are systematically absent. [17] Below 40 C co-deposition of Cu 2 O and Cu occurs, forming Cu/ Cu 2 O composite films. [18] K. H. Schulz, D. F. Cox, J. Catal. 1993, 143, 464. [19] M. Hara, T. Kondo, M. Komoda, S. Ikeda, K. Shinohara, A. Tanaka, J. N. Kondo, K. Domen, Chem. Commun. 1998, 357. [20] a) P. E. de Jongh, D. Vanmaekelbergh, J. J. Kelly, Chem. Mater. 1999, 11, 3512. b) P. E. de Jongh, D. Vanmaekelbergh, J. J. Kelly, Chem. Commun. 1999, 1069. [21] J.-M. Zen, Y.-S. Song, H.-H. Chung, C.-T. Hsu, A. S. Kumar, Anal. Chem. 2002, 74, 6126. [22] W. Siripala, A. Ivanovskaya, T. F. Jaramillo, S.-H. Baeck, E. W. McFarland, Sol. Energy Mater. Sol. Cells 2003, 77, 229. Large Spectral Birefringence in Photoaddressable Polymer Films** By Beth L. Lachut, Stefan A. Maier, Harry A. Atwater,* Michiel J. A. de Dood, Albert Polman, Rainer Hagen, and Sergej Kostromine Polymers containing azobenzene side-chains have attracted much attention due to their high optical activity upon expo- sure to polarized electrical and optical fields. Initially isotro- pic films develop extremely large in-plane birefringences Dn = n ^ ± n i (where n ^ and n i are the refractive indices in the direction perpendicular and parallel to the writing polariza- tion, respectively) when exposed to normally incident polar- COMMUNICATIONS 1746  2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/adma.200400121 Adv. Mater. 2004, 16, No. 19, October 4 ± [*] Dr. H. A. Atwater, B. L. Lachut, Dr. S. A. Maier [+] Thomas J. Watson Laboratory of Applied Physics California Institute of Technology Pasadena, CA 91125 (USA) E-mail: haa@caltech.edu Dr. M. J. A. de Dood, Dr. A. Polman FOM Institute of Atomic and Molecular Physics Kruislaan 407, NL-1098 SJ Amsterdam (The Netherlands) Dr. R. Hagen, Dr. S. Kostromine Bayer Polymers D-51368 Leverkusen (Germany) [+] Present address: Dept. of Physics, University of Bath, Bath BA27AY, UK. [**] Pieter Kik is gratefully acknowledged for stimulating discussions, and Hans Mertens for his help with transmission measurements. The work at Caltech was supported by the Air Force Office of Scien- tific Research and work at AMOLF is part of the research program of FOM, which is financially supported by NWO.