The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Werner J Blau - One of the best experts on this subject based on the ideXlab platform.
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graphene oxide covalently functionalized with zinc phthalocyanine for broadband Optical Limiting
Carbon, 2011Co-Authors: Jinhui Zhu, Werner J Blau, Yu Chen, Jun Wang, Bin Zhang, Jinjuan ZhangAbstract:Abstract A soluble graphene oxide (GO) covalently functionalized with zinc phthalocyanine (PcZn), GO–PcZn, was synthesized by an amidation reaction. The formation of an amido bond between PcZn and GO has been confirmed by X-ray photoelectron and Fourier transform infrared spectroscopy. At the same level of linear extinction coefficient, GO–PcZn exhibited much larger nonlinear Optical extinction coefficients and broadband Optical Limiting performance than GO at both 532 and 1064 nm, indicating a remarkable accumulation effect as a result of the covalent link between GO and PcZn.
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control of Optical Limiting of carbon nanotube dispersions by changing solvent parameters
Journal of Physical Chemistry C, 2010Co-Authors: Jun Wang, Daniel Fruchtl, Zhenyu Sun, Jonathan N Coleman, Werner J BlauAbstract:Nonlinear Optical and Optical Limiting properties of a range of single-walled carbon nanotube dispersions prepared in N-methyl-2-pyrrolidinone (NMP) were studied using the open aperture Z-scan technique at 532 nm. As the appropriate thermodynamic properties of the solvents are much more important than the bundle size of nanotubes for improving the Optical Limiting performance, the solvent parameters were controlled by either changing the temperature of the dispersions or blending a secondary solvent. While the Optical Limiting performance can be varied freely by increasing or decreasing the temperature from room temperature to 100 °C, the reduction of temperature below the freezing point of NMP and then down as far as −80 °C has little influence on the Limiting performance. As a result of adding a small amount of organic solvent into the NMP dispersions, the nonlinear Optical responses were enhanced significantly due to the reduction of surface tension and other parameters. By contrast, the addition of wa...
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preparation and Optical Limiting properties of multiwalled carbon nanotubes with π conjugated metal free phthalocyanine moieties
Journal of Physical Chemistry C, 2009Co-Authors: Yu Chen, Werner J Blau, Jun Wang, Jinrui Bai, Jinhui ZhuAbstract:Phthalocyanines (Pcs) usually exhibit stronger Optical Limiting response that can be used to protect human eyes, Optical elements, and sensors from intense laser pulses. New unsymmetrically substituted metal-free phthalocyanine-covalently functionalized multiwalled carbon nanotubes (PcH2-MWNTs), in which the wt % of MWNTs in the resulting product was found to be 35%, were synthesized. A considerably quenching of the fluorescence intensity was found in the photoluminescence spectrum of PcH2-MWNTs. This observation suggests a quenching of the singlet excited PcH2 by the covalently linked MWNTs. This material exhibits strong scattering at higher intensities, which evidently comes from the MWNT counterpart. The nonlinear response of tBu3NH2PcH2 is due to reverse saturable absorption (RSA), while that of PcH2-MWNTs is due to both RSA and nonlinear scattering, which could be two conflicted mechanisms for Optical Limiting, giving rise to suppression of the whole nonlinear response of PcH2-MWNTs.
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inorganic and hybrid nanostructures for Optical Limiting
Journal of Optics, 2009Co-Authors: Jun Wang, Werner J BlauAbstract:This paper reviews the recent development of inorganic and hybrid nanomaterials for Optical Limiting applications. The synthesis, testing method, Optical Limiting property and mechanism of several representative classes of nanomaterial, including carbon nanotubes, silver and gold nanocomposites, and selected other conducting and semiconducting nanomaterials, are introduced separately. The nonlinear Optical mechanisms observed in inorganic nanomaterials, i.e. nonlinear scattering, two-photon absorption, free-carrier absorption, etc, are discussed in conjunction with the influence of the material properties and the laser source on the Optical Limiting performance.
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nonlinear Optical and Optical Limiting properties of individual single walled carbon nanotubes
Applied Physics B, 2008Co-Authors: Jun Wang, Werner J BlauAbstract:A large number of individual single-walled carbon nanotubes (SWNTs) were obtained by dilution of nanotube dispersions in N-methyl-2-pyrrolidone (NMP). Up to 70% individual SWNTs are contained in the NMP dispersions with concentrations of less than 4.0×10-3 mg/mL. The nonlinear Optical and Optical Limiting properties of SWNT dispersions were studied by using the Z-scan technique at 532 nm. As the concentration of SWNTs is increased, the nonlinear extinction (NLE) and Optical Limiting effects improve significantly, while the Limiting thresholds decrease gradually. The individual SWNTs show similar NLE effect to zinc phthalocyanine nanoparticles, while also exhibiting larger NLE coefficients than Mo6S4.5I4.5 nanowires.
Jun Wang - One of the best experts on this subject based on the ideXlab platform.
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enhanced Optical Limiting properties of composite films consisting of hyperbranched phthalocyanine and polyphenylsulfone with high linear transmittance
Synthetic Metals, 2020Co-Authors: Jiale Ding, Jun Wang, Ningning Dong, Zengduo Cui, Yunhe Zhang, Zhenhua JiangAbstract:Abstract At present, the extensive research on laser protective materials is mainly focused on ensuring the linear transmittance and improving the Optical Limiting ability. Phthalocyanine has become a promising Optical Limiting material because of its special large π electronic conjugated structure, which makes it has excellent nonlinear Optical properties and fast Optical-electron response. Here, we synthesized a sulfonyl-containing hyperbranched lanthanum phthalocyanine (HLaPc) and covalently linked the anthraquinone groups (HLaPc-HAQ) in its axial direction. Since a donor-acceptor system is formed between phthalocyanine and the anthraquinone in HLaPc-HAQ, the electron transfers can effectively enhance the nonlinear Optical properties of HLaPc-HAQ. According to the “like dissolves like” theory, two kinds of homogeneous films have been obtained by blending HLaPc and HLaPc-HAQ with yellow polyphenylene sulfoxide containing anthraquinone groups (YPPSU). The films obtained by solution casting method have high transmittance and excellent Optical Limiting properties. Especially, the Z-scan results show that the lowest incident intensity threshold (Ilim) of HLaPc-HAQ/YPPSU can reach 0.012 J cm-2, and the linear transmittance can still maintain above 57%. This means that the materials obtained in this work surpassed much previously reported work in terms of comprehensive linear transmittance and Optical Limiting performance. In addition, the energy level model was drawn by the results of the cyclic voltammogram of the solution and the solid films. And from the perspective of the energy level transition, it was confirmed that there are a larger proportion of molecules in the solid films for intersystem crossing, thereby improving Optical Limiting performance.
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covalent functionalization of graphene oxide with hyperbranched lanthanum phthalocyanines for improving Optical Limiting
Materials Letters, 2020Co-Authors: Xin Wang, Ningning Dong, Jiale Ding, Yunhe Zhang, Zhenhua Jiang, Jun WangAbstract:Abstract Two graphene oxide (GO)-based nanohybrid materials possessing axially covalent linkages to lanthanum phthalocyanines (LaPc-GO) and hyperbranched lanthanum phthalocyanines (HBLaPc-GO) were prepared. Significant fluorescence quenching demonstrates electron transfer between lanthanum phthalocyanine precursors and GO. At the identical mass concentration of 0.1 mg mL−1, all the hybrids show stronger nonlinear Optical (NLO) performance than the individual components, ascribed to a combination of nonlinear scattering and two-photon absorption with reverse saturable absorption and the photoinduced electron or energy transfer from the electron donor phthalocyanine moiety to the acceptor graphene. Due to the better dispersion and the more flexible electron/energy transfer, the HBLaPc-GO exhibits a stronger Optical Limiting response (the normalized transmittances decrease to 49%) and a larger nonlinear extinction coefficient (1.48 cm GW−1) than that of LaPc-GO hybrid.
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nonlinear absorption induced transparency and Optical Limiting of black phosphorus nanosheets
ACS Photonics, 2017Co-Authors: Jiawei Huang, Saifeng Zhang, Ningning Dong, Wanhong Zhang, Jun WangAbstract:This work reports the wavelength- and pulse-duration-dependent nonlinear Optical properties of exfoliated black phosphorus (BP). We found that BP nanosheets exhibit better saturable absorption response in the visible range than that in the near-infrared range and better response under 6 ns pulse excitation than that under 340 fs excitation. In addition, we propose that the Optically induced transparency and Optical Limiting properties of BP dispersions mainly originate from the competition between saturable absorption and nonlinear scattering.
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covalent functionalization of graphene oxide with porphyrin and porphyrin incorporated polymers for Optical Limiting
Physical Chemistry Chemical Physics, 2017Co-Authors: Ningning Dong, Menghan Zhang, Kai Zhu, Shuling Zhang, Ningwei Sun, Guibin Wang, Jun WangAbstract:Porphyrin–graphene composites have attracted increasing attention due to a number of intriguing functions, and their photoelectrical and catalytic performances are expected to be modulated through different approaches. In the present study, a designed polymer based on phenyl sulfone, (p-amino)phenylhydroquinone, and a symmetrical dinaphthylporphyrin were covalently attached to a graphene oxide (GO) sheet. The formation of the nanohybrid was characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Raman, ultraviolet-visible (UV-vis) absorption, steady and transient fluorescence spectroscopy techniques. The nonlinear Optical and Optical Limiting performances of the hybrid were investigated using Z-scan measurements at 532 nm and 1064 nm. For comparison, a porphyrin functionalized GO hybrid was synthesized as a reference. At the same linear transmittance, the polymer functionalized GO exhibited a stronger Optical Limiting response and a larger nonlinear extinction coefficient than the individual GO, porphyrinated polymer, and porphyrin functionalized GO hybrid analogue, and its intrinsic photophysical mechanism was discussed in detail. More importantly, further improvement of its nonlinear Optical properties can be achieved by the chemical reduction of the hybrid. The enhanced nonlinear Optical performance originated from the effective combination of nonlinear scattering, reverse saturable absorption, and a possible photo-induced electron/energy transfer mechanism from donor porphyrin moieties in the polymer backbone to acceptor graphene. Our result might provide a new avenue for the development of graphene–porphyrin materials in the field of photocatalysis, nonlinear optics, and optoelectronic devices.
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Optical Limiting and theoretical modelling of layered transition metal dichalcogenide nanosheets
arXiv: Optics, 2015Co-Authors: Ningning Dong, Xiaoyan Zhang, Yanyan Feng, Saifeng Zhang, Chunxia Chang, Jintai Fan, Long Zhang, Jun WangAbstract:Nonlinear Optical property of transition metal dichalcogenide (TMDC) nanosheet dispersions, including MoS2, MoSe2, WS2, and WSe2, was performed by using Z-scan technique with ns pulsed laser at 1064 nm and 532 nm. The results demonstrate that the TMDC dispersions exhibit significant Optical Limiting response at 1064 nm due to nonlinear scattering, in contrast to the combined effect of both saturable absorption and nonlinear scattering at 532 nm. Selenium compounds show better Optical Limiting performance than that of the sulfides in the near infrared. A liquid dispersion system based theoretical modelling is proposed to estimate the number density of the nanosheet dispersions, the relationship between incident laser fluence and the size of the laser generated micro-bubbles, and hence the Mie scattering-induced broadband Optical Limiting behavior in the TMDC dispersions.
Yu Chen - One of the best experts on this subject based on the ideXlab platform.
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graphene oxide covalently functionalized with zinc phthalocyanine for broadband Optical Limiting
Carbon, 2011Co-Authors: Jinhui Zhu, Werner J Blau, Yu Chen, Jun Wang, Bin Zhang, Jinjuan ZhangAbstract:Abstract A soluble graphene oxide (GO) covalently functionalized with zinc phthalocyanine (PcZn), GO–PcZn, was synthesized by an amidation reaction. The formation of an amido bond between PcZn and GO has been confirmed by X-ray photoelectron and Fourier transform infrared spectroscopy. At the same level of linear extinction coefficient, GO–PcZn exhibited much larger nonlinear Optical extinction coefficients and broadband Optical Limiting performance than GO at both 532 and 1064 nm, indicating a remarkable accumulation effect as a result of the covalent link between GO and PcZn.
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nonlinear Optical and Optical Limiting properties of graphene families
Applied Physics Letters, 2010Co-Authors: Miao Feng, Hongbing Zhan, Yu ChenAbstract:The nonlinear Optical (NLO) and Optical Limiting (OL) properties of graphene families, including graphene oxide nanosheets, graphene nanosheets (GNSs), graphene oxide nanoribbons (GONRs), and graphene nanoribbons (GNRs), were investigated at 532 and 1064 nm using a nanosecond regime. GNSs, GONRs, and GNRs exhibited broadband NLO and OL properties. Reduced graphene samples exhibited stronger NLO and OL responses than their graphene oxide precursors because of their increased crystallinity and conjugation. Nonlinear scattering and two-photon-absorption were found to have strong effects on the NLO and OL responses of the graphene nanostructures.
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preparation and Optical Limiting properties of multiwalled carbon nanotubes with π conjugated metal free phthalocyanine moieties
Journal of Physical Chemistry C, 2009Co-Authors: Yu Chen, Werner J Blau, Jun Wang, Jinrui Bai, Jinhui ZhuAbstract:Phthalocyanines (Pcs) usually exhibit stronger Optical Limiting response that can be used to protect human eyes, Optical elements, and sensors from intense laser pulses. New unsymmetrically substituted metal-free phthalocyanine-covalently functionalized multiwalled carbon nanotubes (PcH2-MWNTs), in which the wt % of MWNTs in the resulting product was found to be 35%, were synthesized. A considerably quenching of the fluorescence intensity was found in the photoluminescence spectrum of PcH2-MWNTs. This observation suggests a quenching of the singlet excited PcH2 by the covalently linked MWNTs. This material exhibits strong scattering at higher intensities, which evidently comes from the MWNT counterpart. The nonlinear response of tBu3NH2PcH2 is due to reverse saturable absorption (RSA), while that of PcH2-MWNTs is due to both RSA and nonlinear scattering, which could be two conflicted mechanisms for Optical Limiting, giving rise to suppression of the whole nonlinear response of PcH2-MWNTs.
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carbon nanotube based functional materials for Optical Limiting
Journal of Nanoscience and Nanotechnology, 2007Co-Authors: Yu Chen, Ying Lin, Ying Liu, James J Doyle, Xiaodong Zhuang, Jinrui Bai, Werner J BlauAbstract:Optical Limiting is an important application of nonlinear optics, useful for the protection of human eyes, Optical elements, and Optical sensors from intense laser pulses. An Optical limiter is such a device that strongly attenuates high intensity light and potentially damaging light such as focused laser beams, whilst allowing for the high transmission of ambient light. Optical Limiting properties of carbon nanotube suspensions, solubilized carbon nanotubes, small molecules doped carbon nanotubes and polymer/carbon nanotube composites have been reviewed. The Optical Limiting responses of carbon nanotube suspensions are shown to be dominated by nonlinear scattering as a result of thermally induced solvent-bubble formation and sublimation of the nanotubes, while the solubilized carbon nanotubes Optically limit through nonlinear absorption mechanism and exhibit significant solution-concentration-dependent Optical Limiting responses. In the former case the Optical Limiting results are independent of nanotube concentrations at the same linear transmittance as that of the solubilized systems. Many efforts have been invested into the research of polymer/carbon nanotube composites in an attempt to allow for the fabrication of films required for the use of nanotubes in a real Optical Limiting application. The higher carbon nanotube content samples block the incident light more effectively at higher incident energy densities or intensities. The Optical Limiting mechanism of these composite materials is quite complicated. Besides nonlinear scattering contribution to the Optical Limiting, there may also be other contributions e.g., nonlinear absorption, nonlinear refraction, electronic absorption and others to the Optical Limiting. Further improvements in the Optical Limiting efficiency of the composites and in the dispersion and alignment properties of carbon nanotubes in the polymer matrix could be realized by variation of both nanostructured guest and polymer host, and by ex situ alignment and other methods. It would be very desirable, from the practical application point of view, if one can design broadband Optical Limiting chromophores that would function in a multimechanistic fashion.
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molecular engineering of peripherally and axially modified phthalocyanines for Optical Limiting and nonlinear optics
Advanced Materials, 2003Co-Authors: Sean M Oflaherty, Stephanie V Hold, Michael J. Cook, Tomas Torres, Michael Hanack, Yu Chen, Werner J BlauAbstract:Phthalocyanines have remarkable chemical and thermal stability and offer tremendous architectural flexibility in their structure, facilitating the tailoring of physical, optoelectronic, and chemical parameters. In this paper, we summarize experimental measurements of nonlinear Optical adsorption in a comprehensive representative series of modified phthalocyanines substituted with various central metals and peripheral functional groups. Rate equations are used to analytically solve the static-state conditions that simulate the excited-state dynamics that result from the nonlinear excited-state adsorption, and this solution is fitted to the experimental data. General molecular engineering trends relating the Optical Limiting performance of these compounds to their structural characteristics are also explored and discussed.
Yaping Sun - One of the best experts on this subject based on the ideXlab platform.
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Optical Limiting properties of suspended and solubilized carbon nanotubes
Journal of Physical Chemistry B, 2000Co-Authors: Jason E Riggs, David B Walker, And David L Carroll, Yaping SunAbstract:Full and shortened single-walled and multiple-walled carbon nanotubes were suspended in water to form stable suspensions in the presence of a surfactant. Optical Limiting properties of the suspensions were determined for 532-nm pulsed laser irradiation, and the results were comparable with those of carbon black aqueous suspension. Solubilization of the shortened carbon nanotubes was achieved by attaching the nanotubes to highly soluble poly(propionylethylenimine-co-ethylenimine) or by functionalizing the nanotubes with octadecylamine. The soluble carbon nanotube samples formed homogeneous solutions in room-temperature chloroform. Optical Limiting properties of these solutions were also determined for 532-nm pulsed laser irradiation, and the results were found to be quite different from those of the carbon nanotube aqueous suspensions. Apparently, the carbon nanotubes exhibit significantly weaker Optical Limiting responses in homogeneous solutions than in suspensions. Mechanistic implications of the experi...
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organic and inorganic Optical Limiting materials from fullerenes to nanoparticles
International Reviews in Physical Chemistry, 1999Co-Authors: Yaping Sun, Jason E RiggsAbstract:Optical Limiting properties of organic reverse saturable absorbers, fullerenes, and nanoscopic materials are reviewed. The strongly nonlinear absorptive organic dyes are discussed in terms of the potential and limitation in their further improvement. The principle and practice for the development of supramolecular nonlinear absorbers based on a new molecular engineering approach are described along with future prospects. The fullerene based materials are discussed by emphasizing the mechanistic issues of their Optical Limiting properties and the potential for improving their Optical Limiting performance through fullerene cage derivatizations and through the incorporation of fullerene cages into polymeric structures. Finally, the discussion on the development of nano-materials as a new class of strong Optical limiters is centred on the Optical Limiting performance and mechanism of metal and metal sulphide nanoparticles, and on a comparison with strongly nonlinear scattering materials such as suspensions of...
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strong Optical Limiting of silver containing nanocrystalline particles in stable suspensions
Journal of Physical Chemistry B, 1999Co-Authors: Yaping Sun, Jason E Riggs, Harry W Rollins, Radhakishan GuduruAbstract:Metal and metal sulfide nanoparticles are prepared using a method that is based on the rapid expansion of supercritical fluid solution (RESS) into a liquid solution and characterized using transmission electron microscopy and X-ray diffraction methods. The nanoparticles form solution-like stable suspensions in the presence of a stabilization agent such as poly(N-vinyl-2-pyrrolidone) (PVP) polymer. The stable suspensions allow systematic nonlinear Optical measurements. The nanocrystalline silver metal and silver sulfide particles in PVP polymer-stabilized ethanol suspensions of high linear transmittance exhibit excellent Optical Limiting properties, with the Optical Limiting responses toward nanosecond laser pulses at 532 nm being much stronger than those of benchmark materials [60]fullerene and chloroaluminum phthalocyanine in solution. A comparison of the results with those of stable suspensions of other nanoparticles including cadmium sulfide, lead sulfide, and nickel suggests that the Optical Limiting ...
Jason E Riggs - One of the best experts on this subject based on the ideXlab platform.
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Optical Limiting properties of suspended and solubilized carbon nanotubes
Journal of Physical Chemistry B, 2000Co-Authors: Jason E Riggs, David B Walker, And David L Carroll, Yaping SunAbstract:Full and shortened single-walled and multiple-walled carbon nanotubes were suspended in water to form stable suspensions in the presence of a surfactant. Optical Limiting properties of the suspensions were determined for 532-nm pulsed laser irradiation, and the results were comparable with those of carbon black aqueous suspension. Solubilization of the shortened carbon nanotubes was achieved by attaching the nanotubes to highly soluble poly(propionylethylenimine-co-ethylenimine) or by functionalizing the nanotubes with octadecylamine. The soluble carbon nanotube samples formed homogeneous solutions in room-temperature chloroform. Optical Limiting properties of these solutions were also determined for 532-nm pulsed laser irradiation, and the results were found to be quite different from those of the carbon nanotube aqueous suspensions. Apparently, the carbon nanotubes exhibit significantly weaker Optical Limiting responses in homogeneous solutions than in suspensions. Mechanistic implications of the experi...
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organic and inorganic Optical Limiting materials from fullerenes to nanoparticles
International Reviews in Physical Chemistry, 1999Co-Authors: Yaping Sun, Jason E RiggsAbstract:Optical Limiting properties of organic reverse saturable absorbers, fullerenes, and nanoscopic materials are reviewed. The strongly nonlinear absorptive organic dyes are discussed in terms of the potential and limitation in their further improvement. The principle and practice for the development of supramolecular nonlinear absorbers based on a new molecular engineering approach are described along with future prospects. The fullerene based materials are discussed by emphasizing the mechanistic issues of their Optical Limiting properties and the potential for improving their Optical Limiting performance through fullerene cage derivatizations and through the incorporation of fullerene cages into polymeric structures. Finally, the discussion on the development of nano-materials as a new class of strong Optical limiters is centred on the Optical Limiting performance and mechanism of metal and metal sulphide nanoparticles, and on a comparison with strongly nonlinear scattering materials such as suspensions of...
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strong Optical Limiting of silver containing nanocrystalline particles in stable suspensions
Journal of Physical Chemistry B, 1999Co-Authors: Yaping Sun, Jason E Riggs, Harry W Rollins, Radhakishan GuduruAbstract:Metal and metal sulfide nanoparticles are prepared using a method that is based on the rapid expansion of supercritical fluid solution (RESS) into a liquid solution and characterized using transmission electron microscopy and X-ray diffraction methods. The nanoparticles form solution-like stable suspensions in the presence of a stabilization agent such as poly(N-vinyl-2-pyrrolidone) (PVP) polymer. The stable suspensions allow systematic nonlinear Optical measurements. The nanocrystalline silver metal and silver sulfide particles in PVP polymer-stabilized ethanol suspensions of high linear transmittance exhibit excellent Optical Limiting properties, with the Optical Limiting responses toward nanosecond laser pulses at 532 nm being much stronger than those of benchmark materials [60]fullerene and chloroaluminum phthalocyanine in solution. A comparison of the results with those of stable suspensions of other nanoparticles including cadmium sulfide, lead sulfide, and nickel suggests that the Optical Limiting ...
