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Warren S.C.,Ecole Polytechnique Federale de Lausanne | Warren S.C.,Equilibrium Energy | Thimsen E.,Ecole Polytechnique Federale de Lausanne | Thimsen E.,Argonne National Laboratory
Energy and Environmental Science | Year: 2012

The study of the optoelectronic effects of plasmonic metal nanoparticles on semiconductors has led to compelling evidence for plasmon-enhanced water splitting. We review the relevant physics, device geometries, and research progress in this area. We focus on localized surface plasmons and their effects on semiconductors, particularly in terms of energy transfer, scattering, and hot electron transfer. © 2011 The Royal Society of Chemistry.

Dzyuba E.V.,Free University of Berlin | Baytekin B.,Free University of Berlin | Baytekin B.,Equilibrium Energy | Sattler D.,Free University of Berlin | Schalley C.A.,Free University of Berlin
European Journal of Organic Chemistry | Year: 2012

Bromo-substituted Hunter/Vögtle-type tetralactam macrocycles (TLMs) represent key intermediates for the attachment of terpyridyl and phenanthroline metal binding sites through cross-coupling reactions. From these monovalent precursors, metal complexes can easily be obtained that present the macrocycles in a multivalent fashion. Depending on the nature of the metal ion, the properties of the complexes can be tuned with respect to valency (e.g., phen-TLM + Cu I: divalent, phen-TLM + Fe II: trivalent) and lability against TLM ligand exchange (e.g., Cu I: slow, but reversible exchange, Ru IICl 2: kinetically inert). Hunter/Vögtle-type tetralactam macrocycles are equipped with metal coordination sites through Suzuki cross-coupling. The same bromo-substituted macrocycle can be used irrespective of the individual binding site, which provides versatile access to different complexes. The complexes represent multivalent hosts that are potentially useful for the formation of multiply interlocked molecules. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Timonen J.V.I.,Aalto University | Timonen J.V.I.,Equilibrium Energy | Latikka M.,Aalto University | Ikkala O.,Aalto University | Ras R.H.A.,Aalto University
Nature Communications | Year: 2013

The recently demonstrated extremely water-repellent surfaces with contact angles close to 180with nearly zero hysteresis approach the fundamental limit of non-wetting. The measurement of the small but non-zero energy dissipation of a droplet moving on such a surface is not feasible with the contemporary methods, although it would be needed for optimized technological applications related to dirt repellency, microfluidics and functional surfaces. Here we show that magnetically controlled freely decaying and resonant oscillations of water droplets doped with superparamagnetic nanoparticles allow quantification of the energy dissipation as a function of normal force. Two dissipative forces are identified at a precision of ∼ 10 nN, one related to contact angle hysteresis near the three-phase contact line and the other to viscous dissipation near the droplet-solid interface. The method is adaptable to common optical goniometers and facilitates systematic and quantitative investigations of dynamical superhydrophobicity, defects and inhomogeneities on extremely superhydrophobic surfaces. © 2013 Macmillan Publishers Limited. All rights reserved.

Warren S.C.,Cornell University | Warren S.C.,Equilibrium Energy | Perkins M.R.,Cornell University | Werner-Zwanziger U.,Dalhousie University | And 3 more authors.
Zeitschrift fur Physikalische Chemie | Year: 2012

Nanostructured materials with high metal content are interesting for a number of applications, including catalysis as well as energy conversion and storage. Here we elaborate an approach that combines the advantages of simple silica sol-gel chemistry with the ability to tailor metal composition and structure by introducing a ligand that connects a silane with an amino acid or hydroxy acid. Reacting this ligand with a metal acetate generates a precursor for a range of metal-silica nanocomposites. Comparing this chemistry with conventional organic ligand-metal complexes that can be physically mixed into sol-gel derived silicates elucidates advantages, e.g. of going to high metal loadings. Resulting nanomaterials are characterized by a combination of small-angle X-ray scattering (SAXS), transmission electron microscopy (TEM), and solid-state nuclear magnetic resonance (NMR) to reveal structural characteristics on multiple lengths scales, i.e. from the microscopic (molecular) level (NMR) all the way to the mesoscale (SAXS) and macroscale (TEM). © by Oldenbourg Wissenschaftsverlag, München.

Jannasch A.,TU Dresden | Demirors A.F.,University Utrecht | Demirors A.F.,Equilibrium Energy | Van Oostrum P.D.J.,University Utrecht | And 3 more authors.
Nature Photonics | Year: 2012

Optical tweezers are exquisite position and force transducers and are widely used for high-resolution measurements in fields as varied as physics, biology and materials science. Typically, small dielectric particles are trapped in a tightly focused laser and are often used as handles for sensitive force measurements. Improvement to the technique has largely focused on improving the instrument and shaping the light beam, and there has been little work exploring the benefit of customizing the trapped object. Here, we describe how anti-reflection coated, high-refractive-index core-shell particles composed of titania enable single-beam optical trapping with an optical force greater than a nanonewton. The increased force range broadens the scope of feasible optical trapping experiments and will pave the way towards more efficient light-powered miniature machines, tools and applications. © 2012 Macmillan Publishers Limited. All rights reserved.

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