双光子激发钠分子荧光寿命的测量

本文研究了钠分子高位三重态荧光寿命的测量方法。利用倍频晶体模拟等频双光子激发过程和对荧光衰变曲线求卷积的数值计算方法。有效地消除了测量仪器响应函数的影响,测量了Na_2高位三重态2~3∏_g→a~3∑_u~+的荧光寿命。     

Ruby fluorescence lifetime measurements for temperature determinations at high (p,T)

The lifetime of the ruby R₁ fluorescence line was measured as a function of pressure (up to about 20 GPa) and temperature (550 K) in an externally heated diamond anvil cell (DAC). At constant temperatures, the lifetime is increasing linearly with increasing pressure. The slope of the pressure dependence is constant up to a temperature of 450 K and it is decreasing at higher temperatures. At constant pressure, the lifetime is exponentially decreasing with increasing temperature. The (p, T)-dependence can be parametrized by the combination of a linear and an exponential function. This allows an accurate p, T-determination by the combination of fluorescence spectroscopy using Sm²⁺-doped strontium tetraborate and lifetime measurements of ruby, as the energy of the Sm²⁺ fluorescence is nearly temperature-independent.     

单光子调制频谱用于量子点荧光寿命动力学的研究

本文开展了基于单光子调制频谱测量量子点荧光寿命动力学特性的研究.在脉冲激光激发下,对探测到的量子点单光子荧光信号进行频谱分析以获得荧光调制频谱,研究发现特征频谱信号幅值与荧光寿命之间存在确定的非线性对应关系.这种单光子调制频谱方法能有效消除背景噪声和单光子探测器暗计数的影响,用于分析量子点荧光寿命动力学特性时在准确度以及时间分辨率方面都较目前普遍采用的荧光衰减曲线寿命拟合方法呈现出明显优势:当涨落误差为5%时,寿命测量准确度提高了一个数量级;当涨落误差和偏离误差均为5%时,对动力学测量效率以及时间分辨率提高了四倍以上.因此单光子调制频谱可以作为获取量子点在短时间尺度内激发态动力学信息的一种有效技术手段.     

{Cu2[C12H18N2O7S]2[C10H8N2]}n聚合物的合成及晶体结构

采用铜(Ⅰ)盐和邻香草醛缩氨基甲磺酸席夫碱以及4,4'-联吡啶在乙醇溶液中合成了具有三维网状的配位聚合物,通过元素分析、红外光谱对配位聚合物进行了表征,并利用X射线单晶衍射仪对其结构进行了鉴定.晶体结构分析表明,该标题配合物属单斜晶系,空间群P2(1)/c,晶胞参数为a=1.1956nm,6=0.8464nm,c=2....     

Nd∶GGG晶体荧光寿命的测试及受激发射截面的计算

介绍了荧光寿命的测试原理。设计了荧光寿命测试系统。利用脉冲取样技术测试了Nd∶GGG晶体的荧光寿命,约为250μs。采用英国的荧光光谱仪,在室温条件下,用波长为488nm的Ar离子激光器激发Nd:GGG晶体,获得了Nd:GGG晶体的荧光光谱,计算出的Nd∶GGG晶体的受激发射截面σ(λ)为21.57×10-20cm2。     

Nd:GGG晶体荧光寿命的测试及受激发射截面的计算

介绍了荧光寿命的测试原理.设计了荧光寿命测试系统.利用脉冲取样技术测试了Nd:GGG晶体的荧光寿命,约为250μs.采用英国的荧光光谱仪,在室温条件下,用波长为488nm的Ar离子激光器激发Nd:GGG晶体,获得了Nd:GGG晶体的荧光光谱,计算出的Nd:GGG晶体的受激发射截面σ(λ)为21.57×10-20cm2.     

SrTiO3：Cr^3＋晶体荧光光谱及荧光寿命的热效应

测量了SrTiO~3:Cr(3+)晶体5～200K的荧光光谱和寿命。并用单声子吸收与发射过程相关的电子振动跃迁理论较好地解释了150K以下荧光寿命随温度变化的规律。     

金属有机物化学气相法制备YBCO超导薄膜研究

运用金属有机物化学气相沉积法(MOCVD),在LaAlO3(LAO)单晶上沉积YBa2Cu3O7-x(YBCO)超导薄膜。通过使用优化的进液装置,使金属有机源连续、稳定地输送至蒸发皿进行闪蒸。通过优化总气压、氧分压等生长条件,获得高质量的YBCO薄膜。在固定的温度条件下,调节反应总气压和氧分压,在总压为380Pa,氧分压为180Pa获得YBCO薄膜临界电流密度Jc=0.6MA/cm2。随着氧分压增大,YBCO薄膜产生a轴取向,(005)峰向左偏移,且薄膜中的Cu/Ba由1.0变化至1.63。在Cu/Ba=1.48时,YBCO薄膜结构与性能较优。     

水污染物的激光诱导荧光测定

简单介绍了激光诱导荧光（ＬＩＦ） 产生的机理。以３ 倍频Ｎｄ：ＹＡＧ 激光（ 波长３５５ｎｍ） 为激发源,研究了水中几种典型污染物的ＬＩＦ 谱。结果表明这些污染物可用ＬＩＦ 方法加以探测和鉴别。     

(Au)核(Ag)壳纳米微粒-火焰原子吸收光谱法测定过氧化氢

在90 ℃水浴条件下,以粒径为10 nm的纳米金做晶种,用柠檬酸三钠还原硝酸银,制备了平均粒径为30 nm的（Au）核（Ag）壳纳米微粒,用高速离心纯化除去过量的柠檬酸三钠获得了较纯的（Au）核（Ag）壳纳米微粒。在pH 3.8的HAc-NaAc缓冲溶液中,Fe2＋催化H2O2反应产生的羟基自由基可氧化（Au）核（Ag）壳纳米微粒生成银离子。离心后,离心液中的银离子可用火焰原子吸收光谱法在328.1 nm波长处测量。随着H2O2浓度增大,离心液中银离子浓度增加,其吸光度值增加。H2O2浓度在2.64～42.24 μmol·L-1范围内与上清液中银离子的原子吸收值ΔA呈良好的线性关系,回归方程为ΔA=0.014c-0.013 1, 相关系数为0.998 4,检出限为0.81 μmol·L-1 H2O2。当用于水样中H2O2的测定,获得了满意的结果。     

Dissociation of H_2 on Mg-coated B_(12)C_6N_6

The dissociation of H_2 molecule is the first step for chemical storage of hydrogen, and the energy barrier of the dissociation is the key factor to determine the kinetics of the regeneration of the storage material. In this paper, we investigate the hydrogen adsorption and dissociation on Mg-coated B_(12)C_6N_6. The B_(12)C_6N_6 is an electron deficient fullerene, and Mg atoms can be strongly bound to this cage by donating their valance electrons to the virtual 2p orbitals of carbon in the cluster. The preferred binding sites for Mg atoms are the B_2C_2 tetragonal rings. The positive charge quantity on the Mg atom is 1.50 when a single Mg atom is coated on a B_2C_2 ring. The stable dissociation products are determined and the dissociation processes are traced. Strong orbital interaction between the hydrogen and the cluster occurs in the process of dissociation, and H_2 molecule can be easily dissociated. We present four dissociation paths, and the lowest energy barrier is only 0.11 eV, which means that the dissociation can take place at ambient temperature.     

Determination of electrostatic parameters of a coumarin derivative compound C_(17)H_(13)NO_3 by x-ray and density functional theory

This work is devoted to the experimental determination of the electrostatic properties of the molecular 4-methyl-7-(salicylidene amino) coumarin(C17H13NC3) using high resolution x-ray diffraction data. The experimental results are compared with those obtained theoretically from calculation type ab initio. The experimental investigation is carried out using the molecular electron charge density distribution based on the multipolar model of Hansen and Coppens. However the theoretical calculations are conducted by using the molecular orbital B3 LYP method and the Hartree–Fock(HF) approximation with the basis set 6-31G(d,p) implemented in the Gaussian program. In addition to the structural analysis,the thermal agitation is also analyzed in terms of rigid blocks to ensure a better precision of the results. Subsequently, the electrostatic atomic and molecular properties such as the net charges, the molecular dipolar moment to highlight the nature of charge transfer existing within the molecule studied are derived. Moreover, the obtained electrostatic potential enables the localization of the electropositive and the electronegative parts of the investigated molecule. The present work reports in detail the obtained electrostatic properties of this biologically important molecule.     

乙醇-水团簇分子形成激基缔合物及荧光发射机理研究

紫外光照射具有特殊结构的长链式乙醇-水团簇分子时,处于激发态和基态的分子形成了分子间激基缔合物,并发射荧光.根据实验结果分析和能量转移理论可知,激发态单分子和激基缔合物间形成了电子迁移洛合物并发生了能量转移.根据Mulliken理论对电子迁移洛合物进行量子力学处理,得出了团簇分子在基态和激发态能量E^b_N和E^b_E以及由于电子迁移而引起的静电相互作用能E^s;根 关键词： 荧光光谱 激基缔合物 电子迁移 乙醇-水团簇     

Recovery of lifetime distributions from frequency-domain fluorometry data by means of the quantified maximum entropy method

The new quantified version of the maximum entropy method allows one to recover lifetime distributions with a precise statement of the accuracy of position, surface, and broadness of peaks in the distribution. Applications to real data (2,6-ANS in aqueous solutions of sodium dodecyl sulfate micelles of -cyclodextrin) are presented.Died on September 1, 1993.     

Phase transition and thermal expansion property of Cr_(2-x)Zr_(0.5x)Mg_(0.5x)Mo_3O_(12) solid solution

Compounds with the formula Cr2-xZr0.5xMg0.5xMo3O12（x = 0.0, 0.3, 0.5, 0.9, 1.3, 1.5, 1.7, 1.9） are synthesized, and the effects of Zr4＋ and Mg2＋ co-incorporation on the phase transition, thermal expansion, and Raman mode are investigated. It is found that Cr2-xZr0.5xMg0.5xMo3O12 crystallize into monoclinic structures for x 〈 1.3 and orthorhombic structures for x _〉 1.5 at room temperature. The phase transition temperature from a monoclinic to an orthorhombic structure of Cr2Mo3O12 can be reduced by the partial substitution of （ZrMg）6＋ for Cr3＋. The overall linear thermal expansion coefficient decreases with the increase of the （ZrMg）6＋ content in an orthorhombic structure sample. The co-incorporation of Zr4＋ and Mg2＋ in the lattice results in the occurrence of new Raman modes and the hardening of the symmetric vibrational modes, which are attributed to the MoO4 tetrahedra sharing comers with ZrO6/MgO6 octahedra and to the strengthening of Mo-O bonds due to less electronegativities of Zr4＋ and Mg2＋ than Cr3＋, respectively.     

Powder x-ray diffraction and Rietveld analysis of (C_2H_5NH_3)_2CuCl_4

Structural properties of the organic-inorganic hybrid(C_2H_5NH_3)_2CuCl_4 have been investigated by means of x-ray powder diffraction and Rietveld analysis. A structural phase transition from Pbca to Aba2 occurs at T_4= 240 K, which results in a paraelectric–ferroelectric phase transition. The release of the Jahn–Teller distortion with increasing temperature toward T_4 is revealed by the structural analysis.     

氢化物发生-原子荧光光谱法对水中总硒含量测试方法改进研究

为探寻简单可靠的水中硒测试方法,在采用国标中氢化物发生-原子荧光光谱法测定水样中的硒含量时,对影响水中硒消解的因素如消解温度和盐酸用量等进行了比较,并且确定了一种简易可行的新方法,即水样在100℃消解时加入3mL盐酸。采用3,6和10μg.L-1硒标液测定了方法的精密度和准确度,测试的结果分别是2.96,5.43和9.66μg.L-1,回收率在90.50%～98.67%。同时,用不同方法测试了29个水样中的硒含量,国标中氢化物发生-原子荧光光谱法测定水样中的硒含量的标样的误差为8.95%～25.46%,新方法测定标样的误差为1.33%～3.40%。新方法相对于中华人民共和国标准GB/T 5750.6-2006水中硒测试方法而言,具有操作过程简单、易控制和可靠性强、经济等特点。     

分子高激发振动的经典代数方法研究——以C_2H_2的C-H弯曲振动为例

本文以目前探讨得较多的C2H2的CH弯曲振动为例,说明如何应用代数方法来研究分子的高激发振动。由于分子的高激发振动态具有很强的模间非线性偶合以及能量的传递,传统的动力学方法似乎很难有效地用来研究其性质。问题的核心是高激发振动态由于其量子数很大,因此具有经典(或半经典)的性质。同时模间能量的传递可以用二次量子化算子来表示,而这些算子所具有的代数性质,使得人们可以用几何的概念来描述其性质。因此,整个问题就变为用几何的观点来分析分子的高激发振动态。最后,我们用所得的经典的代数哈密顿量和哈密顿方程对CHtrans弯曲和cis弯曲振动模间能量的传递速度与体系所含能量之高低的关系做了探讨     

Investigation of acetone-butanol-ethanol (ABE) fermentation by fluorescence

Photophysical techniques have potential for the development of optical sensors in monitoring and controlling fermentors. In the particular case of acetone-butanol-ethanol (ABE) fermentation, carried out by bacteria of the speciesClostridium acetobutylicum, we have developed two studies based on fluorescence spectroscopy. First, we measured the intrinsic fluorescence of NADH related to bacteria metabolism, leading to a linear relationship between the NADH specific fluorescence and the specific rate of butyric acid production. At the same time, we have correlated enzymatic activities (acetate kinase, butyrate kinase, acetoacetate decarboxylase) with NADH specific fluorescence. Second, we studied the fluorescence polarization of extrinsic DPH (1,6-diphenyl-1,3,5-hexatriene) related to membrane fluidity. A simultaneous increase in both DPH anisotropy (order parameter increase) and butanol production is observed. Even though these results seem contradictory, because of the well-known fluidizing effect of butanol on lipids, they can be explained by a homeoviscous response ofC. acetobutylicum to the presence of butanol during fermentation. Thus the apparent changes in fluidity could be the result of the adaptative membrane alteration.     

Synthesis and spectral-luminescent properties of poly(N-isopropylacrylamide)

The spectral-luminescent characteristics of water and methanol solutions of polymers containing tetraphenylporphyrin substituents were investigated. The water-soluble polymer was obtained by the interaction of poly(N-isopropylamide) containing N-oxysuccinimide substituents with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin. From the synthesized polymer its analog with Zn-porphyrin substituents was obtained. This phenomenon is attributed to the specific features of the conformational behavior of polymeric chains in water solutions. Water solutions of polymers experience a thermally reversible phase transition upon heating, which is accompanied by a considerable enhancement of light scattering. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 483–487, July–August, 2000.