Serge Lefrant

Nantes Université | UNIV Nantes · Jean Rouxel Institute of Materials

This chapter focuses on new aspects concerning the photoluminescence properties of composites based on conjugated polymers and carbon nanoparticles of the type carbon nanotubes, reduced graphene oxide and fullerenes. A review of the photoluminescence properties of various macromolecular compounds, for example poly(para-phenylenevinylene), poly(3-he...

Two methods were used for the synthesis of composites based on reduced graphene oxide (RGO) and poly(para-phenylene vinylene) (PPV) in un-doped and doped state, respectively, i.e. the annealing conversion (AC) of the PPV precursor solution (PS) at 300 °C and the electropolymerization (E) of α,α,α′,α′-tetrabromo-p-xylene. In the case of the E method...

New composite materials based on single-walled carbon nanotubes effectively separated into semiconducting (S-SWNTs) and metallic tubes (M-SWNTs) and poly(ortho-phenylenevinylene) (POPV) were synthesized by the electrochemical polymerization of the α,α,α’,α’-tetrabromo-o-xylene monomer onto the surface of Au supports covered with carbon nanotubes fi...

Optical properties are reported for composites based on single-walled carbon nanotubes (SWNTs) and copolymer poly(3,4-ethylenedioxythiophene-co-pyrene) (PEDOT-Py) prepared by chemical polymerization of two monomers in the presence of carbon nanotubes. A charge transfer between SWNTs and the PEDOT-Py copolymer was demonstrated by Raman scattering. T...

Surface enhanced Raman scattering (SERS) spectroscopic studies reveal a particular chemical interaction of the polyaniline/fullerene (PANI/C60) composite with N-methyl-2-pyrrolidinone (NMP). The chemical polymerization of aniline in the presence of sulfuric acid, potassium dichromate and fullerene has been used for the preparation of the PANI/C60 c...

We present in this paper a comprehensive study of the migration dynamics of the charges underlying transient photoluminescence (PL) processes in poly(para-phenylene vinylene) (PPV) samples from room temperature to 13 K. In order to interpret experimental data, we have modelled the long-time PL decays (from 100 to 1000 ps) using a time function prop...

While changes in resonant Raman scattering measurements are commonly used to measure the effect of chemical functionalization on single-walled carbon nanotubes, the precise effects of functionalization on these spectra has yet to be clearly identified. In this density functional theory study we explore the effects of functionalization on both the n...

In this work, the architecture of ZnO particles was found to be changed from nano-whiskers to flowers via the addition of fullerenes in the reaction mixture consisting of zinc chloride, sodium hydroxide and sodium dodecyl sulfate. The change in the morphological structure of ZnO particles is accompanied by a decrease in the photoluminescence (PL) i...

This paper reports the Raman spectrometric and X-ray diffraction analyses of structural characteristics of opals from the most important localities (Mexico, Australia, Brazil). Volcanic opals from Mexico have similar Raman spectra characterised by a very strong general band (apparent maximum toward 325 cm-1) that shows a complex structure with line...

Although Raman spectra reveal, as a signature of double-walled carbon nanotubes (DWCNTs), two radial breathing mode (RBM) lines associated with the inner and outer tubes, the specification of their nature as metallic or semiconducting remains a topic for debate. Investigating the spectral range of the RBM lines, we present a new procedure of the in...

Using surface-enhanced Raman scattering (SERS) and photoluminescence (PL) studies, new data concerning the electrochemical oxidation both of poly[(2,5-bisoctyloxy)-1,4-phenylene-vinylene] (BO-PPV) and the BO-PPV/HIPCO single-walled carbon nanotubes (SWNTs) composite are presented in this paper. The SERS studies performed at the excitation wavelengt...

A new composite material was synthesized via the electrochemical oxidation of 2,2'-bithiophene (BTh) and pyrene (Py) monomers dissolved in a solution of LiC1O(4) in CH3CN onto a working electrode of Au coated with a film of single-walled carbon nanotubes (SWNTs). The interaction of the poly(2,2'-bithiophene-co-pyrene) (PBTh-Py) with the SWNTs and t...

Surface-enhanced Raman scattering studies were performed using nonresonant (514.5 nm) and resonant (676.4 nm) optical excitations on single-walled carbon nanotubes thoroughly separated into semiconducting (pure 99%) and metallic (pure 98%) components. Regardless of the support (Au or Ag), the metallic nanotubes do not present an anomalous anti-Stok...

By performing comparative Raman studies on nanometric thin films (9.5, 39, 88 and 185 nm) of copper phthalocyanine (CuPc) deposited on glass, Au and Ag supports, we demonstrate that the mechanism of the surface-enhanced Raman scattering (SERS) generated on Au and Ag substrates differs in the Stokes and anti-Stokes Raman branches depending on whethe...

The effect of a small admixture of single-walled carbon nanotubes (SWNTs) HiPCO (high pressure carbon monoxide) (from 0.5 to 2 wt%) on the supramolecular structure in regio-regular poly(3-hexylthiophene) (RR-P3HT) thin films is studied and their optical and photoconductivity properties are investigated. It is demonstrated that the presence of such...

We investigated the local order in individual iron nanoparticles (NPs) embedded in carbon nanotubes (CNTs). The NPs directly come from the CNT growth on stainless steel without addition of external metal catalyst. The structural analysis has been obtained through nanoscale transmission extended electron energy loss fine structure (EXELFS) measureme...

We successfully address the challenge of aligning single-walled carbon nanotubes (SWNTs) and conjugated polymer chains in composite nanofibers for enhancing their opto-electrical properties. A pore-filling template strategy has been developed to prepare such nanocomposites from SWNTs and poly(para-phenylene vinylene) (PPV) chains, with both species...

Polarized Raman scattering studies on stiff layered structure of surfactant intercalated with trilayer graphene were performed at different intensities and excitation wavelengths. The D and 2D Raman bands reach the highest and lowest intensity when the polarization of laser excitation light is oriented along and perpendicular on the edges. The 2D b...

A combined chemical–electrochemical method was used for covalent functionalization of single-walled carbon nanotube (SWNT) with polydiphenylamine (PDPA) doped with heteropolyanions of H3PMo12O40·xH2O. The functionalization process induces in Raman spectra of SWNTs the following changes: (i) an increase in relative intensity of the D band, accompani...

This work presents a simple method to generate ordered chromophore/dispersant nanoarrays through a pore-filling process for nanoporous polymer template to enhance chromophore luminescence. Fluorescence results combining with the morphological evolution examined by scanning probe microscopy reveal that the enhanced luminescence intensity reaches the...

Boron nitride nanotubes (BNNT) have many potential applications as structural and reinforcing materials due to attractive combination of their excellent mechanical characteristics and high thermal and chemical stabilities. Recent progress in their reliable synthesis opened a way to pioneering experiments in BNNT/metal composite fabrication. In this...

Using surface-enhanced Raman scattering (SERS) and Fourier transform infrared spectroscopy (FTIR) in the grazing angle incident reflection geometry, new data concerning the abnormal anti-Stokes Raman emission (AASRE) and the molecular orientation of poly(p-phenylenevinylene) (PPV) deposited on metallic supports of Ag and Au are reported. The partic...

We analyze the local microscopic deformation left by Au, Ag and Cu islands on carbon nanotube walls observed by transmission electron microscopy. We employ finite-element simulations within continuum elasticity theory to demonstrate that the observed deformation of the tube walls is the result of elastic strain energy relaxation induced by the nucl...

Steady-state and time-resolved photoluminescence (TRPL) measurements are used in order to investigate the emission properties of new graft copolymer involving poly(N-vinylcarbazole) (PVK) and poly(3-methylthiophene) (PMeT) named PVK-3MeT. The photo-generated species in PVK-3MeT are identified as singlet intrachain excitons. Furthermore, radiative a...

In this paper, we present Raman scattering and luminescence of poly-paraphenylene vinylene/single-walled carbon nanotubes composites, focused on data recorded in the anti-Stokes branch. We demonstrate that, when the excitation energy is in the long wavelength tail of the fundamental absorption edge, an anti-Stokes signal is generated, whose origin...

Abnormal anti-Stokes Raman emission (AASRE) is defined by an anti-Stokes/Stokes intensity ratio much greater than expected on the basis of the equilibrium population of excited vibration states provided by the Boltzmann law. AASRE can be observed both in materials with intrinsic nonlinear optical properties as LiNbO3 or materials in which the nonli...

In this paper, we present recent results obtained on single-walled carbon nanotubes (SWNTs) and carbon nanotube/conjugated polymer composites by using resonant Raman scattering and Surface Enhanced Raman Scattering (SERS). Besides the characterization of these materials, we report on peculiar properties observed in the anti-Stokes Raman branch of t...

A simple method to decorate multiwalled carbon nanotubes (MWCNTs) with Au, Ag and Cu nanoparticles is illustrated. The method consists in directly depositing the selected metals by thermal evaporation on the carbon nanotubes. Comparative measurements carried out on samples that differ in the quantity and type of the deposited metal, reveal that iso...

Multiwalled carbon nanotubes synthesized directly on austenitic stainless steel result in being filled with pure iron nanoparticles. X-ray diffraction shows that the nanoparticles are either in the γ- or α-phase, although iron in the original alloy is in γ-phase because of the presence of nickel. This phase transformation is due to the selective ex...

In this article, we present quantum chemical calculations, based on density functional theory (DFT), performed to investigate the geometries and the opto-electronic properties of a new synthesized graft copolymer based on poly(N-vinylcarbazole) (PVK) and poly(3-methylthiophene) (PMeT) named PVK-3MeT. First, we have theoretically computed and compar...

The direct mixing of aqueous ferric chloride and o-phenylenediamine (OPD) solution at room temperature in the absence and presence of carbon nanotubes (CNTs) has been used to prepare poly(o-phenylenediamine) (POPD) micro-fibers and composites of the type CNTs/POPD having nanotubes incorporated in polymer fiber mass. Using surface enhanced infrared...

Highly conducting derivatives of polyacetylene formed in the redox reactions with FeCl3 FeBr3 and SnCl4 have been studied by Mossbauer spectroscopy. From the temperature dependence of the recoil-free fraction, the Mossbauer lattice temperatures 89K, of the following binary compounds (CH(FeCl4)y)x, (CH(FeBr4)y)x and (CH(SnCl5)y)x, were calculated as...

We present a systematic Raman study over a range of excitation energies of arc discharge single-walled carbon nanotubes (SWCNTs) covalently functionalized according to two processes, esterification and reductive alkylation. The SWCNTs are characterized by resonance Raman spectroscopy at each step of the functionalization process, showing changes in...

Abnormal anti-Stokes Raman emission (AASRE) is defined by an anti-Stokes/Stokes intensity ratio much greater than expected on the basis of the equilibrium population of excited vibration states provided by the Boltzmann law. Using nonlinear optical materials such as LiNbO3 and CdS in powder form, we demonstrate that under continuous single beam ex...

This work presents a simple method to generate ordered conjugated polymer nanoarrays through a pore-filling process for nanoporous polymer templates so as to enhance the efficiency of photoluminescence (PL). PL results combined with the morphological evolution examined by scanning probe microscopy revealed that the enhanced PL reaches maximum inten...

We investigate the emission properties of two copolymers by steady-state and time-resolved photoluminescence measurements. The copolymers are derived from poly-phenylene-vinylene (PPV) to which a non-conjugated ether group was added. The difference between the two copolymers is the group attached on the phenyl rings. Their fluorescence spectra pres...

In this paper, we report on Raman scattering and Surface Enhanced Raman Scattering (SERS) studies of single walled carbon nanotubes (SWNTs) and carbon nanotube/conjugated polymers composites. We demonstrate that under SERS conditions we induce an abnormal anti-Stokes Raman emission, that can be interpreted as being due to a “single-beam pumped” Coh...

In this paper, we demonstrate that, by continuous single beam excitation, one can generate an abnormal anti-Stokes Raman emission (AASRE) whose properties are similar to a coherent anti-Stokes Raman scattering (CARS). The effect has been observed in materials which possess intrinsically nonlinear properties (LiNbO3 and CdS), which have the electric...

This review deals with recent progress on the development of composite materials based on cojugated polymers (CPs) and carbon nanotubes (CNTs), both from fundamental and applied point of view. In the first part of the manuscript, we present the different types of composites, the new protocols used in their synthesis as well as their vibrational pro...

The capability of anti-Stokes/Stokes Raman spectroscopy to evaluate chemical interactions at the interface of a conducting polymer/carbon nanotubes is demonstrated. Electrochemical polymerisation of the monomer 3,4-ethylenedioxythiophene (EDOT) on a Au support covered with a single-walled carbon nanotube (SWNT) film immersed in a LiClO4/CH3CN solut...

Polydiphenylamine/single walled carbon nanotube (PDPA/SWNT) composites were synthesized electrochemically aiming at their application as active electrode materials for rechargeable lithium batteries. The electrochemical polymerization of diphenylamine (DPA) on a SWNT film immersed in a 1 M HCl solution was studied by cyclic voltammetry. Comparing c...

The chemical polymerization of o-phenylenediamine (OPD) on single-walled carbon nanotubes (SWCNTs) in the presence of phosphomolybdic acid (H3PMo12O40xH2O) has been studied by surface enhanced resonant Raman scattering (SERRS) spectroscopy. One demonstrates that an organic–inorganic hybrid composite of the type poly(o-phenylenediamine)/polyoxometal...

We demonstrate a facile fabrication of gold nanostructures including Au nanoplates (NPs), Au nanothorns (NTs), and Au nanowires (NWs) on indium tin oxide substrates via electrochemical growth. A simple two-electrode electrochemical deposition system was applied for the fabrication process. Dense Au nanostructures were grown directly on an Au seedin...

Carbon nanotubes (CNT) possess remarkable physical properties. However, because of their size, they are difficult to handle. Making composites with them gives an alternative way to handle these objects and to make use of their properties at a macroscopic scale. Here, we present a comparative study of the transport properties of PMMA / nanotubes com...

Carbon nanotubes are attractive materials with numerous possibilities of applications in various domains. Nevertheless, pertinent characterization studies are required in order to insure reproducibility in preparation, handling and incorporation in devices. Several spectroscopic tools have been developed so far, such as transmission electron micros...

In this paper, we report the synthesis and characterization of a new material based on Poly(N-vinylcarbazole) (PVK) and Poly(3-methylthiophene) (PMeT), which has been chemically prepared by cross-linking of PVK in the presence of 3-methylthiophene monomers in chloroform with anhydrous FeCl3. Thus, two samples were prepared, PVK–3MeT1 and PVK–3MeT2,...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

IntroductionCarbon NanotubesSynthesis of Composites Based on Conducting Polymers and Carbon NanotubesVibrational Properties of Composites Based on Conducting Polymers and Carbon NanotubesConclusions AcknowledgmentsReferences

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A new composite consisting of a semiconducting oligomer, namely 2,7-bis-(3,3'''-didodecyl-[2,2',5',2'';5'',2''']quaterthiophen-5-yl)-fluoren-9-one (QTF12), and double walled carbon nanotubes (DWCNT) has been prepd. in view of its application as an active component in bulk heterojunction photovoltaic cells. Raman spectroelectrochem. investigations s...

Electrochemical polymerization of indole in a LiClO4/CH3CN solution on a single-walled carbon nanotubes (SWNTs) film was studied by cyclic voltammetry, Raman scattering and FTIR spectroscopy. Comparing the cyclic voltammograms recorded on a blank Pt electrode with those obtained when carbon nanotubes films were previously deposited onto the Pt elec...

Composites based on carbon nanotubes and ZnO particles with needle shapes were prepared for applications in energy storage. Depending on the temperature (85 or 25 °C) at which the reaction between NaOH and ZnCl(2) was carried out, particles with two different morphologies: needle-shaped (NS) and double-pyramid-shaped (DPS), respectively, are obtain...

The electrochemical polymerization of N-ethyl carbazole (EK) on carbon nanotubes (CNs) films immersed in a LiClO4/acetonitrile solution was studied by cyclic voltammetry. Cyclic voltammograms recorded on a blank Pt electrode were compared with those obtained when CNs films were deposited on a Pt plate. In the latter case, the oxidation maximum is n...

In this paper, surface enhanced Raman scattering (SERS) studies on the chemical polymerization of 3,4-ethylene dioxythiophene (EDOT) in the presence of single-walled carbon nanotubes (SWNTs) are reported. Both a non-covalent and covalent functionalization of SWNTs with poly(3,4-ethylene dioxythiophene) (PEDOT) is invoked as a result of the followin...

The combination of the unique properties of carbon nanotubes (CNTs) with conjugated polymers makes their combined composite materials interesting as multifunctional systems with great potential. Supercapacitors, lithium rechargeable batteries, sensors, photovoltaic cells and photodiodes, optical limiting devices, solar cells, high-resolution printa...

Optical techniques allowing observations and spectroscopic investigations of materials at a nanoscale have been recently developed and applied to carbon nanotubes. They are briefly presented, including Scanning near-field optical microscopy, together with the Surface Enhanced or Tip Enhanced Raman Scattering. Even if new physical properties are dif...

Vibrational properties of composites based on single-walled carbon nanotubes (SWNTs) and conducting polymers of the type polyaniline (PANI) and poly (3,4-ethylene dioxythiophene) (PEDOT) are reported. For PANI-functionalized SWNTs, the intensity increase of the Raman band at 178 cm-1, associated with radial breathing modes of SWNTs bundles, indicat...

Two types of polythiophene—single-wall carbon nanotubes (SWCNTs) composites are comparatively studied. Composites of the first type consisted of nonmodified SWCNTs and nonmodified regioregular poly(3-hexylthiophene) (P3HT), poly(3-octylthiophene) (P3OT) or poly(dioctylterthiophenes) (PDOTT). Composites of the second type (molecular composites) were...

Prototypal photoluminescent nanofibres of poly-(p-phenylene-vinylene) (PPV) were prepared by the wetting template method in polycarbonate nanoporous membranes with an easy all-in solution polymer precursor route. Both nanowires and nanotubes were obtained by varying the dilution of the polymer precursor in methanol prior to thermal conversion. PPV...

We report in this paper experimental data on steady state and transient photoluminescence of poly-p-phenylene vinylene in the form of nanofibers prepared with a template method and converted at 110 degrees C. Results are compared to those obtained from films of different thicknesses converted at the same temperature. Data are analyzed by a model of...

Electrochemical polymerization of 2,2′-bithiophene (BTh) on single-walled carbon nanotube (SWCNT) films has been studied by Raman scattering and infrared absorption spectroscopy. Covalent functionalization of SWCNTs with poly(bithiophene) (PBTh) in its un-doped and doped states is demonstrated. The occurrence of a charge transfer process at the int...

Functionalization of PbI2 with conjugated polymers (polyaniline-emeraldine base (PANI-EB) or polyaniline-emeraldine salt (PANI-ES)) is demonstrated by Raman and luminescence studies. PbI2/PANI hybrid material was prepared by electrochemical polymerization of aniline onto the PbI2 modified Pt electrode and mechanico-chemical reaction between the two...

Mössbauer spectroscopy studies of Fe-Co/MgO catalysts proved that a high dispersion degree of Fe may be achieved for catalysts containing Fe/Co in a ratio close to 1. During materials processing. the presence of hydrogen at high temperatures, even for short time, induced an increased particle size of the catalytic Fe. The evaluation of various iron...

On subjecting a bulk 2H-PbI(2) crystal to vacuum annealing at 500 K followed by a sudden cooling at liquid nitrogen temperature stacking faults are generated that separate distinct layers of nanometric thickness in which different numbers of I-Pb-I atomic layers are bundled together. Such structures, containing two, three, four, five etc I-Pb-I ato...

In this work we present the results on preparation and analysis of structural and electronic properties of graphene flakes with different number of layers. Since the material electronic properties depend strongly on the layer number, a simple and reliable way to estimate this parameter should be found. In this work we propose to perform a quantitat...

Giant optical fields locally generated in nanoscale metal structures through the local excitation of surface plasmons underlie a variety of nonlinear optical processes. Using silver and gold rough metallic films, reproducible enhancements of the Raman signal on various materials including carbon nanotubes have been demonstrated. In addition, an abn...

We report the first soft chemistry synthesis of a new "layered ramsdellite-like" titanate structure, NaTi 2 O 4 (OH) (lattice parameters: primitive monoclinic system, a) 4.09 nm, b) 0.29 nm, c) 0.94 nm, and) 80°), with high-aspect-ratio, platelike morphology (diameter. 20-200 nm; thickness. 10-40 nm; length. 0.05-5 µm) from TiO 2 rutile. The newly...

A detailed characterization of covalently functionalized HiPco single-walled carbon nanotubes (SWNTs) has been carried out using several physicochemical methods (thermogravimetric analysis, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and Raman scattering). The chemical process, finally leading to SWNT−ester derivatives...

The synthesis of new diazonium salts of bipyridine or terpyridine ruthenium complexes is described. Introduction of a phenyl spacer between a metal ligand and the N2+ group play a key role to stabilize these compounds. Electrochemical experiments performed first on vitreous carbon present the reduction of diazonium ion to a radical and the electrog...

Regioregular poly(3-hexylthiophene) containing one diaminopyrimidine side group per ten repeat units (P3HT-co-P3(ODAP)HT) can form molecular composites with 1-(6-mercaptohexyl)thymine capped CdSe nanocrystals (CdSe(MHT)) via hydrogen bonds directed molecular recognition. Here we report complementary spectroscopic, electrochemical and spectroelectro...

Semiconducting single-walled carbon nanotubes resonantly excited by the interband E(22)(S) electronic transitions (at 1064 nm) display for the two components of the radial Raman band-one associated with the isolated tubes and the other associated with the bundled tubes-an anti-Stokes/Stokes Raman intensity ratio (I(aS)/I(S)) which deviates opposite...

Electrochemical reduction of single-walled carbon nanotube (SWNT) films in the presence of Li salts dissolved in acetonitrile (AN), as an anhydrous medium, was investigated by Raman scattering, FTIR spectroscopy and TEM studies. Differences between the in-situ and ex-situ Raman spectra recorded on the SWNT films immersed in the Li salt/AN solution...

Using surface enhanced Raman scattering (SERS) and FTIR spectroscopy, a covalent functionalization of single wall carbon nanotubes (SWNTs) with polystyrene (PST) is demonstrated. For this, two types PST/SWNTs composites were used: one resulting from the radical polymerization reaction of styrene achieved at 90 °C in the presence of benzene and benz...

In this paper, we propose an interpretation for an abnormal anti-Stokes Raman emission observed on nanometric thin films of different materials and in particular carbon nanotubes. We demonstrate that under a tight-focusing of the excitation light, a coherent anti-stokes Raman scattering (CARS) emission is produced, resulting from a wave mixing proc...

Composites based on zinc oxide (ZnO) nanoparticles and single-walled carbon nanotubes (SWNTs) were investigated by photoluminescence (PL) and Raman scattering. The room temperature PL spectrum of ZnO at the excitation wavelength of 335nm displays a narrow excitonic band, peaking at 368nm (3.36eV), and a wide one, disclosing two components with maxi...

Poly(2,5-dithienylene-isothianaphthene) and its analogue, deutered on the benzene ring, have been prepared by voltammetric polymerization of the corresponding monomers in Bu4NBF4/acetonitrile solutions. The polymers obtained are electroactive, showing in cyclic voltammograms two oxidation peaks associated with p-type doping and two reduction peaks,...

Optical absorption, photoluminescence, and Raman scattering spectra of poly(para-phenylene vinylene) (PPV) and single-walled carbon nanotube (SWNT) composite films are investigated at room temperature. Samples have been prepared at different precursor conversion temperatures, T c , (300, 180,and 120 °C) and with SWNT mass concentrations from x) 0%...

In this paper, we recall the main characteristics of Raman spectra of single‐walled carbon nanotubes. We illustrate our studies by results obtained on HiPCO samples on one hand, and “arc electric” samples on the other hand by using two different excitation wavelengths. We focus on the peculiarity of observing separately semi‐conducting and metallic...

The bulk polymerization reaction of N-vinylcarbazole (VK) at 70 °C in the presence of single-walled carbon nanotubes (SWNTs) leads to a new composite, whose optical properties were studied by photoluminescence (PL), surface enhanced Raman scattering (SERS) and Fourier transform infrared (FTIR) spectroscopies. A dramatic reduction of the poly(N-viny...

Raman spectra of silver particles in NaCl and KI are reported, which show the particles to have spheroidal shape and undergo quadrupolar surface vibrations. From the energies of the observed modes the shape and dimension of the metallic particles are deduced.

Mechanico-chemical interactions of single-walled carbon nanotubes (SWNTs) with zinc oxide (ZnO) were investigated by surface-enhanced Raman scattering (SERS) and photoluminescence (PL). We show that SWNTs dispersed into a ZnO host matrix and compressed non-hydrostatically at 0.58 GPa forms a new organic/inorganic hybrid material. The typical PL emi...

For the single-walled carbon nanotubes, the higher values of anti-Stokes/Stokes Raman intensity ratio (Ias/Is) then the predictions of the Maxwell-Bolzmann formula indicates a CARS emission resulting from a wave mixing process between the incident laser light (ωl) and Stokes Raman light (ωs) generated by a SERS mechanism . The weaker value of (Ias/...

We present detailed voltammetric and spectroelectrochemical studies of poly(2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)ethylene])-fluoren-9-one) (PTVF)—a conjugated polymer consisting of thienylene, vinylene, and fluorenone subunits. PTVF can be easily obtained either by electropolymerization of its monomer ((2,7-bis(5-[(E)-1,2-bis(3-octylthien-2-yl)...

An alternating copolymer was synthesized by Suzuki reaction from 4,4′-dibromo-p-quaterphenyl (PPP oligomer) and 9,9-dioctylfluorene-2,7-diboronic acid in good yield (84%). The copolymer is partially crystalline, readily soluble in organic solvents, presents high fluorescence quantum yield (85.6%) and high thermal stability. The copolymer absorption...

Surface enhanced Raman scattering (SERS) with 676.4 and 1064 nm excitations was used to investigate single-walled carbon nanotubes (SWNTs) compressed non-hydrostatically at 0.58 GPa, alone and dispersed into chemical reactive and non-reactive (SiO2 and Al2O3) host matrices. As reactive host matrices, we used inorganic compounds (KI and Ag micropart...

Electrochemical polymerization of N-vinyl carbazole (VK) on carbon nanotube (CN) films was studied by cyclic voltammetry in LiClO4/acetonitrile solutions. Cyclic voltammograms recorded on a blank Pt electrode were compared with those obtained when single or multi-walled CN films were deposited on the Pt electrode; in the latter case, a down-shift o...

Through correlated studies using scanning electron microscopy (SEM), Raman spectroscopy and low-temperature photoluminescence (PL) we have demonstrated that the intercalated PbI2 with ammonia, poly (vinyl alcohol) and polyacrylamide are characterized by a distinctive signature in the Raman and photoluminescence spectra. After intercalation, the Ram...

Single-wall boron nitride nanotubes samples synthesized by laser vaporization of a hexagonal BN target under a nitrogen atmosphere are studied by UV and visible Raman spectroscopy. We show that resonant conditions are necessary for investigating phonon modes of BNNTs. Raman excitation in the UV (229 nm) provides preresonant conditions, allowing the...

The exciton dynamics and optical characteristics of blue-emitting N,N′-diphenyl-1,4-phenylene-diamine oligoaniline films have been determined. Transient photoluminescence experiments are consistent with internal quantum yields of ∼5.3% and 10.1% measured for oriented and nonoriented films, respectively. The data indicate a drastic dependence on nan...