甲醇分子荧光光谱的研究

采用Roper Scientific SP_2558多功能光谱测量系统对色谱纯甲醇溶液在紫外光激励下产生的荧光光谱进行了实验研究。实验结果表明,甲醇溶液能吸收紫外光并向外发射峰值位于340nm附近的荧光光谱,同时得到了能产生荧光光谱的最长激励光波长的临界值为245nm左右。对甲醇分子发射荧光的机理进行了讨论,给出了与实验结果相一致的理论分析。研究甲醇的荧光光谱可为其作为有机溶剂和催化剂时对其他有机大分子相关光谱的影响提供理论和实验上的参考,并可直接为荧光探针技术的发展提供服务。     

荧光波长对共焦显微镜成像特性的影响

导出了共焦显微镜中不同荧光波长情况下的荧光功率传输函数、三维脉冲响应函数（3D－PSF）和三维光学传递函数（3D－OTF）。结果表明，不同的荧光波长对共焦显微镜的空间截止频率、分辨率、光学传递函数存在明显的影响。当激发波长与荧光波长的比值下降到一定程度时，可以看到明显的失锥现象。     

PHOTOPHYSICAL STUDIES ON ORGANIC COMPOUNDS——TIME-RESOLVED TRANSIENT ABSORPTION SPECTRA STUDIES ON TRIPHENYLAMINE IN VARIOUS SOLVENTS

The transient absorption spectra of triphenylamine (TPA) in various solvents have beeninvestigated by the methods of nanosecond laser photolysis. The lifetimes of TPA were meas-ured. In hexane and ethanol, the transient absorptions of triplet state and triplet excimer ofTPA were observed. However, the transient absorptions of the TPA cation radical was alsoobserved in acetonitrile besides that of the triplet TPA monomer and excimer. According tothe experimental facts, the transient photophysical mechanism of TPA in various solvents hasbeen proposed.     

金属UV光敏薄膜的实验研究

介绍了金属Au和Al薄膜的制备方法，研究了其UV光电发射特性，并做了寿命实验。给出了在真空中以及放在大气中光电发射衰减的情况。指出了其在大气中达到一个稳定值之后，再反复多次暴露于干燥大气时仍存在一个稳定光电发射周期的特点，可长达数月。金属薄膜有一个最佳膜层厚度，这与光电发射逸出深度、膜层结构等密切相关。近年来光电子成像器件发展非常迅速，急需光电发射均匀的面电子源，因此在微通道板的特性测试和像管的动态模拟中，Au和Al金属薄膜成为被优选的对象。     

SHI induced modification in CR-39 polycarbonate by positron annihilation lifetime studies

CR-39 is a polycarbonate widely used as SSNTD for recording nuclear charged particles and in other applications. Latent ion tracks produced in the polymers due to the damage produced by the passage of Swift Heavy Ions contain amorphous material with highest degree of disorder, changing the free volume properties which have strong correlation with the macroscopic properties of the material. Positron annihilation lifetime spectroscopy (PALS) provides direct information about the dimension, content and hole size distribution of free volume in polymers. The effect of irradiation of ⁴⁰Ar (14.9 MeV/n) ions on CR-39 polycarbonate by Positron Annihilation Lifetime Spectroscopy (PALS) is reported here. PALS provides a non-destructive and non-interfering probe, having high detection efficiency for free volume hole properties. From o-Ps lifetime mean free volume hole radius and average free volume of the micro-voids have been calculated. PAL measurement shows an increase in free volume on irradiation.     

Influence of relaxation effects on probabilities of the 2s2p35S2－2s22p2 3P1，2 intercombination transitions in NII

Transition probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} intercombination transitions in NII have been calculated by using a large-scale multiconfiguration Dirac－Fock method. In the calculation the most important effects of relativity, correlation, and relaxation are considered. From the calculated transition probabilities, the lifetime of the 2s2p^3 {}^5S_2 metastable state is derived. The result is in excellent agreement with the latest experimental result. In the meantime the influence of anomalously strong relaxation effects on probabilities of the 2s2p^3 {}^5S_2－2s^22p^2 {}^3P_{1,2} lines in NII have been found.     

Integral Method o Reciprocity in the Spectroscopy of Laser Crystals with Impurity Centers

A new method of determining the stimulated emission cross-section spectra from the absorption cross-section spectra, which we call the integral method of reciprocity, is suggested it does not require knowledge of the structure of the impurity-center electron levels. Based on this method, formulas for calculating the radiation lifetime of impurity centers in crystals have been derived. The effectiveness of the integral method of reciprocity was demonstrated in determining the stimulated emission cross sections and radiation lifetime of an ytterbium ion in the laser crystals Yb³⁺:KYW and Yb³⁺:KGW.     

用激光感生荧光法测量亚稳态原子寿命

本文用激光感生荧光法(LIF)分析了Gd原子亚稳态能级215cm~(-1),533cm~(-1),999cm~(-1)在原子束中的速度分布。由原子束轴线上两不同点上的亚稳态原子速度分布的变化得到了亚稳态原子的寿命。理论分析和实验结果表明这是一种简单、灵敏并且有效的亚稳态原子寿命测量方法。     

Effects of oxygen in gamma irradiated aromatic polyesters in film

The effect of gamma irradiation in air is investigated on four thermoplastic polyesters (PET, PBT, PEN, PCT-co-ET) in films containing aromatic rings, in order to evaluate the influence of aromatic density and the role of oxygen on radiation resistance. Physical-chemical-nuclear analyses were used to this purpose. EPR measurements were carried out to detect radical stability against oxygen permeation. Viscometric investigations reported a very similar trend for all the investigated polyesters: a chain break effect that decreases at the highest doses. FT-IR analyses focused on the formation of oxidized species. Positron annihilation spectra pointed out a decrease of the intensity of ortho-positronium formation, while its lifetime remains unchanged with radiation dose.     

Determination of the Constants of Binding of Acridine Dyes with Micelles of Sodium Dodecyl Sulfate Using the Quenching of Delayed Fluorescence by Heavy Atoms

The constants of binding dye molecules with the micelles of sodium dodecyl sulfate are determined using quenching of delayed fluorescence of acridine dyes by sodium iodide in aqueous–micellar solutions. Kinetic equations have been composed that describe the processes of deactivation of the excited states of dyes. By solving these equations at the concentration of the quencher sodium iodide corresponding to the minimum lifetime of triplet states and at the concentration of micelles corresponding to the least value of the delayed fluorescence quenching rate constants, we obtained the constants of binding dyes with micelles equal to 1.3·10⁷, 2.9·10⁷, and 3.1·10⁷ M^–1 for trypaflavine, acridine orange, and acridine yellow, respectively. We calculated the rate constants of quenching of the triplet states of the molecules of dyes by iodide ions (I ^–) that decreased in transition from trypaflavine to acridine orange and acridine yellow.