C_(60)高压相变的拉曼光谱研究

本文对非静水压淬火的 C_(60)样品进行了拉曼光谱研究。在14.8GPa 以上,C_(60)的1468cm~(-1)特征峰的频率和线宽保持不变,这是 fullerite 相己转变成“透明相”的拉曼光谱证据。在32GPa 以上,原 C_(60)的散射峰全部消失,只观察到两个新的弥散的弱散射峰。表明 C_(60)原子团簇已倒塌或严重畸变。     

有机溶剂中C_(60)荧光的研究

本文研究了C6 0 溶于有机溶剂时 ,荧光能级的变化和荧光强度的大幅度增强。通过拉曼光谱结果显示 ,发现C6 0 分子与溶剂分子之间没有发生显著的化学反应。     

C_(60)衍生物超导特性

1985年,美国科学家H·W·Kroto等在研究星际空间中长链状分子的时候,发现了C_(60)。从此,在全世界掀起了一股“C_(60)热”。1990年夏,Krateschmer等首次用电弧合成法合成C_(60)。1991年4月,美国贝尔实验室的Hebard报道了掺K的C_(60)具有转变温度T_c为     

与富勒烯C_(36)直径(0.5nm)相等的碳纳米管及其制备

在电弧放电方法制备碳纳米管中 ,通过用碳纳米管填充阳极进行放电实验 ,成功地得到了小直径单层碳纳米管 .同时在多层管的最内层得到了直径 0 5nm的碳纳米管 .这个结果表明直径小于C60 (直径 0 7nm)的碳纳米管是存在的 .     

NUMERICAL APPLICATION OF THE RECURSION METHOD TO THE ELECTRONIC STRUCTURE OF C_(60)

采用Ｒｅｃｕｒｓｉｏｎ方法计算了Ｃ６０分子的能态密度，所得的能隙、能级的简并度及顺序与ＬＤＡ方法或者解析方法得到的结果吻合。     

C_(60)单晶的低温热力学性质

用X射线粉末衍射测定C_6.单晶在室温下的晶体结构为面心立方(fcc).用差示扫描量热法仔细研究了汽相法生长的C_6.单晶的低温热力学性质,发现引起相变吸热峰异常的原因可能是溶剂化效应,并估算了溶剂化效应的影响为1.13J·B~(-1).通过改进单晶生长过程生长出的C_6.单晶的取向相变温度为261K,相变潜热为8·39J·g~(-1).估算了取向相变激活能为190kJ·mol~(-1). 关键词：     

利用光吸收方法研究C_(60)分子热力学性质

描述了利用光吸收研究C_(60)分子热力学性质的方法。通过对气态C_(60)分子的研究,得到了气态C_(60)分子从410至850℃的气压与温度的关系,同时给出在此温度范围内C_(60)分子的热力学升华热为175kJ·mol~(-1),并给出C_(60)分子笼型结构的破坏温度为850℃。 关键词：     

N,N''-双(3-羧基水杨醛叉缩胺乙基)草酰胺Cu(Ⅱ)-Co(Ⅱ)异双核配合物的密度泛函研究

用密度泛函方法,在ROB3LYP/SDD//ROB3LYP/ANI2MB水平上,对Cu(Ⅱ)-Co(Ⅱ)异双核配合物进行了理论计算,优化得到了它的单、三重态的平衡几何构型,计算了它们的谐振动频率.结果表明:该配合物分子的三重态比单重态稳定,电子自旋布居高度集中在Cu和Co原子上,体系中存在较弱的自旋离城效应.体系的前线分子轨道主要由Cu和Co原子的d轨道和配体原子的p轨道构成,这种构成有利于配体原子与Cu、Co原子之间的电子转移.期望这些研究为这类配合物的合成及分子组装分析研究提供理论参考.     

N,N′-双(3-羧基水杨醛叉缩胺乙基)草酰胺Cu(Ⅱ)-Co(Ⅱ)异双核配合物的密度泛函研究

用密度泛函方法,在ROB3LYP/SDD//ROB3LYP/LANL2MB水平上,对Cu(Ⅱ)-Co(Ⅱ)异双核配合物进行了理论计算,优化得到了它的单、三重态的平衡几何构型,计算了它们的谐振动频率.结果表明:该配合物分子的三重态比单重态稳定,电子自旋布居高度集中在Cu和Co原子上,体系中存在较弱的自旋离域效应.体系的前线分子轨道主要由Cu和Co原子的d轨道和配体原子的p轨道构成,这种构成有利于配体原子与Cu、Co原子之间的电子转移.期望这些研究为这类配合物的合成及分子组装分析研究提供理论参考.     

内陷在C_(60)中的氢原子的性质

在短程球形势阱的模型下 ,运用线性变分法并采用B 样条作为展开基函数计算了内陷于C60 几何中心的氢原子能谱和波函数 ,并计算了势阱深度对能谱的影响 ,详细讨论了内陷氢原子表现出的一系列特殊性质 ,从而对低维半导体材料性能的研究提供了有效的数据 ;同时这一工作也表明 ,用线性变分法结合B 样条函数在处理这类问题时是非常有效的。     

Experimental investigation of optical limiting and thermal lensing in toluene solutions of C70

Optical limiting and thermal lensing studies are carried out in C₇₀-toluene solutions. The measurements are performed using 9-ns pulses generated from a frequency-doubled Nd:YAG laser at 532 nm. Optical limiting studies in fullerene molecules lead to the conclusion that reverse saturable absorption is the major mechanism for limiting. Analysis of thermal lensing measurements showed a quadratic dependence of thermal lens signal on incident laser energy, which also supports the view that optical limiting in C₇₀ arises due to sequential two-photon absorption via excited triplet state (reverse saturable absorption).     

新型富勒烯衍生物的光限幅研究

应用倍频Ｎｄ∶ＹＡＧ脉冲激光，在波长为５３２ｎｍ、脉冲宽度分别为８ｎｓ和２３ｐｓ的条件下，研究了新型富勒氮烯乙酰氨衍生物（Ｎ－ａｃｅｔａｍｉｄｅ１，２－ｄｉｈｙｄｒｏ－１，２－ａｚａ－ｆｕｌｅｒｅｎｅ［６０］）的反饱和吸收与光限幅特性。实验结果表明，同脉宽为纳秒的激发脉冲相比，富勒烯乙酰氨衍生物对脉宽为皮秒的脉冲限幅效果比较好。     

Reverse saturable absorption and optical limiting in indanthrone dyes

Fluence dependence of transmission in three dyes, viz. indanthrone, dichloroindanthrone and violanthrone, is reported at 532 nm as well as at 1.06 µm. These dyes show optical limiting at both these wavelengths for nanosecond pulses. The limiting is due to the combined effect of reverse saturable absorption from the triplet state and thermal defocussing in the dye solutions.     

Mechanisms of optical limiting in fullerene-doped π-conjugated organic structures demonstrated with polyimide and COANP molecules

Possible mechanisms of optical limiting of visible radiation in conjugated organic structures based on polyimides and substituted pyridines sensitized with C₆₀ and/or C₇₀ fullerenes are studied using the Z-scan method. It is shown that reverse saturable absorption, two-photon absorption, and complex formation between the donor fragment of a π-conjugated molecule and fullerene contribute to the processes of nonlinear absorption. The absorption cross sections for excited states of the charge transfer complexes based on polyimide 6B-C₇₀ and 2-cyclooctylamino-5-nitropyridine-C₇₀ systems are calculated. The data obtained are quantitatively interpreted and compared with those provided by alternative methods.     

新型纳米合成物的光限幅特性研究

报道了基于富勒烯 C6 0 结构体系的零价金纳米粒子合成物的光限幅特性。使用 Z- scan技术对实验结果进行了分析。结果表明 ,材料的限幅机理主要起源于非线性吸收和吸收所致的非线性散射     

利用不完全自锁模激光研究C60的反饱和吸收效应

本文报道首次采用色心晶体的不完全自锁模激光（１０６４ｎｍ）对Ｃ６０分子反饱和吸收效应的研究，实验结果与采用平均过程的研究方法是一致的，文中还讨论了Ｃ６０分子反饱和吸收效应产生的原因。     

Optical limiting action of C60 doped poly(dimethylacetylendicarboxylate)

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.     

C60／PSt复合材料的反饱和吸收与光限幅特性

报道了Ｃ６０／ＰＳｔ（Ｐｏｌｙｓｔｒｅｎｅ）复合材料的制备，测量了材料的线性吸收光谱，研究了不同线性透射率的Ｃ６０／ＰＳｔ材料的反饱和吸收与光限幅特性．     

萘酞菁铅化合物的光限幅特性研究

应用调Q倍频ns/ps Nd：YAG脉冲激光,在波长为532nm,脉冲宽度为8ns,重复频率为1Hz的条件下,研究了溶于二甲基亚砜(DMSO)中的萘酞菁铅溶液的反饱和吸收和光限幅特性。实验表明,萘酞菁铅具有良好的光限幅特性,它的有效激发态吸收截面与基态吸收截面的比值约为15．21,大于萘酞菁铜。研究结果表明,萘酞菁铅的光限幅特性优于C60,激发态吸收是其主要的光限幅机理。实验结果证实了重原子效应可以通过增强系际跃迁而使三重态的反饱和吸收增强,从而提高光限幅的能力。     

EXCITED-STATE NONLINEAR ABSORPTION AND ITS APPLICATION IN PHOTONIC TECHNOLOGY

The main achievements in our research on the physical phenomena of the excited-state nonlinear absorption in a molecular system and its applications in photonic technology are described. In the first part of this paper, some energy-level models and rate-equations are used to explain various mechanisms of the excited-state nonlinear absorption under differ-ent conditions, such as reverse saturable absorption caused by the triplet and/or the singlet excited-state absorption; saturable absorption due to the first and/or the second singlet excited-state absorption; and the excited-state nonlinear absorption induced by two-photon absorption. The experimental results for metal-organic and C₆₀ materials irradiated by ps and ns laser pulses are consistent with the simulated curves of the transmittance versus flu-ences. In the second part, the applications of excited-state nonlinear absorption in photonic techniques including optical bistability, optical switching, optical limiting, optical modula-tion, optical logic and optical storage are introduced. The working principles of the photonic devices based on the excited-state nonlinear absorption are presented. The experimental characteristic curves are found in good agreement with the theoretical simulations for these devices.