FORMATION OF FULLERENES AND CARBON CLUSTERS BY LASER IRRADIATION OF POLYMERIC FULLERENE OXIDE (FULLERENE OZOPOLYMER)

ABSTRACT

Polymeric fullerene oxide (PFO) prepared by prolonged ozonation of C₆₀ fullerene has been laser irradiated and the resulting products formed have been studied by ion cyclotron resonance mass spectrometry. It has been found that PFO produces a complete set of carbon clusters from C₆₀ up to C₁₆₄. The mechanism of formation of this set of fullerenic clusters implies necessarily a laser-induced carbonization step of the PFO substrate. Once the PFO target has been changed into the opportune carbon nanostructure by the laser radiation, the sequence of fullerene carbon clusters has been produced.     

ON THE MECHANISM OF CARBON CLUSTERS FORMATION UNDER LASER IRRADIATION. THE CASE OF DIAMOND GRAINS AND SOLID C60 FULLERENE

It is shown by FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry that carbon clusters considered to be the superior homologues of C₆₀ fullerene are formed by laser irradiation of both synthetic diamond grains or from pure C₆₀ fullerene crystals. The surfaces of the laser irradiated diamond or C₆₀ have been examined by Raman spectroscopy. In the case of diamond the Raman spectrum suggests the superficial formation of mixed carbon nanostructures consisting of disordered graphite, fullerenic nanostructures, onion-like carbon nanostructures and diamond-like carbon. Based on the Raman spectra of the surface and on data taken from the phase diagram of carbon, it is shown that the graphitization is needed in order to produce fullerenes from diamond under laser ablation conditions. In the case of C₆₀ fullerene, it is shown by Raman spectroscopy that the laser irradiation of the crystals causes initially their photopolymerization and after further irradiation their transformation into disordered graphite. Based on these results and on a literature survey on the formation of fullerenes from more than 15 completely different substrates, it is concluded that fullerenes are formed always when laser ablation leads to a graphitization of the laser-irradiated substrate. Some astrochemical implications of the conclusions have been discussed.     

ON THE MECHANISM OF CARBON CLUSTERS FORMATION UNDER LASER IRRADIATION. THE CASE OF DIAMOND GRAINS AND SOLID C60 FULLERENE

ABSTRACT

It is shown by FT-ICR (Fourier transform ion cyclotron resonance) mass spectrometry that carbon clusters considered to be the superior homologues of C₆₀ fullerene are formed by laser irradiation of both synthetic diamond grains or from pure C₆₀ fullerene crystals. The surfaces of the laser irradiated diamond or C₆₀ have been examined by Raman spectroscopy. In the case of diamond the Raman spectrum suggests the superficial formation of mixed carbon nanostructures consisting of disordered graphite, fullerenic nanostructures, onion-like carbon nanostructures and diamond-like carbon. Based on the Raman spectra of the surface and on data taken from the phase diagram of carbon, it is shown that the graphitization is needed in order to produce fullerenes from diamond under laser ablation conditions. In the case of C₆₀ fullerene, it is shown by Raman spectroscopy that the laser irradiation of the crystals causes initially their photopolymerization and after further irradiation their transformation into disordered graphite. Based on these results and on a literature survey on the formation of fullerenes from more than 15 completely different substrates, it is concluded that fullerenes are formed always when laser ablation leads to a graphitization of the laser-irradiated substrate. Some astrochemical implications of the conclusions have been discussed.     

激光加热气化法制备TiO_2超细粉

本文报道了用 YAG 激光器在大气中加热气化制取 TiO_2超细粉末的实验结果。透射电子显微镜观察表明,粉末颗粒均匀性较好,直径为6—20nm,主要为锐钛矿结构。本文对颗粒大小和结构等与所用激光束能量密度的关系进行了实验。研究表明,激光加热气化法是制备超细金属氧化物粉末的一种可行方法。     

二氧化碳和环氧丙烷,（甲基）丙烯酸酯类的三元共聚

研究了在聚合物负载双金属ＰＢＭ型阴离子配位催化剂作用下，二氧化碳和环氧丙烷，（甲基）丙烯酸酯类的三元共聚。用ＩＲ、ＮＭＲ、ＤＳＣ、ＴＧＡ等对共聚物进行了表征，探讨了影响共聚反应的各种因素。     

高碳钢盘条氧化皮的激光拉曼光谱分析

采用激光拉曼光谱并结合SEM和XRD等手段对高碳钢盘条表面氧化皮进行了研究,同时,对不同冷却条件下形成的氧化皮机械剥离性能进行了评价。结果表明,氧化皮为三层结构,控冷条件下形成的氧化皮机械剥离性能良好,而炉冷条件下形成的氧化皮经机械剥离后仍有一层Fe3O4残留。     

GENERATION OF HIGHER FULLERENES FROM LASER ABLATION OF CARBYNE AND C60 PHOTOPOLYMER ASTROCHEMICAL IMPLICATIONS

ABSTRACT

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C₆₀ photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target, no C₆₀ has been generated but only fullerene cages from C₇₄ up to C₁₂₄. Larger cages were also obtained but with odd number. Starting from C₆₀ photopolymer, laser ablation regenerates free C₆₀ and creates a sequence of C₆₀ superior homologues all possessing even number and each member of the series is separated from the preceding and the following member by the loss or by the addition respectively of a C₂ unit. Fullerenes up to C₁₆₂ have been recorded. The implications about the presence of free C₆₀ fullerene in the interstellar and circumstellar space, its formation from carbyne chains and its stability towards its photopolymerization tendency and its regeneration from the photopolymer together with its superior homologues have been discussed thoroughly in the present paper.     

GENERATION OF HIGHER FULLERENES FROM LASER ABLATION OF CARBYNE AND C60 PHOTOPOLYMER ASTROCHEMICAL IMPLICATIONS

Laser ablation of targets of carbonaceous matter containing carbyne nanodomains (the sp hybridised carbon chains) or targets of C₆₀ photopolymer produced carbon clusters which have been detected by FT-ICR (Fourier-Transform Ion Cyclotron Resonance) mass spectrometer. When the carbonaceous matter containing carbyne has been employed as laser target, no C₆₀ has been generated but only fullerene cages from C₇₄ up to C₁₂₄. Larger cages were also obtained but with odd number. Starting from C₆₀ photopolymer, laser ablation regenerates free C₆₀ and creates a sequence of C₆₀ superior homologues all possessing even number and each member of the series is separated from the preceding and the following member by the loss or by the addition respectively of a C₂ unit. Fullerenes up to C₁₆₂ have been recorded. The implications about the presence of free C₆₀ fullerene in the interstellar and circumstellar space, its formation from carbyne chains and its stability towards its photopolymerization tendency and its regeneration from the photopolymer together with its superior homologues have been discussed thoroughly in the present paper.     

A STUDY ON THE THERMAL STABILITY OF THE PHOTOPOLYMER,THE OZOPOLYMER,AND THE PHOTOCHLORINATED DERIVATIVE OF C60 FULLERENE

The thermal stability of the C₆₀ photopolymer, the C₆₀ ozo-polymer, and photochlorinated C₆₀ was studied by thermogravimetric analysis (TGA) ultraviolet-visible (UV-vis) and TGA-differential thermal analysis techniques up to 950°C in comparison to graphite and pure C₆₀. The ozopolymer was found to be the least stable material followed by C₆₀Cl _x . The resulting residual carbonaceous matter formed by the decomposition of the photopolymer and the ozopolymer has been studied by Fourier transform-infrared (FTIR) spectroscopy and has been found to be completely comparable to carbon black. The thermal decomposition of the C₆₀ photopolymer prepared in solution yields negligible amounts of C₆₀. The main product is carbon black.     

A STUDY ON THE THERMAL STABILITY OF THE PHOTOPOLYMER, THE OZOPOLYMER, AND THE PHOTOCHLORINATED DERIVATIVE OF C60 FULLERENE

The thermal stability of the C₆₀ photopolymer, the C₆₀ ozo-polymer, and photochlorinated C₆₀ was studied by thermogravimetric analysis (TGA) ultraviolet-visible (UV-vis) and TGA-differential thermal analysis techniques up to 950°C in comparison to graphite and pure C₆₀. The ozopolymer was found to be the least stable material followed by C₆₀Cl_x. The resulting residual carbonaceous matter formed by the decomposition of the photopolymer and the ozopolymer has been studied by Fourier transform-infrared (FTIR) spectroscopy and has been found to be completely comparable to carbon black. The thermal decomposition of the C₆₀ photopolymer prepared in solution yields negligible amounts of C₆₀. The main product is carbon black.     

SINTERING AND COATING OF CERAMICS USING CARBON DIOXIDE LASER

Laser sintering and ceramic coating techniques for synthesis of new ceramics have been investigated. The laser sintering method is useful instead of furnace treatment for the densification of materials having high melting points. The new ceramics, ZrO₂-V₂O_-HfO₂ which have a melting point of 2850^°C and a hardness of about 1850 kgf/cm have been sintered. The single crystal of AI₂O₃3WO₃ was found to form under nonequilibrium states in the Al₂O₃-WO₃ system. A ceramic coating that forms a solid electrolyte layer of a fuel cell was also developed. The laser beam was parallel to the substrate surface on which melted ceramics were deposited by a powder gun. The properties of the coated layer are discussed with the melted particles passing through the laser beam     

脉冲激光法外延生长锰氧化物薄膜

利用脉冲激光法在ＬａＡｌＯ３衬底上外延生长了Ｌａ－Ｃａ－Ｍｎ－Ｏ、Ｌａ－Ｓｒ－Ｍｎ－Ｏ等巨磁电阻薄膜,测定了这些薄膜电阻－温度特性,观测到了其铁磁转变及巨磁电阻效应,实验发现,较高的淀积温度使薄膜的峰值转变温度Ｔｐ降低,峰值电阻率增大,而高温后退火则具有相反的效果,分析比较了多种因素对薄膜生长与性能的影响及其机理。     

气相生长炭纤维增强酚醛树脂制炭/炭复合材料及其物性之研究

以气相生长炭纤维含浸酚醛树脂后经炭化及石墨化处理，制成炭／炭复合材料。观察了不同纤维百分含量的复合材料在升温过程的微细结构及物性之变化，探讨了其强度及电性的变化，并以扫瞄式电子显微镜（SEM）观察破断表面，观察各种复合材料经不同温度处理后之破坏行为。研究结果显示，以气相生长炭纤维所制复材经温度处理后，可以改善其抗弯强度及导电性，最佳纤维含量质量分数为0．5％。超过此比率后，制成之复合材料无论是空孔率或强度皆呈下降。     

60Coγ射线辐照对碳纤维表面及其复合材料层间剪切强度的影响

对60Coγ射线辐照处理的PAN 基碳纤维的力学性能、表面形貌及表面结构的变化和其与环氧树脂复合后层间剪切强度进行了初步的研究。60Coγ射线在1×102～ 1×103Gy 辐照剂量时, 使PAN 基中强碳纤维本身的力学性能显著提高; 使碳纤维表面的含氧官能团浓度和石墨化程度得以提高; 由此制备的碳纤维环氧复合材料的层间剪切强度SIL SS提高了31% 左右。而在辐照剂量≥1×104Gy 时, 由于辐照损伤及热效应, 使碳纤维的力学性能下降, 增加了表面的炭化及其撕裂程度,从而减小了碳纤维环氧复合材料的层间剪切强度SIL SS。     

壳聚糖负载稀土化合物催化环氧乙烷与环氧丙烷共聚合反 …

研究以壳聚糖作为高分子金属催化剂载体,制得负载稀土金属化合物的分高子金属催化剂,应用于环氧乙烷和环氧丙烷的共聚合反应。     

SIMULTANEOUS DETERMINATION OF C60 AND C70 FULLERENES BY A SPECTROPHOTOMETRIC METHOD

In all fullerene-producing systems, reaction products were black soot extracts reported to contain a 5-25% fullerene mixture. Toluene extraction of the soot results in a solution of C₆₀, C₇₀, and higherc fullerenes. Without separation, absolute determination of the contents is not possible, leaving the researcher to comment only on the C₆₀/C₇₀ ratio of the solution. High-performance liquid chromatography, nuclear magnetic resonance, and scanning tunneling microscopy imaging techniques were reported in the literature for determining the C₆₀/C₇₀ ratio of the mixtures. These methods require tedious experiments and produce slightly differing results as well. In this communication, a new and relatively quick method is proposed for the simultaneous determination of the yields of C₆₀ and C₇₀ (not the ratio) in fullerene-containing solutions by ultraviolet-visible spectrophotometric analysis.     

PRODUCTION AND CHARACTERIZATION OF MoSe2 NANOTUBES BY ELECTRON IRRADIATION

In this work, we report the production of MoSe₂ (molybdenum diselenide) nanotubes formed by irradiating the samples with high doses of electron irradiation. The irradiation was performed on a 2 MeV Van de Graff accelerator at the following conditions: voltage 1.3 MeV, current 5 µA current, dose rate 25 Kgy/min, and total dosage 1 Mgy. We observed well-defined nanotubes of several nm long and few nm wide, which suppose to be hollow and capped at one end. As the level of irradiation was increased to 1 Mgy, elongated onion-like structures were observed.     

紫外辐照官能化HDPE及复合材料力学性能

研究了不同紫外光强下辐照的HDPE结构和性能变化。在相同的辐照环境温度和辐照时间下,引入HDPE分子链的C—O、C O和C ( O) O等含氧基团数量随紫外光强提高而增加,提高紫外光强加快了HDPE的官能化,但辐照HDPE中的凝胶含量也有所增加。紫外辐照不影响HDPE的晶型和晶胞参数,但会引起它的熔融温度下降、结晶度提高以及亲水性的改善,其变化幅度随紫外光强提高而加大。辐照HDPE作为增容剂加到HDPE/PVA中,提高了复合材料的力学性能。较高紫外光强下辐照的HDPE表现出更好的增容作用。      

共缩聚聚酰胺酸与聚酰亚胺的微波辐射合成及荧光性能

研究了4,4′-二氨基二苯砜(DDS)、4,4′-二氨基二苯醚(ODA)与均苯四酸二酐(PMDA)的微波辐射溶液聚合反应,将所得的聚酰胺酸进行固相微波辐射亚胺化,并与热聚合进行比较,用红外及核磁共振的测试方法对聚合物的结构进行了表征。结果表明,微波辐射能提高缩聚物的特性粘数和转化率。固相微波辐射使聚酰胺酸的亚胺化时间缩短,亚胺化度增大。合成的聚酰胺酸和聚酰亚胺都具有较强的荧光性能。     

PRODUCTION AND CHARACTERIZATION OF MoSe2 NANOTUBES BY ELECTRON IRRADIATION

ABSTRACT

In this work, we report the production of MoSe₂ (molybdenum diselenide) nanotubes formed by irradiating the samples with high doses of electron irradiation. The irradiation was performed on a 2?MeV Van de Graff accelerator at the following conditions: voltage 1.3?MeV, current 5?µA current, dose rate 25?Kgy/min, and total dosage 1?Mgy. We observed well-defined nanotubes of several nm long and few nm wide, which suppose to be hollow and capped at one end. As the level of irradiation was increased to 1?Mgy, elongated onion-like structures were observed.