5,10—二(对—氨基)四苯基卟啉和吖啶黄之间激发能量的传递

利用Forster能量传递机制,研究了氯仿溶液中吖啶黄向5、10—二(对—氨基)四苯基卟啉(简称TBP)的激发能量传递和TBP.浓度变化时对能量传递速度常数的影响.实验结果表明,吖啶黄和TBP之间具备能量共振传递的条件,并且计算了能量共振传递的临界距离为0.42nm、传递效率为0.72和传递速度常数为1.42×10~7s~(-1).这些数据对复合膜光电转换器件的设计将具有重要意义.     

蒽、吖啶黄和阳离子桃红在溶液中的分子间能量传递

本文使用了荧光光谱和时间校正的单光子计数技术研究了蒽、吖啶黄和阳离子桃红在溶液中分子间能量传递的关系。实验表明:分子蒽吸收的能量可以传递给吖啶黄,再由吖啶黄传递给阳离子桃红,体系中随着给体荧光的猝灭,受体的敏化荧光递增;体系中的能量传递常数KET,猝灭常数KQ、敏化常数Ks是给体的荧光寿命TD和体系能量传递速率常数k的乘积,即KET=Ks=KQ=kτD。由于能量传递速率小于扩散速率常数kdiff,且能量传递速率常数kET对溶剂粘度的变化是敏感的,所以可以认定体系中能量是以电子交换作用的机制传递的。     

1-乙酰乙酰基-3-甲基吲哚对稀土离子能量传递过程研究

通过1-乙酰乙酰基-3-甲基吲哚(I3MK)与各种稀土离子在77K乙醇刚性溶液体系中的荧光光谱、磷光光谱的测定,进行了I3MK向稀土离子能量传递过程的静态分析;从I3MK和I3MK-Tb(Ⅲ)体系的荧光寿命、磷光寿命、量子产率,时间分辨光谱等,计算了各主要能量传递过程的速率常数和能量传递效率,进行了该体系能量传递过程的动态分析,提出了Perrin公式的修正参数,讨论了I3MK-Tb(Ⅲ)体系的能量传递机理.     

两原子相干共振能量传递的单次与N次能量提取

两原子间隔一定距离且两原子跃迁频率接近时,两原子之间可发生能量传递.理论研究了供能原子和受能原子两共振原子的能量传递.求解薛定谔方程得出两原子共振能量传递效率.结果表明,供能原子在真空场中的激发态寿命在能量传递效率中起到十分重要的作用.能量传递效率与两原子间距离的负三次幂的正弦值的平方成正比,在一阶近似条件下,与两原子间距离的6次方成反比.以供能原子处于激发态时为初始时刻,能量从初始时刻随时间由供能原子向受能原子传递,对受能原子的单次能量提取的最大值大约在供能原子寿命的2/3时刻;对受能原子的连续N次能量提取的最大值,每次提取时间大约在供能原子寿命的1/2时刻.     

溶液和熔化状态下分子间的能量传递

通过二维红外光谱研究了GdmSCN/KSCN=1/1,GdmSCN/KS¹³CN=1/1和GdmSCN/KS¹³C¹⁵N=1/1三种混合晶体在熔融和溶液状态下的共振和非共振的分子间振动能量传递的性质. 在这些样品中,给体/受体的能量差越大,能量传递越慢. 而能量传递的快慢与拉曼光谱无关. 非共振能量传递与给体/受体的能量差的关系不能用声子补偿的机理来描述. 相反,它们的关系却可以用退相位机理来定量描述. 在熔融状态下,共振和非共振能量速率与温度的依赖关系也与退相位机理的预测相符合. 这一系列的结果表明只要分子的运动(平动和转动)远远快于非共振能量传递速率,那么退相位机理不仅在溶液中占主导,而且在熔融状态下(纯液体,不含溶剂)也占主导.     

估算供体-受体对荧光共振能量传递效率的研究

在有机白光LED的研究中,能量传递效率计算方法的研究是一项很有意义的工作。作者在总结前人工作的基础上,提出了一种利用有机分子发射谱和激发谱估算有机分子荧光共振能量传递(FRET)效率相对值的新方法,这种方法的优点是数据处理过程简单,对实验仪器设备要求不高,并且不需要通常计算方法所需的荧光量子产率等参数,缺点是只能计算能量传递的相对值。利用这种方法计算了甲萘酚、溴甲酚紫、萤光素钠盐三种能量受体和能量供体核黄素在不同浓度下能量传递效率的相对值,计算结果与实验结果基本符合,验证了此方法的合理性。     

π-Λ耦合常数和π-Λ低能P_(3/2)波散射

本文将改进的Chew-Low展开应用到π-A的P_(3/2)分波散射,以从共振参量(能级和宽度)来确定π∧∑的耦合常数和P_(3/2)相移随能量的变化。当共振宽度采用目前比较公认的值50MeV时,给出的π-A耦合常数为g~2=34或f~2=0.12.文中亦给出了其他可能的宽度值所相应的结果。所得到的P_(3/2)相移曲线虽无实验可以比较,但估计在质心系总能量W≈1450MeV以下,应该是可靠的。     

利用级联式能量传递的有机电致发光器件

为了提高掺杂型有机电致发光器件(OLED)中主体发光材料与客体荧光染料间能量传递的效率,2-对联苯-8-羟基喹啉锌(Zn ₂)作为NPB : DCJTB掺杂体系的能量助传递剂,制备了结构如:ITO/NPB/NPB : DCJTB/Zn ₂/BCP/Al的有机电致发光器件。助传递剂Zn ₂的加入,能够两次利用Frster能量转移,实现NPB向DCJTB级联式的能量传递过程,提高低浓度时掺杂染料DCJTB红光发射的纯度;此外,还探讨了三者间能量传递的有效距离,即当助传递剂与掺杂体系的距离在小于10 nm的范围内,其参与能量传递的效率随着距离的增加而逐渐下降。     

稀土离子发光体系中能量传递和迁移模型的研究

基于以前综合V-F模型(考虑施主受主(D-A)能量传递)和B模型(考虑施主施主(D-D)能量迁移)而提出的V-F-B综合模型,对La_1-xEr_xF₃体系中Er³⁺离子四种低掺杂浓度下(x=0.001,0.003,0.01,0.02)295K时⁴S_3/2→⁴I_15/2发光的时间演化曲线成功地重新进行了数值拟合.结果表明该体系内D-A间交叉弛豫能量传递是偶极-偶极作用,作用常数C_DA为4.75×10^-41cm⁶/s,与Okamoto等人原用YT扩散模型得到的结果一致.而拟合得到的四个D-D平均跳跃时间τ₀粗略地与x_D^α次方(x_D为D离子浓度)成正比(α≈-1.237),并不遵从τ₀很小时与x_D的-2次方成正比的理论关系.同时,通过把D-D迁移和D-A传递同时同样地纳入V-F模型还粗略估计了D-D平均跳跃时间τ₀′的值,发现它与V-F-B给出的τ₀拟合值比较一致,说明V-F-B模型在一定近似程度上是内部自恰的、合理的. 关键词： 能量传递 能量迁移 跳跃时间 交叉弛豫     

在三通道α-螺旋蛋白质中传递生物能量的孤子的特性

用庞小峰先生提出的生物能量传递的新理论和 Runge-Kutta数值模拟方法,研究了三通道α-螺旋蛋白质中激发的孤子的动力学特性,求出在0K和300K温度下该孤子稳定地沿蛋白质链传递.由此可见,它能担任在蛋白质分子中传递生物能量的功能.从而再次证实了新理论的可利用性.     

Pyrene-Naftylamide Bifluorophore for Spectra-Converting Media

New bifluorophore containing pyrene as an excitation energy donor and naphtylamide as an acceptor is synthesized and its optical properties are studied. It is founded that excitation spectrum of the bifluorophore is almost the sum of its constituents—pyrene and naftylamide. At the same time, in the luminescence spectrum there only the peak of acceptor luminescence is observed, which indicates the effective radiationless energy transfer from the donor to the acceptor. This is also proved by time resolved measurements of bifluorophore decay. The decay rate was calculated from decay curve and appear to be 0.25 нс^?1. The same value obtained from the Förster’s theory is almost by an order as high. It indicates that Förster’s does not applicable in this particular case. Instead, we have to use the electron excitation density functions approach.     

Determination of the Efficiency and Energy Transfer Rate in the Fluorescence of a Single Donor–Acceptor Pair Attached to a Biomolecule

Resonance energy transfer from a single donor molecule to a single acceptor molecule (Förster resonance energy transfer) is currently used to determine the microscopic parameters describing interconformational changes in a protein molecule to which this single donor–acceptor pair is attached. A recently developed method makes it possible to intricately search for such parameters using a formula for the efficiency of Förster resonance energy transfer, which is the sum of several Gaussians. Another simpler method for the determination of the desired parameters of interconformational transitions has been proposed in this work on the basis of statistical processing of fluctuating tracks of fluorescence of a single donor–acceptor pair attached to a protein molecule.     

Influence of donor-donor transport on excitation energy transfer

Energy migration and transfer from acriflavine to rhodamine B and malachite green in poly (methylmethacrylate) have been investigated using the decay function analysis. It is found that the influence of energy migration in energy transfer can be described quite convincingly by making use of the theories of Loring, Andersen and Fayer (LAF) and Huber. At high acceptor concentration direct donor-acceptor transfer occurs through Förster mechanism.     

A Modification of Förster's Deactivation Relation due to Inhomogeneous Spatial Distribution and Active Behavior of the Acceptors

The deactivation behavior of excited molecules and impurities in solids is analyzed under consideration of a long-range excitation energy transfer based on dipole-dipole interaction between donors and acceptors. Under the condition of inhomogeneous spatial distribution and active behavior of the acceptors a time evolution formula is derived, which essentially differs from Förster's original relation [2]. The results are discussed for physically representative values of concentration and medium parameters.     

Nonradiative and radiative Förster energy transfer between quantum dots

We theoretically study nonradiative and radiative energy transfer between two localized quantum emitters, a donor (initially excited) and an acceptor (receiving the excitation). The rates of nonradiative and radiative processes are calculated depending on the spatial and spectral separation between the donor and acceptor states and for different donor and acceptor lifetimes for typical parameters of semiconductor quantum dots. We find that the donor lifetime can be significantly modified only due to the nonradiative Förster energy transfer process at donor–acceptor separations of approximately 10 nm (depending on the acceptor radiative lifetime) and for the energy detuning not larger than 1–2 meV. The efficiency of the nonradiative Förster energy transfer process under these conditions is close to unity and decreases rapidly with an increase in the donor–acceptor distance or energy detuning. At large donor–acceptor separations greater than 40 nm, the radiative corrections to the donor lifetime are comparable with nonradiative ones but are relatively weak.     

Luminescence quenching kinetics upon diffusion-accelerated dipole-dipole energy transfer for a realistic condensed-matter model

The hard-sphere model is considered as a more realistic condensed-matter model. In this model, the radial distribution function of molecules in a medium, used for calculations of luminescence decay kinetics, takes into account the short-range order in fluids and has the shape of damped oscillations. It is assumed that the motion of donor and acceptor molecules in a solution for the lifetime of the excited state of the donor is described by the diffusion equation, while the luminescence quenching occurs due to the long-range dipole-dipole energy transfer. It is shown that, if diffusion coefficients are small, the kinetics determined in this study hardly differs at all from the traditional kinetics. At intermediate and large diffusion coefficients, this difference becomes significant and should be taken into account in estimating the Förster energy transfer radius and diffusion coefficients from experimental luminescence decay curves.     

CdTe量子点与罗丹明B水溶液体系下的双光子激发荧光共振能量转移

采用时间分辨荧光光谱技术研究了在双光子激发下不同尺寸的量子点与罗丹明B 之间的荧光共振能量转移. 研究结果表明, 在800 nm的双光子激发条件下, 体系间能量转移效率随着供体吸收光谱与受体荧光光谱的光谱重叠程度增加而增加; 理论分析表明, 供体和受体间的Förster半径增加是导致其双光子能量转移效率增大的物理原因. 同时, 研究了罗丹明B浓度对荧光共振能量转移效率的影响. 研究结果表明, 量子点的荧光寿命随着罗丹明B浓度的增加而减小; 量子点与罗丹明B之间的荧光共振能量转移效率随着罗丹明B浓度的增加而增加; 当罗丹明B浓度为3.0×10^-5 mol·L^-1时, 双光子荧光共振能量转移效率为40.1%.     

Model for photosynthetic light harvesting system: Energy transfer in anthracene- and biphenyl-cholorophyll derivatives

An intramolecular energy transfer from the ultraviolet absorbing donor to the pyro-pheophorbide a moiety occurs with high efficiency in model antenna compounds composed of 4-phenylbenzoic acid or anthracenecarboxylic acid and pyropheophorbide a. The energy transfer mechanism involves a Förster tyoe dipole-dipole coupling between the donor transition dipole(s) and the acceptor transition dipole(s) represented by the Soret band of the pyropheophorbide a moiety.     

仿生色素薄膜的荧光光谱研究

本文利用柱层析法从天然产物中提取分离了叶绿素a(Chl-a)和胡罗h素C(Car),并按Langmuir-Blodgett单分子膜技术制备了Chl-a单分子膜、Chl-a与Car的混合单分子膜。实验中还引入了硬脂酸起辅助支撑作用,选用的硬脂酸与Chl-a的摩尔比为10:1。挂膜载片为经过疏水处理的玻璃片。为制作模仿天然光合膜集光天线系统的功能,我们以Car为给体Chl-a为受体,Caf与Chl-a的摩尔比为5:1、50:1和125:1;这里选用的比例远大于集光天线的色素比例。用荧光光谱的测量发现,L-B膜内的色素分子有特殊的集聚态,这种状态有助于实现高效的激子转移。作者指出,由于二维的L-B膜上会发生Frster型和激子型两种能量转移的协同作用,所以在Car与Chl-a的摩尔比125:1时Chl-a的荧光无相应衰减。Chl-a单分子膜的荧光带为677nm和766nm。吸附在层析纸上Chl-a的荧光,仅长波带有明显位移。     

Study of energy transfer in a solution of coumarin 460 and rhodamine 6G by time-resolved laser-induced fluorescence spectroscopy

A multi-photon fast analog technique has been used to study nonradiative energy transfer from coumarin 460 to rhodamine 6G molecules. At low acceptor concentrations (<10^-2 mol/1) the fluorescence decay from coumarin deviates markedly from monoexponential behavior. The complex decay of the donor fluorescence reflects the time-dependent population of donor-acceptor pairs. Various energy transfer kinetics were investigated. The donor decay was found to be consistent with Förster kinetics and the critical energy transfer radius was found to be (5.46±0.10) nm.