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1.
在B3LYP/6-31G(d,p)水平上对两种富勒烯C60和C70进行了构型优化. 在此基础上,并基于Gelius模型, 计算了这两种富勒烯的紫外光电子能谱曲线. 理论计算的曲线同实验曲线符合的很好.此外, 从理论曲线并结合量子化学计算的结果, 可以看到, C70分子上不同化学环境的的碳原子对紫外光电子能谱曲线的贡献是不同的.  相似文献   

2.
成泰民  葛崇员  孙树生  贾维烨  李林  朱林  马琰铬 《物理学报》2012,61(18):187502-187502
利用不变本征算符法, 计算低温下自旋为1/2的XY模型一维亚铁磁棱型链系统的元激发谱, 讨论在此系统中不同的特殊情形下的元激发能量, 从而给出体系的三个临界磁场强度的解析解HC1, HC2, Hpeak. 分析不同外磁场下 体系的磁化强度随温度的变化规律, 发现三个临界磁场强度的解析解HC1, HC2, Hpeak是正确的, 并从三个元激发对磁化强度的贡献进行了说明. 低温下磁化强度随外磁场的变化呈现1/3磁化平台. 体系的磁化率随温度或者外磁场的变化都出现了双峰现象. 这说明双峰源于二聚体分子内电子自旋平行排列的铁磁交换作 用能和二聚体与单基体分子间电子自旋反平行排列的反铁磁交换作用能, 热无序能, 外磁场强度相关的自旋磁矩势能之间的竞争.  相似文献   

3.
本文介绍了真空紫外光电离质谱结合理论计算研究环戊酮单分子的光电离解离过程. 在9.0∽15.5 eV能量范围内,测量了环戊酮离子及其碎片离子的光电离效率曲线. 通过光电离效率曲线,将环戊酮分子的电离能确定为9.23±0.03 eV,并确认碎片离子为:C5H7O+,C4H5O+,C4H8+,C3H3O+,C4H6+,C2H4O+,C3H6+,C3H5+,C3H4+,C3H3+,C2H5+, C2H4+. 利用量子化学计算方法,在ωB97X-D/6-31+G(d,p)理论水平基础上,提出了C5H8O+的解离机制. 通过对环戊酮解离路径的分析,发现开环和氢迁移过程为环戊酮离子解离的主要路径.  相似文献   

4.
利用密度泛函(wB97XD/6-31G(d))对硼掺杂富勒烯C59B和锌卟吩形成的超分子复合物C59B-ZnP及其阴离子C59B^--ZnP进行了研究. 结果表明硼掺杂富勒烯与锌卟吩间有强烈的相互作用,在C59B-ZnP复合物中,富勒烯上的B原子与锌卟吩的N原子间形成准化学键相互作用. 与硼掺杂富勒烯的相互作用导致锌卟吩的电子吸收发生显著红移.  相似文献   

5.
利用具有同步辐射源的反射式飞行时间质谱仪,研究甲基环己烷的真空紫外光电离和光解离. 观测到母体离子C7H14+和碎片离子C7H13+,C6H11+,C6H10+,C5H10+,C5H9+,C4H8+,C4H7+和C3H5+的光电离效率曲线. 测定甲基环己烷的电离能为9.80±0.03 eV,通过光电离效率曲线确定其碎片离子的出现势. 在B3LYP/6-31G(d)水平上对过渡态、中间体和产物离子的优化结构进行表征,并使用G3B3方法计算其能量. 提出主要碎片离子的形成通道. 分子内氢迁移和碳开环是甲基环己烷裂解途径中最重要的过程.  相似文献   

6.
利用CBS-QB3理论计算方法研究了异戊二烯的可能解离通道.获得了主要碎片离子C5H7+,C5H5+,C4H5+,C3H6+,C3H5+,C3H4+,C3H3+的C2H3+的结构以及这些解离通道的解离能,并给出了相应的过渡态和中间体的结构和位垒.得到的异戊二烯电离势及主要碎片离子的出现势均与实验值符合的较好.最后,通过理论和实验结果的对比讨论了各通道的解离机理.  相似文献   

7.
张泳 《化学物理学报》2020,33(1):101-106
目前在天文环境中探测到了C60、C70、C60+,极大地刺激了对星周包层中富勒烯衍生物的研究. 原行星状星云是富勒烯在天文环境下的可能形成源,其红外光谱中具有丰富的、还未能认证的特征谱带,其中在21 μm处的一条谱带尤为神秘. 当富勒烯被氢化,分子的对称性被破坏,能够激活新的红外振动谱,这有可能部分解释天文光谱中的红外谱带. 本文对氢化富勒烯的理论振动谱进行研究,考查了氢化富勒烯能否作为21 μm辐射的载体,详细讨论了各种支持和反对的证据,并且推测了可能贡献21 μm特征的氢化富勒烯的氢化程度.  相似文献   

8.
 采用爆轰波驱动飞片,对C60样品进行冲击实验,实验产生的烟灰经甲苯萃取后,采用高效液相色谱进行成份分析。结果表明:冲击波的高温高压作用使C60样品大部分分解,少部分形成高碳富勒烯、富勒烯包合物和其它碳簇产物。研究了不同冲击波作用下,C60样品的压强、温度的变化及对C60反应的影响,并对C60的分解与聚合的作用机理进行了探讨。  相似文献   

9.
应用第一性原理计算,研究了椭圆形的C70分子在碳纳米管中的可能取向.采用(14,7)单壁纳米管为原型材料,发现纳米管和C70分子的弱化学相互作用是决定分子取向的决定因素.通过模拟扫描隧道显微镜图像和计算光学性质,发现封装的椭圆体C70分子的局域电子结构敏感地依赖于分子取向  相似文献   

10.
富勒烯掺杂NPB空穴传输层的有机电致发光器件   总被引:1,自引:0,他引:1       下载免费PDF全文
牛连斌  关云霞 《物理学报》2009,58(7):4931-4935
报道了不同掺杂浓度NPB:C60(富勒烯)作为空穴传输层对有机电致发光器件性能的影响.采用真空热蒸镀方法,制作了ITO/ NPB:C60x % )/Alq3/LiF/Mg:Ag结构的四种有机电致发光器件.当NPB:C60的掺杂浓度是15%时,器件的启亮电压是4 V,最大亮度是11000 cd/m2.然而,当NPB:C60的掺杂浓度是20%时,器件的最大亮度降  相似文献   

11.
Soot with a relatively high content of higher fullerenes (C76, C78, C80, C82, C84, C86, etc.) is synthesized in a parallel arc upon evaporation of pure carbon electrodes. The content of higher fullerenes in soot extract amounts to 13.8 wt % when two electrodes are simultaneously burnt in electric-arc reactor. Such a content is comparable with the content obtained upon evaporation of composite graphite electrodes with potassium carbonate impurity.  相似文献   

12.
A large body of data exists about the interaction between curved π systems and C60 or C70. However, little is known about the interaction with fullerenes smaller than C60 or larger than C70. To fill that gap, we studied, by means of density functional theory (M06‐2X), the interaction between corannulene, pentaindenocorannulene, C60H28 buckycatcher and the following fullerenes: C44, C50, C80, C90, C100, C180 and C240. For fullerenes smaller than C60, their high reactivity facilitated the covalent addition to the hosts assayed. Yet, the reaction energies determined for the covalent addition were comparable to those calculated for the formation of supramolecular complexes. Thus, the receptor may host a fullerene and at least have another one attached. As expected, for fullerenes larger than C70, supramolecular complexes were preferred over covalent assemblies. The binding energies with bowls increased with the size of the fullerenes in a non‐monotonic fashion since they depended on the shape of the fullerene. Indeed, for one C80 isomer, it is possible to find a region which forms a complex with corannulene that is stronger than C60@corannulene, while another region exists whose interaction with corannulene is weaker. As the size of the fullerene becomes larger, ball–socket interactions are weakened, and CH–π interactions become important, accounting for the large interaction determined for corannulene and graphene. Finally, for the buckycatcher, the maximum encapsulation energy among the fullerenes assayed was displayed by C90. The fullerenes C80, C90 and C100 formed complexes with the buckycatcher which are stronger than in C60@buckycatcher. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
C60/C70 crystal surfaces were imaged by atomic force microscopy under ethanol with resolution of single molecules. Spherical and elongated elliptical fullerenes can be distinguished corresponding most likely with C60, respectively C70. Determination of the maximum diameter for a large number of molecules confirms the presence of two species of fullerenes, one with 9.4 Å, the other with 11.2 Å. The measured ratio C60:C70 is 81:19 which resembles the spectroscopical data. The molecules are arranged either in hexagonal (hcp) or cubic (fcc) packing, in some areas the two arrangements alternate within a few nm. Elongated fullerenes apparently prefer the hexagonal packing.  相似文献   

14.
Multishell fullerenes are the smallest among multishell carbon clusters, such as the larger graphitic onions or multishell nanotubes. Unlike classical fullerenes, which have a cage structure and are known to have been synthesized in a variety of sizes (C60, C70, C84, C102, etc.), multishell fullerenes have a cage-inside-cage concentric structure, such as double-shell C60@C240 or triple-shell C60@C240@C560. We report on the synthesis of multishell fullerenes by laser vaporization of C60-containing composite carbon targets. Transmission electron microscopy, Raman scattering spectroscopy, and other methods were used for characterization of the product. The yield of the process reaches up to 40%, which permits production in gram amounts even in laboratory conditions.  相似文献   

15.
The stability of fullerenes (C60 and C70) under swift heavy ion irradiation is investigated. C60 and C70 thin films were irradiated with 120 MeV Ag ions at fluences from 1×1012 to 3×1013 ions/cm2. The damage cross-section and radius of damaged cylindrical zone were found to be higher for C60 than C70 as evaluated by Raman spectroscopy, which shows that the C70 molecule is more stable under energetic ion impact. The higher damage cross-section of the C60 molecule compared with that of the C70 molecule is explained on the basis of thermal conductivity in the framework of the thermal spike model. The surface morphology of pristine C60 and C70 films is studied by atomic force microscopy. UV-visible absorption studies revealed that band gap for C60 and C70 fullerenes thin films decreases with increasing ion fluence. Resistivity of C60 and C70 thin films decreases with increasing ion fluence but the decrease is faster for C60 than C70, indicating higher damage in C60. Irradiation at a fluence of 3×1013 ions/cm2 results in complete damage of fullerenes (C60 and C70) into amorphous carbon.  相似文献   

16.
Optical limiting has been investigated for higher fullerenes and compared with C60. The transmission through an aperture placed after solutions of C76, C78, and C84 in tetrahydronaphthalene was measured using Q-switched laser pulses with a wavelength of 532 nm and a pulse width of 8 ns FWHM. Unlike C60, the transmission for these higher fullerene solutions decreased linearly with increasing optical pulse energy. We attribute the linearized optical limiting response to self-defocusing of the optical beam and the absence of excited-state absorption. The ground state absorption spectra for the higher fullerenes suggest their use for optical limiting in the near infrared, and the C84-tetrahydronaphthalene solution was found to be an optical limiter at 1.064 m.  相似文献   

17.
The impact of alkali-metal (Li/Na/Cs) adsorption on work function of fullerenes C60 and C70 was investigated by first-principles calculations. After adsorption, the work functions of fullerenes C60 and C70 decrease distinctly and vary linearly with the electronegativity of the alkali metal elements, and the positions where the alkali atoms are adsorbed considerably influence the work functions. On the contrary, a vacancy defect elevates the work functions of the fullerenes C60 and C70. The variation in the work functions rests with variation in Fermi level (which are attributed to charge transfer) and variation in vacuum levels (which are attributed to the induced dipole moments). Moreover, alkali-metal adsorption can also improve the electric conductivity of a fullerene mixture of C60 and C70.  相似文献   

18.
The static polarizability of the C60, C70, C80, and C186 fullerenes has been calculated within the semiempirical MNDO approximation implemented in the MOPAC quantum-chemical program package. It is demonstrated that the results obtained are comparable with experimental data and the results of the ab initio B3LYP method using the 6–31G(d, p) basis set. The influence of topological defects (five-, seven-, and eight-membered rings), vacancies produced by removing pentagons, and nitrogen and boron atoms on the geometric parameters and the polarizability of the C60, C240, and C540 fullerenes has been investigated by the MNDO method. It is revealed that the polarizability of the fullerene with topological defects is higher than the polarizability of the perfect icosahedral fullerene. The formation of vacancies in the carbon cage leads to a linear decrease in the polarizability of the fullerene and an increase in the specific polarizability. The polarizability of the heterofullerene with nitrogen or boron atoms spaced apart in the carbon cage is higher than that of the fullerene with heteroatoms located adjacent to each other.  相似文献   

19.
Adsorption of helium on free, negatively charged fullerenes is studied in this work. Helium nanodroplets have been doped with fullerenes and ionised by electron attachment. For suitable experimental conditions, C?60 and C?70 anions are found to be complexed with a large number of helium atoms. Prominent anomalies in the ion abundances indicate the high stability of the commensurate 1×1 phase in which all hollow adsorption sites are occupied by one atom each. The adsorption energy for an additional helium atom is about 40% less than for atoms in the commensurate layer, similar to our previous findings for fullerene cations and in agreement with theoretical dissociation energies. Similarly, an anomaly in the adsorption energy occurs when 60 helium atoms are attached to C?60 or 65 to C?70. For C60, the anomaly coincides with the one observed for cationic complexes but for C70 it does not. Implications of these features are discussed in light of several theoretical studies of neutral and positively charged helium–fullerene complexes.  相似文献   

20.
This paper presents an overview of recent works concerned with determination of the electron affinity (EA) and the ionization energy (IE) for higher fullerenes and their endohedral and fluorine derivatives. The numerical values of the electron affinity are analyzed for higher fullerenes up to C106 and lanthanum, gadolinium, and scandium endohedral fullerenes, including Sc3N@C80. Most attention is concentrated on two methods for producing fluorofullerenes, namely, direct fluorination of fullerenes with molecular fluorine in a manganese difluoride matrix and solid-phase reactions between fullerenes and fluorinating agents capable of donating fluorine to fullerene. The structures of three fluorofullerenes (C60F18, C60F20, and C60F48) characterized by a distortion of the carbon cage due to attachment of functional groups are discussed.  相似文献   

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