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Cover image for Vol. 3 Issue 9

September 3, 2007

Volume 3, Issue 9

Pages 1457–1643

  1. Cover Picture

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
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    1. Cover Picture: Nanorod Heterostructures Showing Photoinduced Charge Separation (Small 9/2007) (page 1457)

      Sandeep Kumar, Marcus Jones, Shun S. Lo and Gregory D. Scholes

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200790031

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      The cover picture shows a CdSe–CdTe nanorod heterostructure composite and the spectrally- and time-resolved photoluminescence from a typical sample. Photoexcitation promotes vectorial charge separation between the two halves of the rod and can be tuned by quantum confinement. Rapidly decaying CdTe emission is evident in the 650-nm region, while the charge-transfer emission—signaling recombination of the electron and hole—is seen in the near-infrared region and is found to decay on a microsecond time scale. Such a long-lived charge-separated state is a key requirement for future photovoltaic applications. For more information, please read the Full Paper “Nanorod Heterostructures Showing Photoinduced Charge Separation” by G. D. Scholes and co-workers beginning on page 1633.

  2. Graphical Abstract

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    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
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    1. Graphical Abstract: Small 9/2007 (pages 1459–1467)

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200790032

  3. Corrigendum

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    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
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      Structural Color in Porous, Superhydrophilic, and Self-Cleaning SiO2/TiO2 Bragg Stacks (page 1467)

      Zhizhong Wu, Daeyeon Lee, Michael Rubner and Robert Cohen

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200790033

      This article corrects:

      Structural Color in Porous, Superhydrophilic, and Self-Cleaning SiO2/TiO2 Bragg Stacks

      Vol. 3, Issue 8, 1445–1451, Article first published online: 22 JUN 2007

  4. News

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
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  5. Highlight

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
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    1. Diamond Microelectrodes and their Applications in Biological Studies (pages 1474–1476)

      Carlos A. Martínez-Huitle

      Article first published online: 24 JUL 2007 | DOI: 10.1002/smll.200700272

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      A sensor achievement: Electrochemical sensors are of increasing interest, especially those developed for direct application in biological areas such as pharmacology and neuroscience. This Highlight summarizes research dealing with diamond microelectrodes, which can be used for neurotransmitter measurements in the brain. The SEM image (reproduced with permission from Adamant Technologies) shows diamond crystals deposited on a silicon substrate by CVD.

  6. Communications

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
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    1. Polymer-Mediated Synthesis of Ferritin-Encapsulated Inorganic Nanoparticles (pages 1477–1481)

      Mei Li, Chulanapa Viravaidya and Stephen Mann

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200700199

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      Building only on the inside: Poly(methacrylic acid) mediated inhibition of bulk precipitation is used to direct the nucleation and growth of CaCO3, SrCO3, BaCO3, or calcium phosphate nanoparticles specifically within the empty cavity of the iron-storage protein, apoferritin, to produce new types of biomimetic nanostructures (see image). The approach is facile and should be readily applicable to other capsid-like biological templates, such as viroids, enzyme complexes, and chaperonins.

    2. Monitoring Single-Cell Infectivity from Virus-Particle Nanoarrays Fabricated by Parallel Dip-Pen Nanolithography (pages 1482–1485)

      Rafael A. Vega, Clifton K.-F. Shen, Daniel Maspoch, Jessica G. Robach, Robert A. Lamb and Chad A. Mirkin

      Article first published online: 13 AUG 2007 | DOI: 10.1002/smll.200700244

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      Sting like a bee: Nanoarrays of infectious virus particles, encoded with EGFP, are patterned by dip-pen nanolithography and exposed to a solution of cells. Upon infection, infected cells produce the EGFP protein, generating a green fluorescence signal that allows one to monitor the cellular infection process in real time (as seen in the optical image). These results suggest that antibody-immobilized virus particles retain their biological activity. Scale bar: 35μm.

    3. Direct Enrichment of Metallic Single-Walled Carbon Nanotubes Induced by the Different Molecular Composition of Monohydroxy Alcohol Homologues (pages 1486–1490)

      Yu Wang, Yunqi Liu, Xianglong Li, Lingchao Cao, Dacheng Wei, Hongliang Zhang, Dachuan Shi, Gui Yu, Hisashi Kajiura and Yongming Li

      Article first published online: 13 AUG 2007 | DOI: 10.1002/smll.200700241

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      Showing more metal: Monohydroxy alcohol homologues with a different ratio of carbon to oxygen atoms (RCO) were employed as carbon feedstocks to prepare single-walled carbon nanotube (SWNTs). The relative amount of metallic SWNTs can be directly enriched by increasing the RCO. During growth, selective etching effects of hydroxyl radicals and the protection of amorphous carbon (see image) may be responsible for the direct enrichment.

    4. Intercalating Gold Nanoparticles as Universal Labels for DNA Detection (pages 1491–1495)

      Maryam Mehrabi and Robert Wilson

      Article first published online: 27 JUL 2007 | DOI: 10.1002/smll.200700230

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      Stuck in the middle: Intercalators are small planar molecules that insert specifically between adjacent bases in double-stranded DNA (see picture). Gold nanoparticles coated with intercalators are inexpensive universal labels that allow PCR products that have been hybridized to arrays of single-stranded capture probes to be seen with the unaided eye.

    5. 211AtCl@US-Tube Nanocapsules: A New Concept in Radiotherapeutic-Agent Design (pages 1496–1499)

      Keith B. Hartman, Donald K. Hamlin, D. Scott Wilbur and Lon J. Wilson

      Article first published online: 31 JUL 2007 | DOI: 10.1002/smll.200700153

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      Get shorty: Ultrashort carbon nanotubes (US-tubes) ranging in length from 20–50 nm have been loaded internally (see image) with an α-emitting radionuclide (At-211) for targeted radiotherapy. By loading the radionuclide inside the carbon nanotube as a mixed halogen (211AtCl), the 211AtCl@US-tube nanostructures offer a new paradigm in radiotherapeutic containment and delivery as the first carbon-nanotube-based radiotherapeutic agent.

    6. Inkjet Printing of Transparent, Electrically Conducting Single-Walled Carbon-Nanotube Composites (pages 1500–1503)

      William R. Small and Marc in het Panhuis

      Article first published online: 31 JUL 2007 | DOI: 10.1002/smll.200700110

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      Clearly superior resistance: Flexible, conductive, transparent single-walled carbon nanotube composite films (see picture) have been prepared by inkjet printing of nanotube dispersions. A single printed layer exhibited sheet resistance of 100 kΩ per square at 85 % optical transparency. The films display sensitivity to alcohol vapors.

    7. Titanium Oxide Nanowires Originating from Anodically Grown Nanotubes: The Bamboo-Splitting Model (pages 1504–1507)

      Jae Hoon Lim and Jinsub Choi

      Article first published online: 23 JUL 2007 | DOI: 10.1002/smll.200700114

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      Bamboozled! High-aspect-ratio TiO2 nanowires (see image) that are vertically split off from anodic titanium oxide nanotubes are prepared by anodization of titanium foils. The bamboo-splitting model based on the hydrolysis of a small amount of water in viscous ethylene glycol at high voltage is proposed as the mechanism of the formation of the TiO2 nanowires.

    8. Shape-Controlled Growth of Platinum Nanoparticles (pages 1508–1512)

      Jintian Ren and Richard D. Tilley

      Article first published online: 23 JUL 2007 | DOI: 10.1002/smll.200700135

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      Growing up: The controlled formation of platinum nanoparticles of many shapes (see image) including cubes, rectangular prisms, triangular prisms, rods, tripods, octapods, and polypods have been produced in a simple synthetic protocol by varying reaction parameters.

    9. Nanoscale Microelectrochemical Cells on Carbon Nanotubes (pages 1513–1517)

      Xianbo Jin, Wuzong Zhou, Shengwen Zhang and George Z. Chen

      Article first published online: 27 JUL 2007 | DOI: 10.1002/smll.200700139

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      Nanoscale microelectrochemical cells can form on individual carbon nanotubes in neutral aqueous solutions of KMnO4, leading to corrosion of the nanotubes (see image) and simultaneous deposition of nanocrystalline MnO2 on both external and internal surfaces of the nanotubes.

    10. Large-Scale Synthesis of Titanate and Anatase Tubular Hierarchitectures (pages 1518–1522)

      Changzheng Wu, Lanyu Lei, Xi Zhu, Jinlong Yang and Yi Xie

      Article first published online: 31 JUL 2007 | DOI: 10.1002/smll.200700179

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      Tube to tube: Tubular anatase hierarchitectures have been prepared on a large scale from titanate structures with a similar morphology (see image). The as-obtained anatase hierarchitectures exhibit improved photocatalytic activity over Degussa P-25 and hollow rutile spheres, suggesting their application potential for catalysis.

    11. Tuning the Morphology of Bismuth Ferrite Nano- and Microcrystals: From Sheets to Fibers (pages 1523–1528)

      Xinyi Zhang, Laure Bourgeois, Jianfeng Yao, Huanting Wang and Paul A. Webley

      Article first published online: 25 JUL 2007 | DOI: 10.1002/smll.200700182

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      Shape control: The morphology of bismuth ferrite (Bi2Fe4O9) crystals grown by a hydrothermal method was found to depend strongly on the concentration of hydroxide ions in the presence of surfactant. Bi2Fe4O9 nano- and microcrystals with controllable morphologies (sheets, plates, cubes, rectangular rods, and fibers; see scheme) were obtained. The technique would be applicable to other functional oxide materials.

    12. Fabrication of Hexagonal Lattice Co/Pd Multilayer Nanodot Arrays Using Colloidal Lithography (pages 1529–1533)

      Jong-Ryul Jeong, Sarah Kim, Sang-Hyun Kim, J. A. C. Bland, Sung-Chul Shin and Seung-Man Yang

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200700156

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      Join the dots: Co/Pd multilayer nanodot arrays with tunable sizes have been fabricated using colloidal lithography. The arrays were shown to exhibit maxima in their coercivities due to the magnetostatic interaction between the metal dots. The SEM image shows that smaller particles can often be observed when the arrays are exposed to an O2/CF4 plasma for short periods (disappearing upon longer exposure). Scale bar=500 nm.

    13. DNA Shadow Nanolithography (pages 1534–1538)

      Héctor A. Becerril and Adam T. Woolley

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700240

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      Out of the shadow: DNA shadow nanolithography utilizes the patterning ability of DNA without requiring the nucleic acid to remain in the final construct. DNA patterns are formed on Si surfaces and metal deposition and anisotropic etching are utilized to make DNA-templated trench features in substrates with <30-nm line widths (see scheme). These trenches can be post-processed using standard microfabrication tools to form distinct nanostructures, such as nanochannels and nanowires.

    14. The Electronic Properties of DNA Bases (pages 1539–1543)

      Mingsheng Xu, Robert G. Endres and Yasuhiko Arakawa

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200600732

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      Base level: The electronic properties of the four DNA nucleosides are studied by ultrahigh-vacuum scanning tunneling techniques (see image), and the results are compared with first-principles density functional calculations of the methylated bases. Base-specific electronic signatures are observed, such as molecular energy levels and currents, which shed light on charge injection into and migration along DNA molecules and electronic DNA sequencing.

    15. Nanomechanical Investigation of Mo6S9−xIx Nanowire Bundles (pages 1544–1548)

      Andras Kis, Gábor Csanyi, Daniel Vrbanic, Ales Mrzel, Dragan Mihailovic, Andrezj Kulik and Lázsló Forró

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700164

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      Bundle of joy! The mechanical properties of Mo6S9−xIx nanowires with x=6 and 4.5 (see image) are investigated. Despite the identical atomic structures mechanical measurements based on deformation of suspended nanowires reveal more than a factor of two difference in the shear modulus, which indicates significant variation in the mechanical coupling between individual nanowires arising from different atomic species on the nanowire surface.

  7. Full Papers

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
    9. Preview
    1. Novel Biocatalysts Based on S-Layer Self-Assembly of Geobacillus Stearothermophilus NRS 2004/3a: A Nanobiotechnological Approach (pages 1549–1559)

      Christina Schäffer, René Novotny, Seta Küpcü, Sonja Zayni, Andrea Scheberl, Jacqueline Friedmann, Uwe B. Sleytr and Paul Messner

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200700200

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      Novel types of nanopatterned biocatalysts (see image) were constructed from the self-assembling cell surface layer protein SgsE of Geobacillus stearothermophilus and the glucose-1-phosphate thymidylyl-transferase RmlA by a genetic-engineering approach. Enzyme activity of modular proteins matched that of the sole enzyme. The S-layer portion of the biocatalysts conferred significantly improved shelf life to the fused enzyme and also enabled biocatalyst recycling.

    2. Specific Integrin Labeling in Living Cells Using Functionalized Nanocrystals (pages 1560–1565)

      Oliver Lieleg, Mónica López-García, Christine Semmrich, Jörg Auernheimer, Horst Kessler and Andreas R. Bausch

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700148

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      Twinkle, twinkle, little dot: Quantum dots (QDs) functionalized by cyclic Arg-Gly-Asp (cRGD) peptides using a biotin–streptavidin linkage can specifically label integrins of living cells. The spacer distance between the RGD sequence and the QD surface is a crucial parameter that ensures specific binding to individual αvβ3 integrins of osteoblast cells (see picture). Despite blinking, the position of single QDs is tracked with nanometer precision.

    3. Why Semiconducting Single-Walled Carbon Nanotubes are Separated from their Metallic Counterparts (pages 1566–1576)

      Jing Lu, Lin Lai, Guangfu Luo, Jing Zhou, Rui Qin, Dan Wang, Lu Wang, Wai Ning Mei, Guangping Li, Zhengxiang Gao, Shigeru Nagase, Yutaka Maeda, Takeshi Akasaka and Dapeng Yu

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700127

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      A separate issue: The underlying mechanism of the unusual selective adsorptions of pyrene and pyrenyl-N-oxide on neutral semiconducting single-walled carbon nanotubes (SWNTs), and of amine, H2O2, and porphyrin on oxidized semiconducting SWNTs (see picture) versus their metallic counterparts is studied. Density functional theory shows that the hole doping of SWNTs can affect the selectivity of a molecule towards them.

    4. Cell Apoptosis Control Using BMP4 and Noggin Embedded in a Polyelectrolyte Multilayer Film (pages 1577–1583)

      Amal Nadiri, Sabine Kuchler-Bopp, Hajare Mjahed, Bing Hu, Youssef Haikel, Pierre Schaaf, Jean-Claude Voegel and Nadia Benkirane-Jessel

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700115

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      Bone morphogenetic proteins (BMPs) play a major role in signaling apoptosis; this can be stopped by treatment with a BMP antagonist (“Noggin”). In situ control of apoptosis mediated by both BMP4 and Noggin embedded in a polyelectrolyte multilayer film is possible. It is shown that in the presence of BMP4 and Noggin embedded in a multilayered film (see image) cell death in tooth differentiation is induced or inhibited, and their biological effects conserved.

    5. Creating Nanopatterns of His-Tagged Proteins on Surfaces by Nanoimprint Lithography Using Specific NiNTA-Histidine Interactions (pages 1584–1592)

      Pascale Maury, Maryana Escalante, Mária Péter, David N. Reinhoudt, Vinod Subramaniam and Jurriaan Huskens

      Article first published online: 23 JUL 2007 | DOI: 10.1002/smll.200700046

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      Tag team: Different, histidine-tagged, natively fluorescent proteins are reversibly and specifically assembled onto self-assembled monolayers of NTA adsorbate molecules, patterned by nanoimprint lithography (see image).

    6. Quantitative Enhanced Raman Scattering of Labeled DNA from Gold and Silver Nanoparticles (pages 1593–1601)

      Robert J. Stokes, Alexandra Macaskill, P. Johan Lundahl, W. Ewen Smith, Karen Faulds and Duncan Graham

      Article first published online: 23 JUL 2007 | DOI: 10.1002/smll.200600662

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      The return of the red dye: The relative performance of gold and silver nanoparticles as surface-enhanced resonance Raman scattering (SERRS) substrates was assessed at different excitation wavelengths with a range of 13 commercially available dye-labeled oligonucleotides (see picture). The best detection limits using gold nanoparticles were observed when red-shifted dyes were resonance matched with a 632.8-nm laser source.

    7. Hybridization Kinetics and Thermodynamics of DNA Adsorbed to Individually Dispersed Single-Walled Carbon Nanotubes (pages 1602–1609)

      Esther S. Jeng, Paul W. Barone, John D. Nelson and Michael S. Strano

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200700141

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      Hybridization of DNA is slower on the surface of single-walled carbon nanotubes, than when free in solution. The kinetics and thermodynamics of this process were measured using an energy increase in the near-infrared fluorescence of the nanotubes. The preadsorption of DNA to the nanotube surface, before hybridization, was found to be the cause for the slow kinetics. The schematic describes DNA attached to the carbon nanotubes in folded sections.

    8. Dielectrophoretic Manipulation and Real-Time Electrical Detection of Single-Nanowire Bridges in Aqueous Saline Solutions (pages 1610–1617)

      Matthew S. Marcus, Lu Shang, Bo Li, Jeremy A. Streifer, Joseph D. Beck, Edward Perkins, Mark A. Eriksson and Robert J. Hamers

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700130

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      Bridging the gap: The use of dielectrophoretic manipulation to form nanowire bridges (see picture) in saline media is demonstrated. By using nulling methods, digital-like changes in impedance can be detected that arise from the bridging and unbridging of individual nanowires in solution. This work provides a pathway for the assembly of bioelectronic switches and related devices.

    9. Bi2WO6 Nano- and Microstructures: Shape Control and Associated Visible-Light-Driven Photocatalytic Activities (pages 1618–1625)

      Lisha Zhang, Wenzhong Wang, Lin Zhou and Haolan Xu

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700043

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      Shaping up: Bi2WO6 samples with complex morphologies of flower- (A), tyre- (B), helix- (C), and platelike (D) shapes (see image), are controllably synthesized by a facile hydrothermal process. All of the synthesized Bi2WO6 nano- and microstructures exhibit interesting shape-associated optical properties and visible-light-driven photocatalytic activity.

    10. Large-Scale Synthesis of Organophilic Zirconia Nanoparticles and their Application in Organic–Inorganic Nanocomposites for Efficient Volume Holography (pages 1626–1632)

      Georg Garnweitner, Leonid M. Goldenberg, Oksana V. Sakhno, Markus Antonietti, Markus Niederberger and Joachim Stumpe

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200700075

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      A multigram-scale, one-step nonaqueous synthesis route to monodisperse, highly crystalline ZrO2 nanoparticles (see image) that can be stabilized in nonpolar solvents via a simple post-functionalization step is presented. Organic–inorganic nanocomposites were prepared to demonstrate their great application potential; extremely effective and low-scattering-volume holographic gratings with the highest refractive-index contrast achieved so far (n1 up to 0.024) were obtained.

    11. Nanorod Heterostructures Showing Photoinduced Charge Separation (pages 1633–1639)

      Sandeep Kumar, Marcus Jones, Shun S. Lo and Gregory D. Scholes

      Article first published online: 20 AUG 2007 | DOI: 10.1002/smll.200700155

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      Supramolecular analogs of donor–acceptor pairs in nanorod heterostructures are reported. The charge-transfer band position and respective photoluminescence decay times depend on the segmental nanorod dimensions (see image). A PL lifetime almost an order of magnitude higher than the respective band-edge emissions of constituting nanorods is measured.

  8. Preview

    1. Top of page
    2. Cover Picture
    3. Graphical Abstract
    4. Corrigendum
    5. News
    6. Highlight
    7. Communications
    8. Full Papers
    9. Preview
    1. You have free access to this content
      Preview: Small 10/2007 (page 1643)

      Article first published online: 4 SEP 2007 | DOI: 10.1002/smll.200790035

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