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61.
V. B. Nazarov V. G. Avakyan T. G. Vershinnikova M. V. Alfimov 《Russian Chemical Bulletin》2000,49(10):1699-1706
Fluorescence of the inclusion complexes with different compositions formed by naphthalene-h8, naphthalene-d8, 2,7-dimethylnaphthalene (DMN), and 2-benzylnaphthalene (BN) with β-cyclodextrin (β-CD) in water was studied. Two types of fluorescence are observed, monomer (MF) and excimer (EF_ fluorescence. The excimer fluorescence of the 2∶2 complex emitted by aggregated light-dispersing crystals forming a precipitate, whereas is the MF is concentrations, EF predominates for the resulting complexes. A proposed structure of the inclusion complexes was derived from MNDO/PM3 semiempirical quantum-chemical calculations. The EF is caused by the structure of the complex, in which both naphthalene molecules are separated by a distance of 4.7 Å: they lie in parallel orientation to each other, whereby one ring is displaced from the other by one-fourth of the length of the naphthalene ring. The complexes of 2,7-DMN and 2-benzylnaphthalene with β-CD do not exhibit EF. For the 2∶2 complex of 2,7-DMN with β-CD, this is due to the fact that the aromatic fragments are removed too far from one another 2-Benzylnaphthalene is unable to form an inclusion complex with β-CD, in whose structure the aromatic fragments inside the cavity could be arranged in parallel planes; instead, it forms a 1∶2 complex with β-CD. 相似文献
62.
研制了一台KrF大能量准分子激光器,激光器采用紧凑型Chang电极与紫外火花预电离的结合, 实现了激活区大面积的均匀辉光放电,利用LC反转倍压以及一级磁脉冲压缩技术在放电电容上实现了峰值电压40 kV、脉冲上升时间约为100 ns的高压快脉冲激励。研究了工作气体含量对激光器能量输出的影响,在总气压3.3105 Pa,F2/He, Kr, Ne体积分数比值为1.97∶3.18∶94.85,充电电压27 kV时,得到了738 mJ的单脉冲能量输出,激光近场光斑30 mm14 mm,在充电电压23 kV时,全电效率最高,达到2.0%。 相似文献
63.
Excimer emission of caffeine with α-CD and β-CD were studied by UV-visible, fluorescence, time-resolved fluorescence, FTIR, 1H NMR and molecular modelling techniques. Changes in the absorbance and fluorescence and lifetime of the caffeine with cyclodextrin (CD) solutions indicate (i) caffeine shows dual emission in the CD solutions, (ii) normal emission originates from a monomer and the longer wavelength emission is due to excimer and (iii) in both CDs caffeine forms 1:2 inclusion complex. Carbonyl stretching frequency moved to higher wave numbers and broadening of the N–H stretching band indicated the formation of inclusion complex. The resonance of the methyl protons of caffeine show remarkable upfield or downfield shift in the 1H NMR, which indicates imidazole ring of the caffeine entrapped in the CD cavities. Investigations of energetic, thermodynamic and electronic properties of PM3 computational calculations confirmed the stability of the inclusion complex. 相似文献
64.
Photophysical and photochemical processes of riboflavin (vitamin B_2) by means of the transient absorption spectra in aqueous solution 总被引:1,自引:0,他引:1
Using time-resolved techniques of 337 and 248 nm laser flash photolysis, the photo-physical and photochemical processes of riboflavin (RF, vitamin B2) were studied in detail in aqueous solution. The excited triplet state of riboflavin (3RF*) was produced with 337 nm laser, while under 248 nm irradiation, both 3RF* and hydrated electron (eaq) formed from photoionizationcould be detected. Photobiological implications have been inferred on the basis of reactivity of 3RF* including energy transfer, electron transfer and hydrogen abstraction. The RF.+ was generated by oxidation of SO4.- radical with the aim of confirming the results of photolysis. 相似文献
65.
用微透镜阵列在单模光纤中写入长周期光纤光栅的新方法 总被引:2,自引:0,他引:2
报道了用微透镜阵列、几百个准分子激光脉冲有效地写入长周期光纤光栅的新方法。 相似文献
66.
V.?V.?BryukhanovEmail author A.?M.?Ivanov I.?G.?Samusev 《Journal of Applied Spectroscopy》2005,72(6):804-808
The processes of homo-and hetero-triplet—triplet annihilation (TTA) of Bengali rose on the spongy silicon surface have been
investigated. It has been found that upon pulse photoexcitation on the silica surface photophysical processes involving the
triplet states of monomers and their associates can develop. It has been shown that the processes of hetero-TTA are inhibited
due to the decomposition of associates under the influence of hexane molecules in the molecular clusters of the dye adsorbates.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 6, pp. 734–737, November–December, 2005. 相似文献
67.
Ying-Tung Chen Kris Naessens Roel Baets Yunn-Shiuan Liao Ampere A. Tseng 《Optical Review》2005,12(6):427-441
For many years, the development of effective ablation or laser machining techniques for making micro-optical components has
been the key factor in the birth of new photonic devices and systems. In this article, the ablation characteristics of two
types of the most important transparent materials, transparent polymers and glasses, are studied. Simple shaped microcavities
are first machined for studying the fundamental ablation parameters, including threshold fluence, effective absorption coefficient,
and ablation rate. In studying polymer ablation, five standard grades and five proprietary polymeric compounds are selected.
Ablation techniques using these transparent polymers for making arrayed ferrules and curved microlenses are presented. Applications
of these ablated microstructures for optical fiber connectors, optical fiber coupling and alignment, and transparent chip
encapsulants, are introduced and demonstrated with emphasis on the quality of the ablated profiles and dimensions to satisfy
the required performance. In glass ablation, borosilicate glasses are considered and their associated ablation behaviors are
studied. The procedures to ablate glass-based arrayed microstructures with flat and curved surfaces are described. The utilizations
of these arrayed microstructures for optical waveguide, wave absorber, and beam guider, are specifically discussed. Finally,
concluding remakes for future trends are presented. 相似文献
68.
The lepton-number-violating decays of singly-charged Higgs bosons H± are investigated in the minimal type-(Ⅰ+Ⅱ) seesaw model with one SU(2)L Higgs triplet Δ and one heavy Majorana neutrino N1 at the TeV scale.We find that the branching ratios B(H+ → lα+ ν)(for α = e,μ,τ) depend not only on the mass and mixing parameters of three light neutrinos νi(for i=1,2,3) but also on those of N1.Assuming that the mass of N1 lies in the range of 200 GeV to 1 TeV,we figure out the generous interference bands for the contributions of νi and N1 to B(H+ →lα+ ν).We illustrate some salient features of such interference effects by considering three typical mass patterns of νi,and show that the relevant Majorana CP-violating phases can affect the magnitudes of B(H+ →l+αν) in this parameter region. 相似文献
69.
San-E Zhu Jian-Hui Zhang Yu Gong Li-Feng Dou Li-Hua Mao Hong-Dian Lu Chun-Xiang Wei Hong Chen Xue-Fei Wang Wei Yang 《Molecules (Basel, Switzerland)》2021,26(5)
A broadband visible light-absorbing [70]fullerene-BODIPY-triphenylamine triad (C70-B-T) has been synthesized and applied as a heavy atom-free organic triplet photosensitizer for photooxidation. By attaching two triphenylmethyl amine units (TPAs) to the π-core of BODIPY via ethynyl linkers, the absorption range of the antenna is extended to 700 nm with a peak at 600 nm. Thus, the absorption spectrum of C70-B-T almost covers the entire UV–visible region (270–700 nm). The photophysical processes are investigated by means of steady-state and transient spectroscopies. Upon photoexcitation at 339 nm, an efficient energy transfer (ET) from TPA to BODIPY occurs both in C70-B-T and B-T, resulting in the appearance of the BODIPY emission at 664 nm. Direct or indirect (via ET) excitation of the BODIPY-part of C70-B-T is followed by photoinduced ET from the antenna to C70, thus the singlet excited state of C70 (1C70*) is populated. Subsequently, the triplet excited state of C70 (3C70*) is produced via the intrinsic intersystem crossing of C70. The photooxidation ability of C70-B-T was studied using 1,5-dihydroxy naphthalene (DHN) as a chemical sensor. The photooxidation efficiency of C70-B-T is higher than that of the individual components of C70-1 and B-T, and even higher than that of methylene blue (MB). The photooxidation rate constant of C70-B-T is 1.47 and 1.51 times as that of C70-1 and MB, respectively. The results indicate that the C70-antenna systems can be used as another structure motif for a heavy atom-free organic triplet photosensitizer. 相似文献
70.
Dibyendu S. Bag Sukumar Maiti 《Journal of polymer science. Part A, Polymer chemistry》1998,36(10):1509-1513
Methylene blue sensitized photopolymerization of acrylamide (AM) and methyl methacrylate (MMA) using triethanolamine or the sodium salt of EDTA as a reducing agent has been investigated under the influence of a magnetic field (0–7.3 kG). There was no effect of the magnetic field (MF) on the polymerization of AM and MMA in aqueous medium. However, in the water–methanol mixture (1 : 1) the yield of polymer decreases and the molecular weight increases in both cases under MF. This has been explained on the basis of the triplet mechanism. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1509–1513, 1998 相似文献