太阳辐射对溶解有机质荧光光谱特征的影响

利用三维荧光光谱研究了太阳辐射对溶解有机质(DOM)荧光光谱特征的影响。实验结果表明,太阳辐射使DOM的荧光发射光谱强度减弱。在三维荧光光谱图中,红枫湖样品的荧光峰A,C,南明河样品的荧光峰A,B,C,尤其是荧光峰C的λ_Exmax／λ_Emmax位置随着太阳辐射时间的延长而逐渐向短波长移动。从腐殖酸样品的三维荧光光谱图中则发现,原始样品荧光峰位置出现在λ_Ex／λ_Em=275/500 nm处,光照作用后出现两个荧光峰：λ_Ex／λ_Em=245/450 nm和310/450 nm。太阳辐射对DOM中不同荧光组分的光降解速率存在差异,从荧光峰A和C的比值r(A, C)随太阳辐射时间的变化趋势得知,荧光峰C比荧光峰A的荧光丢失速率更大,即对于太阳辐射作用更敏感。在整个光降解过程中,红枫湖、南明河DOM的r(A, C)值比标准腐殖酸Fluka HA的r(A, C)值的变化更显著。通过本研究表明,可以利用三维荧光光谱所提供的完整的光谱信息来研究DOM在光降解过程中的光谱特征以及物理化学组成等变化。     

城市污水的三维荧光指纹特征

传统表征有机物含量的水质参量如化学需氧量(COD)和生化需氧量(BOD)等只能表示总量,无法展示有机物成分.荧光光谱可以作为一种新型的水质表示方法,它像指纹一样与水样一一对应,被称为水质荧光指纹.采用三维荧光光谱(EEM)技术研究了城市污水荧光指纹特征,结果表明城市污水具有4个典型荧光区,各区的荧光中心、强度以及1区荧光中心λex=280 nm,λem=340 nm与2区荧光中心λex=225 nm,λem=340 nm的荧光强度的比值可以作为城市污水的主要荧光指纹特征.荧光指纹包含了大量污染物信息,通过与城市污水中典型污染物质的荧光光谱的比对,初步确定了各荧光区可能的荧光信号来源.荧光指纹法可表示有机物类型和含量,可作为化学需氧量和生化需氧量等参量的有益补充.     

溶解有机质的三维荧光光谱特征研究

利用三维荧光光谱研究了河流、湖泊等不同来源溶解有机质(DOM)的荧光光谱特性。河流DOM的三维荧光光谱图中含有类富里酸荧光峰A和C以及类蛋白荧光峰B和D,一般而言,类富里酸荧光峰强度比较大,或者只有类富里酸荧光,但是受人类活动污染河流DOM的三维荧光光谱图中具有极强的类蛋白荧光。同样,红枫湖DOM可以由陆源输入,还可以由水体内微生物活动产生,具有4个荧光峰,受人类活动影响比较显著的百花湖DOM则表现出强的类蛋白荧光。贵阳市地下水中DOM含量相对较低,一般只含有类富里酸荧光峰,但是若受生产生活污水污染,也可检测出强的类蛋白荧光峰。考察DOM含量(以DOC表示)与类富里酸荧光强度(peak C)以及在254 nm处紫外吸收光谱强度的关系时发现它们都具有良好的线性相关关系(r2＝0.82和0.95),而紫外区类富里酸荧光与可见区类富里酸荧光之间也存在良好的线性相关关系(r2＝0.96)。此外,pH对DOM的三维荧光光谱具有显著影响,并且类富里酸荧光峰A和C的pH值效应基本一致,荧光强度最大值出现在pH 10左右,类蛋白荧光峰B的pH值效应与之略有区别,荧光强度最大值出现pH 8.5左右。     

常规净水工艺去除有机物效果的三维荧光光谱分析法

有机物的荧光特性被广泛用来解析其在水体中的来源与分布。荧光光谱技术具有灵敏度高、选择性好、且不破坏样品结构的优点,非常适合用来研究有机物的化学和物理性质。运用三维荧光光谱分析技术对常规净水工艺中有机物的去除效果进行了研究。实验结果表明,三维荧光光谱技术能有效地揭示净水工艺中有机物的变化过程。在整个净水过程中,没有完全消除类富里酸荧光物质,也没有产生新的荧光物质。就类富里酸荧光物质的去除效果而言,混凝沉淀基本没有去除作用,过滤作用的去除率在5%～15%之间。     

Fluorescence of Substituted Tetraazabacteriochlorin

The spectral, energy, and polarization characteristics of the fluorescence of substituted tetraazabacteriochlorin in solution have been obtained. On the basis of the polarization spectrum, the electronic absorption spectrum is interpreted. The quenching of the fluorescence of bacteriochlorin on substitution of methine bridges by aza bridges is noted.     

Polarized Fluorescence of Jet‐Cooled Indole

The polarization of indole fluorescence on excitation in the P, Q, and R branches of a purely electron transition has been investigated. Relations are given to calculate the fluorescence polarization with arbitrary orientation of the dipole moments of transitions with absorption and emission and with excitation in the Q branch of the vibronic line. The coincidence of the measured (7.3%) and calculated (7.7%) values of the polarization degree confirms the reported intramolecular orientation of the dipole moment of transition. The measured fluorescence polarization degree on nonselective excitation is about 3%.     

Fluorescence polarization of helical molecules cooled in a supersonic jet

The β-binaphthylene oxide molecules studied under supersonic cooling conditions have a number of specific properties due to their nonplanarity. Low-frequency vibrations of the molecules in the excited S1 state are higher than the frequencies for the S0 state, and conversely the high-frequency vibrations have lower frequencies. The S₀-S₂ fluorescence excitation spectrum is structureless. The absence of a Q branch in the rotational contour of the line for the purely electronic transition indicates that it is substantially broadened and shifted toward shorter wavelengths as a result of rotational perturbations of the helical structure of the molecule. Multiplet lines in the spectra of β-binaphthylene oxide complexes with argon, krypton, and xenon correspond to different isomeric complexes. Their bond energies are below those observed previously for planar polycyclic molecules such as perilene, fluorene, and carbazole. The greater number of isomers with xenon is due to strengthening of the bond in the van der Waals complex and the nonequivalence of the position of the xenon atoms on the outside and inside of the helical molecule. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 473–477, July–August, 2006.     

Polarization of Fluorescence of Excimer Vinylpyrene

The polarization of the excimer luminescence of copolymers of 1-vinylpyrene with methyl methacrylate has been studied. The obtained polarization dependences in absorption and fluorescence spectra differ for luminescence in the region of the maximum of the excimer band and of its longwave portion, which is due to the influence of the nonequilibrium configurations of the dimeric complex on the polarization properties of its luminescence.     

Polarization Kinetics of the Fluorescence of Solutions of Complex Molecules Undergoing Impulse Optical Quenching

The influence of optical quenching on the polarization of the integral (in time) fluorescence of solutions of complex molecules using picosecond pulses has been investigated theoretically. The resulting dependences of the degree of polarization on the time shift of pulses for the case of a thin layer of a medium (with no regard for the change in the intensity of the pulses) are in qualitative agreement with the results obtained for quasistationary excitation. A calculation has been made for the case of an extended medium with regard for the amplification of the quenching pulse. It is shown that scanning of the degree of polarization along the length of the cuvette makes it possible to obtain additional information on the mechanism of optical quenching in solutions and on the routes of deactivation of the energy of the molecule's excited state.     

某兽药抗生素废水的荧光水质指纹特征

以某兽药抗生素废水为例,研究了基于三维荧光光谱的水质指纹(简称水纹)技术用于揭示废水有机成分性质的可行性。该废水具有4个典型水纹峰,峰的激发波长/发射波长分别为225/345,275/345,325/405和405/470 nm,编号A,B,C和D,各峰强度关系B>A>C>D。其中A峰和B峰的荧光强度较高,分别为(0.64±0.21)和(0.99±0.30) R.U,线性相关系数为0.95,且发射波长相同,很可能是同一种物质产生的。各水纹峰强度与COD都有明显的正相关性,线性相关系数R2达到0.66～0.70。C峰对应的有机物部分降解或降解速率较低,而其余3个水纹峰对应的有机物可以被较好降解。出水中新出现的荧光峰260/425 nm可能是废水微生物处理过程中新生成的腐殖质。上述研究表明,该兽药抗生素制药废水具有独特的水纹特征,水质指纹鉴别技术可以作为水体中识别该废水存在的新方法,水纹信息还可以反映废水有机物总量和有机成分的性质,对难降解废水的处理设计和运行均有一定价值。     

城市污水的三维荧光指纹特征比较

监控污水偷排以及诊断污染类型是当前水质预警研究的重点问题.由于污染物种类和含量各异,污水的荧光光谱与水样一一对应,被称为污水的"荧光指纹".以两种城市污水为例,探索了利用荧光指纹参数区分污水的可行性.两种城市污水荧光指纹特征的主要差异在于:A厂污水最强荧光峰强度(I280/340)平均为8308±1560,次强荧光峰强度(I225/340)平均为6350±1173;B厂污水I280/340平均为5929±400,I225/340平均为4224±90;平均最强和次强荧光峰强度之比分别为1.31和1.41.荧光指纹特征可以区分这两种城市污水的差异.     

饱和激发情况下的荧光关联谱测量

研究了激发光增强时其对荧光关联谱(FCS)测量的影响. 强激发光产生的饱和激发会改 变激光诱导荧光的空间分布函数,从而影响FCS的测量结果. 首先根据饱和吸收的物理模型,推导出强激发光情况下有效探测区域变化的定量公式,获得了FCS测量所得到的粒子数和扩散时间与饱和激发光强和激光光强的函数关系,并用于消除饱和吸收造成的系统误差.采用Monte-Carlo模拟方法和实验,对理论分析结果进行了验证. 这将有助于完善FCS分析方法的理论模型,为高激发光强度下的FCS探测提供依据. 关键词： 荧光关联谱 饱和激发 Monte-Carlo模拟     

准波导结构染料薄膜中荧光和放大自发辐射的泄漏模特性

通过理论分析和实验测量,研究准波导结构染料薄膜中荧光和放大自发辐射（ASE）的泄漏模特性。理论上,考虑薄膜传输损耗及染料吸收损耗对准波导结构中泄漏模特性的影响,通过计算准波导结构中泄漏模的光强分布,给出了相应的物理机制分析;实验上,以棱镜为衬底制备染料薄膜,根据棱镜耦合法测量不同出射角对应的泄漏模的荧光与ASE光谱,验证理论的正确性。此外,采用光束分析仪探测各泄漏模式对应的荧光及ASE的光强分布,研究了准波导结构中ASE的激励特性。结果证明,荧光峰及ASE峰的红移以及泄漏模的激发是界面反射率、薄膜传输损耗及染料吸收损耗等共同作用的结果,而界面反射率对ASE泄漏模激发特性有重要影响,染料的自吸收是荧光峰及ASE峰产生红移的主要因素。     

Steady-State and Time-Resolved Fluorescence Polarization Behavior of Acenaphthene

Steady-state and time-resolved fluorescence polarization studies have been carried out on acenaphthene (ACE) in low-temperature glass solutions and at room temperature. In the low-temperature glass the fluorescence polarization values vary considerably with both emission and excitation wavelength. There is a time dependence (on the nanosecond time scale) of the fluorescence anisotropy, r(t), at 77 K, which has a strong dependence upon the excitation and emission wavelengths. Under these conditions, the time-dependent decay of the anisotropy is not attributable to chromophoric motion. The observations are consistent with emission from two closely lying and interconverting excited states. Rate constants for the photophysical processes involved have been determined by fitting the data using a model proposed by Fleming et. al. The results are discussed with particular reference to the care required in using dynamic fluorescence polarization measurements to determine energy transfer rates in systems containing this chromophore.     

Spectral-Luminescent Properties of Substituted Tetraazachlorin and of Its Zinc Complex

The spectral, energy, kinetic, and polarization characteristics of fluorescence of di(tert-butylbenzo)barrelene-substituted tetraazachlorin and of its zinc complex in solutions are measured. The results are compared with similar data for tetraazaporphin and unsubstituted chlorin. Quenching of the fluorescence of the tetraazachlorins under investigation is noted.     

Fluorescence spectra of human neuroglobin

The fluorescence quenching spectra of neuroglobin by cesium ion, iodide and acrylamide, synchronous fluorescence spectra, and 8-anilino-1-naphthalene-sulfonic acid binding property were investigated. The intrinsic fluorescence of neuroglobin cannot be effectively quenched by cesium ion, with a Stern–Volmer constant of 0.23?±?0.01. However, it can be significantly quenched by iodide and acrylamide with Stern–Volmer constants of 1.30?±?0.04 and 4.56?±?0.10, respectively. The results of synchronous fluorescence spectra indicate that tryptophan residues are distributed on both the surface and interior of neuroglobin molecule, but most of them are buried in the hydrophobic interior. The neuroglobin molecule has different conformational states in various pH solutions.     

人工湿地中水溶性有机物三维荧光光谱特性的分析

采用三维荧光技术,结合荧光区域一体化积分的分析方法,研究了一个表面流+垂直流复合人工湿地处理两条污染河流废水中水溶性有机物的荧光特征变化,结果表明:(1)该人工湿地中水溶性有机物腐殖质的主要来源为生物代谢输入而非陆源输入;(2)在表面流人工湿地的后段,部分类蛋白类物质转化为类富里酸类物质,表明经过表面流人工湿地处理之后,水溶性有机物的组成成分发生显著变化,并且有机物结构趋于稳定。而垂直流人工湿地对类腐殖酸物质峰具有明显的削弱作用;(3)表面流人工湿地对水溶性有机物的结构转化意义重大,可以显著提高水溶性有机物的稳定性。表面流+垂直流的复合人工湿地工艺对水溶性有机物具有良好的去除效果。     

pH值对秸秆腐殖化溶解性有机质紫外光谱和荧光光谱的影响

秸秆是农业生产的主要副产物,也是农业面源污染的新源头。秸秆还田能有效解决其减量化和资源化利用问题,国家“十二五”规划已明确提出“加大秸秆还田力度,保障农业的稳产、增产和可持续发展”。现阶段,对于典型地区不同环境条件下还田秸秆腐殖化行为的研究不多,同时对于腐殖化组分的精细化检测和分析也有待加强。针对黄土区秸秆还田问题,以紫外光谱法和荧光光谱法为切入点,分析pH值对腐殖化产物溶解性有机质(Dissolved organic matter, DOM) 性质的影响,深度揭示秸秆腐殖化过程的内在本质。结果表明：在200～700 nm波长范围内,DOM的紫外吸收强度先增加后减小,主要吸收峰出现于240 nm附近。相对于中性(pH 7)体系,酸性(pH 6)和碱性 (pH 8和9) 条件下的最大吸收波长λ_max值红移。SUVA₂₅₄,E₃/E₄和A₂₅₃/A₂₀₃比值的规律性变化说明反应体系腐殖化程度较低,这与秸秆腐殖化周期较短有关。黄土浸提液DOM的荧光峰主要位于λ_ex/em=250/330和λ_ex/em=325/450区域,分别归属为紫外区类富里酸荧光峰和可见光区类富里酸和腐殖酸类物质荧光峰。随着腐殖化体系pH值的升高,荧光峰位发生红移,表明DOM苯环结构逐渐增多,共轭度有所增加,同时在λ_ex/em=250/450附近检测到新荧光峰。pH值对荧光强度的影响主要体现在紫外区类富里酸荧光峰,峰强先升高后下降,而对可见光区荧光峰强影响不大,这与浸提液的缓冲效应、荧光猝灭(或副反应)和DOM组分结构有关。紫外光谱和荧光光谱能够一定程度上阐释pH值对秸秆腐殖化DOM性质的影响。     

Study of Spectroscopic Properties of Yb-doped Calcium Fluorapatite

The spectroscopic performance of Yb-doped calcium fluorapatite (Yb:FAP) was assessed by measuring polarization absorption spectra, polarization emission spectra and fluorescence lifetime. The emission cross section has been evaluated using the absorption cross section and principle of reciprocity. The π polarization absorption and emission cross sections of Yb3+ in FAP are found to be substantially larger than those of other Yb-doped media. Favorable spectroscopic parameters show that Yb:FAP crystal is more desirable for many diode-pumped solid state laser application with low- and medium-power in the near future.     

Study of Spectroscopic Properties of Yb-doped Calcium Fluorapatite

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