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Barth C.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Foster A.S.,Tampere University of Technology | Foster A.S.,Aalto University | Henry C.R.,CNRS Interdisciplinary Center on Nanoscience in Marseille | And 2 more authors.
Advanced Materials | Year: 2011

The current status and future prospects of non-contact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM) for studying insulating surfaces and thin insulating films in high resolution are discussed. The rapid development of these techniques and their use in combination with other scanning probe microscopy methods over the last few years has made them increasingly relevant for studying, controlling, and functionalizing the surfaces of many key materials. After introducing the instruments and the basic terminology associated with them, state-of-the-art experimental and theoretical studies of insulating surfaces and thin films are discussed, with specific focus on defects, atomic and molecular adsorbates, doping, and metallic nanoclusters. The latest achievements in atomic site-specific force spectroscopy and the identification of defects by crystal doping, work function, and surface charge imaging are reviewed and recent progress being made in high-resolution imaging in air and liquids is detailed. Finally, some of the key challenges for the future development of the considered fields are identified. Non-contact atomic force microscopy (nc-AFM) and Kelvin probe force microscopy (KPFM) for studying insulating surfaces and thin insulating films in high resolution are reviewed. The methods are introduced, then experimental and theoretical studies of insulating surfaces and thin films, with specific focus on defects, atomic and molecular adsorbates, doping, and metallic nanoclusters are discussed. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Paramonov S.V.,RAS Nesmeyanov Institute of Organoelement Compounds | Lokshin V.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Fedorova O.A.,RAS Nesmeyanov Institute of Organoelement Compounds
Journal of Photochemistry and Photobiology C: Photochemistry Reviews | Year: 2011

The review describes photoswitchable molecular receptors based on spiropyran, spirooxazine, and chromene molecules. The presence of coordination centers in their structures defines the ability of such compounds to coordinate metal ions, amino acids and DNA molecules, the process being accompanied by changes in optical characteristics. Major reports describing the complex formation of spiropyrans are devoted to complexation of metal ions. Except simple substituted spiropyrans, the crown and calixarene containing spiropyrans as well as polymer composition with spiropyrans possess the effective photoswitching receptor properties. The metal complexes of spiropyrans demonstrate the photocontrolled charge and energy transfer properties. Several examples of the photochromic systems sensitive to a number of biological objects such as amino acids, proteins and DNA are described. A number of papers are devoted to the complex formation involving of spirooxazine molecules with metal ions, cyclodextrins and amino acids. The studies of benzo- and naphthopyran ligands involved mainly the incorporation of crown ether fragments into naphthopyran molecules. Very few articles describe alternative coordination functions. © 2011 Elsevier B.V.


Vielzeuf D.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Saul A.,CNRS Interdisciplinary Center on Nanoscience in Marseille
Contributions to Mineralogy and Petrology | Year: 2011

Diffusion profiles in minerals are increasingly used to determine the duration of geological events. For this purpose, the distinction between growth and diffusion zoning is critical; it requires the understanding of complex features associated with multicomponent diffusion. Seed-overgrowth interdiffusion experiments carried out in the range 1,050-1,250°C at 1.3 GPa have been designed to quantify and better understand Fe-Mg-Ca interdiffusion in garnet. Some of the diffusion profiles measured by analytical transmission electron microscope show characteristic features of multicomponent diffusion such as uphill diffusion, chemical solitary waves, zero-flux planes and complex diffusion paths. We implemented three different methods to calculate the interdiffusion coefficients of the D matrix from the experimental penetration curves and determined that with Ca as the dependent component, the crossed coefficients of the D matrix are negative. Experiments and numerical simulations indicate that: (1) uphill diffusion in garnet can be observed indifferently on the three components Fe, Mg and Ca, (2) it takes the form of complementary depletion/repletion waves and (3) chemical waves occur preferentially on initially flat concentration profiles. Derived D matrices are used to simulate the fate of chemical waves in time, in finite crystals. These examples show that the flow of atoms in multicomponent systems is not necessarily unidirectional for all components; it can change both in space along the diffusion profile and in time. Moving zero-flux planes in finite crystals are transitory features that allow flux reversals of atoms in the diffusion zone. Interdiffusion coefficients of the D matrices are also analyzed in terms of eigenvalues and eigenvectors. This analysis and the experimental results show that depending on the composition of the diffusion couple, (1) the shape of chemical waves and diffusion paths changes; (2) the width of the diffusion zone for each component may or may not be identical; and (3) the width of diffusion calculated at a given D and duration may greatly vary. D matrices were retrieved from thirteen sets of diffusion profiles. Data were cast in Arrhenius relations. Linear regressions of the data yield activation energies equal to 368, 148, 394, 152 kJ mol-1 at 1 bar and frequency factors Do equal to 2.37 × 10-6, -4.46 × 10-16, -1.31 × 10-5, 9.85 × 10-15 m2 s-1 for D̃Ca FeFe' D̃Ca FeMg' D̃Ca MeFe' D̃Ca MgMg' respectively. These values can be used to calculate interdiffusion coefficients in Fe-Mg-Ca garnets and determine the duration of geological events in high temperature metamorphic or magmatic garnets. © 2010 Springer-Verlag.


Floquet N.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Vielzeuf D.,CNRS Interdisciplinary Center on Nanoscience in Marseille
American Mineralogist | Year: 2011

Mesocrystals attract increasing interest in the fields of physics, chemistry, materials, and Earth sciences. Yet, structural properties of this new class of solid materials are not fully described. Biominerals often display complex hierarchical mesocrystalline organizations. We report on the crystallography of sclerites, which are small (∼80 μm), beautifully shaped calcitic biomineral structures found in the living tissues of octocorals. Despite a layered concentric structure, the submicrometer crystalline units constituting the sclerites display a remarkably simple crystallographic organization of similarly oriented units with only a low degree of misorientation between them. Some sclerites display crystallographic sectors, leading to the concept of "mesotwin." A mesotwin is to a twin what a "mesocrystal" is to a crystal: an analog with defects. On the basis of EBSD data, we propose a simple conceptual crystallographic model that accounts for the observed features. This model involves different rhombohedral unit blocks, with identical shapes and volumes, but different crystallographic faces. EBSD data show that quite unexpectedly slight misorientations of crystallites in the sclerites are not at random but organized around the three equivalent a axes of the hexagonal unit cell of calcite. In a subtle way, the overall organization and morphologies of the red coral sclerites are connected to the calcite crystallography.


Thibaudau F.,Aix - Marseille University | Thibaudau F.,CNRS Interdisciplinary Center on Nanoscience in Marseille
Journal of Physical Chemistry Letters | Year: 2012

We report results on ultrafast photothermal release of DNA from gold nanoparticles. We show that dehybridization of oligonucleotide duplex anchored on a gold nanoparticle surface occurs during a single laser pulse, leading to the release of single-strand DNA in solution. Breaking of the Au-S bond anchoring the duplex and the release of thiolated DNA are also evidenced. Our findings show that the size distribution of the nanoparticles plays a major role in the control of both phenomena. We establish a criterion regarding the size distribution of nanoparticles that allows full release of DNA without breaking of the anchoring thiol bonds. © 2012 American Chemical Society.


Gingras M.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Gingras M.,Aix - Marseille University
Chemical Society Reviews | Year: 2013

Carbohelicenes are a class of fascinating chiral helical molecules which have a rich history in chemistry. Over a period of almost 100 years, chemists have developed many methods to prepare them in a racemic or in a non-racemic form. They also possess a series of interesting chiral, physical, electronic and optical properties. However, their utilization in chemistry or chemistry-related fields has rarely appeared in a detailed and comprehensive review. It is the purpose of this review to collect fundamental applications and functions involving carbohelicenes in various disciplines such as in materials science, in nanoscience, in biological chemistry and in supramolecular chemistry. From the numerous synthetic methodologies reported up to now, carbohelicenes and their derivatives can be tailor-made for a better involvement in several subfields. Among those domains are: nanosciences, chemosensing, liquid crystals, molecular switches, polymers, foldamers, supramolecular materials, molecular recognition, conductive and opto-electronic materials, nonlinear optics, chirality studies and asymmetric synthesis. Helicene chemistry is now at a developmental stage, where sufficient application data are now collected and are extremely useful. They provide many more ideas for setting up the basis for future innovative applications. © 2013 The Royal Society of Chemistry.


Gingras M.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Gingras M.,Aix - Marseille University | Felix G.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Felix G.,Aix - Marseille University | And 2 more authors.
Chemical Society Reviews | Year: 2013

Carbohelicenes generally incorporate a helical, distorted, conjugated, polyaromatic system with ortho-fused benzenoid rings, which is a fundamental molecular characteristic of this class of compounds. They have been described as "molecules in distress" due to their distortion. The generation of a chiral helicity in helicenes was observed because of a severe intramolecular steric strain. Helicity is a molecular necessity in the higher series of carbohelicenes, when at some point, a helical pitch occurs when a second coil is formed. The most interesting properties resulting from such molecular distortion are the very high chiroptical and circular dichroism values. For instance, the resolution of some helicene racemates by "hand picking" of a few homochiral single enantiomeric crystals allowed for a measurement of their optical rotation. Due to that intrinsic chirality spanned over a large polyaromatic template, preliminary results clearly established the efficiency of carbohelicenes to induce asymmetry and chirality in organic synthesis and in supramolecular chemistry. Additionally, they have some potential uses in several fields: materials science, nanoscience, chemical biology and supramolecular chemistry. It has encouraged many attempts to develop new asymmetric syntheses of carbohelicenes, as well as some chiral separations of enantiomers and diastereoisomers. This review is thus dedicated to carbohelicene chirality. It gathered a substantial collection of data, and a comprehensive review on the preparations of enantioenriched helicenes, either from an asymmetric synthesis or from a chiral separation. Utilizations of non-racemic helicenes and their applications will be treated in the following review (Part 3), and will not be the subject of this manuscript. © 2013 The Royal Society of Chemistry.


Gingras M.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Gingras M.,Aix - Marseille University
Chemical Society Reviews | Year: 2013

Carbohelicenes belong to a class of fascinating, chiral, and helicoidal molecules, which have a rich history in chemistry since the very beginning of the 20th century. A renewed interest in polyaromatic chemistry and new synthetic challenges toward the search for innovative physical, biological, chemical and opto-electronic properties have brought high motivation in this field of studies. Theoretical insights gained from polyaromatic, chiral, conjugated and distorted π-systems are also responsible for this development. Several synthetic avenues were originally reported for making lower helicenes, but for many years, photochemical synthesis has remained a major method for producing small amount of helicenes. High-dilution conditions is still a limiting factor in their synthesis. The fulgurous impact of organometallic chemistry, novel synthetic methods, and recent catalytic systems has promoted the development of helicene chemistry, toward a library of tailor-made and highly functionalized helicene molecules. Helicene chemistry is being considered as an expanding and modern field, leading to several applications in supramolecular chemistry, in nanosciences, in chemical-biology, in polymers and materials science. This first part of a series of three reviews on carbohelicenes will be devoted to a comprehensive report on non-stereoselective reactions and methods for producing helicenes, along with their functionalization. © 2013 The Royal Society of Chemistry.


Nikitin A.G.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Nikitin A.G.,Aix - Marseille University | Kabashin A.V.,Aix - Marseille University | Dallaporta H.,CNRS Interdisciplinary Center on Nanoscience in Marseille
Optics Express | Year: 2012

We examine the excitation of plasmonic resonances in arrays of periodically arranged gold nanoparticles placed in a uniform refractive index environment. Under a proper periodicity of the nanoparticle lattice, such nanoantenna arrays are known to exhibit narrow resonances with asymmetric Fano-type spectral line shape in transmission and reflection spectra having much better resonance quality compared to the single nanoparticle case. Using numerical simulations, we first identify two distinct regimes of lattice response, associated with two-characteristic states of the spectra: Rayleigh anomaly and lattice plasmon mode. The evolution of the electric field pattern is rigorously studied for these two states revealing different configurations of optical forces: the first regime is characterized by the concentration of electric field between the nanoparticles, yielding to almost complete transparency of the array, whereas the second regime is characterized by the concentration of electric field on the nanoparticles and a strong plasmon-related absorption/scattering. We present electric field distributions for different spectral positions of Rayleigh anomaly with respect to the single nanoparticle resonance and optimize lattice parameters in order to maximize the enhancement of electric field on the nanoparticles. Finally, by employing collective plasmon excitations, we explore possibilities for electric field enhancement in the region between the nanoparticles. The presented results are of importance for the field enhanced spectroscopy as well as for plasmonic bio and chemical sensing. © 2012 Optical Society of America.


Nikitin A.G.,CNRS Interdisciplinary Center on Nanoscience in Marseille
Applied Physics Letters | Year: 2015

This Letter reports theoretical and experimental study of transverse-magnetic-like lattice plasmon modes originating from diffraction in periodic two dimensional arrays of metal nanoparticles. These modes lead to the transmission and reflection spectra exhibiting narrow linewidth Fano-like resonances which can appear as maxima, minima, or can have asymmetric peak-and-dip profile. The dependencies of the position and lineshape of the resonance on the lattice periodicity and angle of incidence are investigated. Numerical simulations of electric field distributions for different excitation conditions of lattice plasmon modes are also performed. © 2014 AIP Publishing LLC.

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