大豆愈伤组织超弱光子辐射的双指数模型

在研究生物超弱光子辐射机理的基础上,建立了大豆愈伤组织超弱光子辐射的双指数模型.用20μW/cm2的UV-B辐射处理大豆愈伤组织2 h,测定处理后4 d内的超弱光子辐射.结果显示,双指数模型准确描述了大豆愈伤组织的超弱光子辐射及其在UV-B辐射下的变化,表明大豆愈伤组织的超弱光子辐射由快项和慢项两个部分组成;通过对双指...     

H_2O_2胁迫下菠菜叶片延迟发光动力学过程的分析

从生物延迟发光的机理出发,建立了生物延迟发光动力学方程,发现菠菜叶片的延迟发光随时间按双指数规律衰减,表明菠菜叶片延迟发光来源于快项和慢项两个发光系统,其动力学行为可以通过发光动力学参数积分强度、初始光子数和衰变时间定量描述。用体积分数为10%的H2O2溶液处理菠菜叶片,随着处理时间的延长,延迟发光积分强度和初始光子数快速降低,积分强度和初始光子数的变化呈正相关,表征快相和慢相发光特征的两个衰变时间表现出逐渐减小的趋势。积分强度和初始光子数的变化代表了叶片的光合能力和代谢强度的下降,衰变时间的变化暗示H2O2可能对叶片PSⅡ中D1和D2两条多肽造成了破坏。     

基于生物延迟发光评价玉米萌发期抗旱性的方法

玉米种子萌发期抗旱性评价是节水农业研究中的难点和热点问题之一,生物延迟发光分析技术的应用有可能解决这一问题。采用生物延迟发光评价方法研究了玉米种子萌发期的抗旱性能力,探讨了在渗透势-0.1 MPa和-0.3 MPa的PEG-6000溶液中萌发的玉米品种万瑞168号和堰单8号延迟发光的变化规律。结果表明,万瑞168号和堰单8号玉米品种的延迟发光积分强度都随着萌发进程逐渐升高,-0.1 MPa和-0.3 MPa的PEG-6000溶液形成的干旱胁迫对两个玉米品种延迟发光积分强度的升高有不同的抑制作用,胁迫强度越大,两个品种延迟发光积分强度的差异就越大。研究还发现,在干旱胁迫下萌发的万瑞168号和堰单8号玉米延迟发光相对变化率R_DL与种子萌发抗旱指数和储藏物质转运率的变化是一致的,依据干旱胁迫下种子萌发过程中延迟发光积分强度相对变化率R_DL的大小可以评价玉米种子萌发期抗旱性的强弱。     

Effect of phonon-induced desorption of oxygen molecules from the surface of a solid on adsorbate luminescence kinetics

A mathematical model to describe the pulse shape of delayed adsorbate fluorescence is proposed that accounts for desorption of oxygen molecules from the surface of a substrate induced by interaction with phonons. A numerical study of the temperature dependence of the probability of desorption of oxygen molecules from the substrate surface and of the luminescence intensity is carried out.     

Relation between delayed luminescence and functional state in soya seeds

Summary The possibility of using the parameters connected to delayed luminescence to detect thermal stress conditions in soya seeds is discussed here and the results of the measurement of photoinduced emission conducted on soya seeds characterized by a different vegetative vigour are presented. A phenomenological relationship between the total re-emission and the growth velocity was found. The distributions of the decay times relative to the different conditions of stress on the seeds have given indications towards the existence of different dynamics. On the basis of the results it seems that a correlation exists between the functional state of the seeds and delayed luminescence. The authors of this paper have agreed to not receive the proofs for correction.     

渗透胁迫下萌发小麦种子超弱光子辐射的变化及意义

为了将生物超弱光子技术应用于萌发过程中小麦种子的抗旱性评价,采用聚乙二醇处理萌发的小麦种子,跟踪测量了正常和渗透胁迫下小麦种子萌发过程中的超弱光子辐射,得到了小麦种子萌发过程中超弱光子辐射的自发发光和延迟发光信号.通过建立延迟发光动力学方程和数学拟合获得了种子萌发过程中延迟发光初始光强I（0）、衰减参量β、相干时间τ和延迟发光积分强度I(T),根据延迟发光积分强度和自发发光的生物学意义构建了用于描述细胞状态及其有序性的状态参量和序参量.实验结果发现:小麦种子萌发过程中,自发发光和延迟发光积分强度呈现阶跃式增长,细胞系统的状态参量和序参量也呈现阶跃式的增长,渗透胁迫抑制了这种增长,提示基于光子辐射的细胞系统的状态参量和序参量有可能作为种子抗旱性评价的物理指标.     

时间分辨光子计数系统的研究和应用

对由SPCM-AQR-14和MCS组成的时间分辨光子计数系统进行了研究,分析了SPCM和MCS的工作原理及主要特性.利用该系统对磷光物质和洋葱的延迟发光进行了测量,对它们的光子计数率曲线进行拟合,发现其光强衰减符合双曲线规律.     

Two-photon spectroscopy and microscopy of II–VI semiconductor nanocrystals

We review our recent nonlinear spectroscopies of nanocrystals and synthetic efforts to improve their luminescence properties. A two-photon spectroscopic study of CdSe nanocrystals as a function of size is presented and compared with predictions from the effective mass model with spherical confinement. We also detail our efforts at improving the luminescence properties of nanocrystals which have culminated in a 50% fluorescence quantum yield for inorganic capping of some sizes of CdSe nanocrystals. Finally, we present the application of two-photon microscopy to resolve fluorescence from single nanocrystals at room temperature and cryogenic temperatures.     

不同盐胁迫时间对叶片延迟发光的影响

以荷叶为实验材料,用BPCL型微弱发光测量仪,测定了不同浓度NaCl溶液处理不同时间的叶片的延迟发光,观察了延迟发光初始强度随处理时间的变化和延迟发光衰减参数随处理时间的变化。结果表明:随着胁迫时间的增加,0％,0.01％和0.10％处理的叶片,其延迟发光初始强度和衰减参数在一个小范围的上升之后一直呈下降趋势,1.00％,5.00％处理的初始延迟发光强度和衰减参数一直呈下降趋势,10.00％,20.00％处理的初始延迟发光强度和衰减参数从一开始就处于很低的水平。从整体上看,0.10％浓度处理对叶片延迟发光初始强度和衰减参数影响最小。整个实验表明,延迟发光可以规律性地反应盐胁迫对叶片的伤害程度。该结论为生物物理方法测量外界胁迫对叶片的影响具有一定的参考意义。     

UV-B诱导的大豆愈伤组织超弱光子辐射的动力学分析

为了研究细胞超弱光子辐射的动力学特征及其所揭示的生物学意义,用20 μW/cm2UV-B辐射大豆愈伤组织2 h,测定停止辐射后4 d内大豆愈伤组织在LED光诱导下的延迟发光.通过建立延迟发光动力学方程和数学拟合得到了大豆愈伤组织超弱光子辐射中的延迟发光积分强度、初始光子数、衰减参数和自发发光,讨论了这些发光动力学参数的生物学意义.研究结果表明,在停止UV-B辐射后的4 d内,大豆愈伤组织的光诱导延迟发光服从双曲线弛豫.动力学分析发现,延迟发光积分强度和初始光子数随处理后时间的进行呈现波动变化,停止UV-B辐射后,自发发光和丙二醛（MDA）含量均呈现升高的趋势,在辐射后2 d附近达到峰值,此后同步下降.用延迟发光积分强度和自发发光的比值定义细胞的状态参量Q和序参量R,发现UV-B辐射后大豆愈伤组织细胞Q值或R值的变化反映了UV-B辐射对大豆愈伤组织细胞的损伤以及细胞的恢复过程.     

Novel ultra-fast luminescence from incipient ion tracks of insulator crystals: electron–hole plasma formation in the track core

Measurements of fast luminescence decay and time-resolved spectra revealed novel ultra-fast luminescence with the lifetime of several tens ps in heavy-ion-irradiated single crystals of LiF, NaF, NaCl, KCl, KBr, KI, RbI, CsCl, CsBr, CsI, -alumina, and MgO. The luminescence is furthermore characterized by a super-linear increase in the efficiency with increasing excitation density, non-tailed decay curve, and temperature-insensitive decay-rate and yield. The results mean that the luminescence neither originates from localized excited states such as self-trapped excitons, free excitons, excited defects, and excited impurity centers nor their interaction. A process which does not contradict the experimental results is the formation of the e–h plasmas and the luminescence from them.     

Nature of delayed luminescence of N-methylindole and indole in the gas phase

We have studied the spectral characteristics and the kinetics of delayed (long-lived) luminescence of N-methylindole and indole in the gas phase. For N-methylindole, we observed delayed annihilation fluorescence, spectrally matching fast fluorescence. There is no delayed annihilation fluorescence for indole, but we observed a delayed luminescence band with wavelength at the maximum 535 nm, which we interpreted as luminescence of free radicals formed as a result of dissociation of the N-H bond. We hypothesize that the excited states of the free radicals arise as a result of nonradiative energy transfer from indole in the triplet state to indole free radicals in the doublet state. The lifetimes of the triplet states of N-methylindole and indole in the gas phase at T = 373 K, obtained from analysis of the delayed luminescence kinetics, are 2.5 msec and 1.0 msec. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 341–345, May–June, 2007.     

Spectroscopic study of the purple sulfur bacteria <Emphasis Type="Italic">Chromatium</Emphasis> sp. cultured in an aqueous medium

A spectroscopic study of the photosynthetic purple sulfur bacteria of the Chromatium genus is performed at various growth stages and under different culture conditions. Absorption and luminescence spectra of the bacterial cells are found to be useful in estimating their populations within certain concentration ranges. The relative proportion between the porphyrin and blue-band luminescence intensities can be used as an indicator of the physiological state of the culture.     

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.     

Low-dimensional transport of the triplet excitation of chrysene in porous matrices

The transport kinetics of the triplet state of solid chrysene embedded in the channels of various porous matrices is studied by observing its delayed luminescence. As matrices, a porous glass was used, which was obtained by leaching a sodium borosilicate glass and natural chrysotile-asbestos minerals. It is shown that the annihilation kinetics of the triplet states for all the samples studied is inhomogeneous, with the rate described by a power dependence on time. The value of the exponent depends on the system topology. Its values obtained from the analysis of the decay kinetics of delayed luminescence suggest that the geometry of the porous network of a sodium borosilicate glass is close to that of a three-dimensional percolation cluster.     

Self-trapping of the <Emphasis Type="Italic">d</Emphasis>-<Emphasis Type="Italic">d</Emphasis> charge transfer exciton in bulk NiO evidenced by X-ray excited luminescence

Soft X-ray (XUV) excitation did make it possible to avoid the predominant role of the surface effects in luminescence of NiO and revealed a bulk luminescence with a puzzling well isolated doublet of very narrow lines with close energies near 3.3 eV which is assigned to recombination transitions in self-trapped d-d charge transfer (CT) excitons formed by coupled Jahn-Teller Ni⁺ and Ni³⁺ centers. The conclusion is supported both by a comparative analysis of the CT luminescence spectra for NiO and solid solutions Ni _x Zn_{1 − x} O, and by a comprehensive cluster model assignment of different p-d and d-d CT transitions, their relaxation channels. To the best of our knowledge, it is the first observation of the luminescence due to self-trapped d-d CT excitons.     

Spontaneous luminescence of Eu<Superscript>3+</Superscript> ions in porous Y<Subscript>2</Subscript>O<Subscript>3</Subscript> nanospheres

A study of the luminescence of Eu³⁺ ions in Y₂O₃ nanospheres indicates a significant influence of the porous structure of nanoparticles on the luminescence of dopant ions. It is shown that filling the nanopores of initially porous Y₂O₃ nanospheres shortens the decay time of the spontaneous luminescence of doping europium ions. The change in the decay time is associated with the change in the effective refractive index of the porous nanospheres.     

Recombination luminescences resulting from the photoionization of N,N, N′, N′-tetramethyl-p-phenylenediamine in the low temperature matrices. II

The delayed luminescences and thermal glow curves from ultraviolet-irradiated rigid solutions of N, N, N′, N′-tetramethyl-p-phenylenediamine (TMPD) were investigated. The luminescence which comprises the flourescence and phosphorescence of TMPD was affected by the composition of the matrix and an added electron trap, that is, benzene, diphenyl, carbon dioxide, oxygen, etc. It was found that the glow curves for systems containing these electron-trapping reagents show two components, which are concluded to be due, respectively, to electrons trapped by the solvent and these reagents. The electrons trapped by the solvent are released at the lower temperature. These results are indicative of the capabilities of these added molecules to capture electrons in the rigid organic matrices. It has also been found that the glow curve for a concentrated solution of TMPD shows two maxima, suggesting that TMPD itself acts as an electron trap. Oxygen quenches the delayed luminescence and thermoluminescence strongly. The intensity ratios between fluorescence and phosphorescence were measured and correlated with the glow curves.     

X‐ray‐excited optical luminescence and X‐ray absorption fine‐structures studies of CdWO4 scintillator

X‐ray‐excited optical luminescence (XEOL) emission and excitation spectra as well as the EXAFS signal of CdWO₄ were measured in the energy region of the Cd and W absorption edges. From EXAFS refinement, structural parameters such as number of atoms, distance from the absorbing atom and width of coordination shells in the W neighborhood were determined. The role of W–O interactions on the intrinsic luminescence of CdWO₄ is discussed. The efficiencies of conversion, transfer and emission processes involved in the scintillation mechanism showed to be high when self‐trapped excitons are formed locally by direct excitation of W ions. Annihilation of these excitons provides the characteristic scintillation of CdWO₄, a broad band emission with maximum at 500 nm. The presence of two energetically different O positions in the lattice gives rise to the composite structure of the luminescence band, and no influence of extrinsic defects was noticed. A mismatch between the X‐ray absorption coefficient and the zero‐order luminescence curves corroborates that the direct excitation of Cd ions induces secondary electronic excitations not very effective in transferring energy to the luminescent group, WO₆.     

局域化电子态集体的荧光

载流子局域化对固体材料的光电性质有着深刻的影响。长期以来，人们就发现许多固体材料的发光异常行为与固体中电子态的局域化密切相关．文章介绍了作者最近所发展的一个局域态荧光模型．借助于一个新推导出来的局域化电子态的分布函数，文章作者发展出了该模型．该模型不但定量地解释了局域态集体荧光的温度依赖的异常现象，而且清晰地揭示了异常现象背后的载流子热动力学物理．文章还介绍了该模型在一些材料的荧光数据分析中的应用。