C_(60)O_n(n=2,3)异构体的合成和理论计算研究

本文通过臭氧氧化C60得到C60On的混合物,反相高压液相色谱图表明有两种C60O2异构体和两种C60O3异构体,分别标记为C60O2(I)、C60O2(II)和C60O3(I)、C60O3(II),同时得到了它们的UV-vis谱图。为了确定它们的最可能结构,我们对四种最可能的C60O2异构体和九种最可能的C60O3异构体进行了理论计算,从能量、偶极矩、电子光谱方面进行了系统研究,提出了实验得到的C60On(n=2,3)的稳定结构。计算结果与实验吻合良好。     

C_(60)在室温有机溶剂中荧光的研究

本文在室温下对C60分别在吡啶、甲苯和乙腈中的荧光了研究,实验表明:C60在吡啶中的荧光由以440nm、570nm和700nm为中心的三个荧光带组成;C60在甲苯中的荧光由以430nm和700nm为中心的两个荧光带组成;C60在乙腈中的荧光由以570nm和700nm为中心的两个荧光带组成。经比较分析发现C60-有机溶剂体系700nm区域的荧光带的发射与溶剂的种类无关,而440nm和570nm区域的荧光带及其精细结构可以反映C60与溶剂分子的特殊相互作用。进一步提出C60-吡啶体系以570nm为中心的荧光带是由吡啶分子通过含孤对电子的N与C60形成的电荷转移络合物发出的。     

苯氧乙酸、邻菲啰啉铽-钇配合物的合成、表征及荧光性能(英文)

以苯氧乙酸和邻菲啰啉为配体,不同比例铽钇为中心,在无水乙醇中合成了一系列铽掺钇配合物?素分析和稀土络合滴定推测配合物的组成为TbxY1-x(POA)3phen·1/2H2O(POA-=C6H5OCH2COO-,x=1.0,0.9,0.8,0.7,0.6,0.5,0.4,0.3,0.2,0.1)。红外光谱测试表明,苯氧乙酸的羧基氧及苯氧基氧与稀土离子配位。邻菲啰啉的两个氮原子也与稀土离子配位;热分析表明:该系列配合物在274℃附近失去配位水,温度高于576℃发生氧化分解。荧光光谱测试结果表明:该系列配合物都可发出较强的特征荧光,在一定比例范围内,钇可以增强铽的发光,组成为配合物Tb0.7Y0.3(POA)3phen·1/2H2O荧光最强;荧光寿命与荧光强度变化一致。     

新型镧配合物的合成与荧光性质

在氮气保护下,以无水乙醇为溶剂,制备了硝酸镧与4-氨基-1,2,4-三氮唑缩对二甲氨基苯甲醛(L)配合物,单晶结构分析确定其组成为LaL_3(NO_3)_3·(H_2O)_2·(C_2H_5OH)_2,配合物中La~(3+)分别与3个硝酸根、2个水分子和2个分子乙醇中的氧原子配位,配位数为10,并与4-氨基-1,2,4-三氮唑缩对二甲氨基苯甲醛以氢键形式结合形成立体结构分子.通过元素分析、红外光谱、固体荧光光谱等手段对合成的配体及配合物进行了表征.实验结果表明,4-氨基-1,2,4-三氮唑缩对二甲氨基苯甲醛是一种多晶粉末状的发光材料,固体荧光谱图显示荧光发射峰在451 nm处,为蓝色荧光,色纯度高,荧光量子效率高,而合成的配合物的荧光发射峰则红移至464 nm左右,同时荧光强度显著增强近一倍.     

C77N+异构体的稳定性和电子光谱研究

用INDO系列方法对C78(C2V)的等电子体C77N+的所有21种可能异构体进行系统的理论研究.研究结果表明,最稳定异构体是由C78(C2V)沿Y方向椭球短轴所穿过的C(78)-C(73)键上的原子C(78)被N+取代所形成,椭球长轴附近的原子被取代所形成的异构体能量较低,取代位置附近易成为进一步反应的中心.用INDO/SCI方法计算了C77N+电子光谱,表明其吸收峰与C78(C2V)相比发生红移,对特征吸收峰进行了理论指认,讨论吸收峰红移的原因.     

Generation of dual-wavelength pulses by frequency doubling with quasi-phase-matching gratings

We demonstrate generation of two synchronized picosecond pulses at different wavelengths near 778 nm by frequency doubling of a femtosecond pulse. We use nonlinear frequency filtering with quasi-phase-matching gratings, which allow us to obtain second-harmonic spectral intensities that are higher than the spectral intensities of the pump.     

FRET structure with non-radiative acceptor provided by dye-linker–glass surface complex and single-molecule photodynamics by TIRFM-polarized imaging

We present our recent study of microscopic single-molecule imaging on the artificial complex of tetramethylrhodamine linked with a propyl chain onto silica glass surface, i.e. an asymmetric fluorescence resonance energy transfer (FRET) structure with non-radiative acceptor. In the synthesis of the complex, we used a mixture of two kinds of isomers to introduce rather small photodynamic difference among them. This isomeric structure change will provide more or less a distinctive photophysical change in e.g. non-radiative relaxation rate. Our recent observation at room temperatures, so far, shows that such contributions can be discriminated in the histograms of the fluorescent spot intensities; broad but distinctive multi-components appear. To identify the isomeric difference as a cause of structures, some configurational assumptions are necessary. One such basic prerequisite is that the transition dipoles of the chromophores should be oriented almost parallel to the glass surface. In order to make clear the modeling, we also provide preliminary experiments on the polarization dependence of the imaging under rotating polarization in epi-illumination.     

团簇分子[Zn-(CH_3CH_2OH)_n]~(2+)的荧光光谱研究及理论光谱验证

通过荧光光谱实验和理论计算对金属离子在乙醇溶液中的微团簇结构进行了研究。荧光光谱实验发现在275~330 nm范围存在较强的乙醇分子荧光峰,当加入盐离子(Zn~(2+))后该处荧光强度逐渐变弱,说明盐的加入对乙醇体系的荧光效率产生了影响,破坏了原有乙醇分子之间的作用,使得其刚性结构发生改变,荧光效率降低,同时Zn~(2+)与乙醇分子通过溶剂化作用形成了新的微团簇,在350~380 nm之间出现了新峰。通过对团簇结构[Zn-(H_2O)_n]~(2+)(n=1~3)进行优化比较,得到了相对精确及运算成本较低的密度泛函理论B3LYP方法,并应用于Zn~(2+)在乙醇溶液中团簇结构计算。结果表明体系的第一溶剂化层存在着n=1~6的微团簇分子,且最多为6。比较理论计算荧光光谱与实验荧光光谱,进一步说明了Zn~(2+)与乙醇形成了新的微团簇及计算方法的可行性。     

Overrun phenomenon and neutron yield in Coulomb explosion of deuterated alkane clusters driven by intense laser field

By using a simplified Coulomb explosion model, the laser-driven Coulomb explosion processes of three deuterated alkane clusters, i.e., deuterated methane(CD_4)_N, ethane(C_2D_6)_N and propane(C_3D_8)_N clusters are simulated numerically.The overrun phenomenon that the deuterons overtake the carbon ions inside the expanding clusters, as well as the dependence of the energetic deuterons and fusion neutron yield on cluster size, is discussed in detail. Researches show that the average kinetic energy of deuterons and neutron yield generated in the Coulomb explosion of(C_2D_6)_N cluster are higher than those of(CD_4)_N cluster with the same size, in qualitative agreement with the reported conclusions from the experiments of(C2 H6)_N and(CH4)_N clusters. It is indicated that(C_2D_6)_N clusters are superior to(CD_4)_N clusters as a target for the laser-induced nuclear fusion reaction to achieve a higher neutron yield. In addition, by comparing the relevant data of(C_3D_8)_N cluster with those of(C_2D_6)_N cluster with the same size, it is theoretically concluded that(C_3D_8)_N clusters with a larger competitive parameter might be a potential candidate for improving neutron generation. This will provide a theoretical basis for target selection in developing experimental schemes on laser-driven nuclear fusion in the future.     

甲基紫精与醇类间的光诱导电子转移及光催化反应的ESR研究

用ESR方法研究了甲基紫精(MV⁺⁺)与甲醇,乙醇及苄醇等之间的光诱导电子转移和光反应过程.结果发现,甲基紫精存在条件下,某些很稳定的醇类也可以发生光催化分解和光催化氧化的反应,甲基紫精在反应过程中起的是催化剂的作用在无氧条件下,MV⁺⁺/C₂H₅OH体系经UV光照10min后即可观察到很强的MV⁺离子基的信号,表明甲基紫精与乙醇分子之间发生了电子转移;当进行较长时间光辐照,则MV⁺离子基逐步消失而生成H原子和碳中心自由基。在通氧条件下进行光照时,则无MV⁺基信号而产生OOH基和碳中心自由基的信号.当体系中有一定量的水存在时,OOH基减弱而产生·OH基,且随着水量的增加,·OOH基的强度更为减弱直至消失,而同时羟基浓度则大大增加.另一个有趣而重要的现象是,对于MV⁺⁺/苄醇体系,在通氧条件下辐照时可给出很强的超氧阴离子基O₂^-的信号,而MV⁺⁺/甲醇体系可产生较弱的O₂^-信号.但是在无氧时甲基紫精的存在进行光辐照甲醇并不发生反应,而苄醇却可被甲基紫精光催化分解产生很强的苄氧基,羟甲基等自由基.本文详细地研究和讨论了甲基紫精与几种醇之间的光诱导电子转移和相应的均相光催化反应过程的机理.     

介质阻挡放电分解甲醇发射光谱分析

利用光学多道分析系统（Optical Multiple Analysis -OMA）,采用发射光谱方法,对甲醇气体介质阻挡放电 (dielectric barrier discharge---DBD)分解制氢过程进行了实验研究.通过对甲醇气体DBD放电等离子体荧光光谱的归属,确定了甲醇放电的主要荧光产物为CO、OH、H和CH;另外,还对CO和Ｈａ的荧光辐射强度随放电时间的演变过程进行了实验研究,发现在放电初始阶段,CO和Ｈａ的荧光辐射强度随放电时间急剧增强,表明了DBD放电能有效地分解甲醇气体,并由此对甲醇分解过程进行了分析讨论.在放电等离子体甲醇制氢过程中,最终产物是H2和CO;H2主要来自于ＣＨ２Ｏ分解以及甲醇分解产生的H原子直接生成;CO主要来源于ＣＨ２Ｏ分子分解产生.ＣＨ２Ｏ是甲醇分解制氢过程中一个关键的中间产物.     

不同激发波长下C_(60)/C_(70)的荧光研究(英文)

在室温吡啶溶液中得到了较以往丰富的C6 0 /C70 荧光谱,研究了其荧光谱随激发波长的变化,并且比较了C6 0 和C70 的荧光谱     

The influence of temperature on red-edge excitation effects in liquid solutions of N,N′-dimethylaminobenzonitrile

A systematic study of new photophysical and photochemical processes in solutions is continued by the example of a recently found phenomenon of redistribution of the intensities of two fluorescence bands of N,N′-Dimethylaminobenzonitrile (DMABN) in polar solutions at room temperatures under selective irradiation by light with different photon energies in the region of the long-wavelength absorption band. The effects observed are explained using data of quantum-mechanical calculations, which reveal that solutions of these systems are very likely to contain rotational isomers with different orientations of the dimethylamino group with respect to the plane of the benzonitrile residue. The excited-state charge transfer reactions in these rotamers occur in different ways and, hence, with different rates, because of which the intensity ratio of recorded fluorescence bands is different for different wavelengths of selective excitation. In this study, the influence of the temperature on the red-edge excitation effect observed in the fluorescence of DMABN solutions in acetonitrile is studied in the temperature range of 274–313 K using the previously used selective excitation method. It is found that these effects manifest themselves at any temperature within this range, but are especially strong at 313 K. The parameters of the dual fluorescence that are most sensitive for recording of the considered effects are determined, and the obtained temperature dependences are interpreted.     

On the Viscoelastic and Dielectric Behavior of Some Organic Compounds and Their Binary Mixtures

The dependence of dielectric relaxation time on the viscosity of the medium is being extensively used to draw certain quantitative conclusions regarding molecular motion and inter-molecular forces in liquids, liquid mixtures, dilute solutions, and multi-component polar solutes in dilute solution. In the absence of proper empirical or theoretical equations for the variation of dielectric relaxation time with viscosity, only the experimental investigations on different systems can give an insight. In the present study, the results of dielectric measurements carried out on pure samples of bromohexane, bromooctane and bromodecane in dilute solutions in different mixed solvents (benzene + paraffin) and on binary mixtures (1 : 1) of (bromohexane + bromodecane); (bromodecane + propyl alcohol) and (propyl alcohol + methyl alcohol) are reported. For comparison, the results of bromodecane + propyl alcohol and propyl alcohol + methyl alcohol are chosen as they form examples of mixture of non-associative + associative and associative + associative liquids, respectively. Different parameters determined using these dielectric measurements are also presented using different models. These studies indicate that the dielectric behavior at microwave frequencies favor the concept of dynamic viscosity and a single viscoelastic relaxation time for the systems under study.     

Femtosecond noncollinear parametric amplification for ultrafast spectral dynamics

We setup an ultrafast noncollinear optical parametric amplification system for fluorescence spectral dynamics study. The simultaneous broadband amplifying ability makes it suitable as an ultrafast spectrometer with femtosecond time-resolution. By real-time fluctuation correction, femtosecond fluorescence spectra are obtained efficiently by a single scan. With this technique, the solvation dynamics of DCM dye in four solvents are measured to demonstrate the performance of the system. We show that this ultrafast time-resolved spectrometer is very useful and efficient in studying ultrafast spectral dynamics.     

物理喷束淀积制得的C_（60）、C_（70）等薄膜的拉曼和荧光光谱研究

物理喷束淀积制得的Ｃ＿（６０）、Ｃ＿（７０）等薄膜的拉曼和荧光光谱研究王德嵘，柯国庆，黄大鸣，钱士雄（复旦大学物理系上海２００４３３）ＲａｍａｎａｎｄＦｌｕｏｒｅｓｃｅｎｅＳｐｅｃｔｒａｏｆＣ＿（６０），Ｃ＿（７０）ＦｉｌｍＦａｂｒｉｃａｔｅｄｂｙＰ...     

High-resolution spectroscopy with a femtosecond laser frequency comb

The output of a mode-locked femtosecond laser is used for precision single-photon spectroscopy of 133Cs in an atomic beam. By changing the laser's repetition rate, the cesium D1 (6s 2S(1/2)-->6p 2P(1/2)) and D2 (6s 2S(1/2)-->6p 2P(3/2)) transitions are detected and the optical frequencies are measured with accuracy similar to that obtained with a cw laser. Control of the femtosecond laser repetition rate by use of the atomic fluorescence is also implemented, thus realizing a simple cesium optical clock.     

Characteristic of femtosecond laser-pulsed digital holography

Digital holography can be applied to ultrafast detection when a femtosecond laser pulse is used. In this paper, the interference process of two femtosecond laser pulses is studied and the recording process of the femtosecond laser pulsed digital hologram is simulated. Holograms at different recording angles are generated by integrating the instantaneous interference field. By analyzing the distribution of the reconstructed phase error, the characteristics of femtosecond laser pulsed digital holography are discussed.     

Microstructure of Polyelectrolyte Nanoaggregates Studied by Fluorescence Probe Method

The microstructure of water soluble nanoaggregates based on polyelectrolyte complex formed by the cationic comb-type copolymer poly(acrylamide -co-[3- (methacryloyl-amino)propyl] trimethylammonium chloride)-graft- polyacrylamide [P(AM-co-MAPTAC)-g-PAM] and the anionic linear polyelectrolyte sodium polyacrylate (NaPA) was investigated using the fluorescence probe technique. The fluorescence probe were 1-anilinonaphthalene-8-sulfonic acid (ANS), pyrene (Py) and 1,10-bis(1-pyrene) decane (PD). The fluorescence properties in polyelectrolyte complex solutions, which are sensitive to either micropolarity (ANS, Py) or microviscosity (PD), were related to the quantities obtained in different pure or mixed solvents. Micropolarities were quantified utilizing the polarity common index (Reichardt) E _T(30). ANS and Py showed a variation of the micropolarity with the charge ratio of the two polymers, with the lowest polarity reached at the complex neutralization. The PD probe, by its excimer-to-monomer fluorescence intensities ratio, enabled us to evidence the effect of the composition and the comb-type copolymer grafting density on the microviscosity of the interpolyelectrolytes aggregates. It has been found that the microviscosity increased with the density of the grafting PAM chains.