Chimin Du

Optical nonlinearities and optical limiting properties in gold nanoparticles protected by ligands

Abstract Optical nonlinearities of gold nanoparticles protected by ligands have been investigated by Z-scan technique. Absorptive and refractive optical limiting (OL) effects have been measured with 8 ns duration laser pulses at 532 nm. Significant differences have been found experimentally for these two nanoparticles that differ only by their ligands. Such differences indicate that nonlinear optical responses in two nanocomposites are strongly influenced by the surface plasmon resonance of gold nanoparticles and also the nature of ligands. Both of these two nanocomposites show stronger refractive optical limiting effects than C 60 in toluene.

Nonlinear optical properties in three novel nanocomposites with gold nanoparticles

Nonlinear optical properties of three novel nanocomposites with zerovalent noble metal gold nanoparticles were investigated by using Z-scan technique. Optical limiting effects has been measured with 8 ns pulses at 532 nm. The cross-sections of nonlinear absorption were obtained by the simulation with a simplified model in which the effective excited-state absorptions of three ligands in nanocomposites were considered. The nonlinear refractive indices were calculated from the data of Z-scan measurement. The experimental results were found to be significantly different in these nanocomposites. Optical nonlinearities in these nanocomposites can be attributed to the strong excited-state absorptions of the ligands and the surface plasmon resonance of gold nanoparticles.

Self-assembly of the (60)fullerene-substituted oligopyridines on Au nanoparticles and the optical nonlinearities of the nanoparticles

The cycloaddition reaction of azido oligopyridine with [60]fullerene was used to synthesize two novel [60]fullerene derivatives containing bi/tri-pyridyl group, which were employed to self-assemble on the surface of gold nanoparticles. Optical nonlinearities of the gold nanoparticles in chloroform were determined by Z-scan technique and the optical limiting experiments with 532 nm, 8 ns and 40 ps duration laser pulses.

The self-assembly of [60]fullerene-substituted 2,2'-bipyridine on the surface of Au(111) and Au nanoparticles

The cycloaddition reaction of the azide of 4,4′-dimethyl-2,2′-bipyridine to [60]fullerene was used to synthesize a novel [60]fullerene derivative, which was employed to self-assemble on the surface of Au(111) and gold nanoparticles. Scanning tunneling microscopy results show that the [60]fullerene derivative forms a self-assembled monolayer on the Au(111) surface spontaneously. Transmission electron micrographs indicate the presence of spherical particles with an average radius of about 10 nm in the nanoparticle preparations.

Synthesis and characterization of new C60–PPV dyads containing carbazole moiety

Abstract New C 60 covalently linked PPV derivatives containing carbazole moiety poly{(2,5-di-pentoxyl-phenylene)-1,4-diylvinylene-3,6-[9-(1-azafulleroid-propyl)carbazolenevinylene]} (PPV-AFCAR) were synthesized and characterized. The polymers containing different percentage of C 60 were obtained through the percentage of azido unit being controlled by the initial feed ratio. Cyclic voltametric analysis showed that the electronic characteristic remained while it covalently attached to polymer by the cycloaddition reaction. The fluorescences of PPV moieties were strongly quenched due to the presence of fullerene.

Self-assembled film of a new C60 derivative covalently linked to TiO2 nanocrystalline

Abstract A new salicylic acid modified [60]fulleropyrrodine (SFP) was synthesized and the assembly of SFP onto the surface of TiO 2 nanocrystalline thin film was accomplished through the moiety of salicylic acid as spacer. The film was fluorescent, and a strong photo-induced charge transfer from SFP to TiO 2 was observed with the maximum incident photon-to-current efficiency value exceeding 15% in visible region.

Synthesis and characterization of [60]fullerene-substituted oligopyridines ruthenium complexes

The cycloaddition reaction of azide of oligopyridine to [60]fullerene was used to synthesize two new [60]fullerene ligands, which were used to prepare metal complexes with ruthenium oligopyridines.

Synthesis and properties of an organo-[C60]fullerene-containing PPV unit

Abstract A novel PPV-[C60] dyad which was partly soluble in common organic solvent was synthesized via the cycloaddition reaction of azide group with [C60]fullerene. Copolymer PPV-[C60] was isolated in up to 70% yields with molecular weights ranging up to 3615 relative to polystyrene standards. Cyclic voltammeter (CV) analysis for the copolymers showed three reversible waves. UV–VIS and fluorescence spectra of the copolymer were also studied.

Preparation and characterization of a novel dumbbell-type [60]fullerene dimer containing a cyanine dye

Two* [60]fullerene units were covalently linked by a cyanine dye to form a novel dumbbell-type molecule whose structure was observed by STM.

Synthesis and characterization of new dyads containing different percentages of C60 and PPV covalently linked

A series of new poly(phenylenevinylene) (PPV) derivatives covelently linked with fullerenes (C 60 ) were synthesized and characterized. Copolymers containing different percentage of C 60 were obtained by controlling the percentage of azido groups in the initial feed ratio. The absorption spectra of copolymer (PPV-C 60 ) showed two peaks in the regions of 410 and 330 nm. The former peak was interpreted as being the π-π* interband excitation of copolymer PPV followed by electron transfer to C 60 , while the latter was attributed to the optical excitation of the C 60 moiety. Cyclic voltammetry (CV) analysis showed the presence of interaction between the PPV unit and fullurene moiety in the ground state. Fluorescence spectra of the copolymers indicated charge transfer from the π* band of the photoexcited PPV of the copolymer to the C 60 .