Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of...Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose.Similar behavior was observed in terahertz range,where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose.The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.展开更多
Multi-Walled carbon nanotubes are used as preconcentrating probes for the quantitative determination of trace cadmium, copper and lead in environmental and biological sample using graphite Furnace Atomic Absorption Sp...Multi-Walled carbon nanotubes are used as preconcentrating probes for the quantitative determination of trace cadmium, copper and lead in environmental and biological sample using graphite Furnace Atomic Absorption Spectrometry and inductively coupled Plasma Optical Emission spectrometry. The method is based on the electrostatic interactions of positively charged Cd+, Cu+ and Pb+ with the negatively charged multi-walled carbon nanotubes (MWCNTs) for the preconcentration and isolation of analytes from sample solutions. Effective preconcentration of trace cadmium, copper and lead was achieved in a pH range of 5 - 7, 5 - 7 and 4 - 7, respectively. The retained cadmium, copper and lead were efficiently eluted with 0.3 mol·L-1 HCl for graphite Furnace Atomic Absorption Spectrometry determination. The multi-walled carbon nanotubes packed micro-column exhibited fairly fast kinetics for the adsorption of cadmium, copper and lead, permitting the use of high sample flow rates up to at least 3 mL·min-1 for the flow injection on micro-column preconcentration without the loss of the retention efficiency. The detection limits (3σ) were 0.03, 0.01 and 0.5 ng·mL-1 for Cd, Cu and Pb, respectively. The relative standard deviation under optimum condition is less than 2.9% (n = 10). The developed method was successfully applied to the determination of trace Cd, Cu and Pb in a variety of environmental and biological samples.展开更多
The predicted extraordinary properties of carbon nanotubes(CNTs)from theoretical calculations have great potential for many applications.However,reliable experimental determination of intrinsic properties at the singl...The predicted extraordinary properties of carbon nanotubes(CNTs)from theoretical calculations have great potential for many applications.However,reliable experimental determination of intrinsic properties at the single-tube level is currently a matter of concern,and many challenges remain because of the unhandled and nanoscale size of individual nanotubes.Here,we demonstrated a prototype to detect the intrinsic thermal conductivity of the single-wall carbon nanotube(SWCNT)and verify the significant non-resonant optical absorption behavior on tiny nanotubes by integrating the nanotube and ice into a new core-shell design.In particular,a reversible optical visualization method based on the individual suspended ultra-long SWCNT was first developed by wrapping a nanotube with ice in the cryogenic air environment.The light-induced thermal effect on the hybrid core-shell structure was used tomelt the ice shell,which subsequently acted as a temperature sensor to verify the intrinsic thermal conductivity of the core-like nanotube.More interestingly,we successfully determined for the first time the thermal response phenomenon of the tiny absorption cross section in SWCNT in the vertical-polarization configuration and the significant non-resonant absorption behavior in the parallel-polarization configuration.These investigations will provide a better understanding for the unique optical behaviors of CNT and enable the detection of intrinsic properties of various one-dimensional nanostructures such as nanotubes,nanowires,and nanoribbons.展开更多
Single-walled carbon nanotubes （SWCNTs） with specific diameters are required for various applications particularly in electronics and photonics, since the diameter is an essential characteristic determining their el...Single-walled carbon nanotubes （SWCNTs） with specific diameters are required for various applications particularly in electronics and photonics, since the diameter is an essential characteristic determining their electronic and optical properties. In this work, the selective growth of SWCNTs with a certain mean diameter is achieved by the addition of appropriate amounts of CO2 mixed with the carbon source （CO） into the aerosol （floating catalyst） chemical vapor deposition reactor. The noticeable shift of the peaks in the absorption spectra reveals that the mean diameters of the as-deposited SWCNTs are efficiently altered from 1.2 to 1.9 nm with increasing CO2 concentration. It is believed that CO2 acts as an etching agent and can selectively etch small diameter tubes due to their highly curved carbon surfaces. Polymer-free as-deposited SWCNT films with the desired diameters are used as saturable absorbers after stamping onto a highly reflecting Ag-mirror using a simple dry-transfer technique. Sub-picosecond mode-locked fiber laser operations at -1.56μm and -2 μm are demonstrated, showing improvements in the performance after the optimization of the SWCNT properties.展开更多
利用基于传输矩阵法(Transfer matrix method,TMM)的光学模型系统地研究了金属电极材料(Ag、Al、Au)对聚合物太阳能电池光学性能的影响。研究表明,与传统铟锡化合物(Indium tin oxide,ITO)透明电极相比,以合适厚度的金属Ag膜作透明电极...利用基于传输矩阵法(Transfer matrix method,TMM)的光学模型系统地研究了金属电极材料(Ag、Al、Au)对聚合物太阳能电池光学性能的影响。研究表明,与传统铟锡化合物(Indium tin oxide,ITO)透明电极相比,以合适厚度的金属Ag膜作透明电极,可提高活性层对入射光子的吸收效率;同时,以Ag膜作背电极时,其相应的聚合物太阳能电池的效率优于以Al或者Au为背电极的电池的效率。展开更多
基金Supported by Chinese Academy of Sciences Knowledge Innovation Program(No.KJCX3.SYW.N10)National Natural Science Foundation of China(No.10775171)
文摘Optical absorption of Ar and H ion beam irradiated multi-walled carbon nanotube (MWCNT) sheets at various doses in the visible and terahertz spectral ranges was investigated.It was found that the optical absorption of MWCNT sheets in the visible range was decreased with increasing ion irradiation dose.Similar behavior was observed in terahertz range,where the optical absorption of MWCNT sheets in the range of 0 to 1.5 THz was also decreased with increasing ion irradiation dose.The optical absorption decreases in irradiated MWCNT sheets can be ascribed to the increase of defects in the irradiated MWCNTs.
文摘Multi-Walled carbon nanotubes are used as preconcentrating probes for the quantitative determination of trace cadmium, copper and lead in environmental and biological sample using graphite Furnace Atomic Absorption Spectrometry and inductively coupled Plasma Optical Emission spectrometry. The method is based on the electrostatic interactions of positively charged Cd+, Cu+ and Pb+ with the negatively charged multi-walled carbon nanotubes (MWCNTs) for the preconcentration and isolation of analytes from sample solutions. Effective preconcentration of trace cadmium, copper and lead was achieved in a pH range of 5 - 7, 5 - 7 and 4 - 7, respectively. The retained cadmium, copper and lead were efficiently eluted with 0.3 mol·L-1 HCl for graphite Furnace Atomic Absorption Spectrometry determination. The multi-walled carbon nanotubes packed micro-column exhibited fairly fast kinetics for the adsorption of cadmium, copper and lead, permitting the use of high sample flow rates up to at least 3 mL·min-1 for the flow injection on micro-column preconcentration without the loss of the retention efficiency. The detection limits (3σ) were 0.03, 0.01 and 0.5 ng·mL-1 for Cd, Cu and Pb, respectively. The relative standard deviation under optimum condition is less than 2.9% (n = 10). The developed method was successfully applied to the determination of trace Cd, Cu and Pb in a variety of environmental and biological samples.
基金This work was supported by the National Basic Research Program of China(Grant Nos.2012CB932302,2014CB848900)National Natural Science Foundation of China(U1232131,90921012,51172271,51372269 and 11375198)+3 种基金“Strategic Priority Research Program” of the Chinese Academy of Sciences(XDA09040202)Beijing Municipal Education Commission(Grant No.YB20108000101)and Fundamental Research Funds for the Central Universities(WK2310000035)Li Song thanks the recruitment program of global experts and the CAS Hundred Talent Program of China.The authors thank M.Habib from University of Science and Technology of China for his useful discussion.
文摘The predicted extraordinary properties of carbon nanotubes(CNTs)from theoretical calculations have great potential for many applications.However,reliable experimental determination of intrinsic properties at the single-tube level is currently a matter of concern,and many challenges remain because of the unhandled and nanoscale size of individual nanotubes.Here,we demonstrated a prototype to detect the intrinsic thermal conductivity of the single-wall carbon nanotube(SWCNT)and verify the significant non-resonant optical absorption behavior on tiny nanotubes by integrating the nanotube and ice into a new core-shell design.In particular,a reversible optical visualization method based on the individual suspended ultra-long SWCNT was first developed by wrapping a nanotube with ice in the cryogenic air environment.The light-induced thermal effect on the hybrid core-shell structure was used tomelt the ice shell,which subsequently acted as a temperature sensor to verify the intrinsic thermal conductivity of the core-like nanotube.More interestingly,we successfully determined for the first time the thermal response phenomenon of the tiny absorption cross section in SWCNT in the vertical-polarization configuration and the significant non-resonant absorption behavior in the parallel-polarization configuration.These investigations will provide a better understanding for the unique optical behaviors of CNT and enable the detection of intrinsic properties of various one-dimensional nanostructures such as nanotubes,nanowires,and nanoribbons.
文摘Single-walled carbon nanotubes （SWCNTs） with specific diameters are required for various applications particularly in electronics and photonics, since the diameter is an essential characteristic determining their electronic and optical properties. In this work, the selective growth of SWCNTs with a certain mean diameter is achieved by the addition of appropriate amounts of CO2 mixed with the carbon source （CO） into the aerosol （floating catalyst） chemical vapor deposition reactor. The noticeable shift of the peaks in the absorption spectra reveals that the mean diameters of the as-deposited SWCNTs are efficiently altered from 1.2 to 1.9 nm with increasing CO2 concentration. It is believed that CO2 acts as an etching agent and can selectively etch small diameter tubes due to their highly curved carbon surfaces. Polymer-free as-deposited SWCNT films with the desired diameters are used as saturable absorbers after stamping onto a highly reflecting Ag-mirror using a simple dry-transfer technique. Sub-picosecond mode-locked fiber laser operations at -1.56μm and -2 μm are demonstrated, showing improvements in the performance after the optimization of the SWCNT properties.
文摘利用基于传输矩阵法(Transfer matrix method,TMM)的光学模型系统地研究了金属电极材料(Ag、Al、Au)对聚合物太阳能电池光学性能的影响。研究表明,与传统铟锡化合物(Indium tin oxide,ITO)透明电极相比,以合适厚度的金属Ag膜作透明电极,可提高活性层对入射光子的吸收效率;同时,以Ag膜作背电极时,其相应的聚合物太阳能电池的效率优于以Al或者Au为背电极的电池的效率。
