光系统Ⅱ捕光复合物中能量传递动力学研究

采用时间分辩荧光光谱技术研究捕光色素复合体(LHCⅡ)荧光的时间光谱特性.以脉宽为120fs、重复率为82MHz、波长为360nm～420nm激光激发LHCⅡ样品荧光.原始信号经过数据处理,多指数拟合,解得了能量在LHCⅡ中传递的时间常量分别为320±10fs、4.0±0.1ps、20.0±0.1ps.相对应的各组分荧光占总荧光的百分比分别为3.4%、50%、46.6%.经过全局分析,解得荧光强度随波长变化曲线,其三个峰值波长分别为652nm、673nm、692nm(以去离子水为悬浮液)和658nm、687nm、700nm(以酒精为悬浮液).根据LHCⅡ结构以及荧光的时间、光谱特性分析,认为320±10fs的时间组分属于一个单体内同一膜平面中Chlb→Chla的能量传递时间;4.0±0.1ps的时间组分属于同一单体中不同膜平面间Chlb→Chla和Chla→Chla的能量传递时间;20.0±0.1ps的时间组分属于不同单体之间、不同三聚体之间Chla→Chla的能量传递时间.     

Fenna-Matthews-Olson捕光复合物中的冗余结构

研究了绿色硫细菌中捕光天线复合物Fenna-Matthews-Olson的一个子单元和反应中心的能量传递.通过细菌叶绿素分子的能量和耦合强度,构建了包含反应中心的哈密顿量及约化模型.通过级联运动方程研究了不同分子间和反应中心的激子布居演化.计算了Fenna-Matthews-Olson及其约化模型的二维三阶光子回波谱,获得能量传榆过程中不同激子态间的相干性.结果表明在能量捕获过程中,Fenna-Matthews-Olson复合物存在冗余结构.     

捕光复合物LHCⅡ的荧光动力学特性

采用时间分辨荧光光谱技术,在273 K下用波长为507 nm的光激发对菠菜光系统Ⅱ捕光天线LHCⅡ的光谱特性和时间特性作了研究.将获得的荧光光谱进行高斯解析,得到6个光谱组分,反映了光谱特性：Chl a６６２６６０／６６１、Chl a/b６７２６７０／６７１、Chl a６８３.5６８０／６８１和Chl a６９９.9６９５.0,而中心波长为738.6nm、761.0 nm的光谱组分则可能对应着主发射峰的振动副带.通过对荧光衰减曲线进行三指数时间拟合,得到激发能在LHCⅡ中传递的时间常数：8.8 ps、500 ps、1.6 ns,并分析得出了时间常数与光谱组分的对应关系.     

JMCT光子-电子耦合输运模拟计算研究

为满足光子-电子耦合输运应用模拟需求,自主研发了JMCT光子-电子耦合输运功能,并实现了多种光电耦合输运处理方式,以便满足不同的工程需求。利用光子-电子耦合输运典型算例验证了JMCT光子-电子耦合输运功能的正确性,并应用到了探测器响应函数模拟、闪光照相模拟计算中,表明JMCT在实验核物理、核分析技术应用等方面发挥着越来越重要的作用。     

Fenna-Matthews-Olson捕光复合物中的冗余结构（英文）

研究了绿色硫细菌中捕光天线复合物Fenna-Matthews-Olson的一个子单元和反应中心的能量传递.通过细菌叶绿素分子的能量和耦合强度,构建了包含反应中心的哈密顿量及约化模型.通过级联运动方程研究了不同分子间和反应中心的激子布居演化.计算了Fenna-Matthews-Olson及其约化模型的二维三阶光子回波谱,获得能量传输过程中不同激子态间的相干性.结果表明在能量捕获过程中,Fenna-Matthews-Olson复合物存在冗余结构.     

圆极化光中∑-型原子的相干囚禁

文章证明：对圆极化光中的∑－原子，存在着由它其中的两个态构造的一个特殊的相干叠加态，当原子最初处于这个态时，它以后将总是几乎处于这个态，而原子处于其他态的概率接近于0。     

光折变非相干耦合空间孤子族统一理论

理论证明了稳态条件下有分压电阻和e偏振非相干均匀背景光辐照的光伏光折变晶体中存在非相干耦合空间孤子族.这种孤子族是由多束偏振方向和波长都相同的互不相干光束耦合形成的.孤子族各分量成分光束都能在晶体中稳定传播.当入射光束中只含有一个或两个分量时,空间孤子族退化为空间孤子或非相干耦合孤子对.当分压电阻、 e偏振背景光、 外加电场和光伏场取不同值时,可获得14种光折变非相干耦合空间孤子族.先前已报道的非相干耦合空间孤子族都可在不同条件下从本文中得到.     

超导-量子点耦合系统的相干输运

研究超导-量子点耦合系统的量子相干输运,主要考虑系统在微波场及Zeeman场作用下的输运电流特性.应用BCS平均场理论及非平衡格林函数技术,对超导体各极作Bogoliubov变换使其对角化,从而推导出用格林函数表示的电流公式.对几种特殊情况进行数值分析,计算出电流-电压、电流-磁场及直流Josephson电流的共振隧穿曲线.     

CH3S(X2E)中电子-振动-自旋耦合能级的理论计算

基于透热模型,我们独立开发一套完整的程序包,结合采用量子化学从头计算法研究了CH3S(X2E)自由基中电子-振动-自旋轨道相互作用。透热势能面通过CASPT2/cc-pVTZ方法计算获得。通过对比前人计算结果,根据我们的程序包计算得到的电子-振动-自旋能级较以往的报道符合得较好,并能很容易扩展到更大的分子体系。     

单分子瞬时带电态中电子-振动耦合特性的亚纳米荧光成像研究

分子内的电子-振动耦合特性对电子跃迁和分子光谱特征有重要影响,是分子光谱学研究的中心课题之一.本文利用具有亚纳米分辨的扫描隧道显微镜诱导发光成像技术,通过高度局域的隧穿电子来充电激发单个苝四甲酸二酐分子,研究该分子的瞬时带电态(–2价态)的电致发光特性以及相应的电子-振动跃迁的实空间成像特征.具有亚分子分辨的光谱成像结果表明, 0-0纯电子跃迁的光子图“两点”亮斑特征是沿分子短轴的,而某些电子振动峰的光子图“两点”亮斑方向却沿着分子长轴,相对于0-0跃迁光子图的图案旋转了90°.这表明这些振动态所对应的跃迁偶极取向是沿着分子长轴的,相对于0-0的纯电子跃迁的偶极取向发生了明显的变化,说明这些分子振动模式在电子的跃迁过程中对电子态空间分布产生了重要扰动.理论计算表明,这种跃迁偶极的变化源自于与Herzberg-Teller贡献相关的电子-振动耦合.反对称的振动模式对纯电子跃迁的跃迁密度、特别是具有较大跃迁密度的原子产生了强烈的动态扰动,或者说对分子波函数进行了“整形手术”,从而诱导出沿分子长轴方向的跃迁电荷振荡,引发沿分子长轴的跃迁偶极.本文结果为从实空间的视角来直观理解分子瞬时带电态中...     

两种铽配合物与PVK混合体系的发光机理研究

研究了稀土配合物Tb(p-MBA)₃phen(样品Ⅰ)和Tb(p-ClBA)₃phen(样品Ⅱ)与导电聚合物材料PVK掺杂体系的光致发光和电致发光特性。发现在样品Ⅰ与PVK混合薄膜的光致发光中,除了三价铽离子的发光外,还能看到明显的PVK的发光;而在电致发光中,PVK的发光完全被抑制,只能看到Tb3+的绿光发射。对样品Ⅱ与PVK的混合发光层,无论其光致发光谱还是电致发光谱,都没有看到410 nm处PVK的发射。进一步测量两种材料的激发光谱,初步探讨了器件的发光机理。样品Ⅰ的发光可能来源于两个方面,一是PVK到稀土配合物的不完全的能量传递,二是由于载流子俘获机理;样品Ⅱ的发光则是由于PVK到稀土配合物的完全的能量传递。     

Decoherence-and Dimerization-assisted Energy Transport in Protomer of Light-Harvesting Complexes

We have investigated the dynamics of a protomer coupled to two different decoherent environments,each in a configuration called the spin star configuration.Using the quantum mechanics method,in different situations,we obtain the analytical expressions for the transition probability in the protomer system.In thermal equilibrium,there exist well-defined ranges of parameters for which decoherent interaction between the protomer and the environment assists energy transfer in the protomer system,while in pure quantum mechanics states,the decoherent interaction assists energy transfer for an eigenstate but against energy transfer for quantum mechanics averages.In particular,we also find that the dimerization of two bacteriochlorophylls in protomer can always assist energy transfer in certain parameter range,and in the appropriate spin bath energy,the efficiency of energy transport is sensitively depended on the temperature of environments.     

Energy Transfer in the Light-Harvesting Complexes of Purple Bacteria

In this paper, we use a nonlinear decohering quantum model to study the initial step of photosynthesis which is an ultrafast transfer process of absorption the sunlight by light-harvesting complexes and electronic excitation transfer to the reaction center (RC). In this decohering model, the Hamiltonian of the system commutes with the systemenvironment interaction. We take B850 ring of light-harvesting complex Ⅱ (LH-Ⅱ) in purple bacteria as an example to calculate the efficiency of the energy transfer as a function of time. We find that the environmental noise can make the LH-Ⅱ have stable energy transfer efficiency over a long time. This is to say that the environmental noise which is the decohering source has advantage of the energy transfer in the process of photosynthesis.     

New type charge transfer states in ferroelectric oxides: Actual problems

Brief review of recent theoretical and experimental studies of Charge Transfer Vibronic Excitons and induced by defects, charge transfer - lattice ground states in ferroelectric oxides and analysis of actual problems is presented. Predictions of new effects related to such charge transfer states are made.     

Coherence and stacking interaction in DNA duplex

It is shown that a chaotic (deterministic) order, rather than a stochastic randomness, controls the energy minima positions of the stacking interactions in the DNA sequences on large-scales. The chaotic order results in a long-range chaotic coherence between the two complimentary DNA-duplex?s strands. A competition between this broad-band chaotic coherence and the resonance coherence produced by genetic code has been briefly discussed.     

Coherence and squeezing in superpositions of spin coherent states

We consider the superpositions of spin coherent states and study the coherence properties and spin squeezing in these states. The spin squeezing is examined using a new version of spectroscopic squeezing criteria. The results show that the antibuching effect can be enhanced and spin squeezing can be generated in the superpositions of two spin coherent states.     

Coherence resonance in an excitable potential well

The excitable behaviour is considered as motion of a particle in a potential field in the presence of dissipation. The dynamics of the oscillator proposed in the present paper corresponds to the excitable behaviour in a potential well under condition of positive dissipation. Type-II excitability of the offered system results from intrinsic peculiarities of the potential well, whose shape depends on a system state. Concept of an excitable potential well is introduced. The effect of coherence resonance and self-oscillation excitation in a state-dependent potential well under condition of positive dissipation are explored in numerical experiments.     

Coherence and stochastic resonance in a delayed bistable system

Both coherence resonance (CR) and stochastic resonance (SR) in a delayed bistable system driven by additive and multiplicative white noises and a weak harmonic excitation are studied by using the theory of two-state model. For the weak noise intensity and delayed feedback, the analytic expressions of power-spectrum and linear-spectrum amplification are derived to quantify the CR and the SR, respectively. The study shows that the peak in the power spectrum at the frequency corresponding to the time delay attains the maximum for an appropriate amount of additive noise intensity and the CR manifests. The feedback gain plays an important role in the SR. For example, the positive feedback gain enhances the SR, but the negative feedback gain suppresses the system output and makes the SR disappear. Moreover, the system also exhibits the frequency SR.     

倒Y型四能级系统中自发辐射诱导相干对弱探测场的色散和吸收特性的影响

本文研究了倒Y型四能级系统中自发辐射诱导相干对探测场的色散和吸收特性的影响。在稳态条件下利用密度矩阵微扰理论推导出了密度矩阵的迭代解。数值分析了自发辐射诱导相干对线性和非线性折射率和吸收系数的影响,分析了泵浦场和耦合场偏离双光子共振对弱探测场色散和吸收特性的影响。研究发现自发辐射诱导相干使弱探测光的线性和非线性折射率增强,同时形成一个较宽的透明窗。在没有自发辐射诱导相干的情况下,泵浦场和耦合场偏离双光子共振对探测场的线性和非线性折射率影响明显,在有自发辐射诱导相干的情况下,泵浦场和耦合场偏离双光子共振使得探测场的线性透明窗变窄,非线性吸收增加。     

紫细菌捕光天线LH2中的超快光物理研究

采用飞秒泵浦探测技术研究了紫细菌外周捕光天线LH2中的超快光动力学过程.从B800蓝侧的激发态动力学中观察到B800到B850的能量传递时间,实验结果与理论计算结果的差别说明激发B800时可能引起B850上激子带的直接激发,或存在由B800到B850上激子态的能量传递通道.在B800红侧激发的动力学过程中,漂白信号前端存在的一个快速光吸收信号主要来源于B850上激子带的直接激发.在天然RS601和突变体GM309的LH2中,800 nm激发时的动力学过程都表现为一个类似的光漂白过程,动力学曲线的衰减时间常量在天然LH2中明显快于突变体中,说明在GM309中B800到B850的激发能传递速率有所降低.而在845 nm激发下两个样品中的快过程类似,但慢过程在GM309中有所增快,激发态中的能量重新分布包括逆向的能量传递也受到类胡萝卜素微结构的影响.