用光学-光学双共振光谱技术研究Cs蒸气中的共振交换碰撞

利用窄带半导体激光器泵浦所有具有相同z分量速度的基态Cs原子至激发态,研究了Cs(6P_3/2, v) +Cs(6S_1/2, v′)→Cs(6S_1/2, v) +Cs(6P_3/2, v′)的共振交换碰撞过程。与泵浦光反向平行的另一单模激光器激发6P_3/2至8S_1/2态,以检测6P_3/2态原子的速度分布,确定激发态原子的热能化效应。通过测量8S_1/2→6P_1/2荧光的尖峰强度与相应的多普勒背景的强度比,得到共振交换碰撞速率系数为k=9.62×10-7 cm3·s-1。证明了在纯碱金属蒸气中,由共振交换机制产生的热能化效应的大小比由速度改变碰撞引起的大3个数量级。     

化学发光法测定巯嘌呤的含量

在流动注射系统中,利用巯嘌呤在碱性Luminol-K₃Fe(CN)₆化学发光体系中发光信号强的特点,建立了一种测定巯嘌呤的新方法。在优化条件下,方法的线性范围是1.02×10-7～1.02×10-9mol·L-1, 回归方程是Y=36.315c+140.72(Y是相对发光强度,c是巯嘌呤浓度与10-8 mol·L-1的乘积), 相关系数是0.998 2,检出限(S/N=3)是6.33×10-10mol·L-1,RSD为3.54%（c_i=2.0×10-9mol·L-1, n=12）。该法用于合成样品的测定,简便、灵敏、快速,结果令人满意。文章简要地探讨了巯嘌呤在碱性Luminol-K₃Fe(CN)₆化学发光体系中的化学发光机理：在反应过程中,产生大量的过氧自由基和羟基自由基,自由基与鲁米诺反应,形成激发态的鲁米诺分子,鲁米诺分子由激发态回到基态产生化学发光现象。     

三乙烯四胺基双(二硫代甲酸钠)及其重金属配合物的光谱研究

采用红外光谱、紫外光谱、原子吸收光谱及元素分析研究了三乙烯四胺基双(二硫代甲酸钠)(DTC-TETA)的结构及其重金属配合物的配位行为。在DTC-TETA的红外光谱图中,在1 461～1 388 cm-1处和1 174～996 cm-1处分别出现含有部分双键性质的CN键和CS键的特征吸收峰;在紫外光谱图中,分别在265和290 nm处出现两个最大吸收峰,分别对应于N…C…S基团的π—π*跃迁和S…C…S基团中硫原子上非键电子向共轭体系的n—π*跃迁;元素分析结果表明该化合物中碳、氢、氮、硫的摩尔比近似为2∶4∶1∶1。在Cu(Ⅱ), Cd(Ⅱ), Zn(Ⅱ), Ni(Ⅱ)配合物的紫外光谱图中分别在紫外区的321, 310, 311, 325 nm处出现新的最大吸收峰。流动注射与火焰原子吸收联用分析结果表明DTC-TETA对铜、镉、镍、锌等重金属离子的络合能力强于二乙基二硫代氨基甲酸钠(DDTC)。     

少量氩气对大气介质阻挡放电光谱的增强

采用双水电极介质阻挡放电装置,测量了大气介质阻挡放电的光谱,并研究了加入少量氩气后光谱的变化。在300～800 nm波长范围内,发现了氮分子(C3Π_u(v′=0)→B3Π_g(v″=0～4))的光谱和氮原子(4d4D_7/2→3p4P0_1/2)的光谱。在大气中加入少量氩气后,击穿电压明显降低,在相同电压条件下,氮分子光谱线和氮原子光谱线强度都增强。同时,加入氩气后上述谱线的半宽度明显加大。由于谱线的Stark加宽与电子密度成正比, 说明加入氩气后等离子体的电子密度增大, 使得电子碰撞激发氮分子及氮原子的概率增大,激发到较高激发态的氮原子或氮分子增多,从而使光谱强度增强。     

催化动力学分析法测定粗硒粉中微量碲的研究

提出基于Te(Ⅳ)催化S2-还原亚甲基蓝褪色反应,建立了新的测定微量碲的动力学分析方法。研究了催化反应条件,并测定了催化反应的表观活化能为68.94 kJ·mol-1,反应速率常数为1.63×10-2 s-1。Te(Ⅳ)浓度在20～220 ng·mL-1范围内服从比尔定律,回归曲线的线性方程为y=0.003 8x+0.219 1,相关系数r=0.999 5,方法的检出限为3.04 ng·mL-1。应用于粗硒粉中微量碲的测定,相对标准偏差为3.1%(n=7),加标回收率为98.4%～100.4%。     

紫细菌Rb.Sphaeroides 601外周捕光天线(LH2) B800吸收带的超快动力学研究

利用从紫细菌Rb.sphaeroides 601 所提取出的外周捕光天线LH2以及其不同pH值酸化样品(部分和全部去除B800分子LH2)并采用不同波长下的飞秒单色抽运探测技术详细研究了LH2中B800吸收带内的激发态动力学过程.通过对野生型与部分/完全去B800分子LH2的比较研究，分析了B800吸收带激发后所表现出的丰富变化的动力学过程，研究结果表明激发B800带的动力学过程中包含着B850上激子带的直接激发而产生的对激发态动力学的贡献. 关键词： 紫细菌外周捕光天线LH2 部分和全部去除B800分子LH2 激发态动力学的演变 飞秒抽运探测     

FAAS法测定甘青铁线莲花中微量元素

采用浓硝酸-高氯酸(4∶1)溶解消化方法进行样品处理,用火焰原子吸收光谱法对甘青铁线莲花中K,Mg,Ca,Na,Fe,Zn,Mn,Cu,Cd,Ni和Co(11种)微量元素进行了分析测定,测定介质为4%硝酸溶液。实验研究了测定不同元素仪器的最佳工作条件、方法的准确性和精密度。结果表明,在选定的测定条件下,甘青铁线莲花中各元素间相互干扰小,对测定结果无明显影响。方法的标准曲线线性关系良好(r=0.987 1～1.000 0),方法回收率(n=7)在98.3%～105.1%之间,RSD值(n=7)在0.23%～1.07%,能用于甘青铁线莲花中多种微量元素的同时测定,该方法快速、简单,准确度和精密度均较好,并能达到分析要求。甘青铁线莲花中Ca,Mg,K,Cu,Fe,Zn,Mn,Na和Co含量分别为206.30,284.50,3 415.20,0.116 6,62.171,3.275,67.826 5,28.00,0.133 3 mg(100 g)-1,未检出Cd和Ni。研究结果为进一步探讨甘青铁线莲草药的功效提供了理论依据。     

一种分子内电荷转移荧光探针与牛血清白蛋白相互作用的研究

应用荧光光谱法研究了分子内电荷转移荧光探针1-酮-2-(对二甲氨基苯亚甲基)-四氢萘(KDTN)与牛血清白蛋白(BSA)的相互作用。研究表明,KDTN能与牛血清白蛋白形成稳定的络合物从而猝灭BSA的荧光,疏水作用是结合反应的主要作用力,二者的结合常数为3.274 2×104 L·mol-1,结合位点数n=0.938 9(30 ℃时)。同时考察了KDTN的加入对BSA构象的影响。     

胶束体系中曲克芦丁的荧光特性及其分析应用

对曲克芦丁在胶束体系中的荧光性质进行了研究。实验发现在NaAc-HAc缓冲体系中,曲克芦丁自身具有较弱的内源性荧光,加入适量的表面活性剂十二烷基苯磺酸钠-6(SDBS-6),可使曲克芦丁与SDBS-6形成胶束配合物,体系微环境发生改变,使荧光发射强度显著增强,荧光增强程度与曲克芦丁的含量在一定范围内呈良好的线性关系。据此提出了基于SDBS-6增敏胶束荧光光谱法测定微量曲克芦丁的新方法。对测定条件进行了详细研究,结果表明： 在pH 5.53的NaAc-HAc缓冲体系中,当最大激发波长λex=350.0 nm,最大发射波长λ_em=456.3 nm时,方法线性范围为1.6×10-6 mol·L-1～8.0×10-10 mol·L-1,检出限1.1×10-10 mol·L-1,相对标准偏差为1.7%(n=11,c=6.0×10-7 mol·L-1)。方法用于片剂和注射液中曲克芦丁的测定,回收率为98.5%～100.4%,结果令人满意。     

紫细菌B800缺失LH2能量传递模型的构建及性质

构建B800缺失LH2对于阐明光合作用中光能传递的分子机制与捕光复合体组装机制具有重要意义。采用吸收光谱、荧光光谱、分子筛层析、超滤和SDS-PAGE等方法研究了紫细菌两个典型种外周捕光复合体 (LH2) 约800 nm特征光谱 (B800) 细菌叶绿素 (BChl) 缺失能量传递模型的构建方法及性质。结果表明：在pH 8.0 Tris-HCl(10 mmol·L-1) 缓冲液中,0.08% SDS能够使来自Rhodobacter azotoformans的LH2 B800 BChl特异性解离,解离体系中加入10%(φ) 甲醇,通过超滤脱除游离BChl,构建了B800缺失LH2,但该缺失模型不够稳定。在pH 1.9缓冲液中,来自Rhodopseudomonas palustris的LH2 B800 BChl能够特异性解离,通过层析得到两个组分。一个组分的B800 BChl不能通过层析脱除,能够重新自组装成LH2。另一个组分为B800缺失LH2,该缺失模型稳定。两种LH2均存在2类以上B800 BChl结合位点,并得到了两类Rhodopseudomonas palustris B800 BChl解离的LH2,但未发现类似紫色硫细菌中的B800吸收光谱劈裂现象。B800缺失LH2均未呈现约800 nm特征荧光光谱。采用两种方法构建了两个物种B800缺失LH2能量传递模型。利用BChl与缺失B800 LH2结合能力不同的特性,将Rhodopseudomonas palustris中的LH2分成两个类型,实现了异质性亚基LH2的分离。     

Effect of the mutation of carotenoids on the dynamics of energy transfer in light-harvesting complexes （LH2） from Rhodobacter sphaeroides 601 at room temperature

Energy transfers in two kinds of peripheral light-harvesting complexes (LH2) of {Rhodobacter sphaeroides} (RS) 601 are studied by using femtosecond pump--probe spectroscopy with tunable laser wavelength at room temperature. These two complexes are native LH2 (RS601) and green carotenoid mutated LH2 (GM309). The obtained results demonstrate that, compared with spheroidenes with ten conjugated double bonds in native RS601, carotenoid in GM309 containing neurosporenes with nine conjugated double bonds can lead to a reduction in energy transfer rate in the B800-to-B850 band and the disturbance in the energy relaxation processes within the excitonic B850 band.     

The Paths of Excitation Energy Deactivation in LH1 Reduced Mutant and Wild-Type Strains of Rhodobacter sphaeroides

The P3 mutant of Rhodobacter sphaeroides had an altered ratio of reaction center to core (LH1) and peripheral (LH2) antenna complexes compared to the wild-type strain. Intracytoplasmic membranes from these two strains were purified and then resuspended in buffer or immobilized in isotropic and stretched polymer film. The absorption, photoacoustic, and delayed luminescence spectra were measured. The ratios of infrared absorption and photoacoustic bands (located at about 880 nm for LH1 and at 850 and about 800 nm for LH2) as well as the half-width of these bands are different for the LH2 and LH1 mutants and wild-type strain. The whole yields of thermal deactivation of the two strains were comparable, but in the absorption region of LH2 it was slightly lower in the case of the mutant than for the wild-type strain. The delayed luminescence main maxima were observed at about 860 and 700 nm. The first one could be due to emission of bacteriochlorophyll a of LH2 complexes. The emission at about 700 nm is probably due to dihydromesochlorophyll, which is usually, to some extent, produced from bacteriochlorophyll a in bacterial complexes. The delayed luminescence emission is competing with excitation energy transfer to the reaction center. The intensity of the delayed luminescence of the mutant strain was higher than that of the wild-type strain when both samples were excited in a region of carotenoid absorption. The mutant contains less carotenoids than the wild-type strain. Carotenoids work as efficient antenna. When they at a lower concentration the excitation can be trapped more easily by some chlorophyll-like pigment isolated from the excitation energy chain. The dependences of delayed luminescence spectra on the light polarization and excitation wavelengths for the wild-type strain and for the mutant were different. The anisotropy of delayed luminescence showed that bacteriochlorophyll a molecules of different orientations were contributing to the mutant and the wild-type strain emission. All the results suggest that the excitation energy transfer from the antenna to the reaction center in the mutant and the wild-type strain is similar.     

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.     

利用CARS技术研究激发态Rb2和H2的碰撞转移

利用相干反斯托克斯拉曼光谱(coherent anti-stokes Raman spectroscopy,CARS)探测技术,研究了激发态Rb2与H<,2>间的电子-振转能级的碰撞转移.扫描CARS谱确认了H<,2>分子仅在v=1,J=1,2及v=2,J=0,1,2能级上有布居,用n1,n2,n3,n4,n5分别表示...     

FDMR of Carotenoid and Chlorophyll triplets in light-harvesting complex LHCII of spinach

Fluorescence detected magnetic resonance (FDMR) of the light-harvesting complex LHCII of the spinach photosynthetic machinery revealed triplet contributions both from Carotenoids and Chlorophylls. All three carotenoids present in the complex (lutein, neoxanthin and violaxanthin) are evidenced as triplet states in the FDMR signals obtained as variation of the emission intensity of the Chlorophylls in the 680 nm region. The triplets show ?D? values of 0.0401, 0.0388 and 0.0382 cm^?1. A comparison with the results obtained by ADMR (Absorption Detected Magnetic Resonance) is made and discussed. An interesting concentration effect is discovered and discussed in terms of specific interactions between carotenoids and chlorophyll molecules. Signals are also obtained by microwave sweeping in the Chlorophyll regions and one triplet is detected (?D?=0.028?0.029 cm^?1). The polarization of the carotenoid signals is discussed in terms of singlet-singlet and triplet-triplet energy transfer between carotenoids and chlorophylls, also with the help of double resonance experiments. Double resonance experiments involving both carotenoids and chlorophylls signals gave negative results. It is not possible as a consequence to assess that the chlorophyll whose triplets levels are scanned in the FDMR spectra are functionally connected to the carotenoids.     

含氮配体构筑的单核锌Zn(Ⅱ)/双核Cu(Ⅰ)配合物蓝光材料的结构和荧光性能研究

采用溶剂热法合成出单核Zn(Ⅱ)配合物[Zn(2,6-PDA)(phen)H₂O]·H₂O (1)和双核Cu(Ⅰ)配合物{[Cu(μ-Ⅰ)(phen)H₂O]·H₂O}₂ (2) (2,6-H₂PDA=2,6吡啶二甲酸,phen=1,10-邻菲罗啉),通过单晶结构测试、元素分析和红外吸收光谱对结构进行表征,并研究了两种配合物在二甲基亚砜(DMSO)中及固态时的荧光光谱及DMSO溶液中紫外可见吸收光谱。配合物1和2的最大吸收峰分别出现在253和242 nm附近,相比于配体吸收峰均发生红移,在1和2中,主要呈现出中心金属离子微扰的phen的π→π*的跃迁,且吸收强度强于phen,说明中心金属离子与phen配位后,增加了有机配体在紫外区的吸收,利于配体对能量的吸收。1在DMSO溶液中的荧光发射峰位于361,379和392 nm,在固态时的荧光发射峰为407,434和467 nm,2在DMSO溶液中的荧光发射峰出现在422,443和461 nm,固态时荧光发射峰在442,469,501 nm,均呈现蓝光发射。配合物1和2的固态荧光发射光谱与相应的DMSO溶液中的发射峰相比分别红移55和23 nm,这是由于在固态时配合物1和2的分子中的π—π堆积相互作用和分子间的相互作用,特别是配合物2中存在强烈的Cu(Ⅰ)…Cu(Ⅰ)相互作用,降低了体系前线轨道之间的能量差。     

Microwave and optical spectroscopy of carotenoid triplets in light-harvesting complex LHC II of spinach by absorbance-detected magnetic resonance

Absorbance-detected magnetic resonance (ADMR) of the light-harvesting complex LHC II of spinach revealed two triplet contributions, having differentD values, but equalE value (|E|=0.00379 cm^?1). The two triplets are assigned to two of the three carotenoids present in LHC II: lutein (|D|=0.03853 cm^?1) and neoxanthin (|D|=0.04003 cm^?1). The ADMR-detected Triplet-minus-Singlet (T—S) optical difference spectrum of the carotenoid (Car) triplet transition of LHC II showed, apart from bands in the Car absorption region, a contribution in the chlorophyll (Chl) absorption region due to a change in interaction between lutein and Chla at 670 nm, and neoxanthin and Chla at 670 and 677 nm. From Linear Dichroic (LD-)ADMR-detected LD-(T—S) spectra we have determined that the tripletz-axis (which corresponds roughly to the polyenal axis) of lutein and neoxanthin makes an angle of 47° and 38° with theQ _y transition moment of their adjacent Chla molecules, for the Chls absorbing at 670 and 677 nm, respectively. TheT _z triplet magnetic transition moment of lutein is parallel to the lutein singlet and triplet absorptions, whereas theT _x axis of neoxanthin makes an angle of about 20 degrees with the optical transition moments of the carotenoid molecule. The major Chla absorption bands of the optical absorption spectrum and the ADMR-detected T—S spectrum is best explained by assuming that all Chla is present in dimers. It is proposed that a free Chl dimer absorbs at 664 and 670 nm, whereas a Chl dimer bound to a carotenoid absorbs at 670 and 677 nm.     

Quantum Dynamics of Entanglement and Single Excitation Transfer in LH1-RC-Type Trimer

In this paper, we study quantum dynamics of entanglement and single excitation transfer (SET) in an LH1-RC-type trimer which can describe a basic unit cell in the LH1-RC complex in the photosynthetic process. It is shown that there exists a sudden change of entanglement at the critic point of quantum phase transition (QPT) of the system at low temperatures, the entanglement sudden change caused by the QPT is suppressed at higher temperatures. We investigate the influence of environment on entanglement and SET. We show the generation of the dephasing-assisted entanglement between a donor and an acceptor and the existence of the steady-state entanglement, and demonstrate the entanglement transfer from donor-donor entanglement to donor-acceptor entanglement in the dynamic evolution. We reveal the close relation between the SET probability and donor-acceptor entanglement. Especially, we find that the SET probability is proportional to the amount of donor-acceptor entanglement under certain conditions.     

血红蛋白与铜(Ⅱ)-茜素红S络合物相互作用的研究

采用UV-Vis光谱法,研究在pH 4.2的H₃PO₄-KH₂PO₄缓冲溶液中血红蛋白(Hb)与铜(Ⅱ)-茜素红S(ARS)络合物的反应。结果表明：Hb与Cu(Ⅱ)-ARS络合物相互作用形成红色的离子缔合复合物,该复合物的最大吸收波长为537 nm。在此波长下测得复合物的组成为n_Hb∶n_Cu(Ⅱ)∶n_ARS=1∶4∶8,表观摩尔吸光系数为1.52×105 L·mol-1·cm-1,Hb浓度在1.0×10-7～2.0×10-6 mol·L-1范围内与吸光度呈线性关系,回归方程为A=0.026 9+151 675ｃ(mol·L-1),相关系数r=0.997 2。考察了溶液酸度、试剂用量、反应时间与温度、离子强度、表面活性剂等因素对Hb-Cu(Ⅱ)-ARS复合物形成的影响,并对反应机理做了初步探讨,发现Hb与Cu(Ⅱ)-ARS络合物之间主要以静电引力相结合。进一步考察了常见氨基酸及金属离子对Hb-Cu(Ⅱ)-ARS复合物形成的影响。