共查询到18条相似文献,搜索用时 140 毫秒
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采用基于密度泛函理论的广义梯度近似,对C60富勒烯-巴比妥酸及其二聚体的几何结构和电子结构进行了计算研究.发现:C60富勒烯-巴比妥酸只有一种稳定结构,且掺杂巴比妥酸基团对C60分子构型的影响是局域的.C60富勒烯-巴比妥酸的二聚体有三种同素异构体,分别以[6,5]—[6,5],[6,6]—[6,5]和[6,6]—[6,6]三种方式键合,从能隙大小顺序和总能相对大小来看,[6,6]—[6,6]结构最为稳定.电子结构方面,在C60富勒烯-巴比妥酸单体中,Donor-Acceptor电荷转移体系为C60富勒烯-巴比妥酸,即电荷是从C60向巴比妥酸转移.由前线轨道和自旋布居数得知,C60富勒烯-巴比妥酸单体很好地保留了C60的电磁性质,但稳定性下降,易发生二次加成反应形成二聚体.对于C60富勒烯-巴比妥酸二聚体,Mulliken电荷分析显示,在加成四元环处的碳原子分别得到0104e和0106e电荷,而与它们邻近的碳原子则失去电子,带有正电荷,且距加成位置越近的碳原子失去的电荷越多.在远离加成位置处,碳原子的净电荷变化相对较小.与单体152eV能隙相比,二聚体中的能隙为1.45eV.其前线轨道分布与单体相比,最高占据轨道几乎未变,但最低未占据轨道发生了很大变化.
关键词:
几何结构
电子结构
密度泛函 相似文献
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本文采用密度泛涵理论对富勒烯C40分子进行了结构优化,得到了稳定构型,然后构建了以金原子面为电极的电子输运模型.使用非平衡格林函数方法对构建的电子输运模型进行了电子输运性质的计算,得到了电子透射谱和伏安曲线,并分析了分子器件产生电子输运性质的原因.研究结果发现:C40富勒烯的化学活性明显强于富勒烯C60和C32分子,在一些分子能级处,该分子为一个良导体. 相似文献
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运用基于密度泛函理论和基于非平衡格林函数的第一性原理方法研究了富勒烯C20分子及连接电极构成的C20分子器件的电子结构及电子输运性质.构建了三个基于C20分子的嵌入K和Si原子的电子输运系统,并得到了电子透射谱和分子轨道分布.分析了三种器件的电子结构和输运性质的产生原因,说明C20分子器件的电子传导主要集中在外壳.在C20分子空笼中嵌入K和Si原子后,其电子输运仍然主要集中于富勒烯C20的外壳.
关键词:
20分子')" href="#">富勒烯C20分子
电子结构
电子传导 相似文献
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热激活延迟荧光(TADF)作为一种特殊的分子荧光机制,对于提高发光效率有着重要意义.以C60和C70为代表的碳富勒烯具有高对称结构和离域π电子,被广泛证明具有显著的TADF效应;相比之下,其他类富勒烯团簇的光物理性质尚不清楚.本文利用含时密度泛函理论探索了一系列类富勒烯团簇的激发态性质,包括实验合成的具有不同尺寸的氮化硼笼型团簇B12N12, B24N24和B36N36,以及与B12N12结构相同、元素组成不同的B12P12, Al12N12和Ga12N12.计算结果表明,这些类富勒烯化合物团簇具有2.83—6.54 eV的能隙,主要吸收紫外光,荧光发射波长在可见光区间,包括红光、橙光、蓝光和紫光.它们的第一激发单重态和三重态的能量差较小(... 相似文献
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采用密度泛函理论中的广义梯度近似(generalized gradient approximation,简称GGA),对内掺氢分子富勒烯H2@C60及其二聚体的几何结构和电子结构进行了计算研究.发现无论是在H2@C60单体,还是在其二聚体中,氢倾向以分子形式存在于碳笼中心处,且在室温下氢分子可以做自由旋转.电子结构分析表明,氢分子掺入到C60和C120中,仅对距离费米能级以下-8eV至-5eV能级处有一定的贡献,其他能级的分布和能隙几乎没有变化.
关键词:
几何结构
电子结构
密度泛函 相似文献
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报道了超分子材料[二苯并18冠醚6]KC60是一种具有奇异磁特性的富勒烯衍生物,经13C NMR研究发现,C60的取向有序与磁性之间存在着很强的相关性. 相似文献
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M.D. Zidan M.B. Alsous A.W. Allaf A. Allahham A. AL-Zier 《Optics & Laser Technology》2011,43(7):1343-1346
The optical limiting action of poly(dimethylacetylendicarboxylate) polymer doped with fullerene C60 has been investigated under irradiation with 10 ns laser pulses at 532 nm. The optical limiting measurements were performed at four different dopant concentrations. The threshold limiting fluence at 0.3 J/cm2 was observed at high doping concentrations, with transmission of about 55%. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its nonlinear optical absorption behavior. 相似文献
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This paper reports on the structural, thermal, and dielectric properties of polypyrrole/fullerene C60 nanocomposites synthesized by a interfacial polymerization method. Fourier transform infrared (FT-IR) and ultraviolet-visible (UV-vis) analyses clearly indicated the existence of interactions between polypyrrole (PPy) and the fullerene C60 nanoparticles. Thermal analyses indicated that the extrapolated onset degradation temperature (Tdeg) of PPy increased with increasing doping level. Scanning electron microscopy (SEM) images showed that the fullerene C60 changed the morphology of PPy. Dielectric analyses showed a temperature dependent dielectric relaxation behavior. The relaxation time of the nanocomposites with high doping levels tended to increase with increasing temperature. This behavior of the polypyrrole/fullerene C60 nanocomposites indicated that they could be used as a high temperature ultrasonic transducer. 相似文献
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Nanocrystals of magnesium phthalocyanine in the β-and X-crystalline forms and the magnesium phthalocyanine C60 fullerene system are studied in the near-IR spectral region. The absorption spectra of new nanocomposites are measured. The possibilities of using these systems for optical limiting in the near-IR spectral region (at the wavelength λ=1047 nm) are investigated. The relation between the photoconductivity and nonlinear absorption of phthalocyanine in different crystalline forms is discussed. 相似文献
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Optical limiting measurements on C60 in toluene-ethylenepropylenediene polymethylene (EPDM) polymer blends and in EPDM polymer films at three different concentrations have been carried out. The measurements were undertaken using 532 nm wavelength, 10 ns pulses from a frequency-doubled Nd-YAG Laser. The results show that the optical limiting efficiency is concentration dependent and that the limiting efficiency for C60 in toluene-EPDM polymer blends is better than in EPDM polymer film samples. 相似文献
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M.D. Zidan M.B. Alsous A.W. Allaf A. Allahham A. AL-Zier 《Optics & Laser Technology》2012,44(7):2282-2285
The optical limiting action of C60 doped poly(ethylacetylenecarboxylate) polymer has been carried out using Pulse Nd-YAG laser at 532 nm as the source of excitation. The optical limiting measurements were performed at three different doping concentrations. The optical limiting efficiency of the C60 doped poly(ethylacetylenecarboxylate) polymer was studied at various doping concentrations, the threshold limiting fluence at 0.15 J/cm2 was observed with transmission of about 89%. An explanation based on the combination of two-photon absorption and reverse saturable absorption was proposed for its nonlinear optical absorption behavior. 相似文献
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C. Liu Q. Gong Y. Chen H. Chen D. Qiang 《Applied Physics A: Materials Science & Processing》2001,73(4):477-479
A novel rhodamine-B cation fulleride salt was synthesized by metathetical reaction. Its tetrahydrofuran solution was prepared
and the fluence-dependent transmission was measured with 10-ns 532-nm laser pulses in a collimated optical setup. With increases
in the input fluence, its transmittance decreased significantly, which indicated reverse saturable absorption behavior. For
comparison, the input fluence-dependent transmittance of fullerene C60 and rhodamine-B solution were also measured. The nonlinear optical limiting effect of the fulleride salt in tetrahydrofuran
is slightly lower than that of C60 in toluene and the explanations are provided.
Received: 25 August 2000 / Accepted: 6 November 2000 / Published online: 3 April 2001 相似文献
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Fang Zhang 《Journal of luminescence》2010,130(5):787-791
Different C60 aggregates, i.e. nanoparticles, clusters of nanoparticles and microcrystals in room-temperature solutions, are reported to account for the colors of fluorescence emissions centered at 440, 575 and 700 nm, respectively. And the configurations of C60 aggregation created in solutions are revealed to be closely associated with the characteristic interactions between C60 and solvent molecules. On this basis, aggregation behaviors and thus induced optical properties of C60 have been tentatively controlled through adopting solvent mixtures. 相似文献
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Crystals of lithium niobate LiNbO3 are implanted with 60-keV Cu? ions at different ion fluxes to a fluence of 2 × 1017 ions/cm2. The structure and the linear and nonlinear optical properties of the implanted layers are investigated. The optical transmission and ion-induced photon spectra of the LiNbO3 crystals are measured in the course of implantation. It is revealed that the implantation brings about the formation of complex nanocomposites consisting of metallic copper nanoparticles and nanodomains of the matrix. The distributions of nanoparticles and nanodomains in the implanted layers do not correlate with each other. It is shown that the variations in the linear and nonlinear optical absorption of the nanocomposites are predominantly determined by the changes in the chemical composition and the structure of the matrix. 相似文献