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1.
本文用激光脉冲多光子激发的技术获得了碘分子高激发态F'(0^+u)(Te=51706.7cm^-1)的布居,并对该态10个荧光辐射(310nm带)的时间分辨谱进行了测量。采用二步三光子的非线性激发模型对荧光时间分辨谱的数据进行处理,得到了离子对态F'(0^+u)的310nm荧光带的辐射寿命。 相似文献
2.
Chil-Chyuan Kuo 《Journal of Russian Laser Research》2009,30(1):12-20
A real-time in-situ time-resolved (~1 ns) optical reflectivity and transmission (TRORT) measurement system combining two He–Ne
probe lasers, a digital oscilloscope, and three fast photodiodes is developed to investigate the rapid phase-change processes
of Si thin films during the excimer-laser crystallization (ELC). The changes in both reflectivity and transmission of Si thin
films during ELC are recorded by the TRORT measurement system. Melting and resolidification behaviors of Si thin films during
ELC are interpreted. The fall time of liquid Si is reduced with increase in the excimer-laser energy density, while the rise
time of liquid Si remains approximately constant at 5 ns. The first small peak in the reflectivity spectrum is proved to be
not a phenomenon of explosive crystallization. 相似文献
3.
Enhancing redshift phenomenon in time-resolved photoluminescence spectra of AlGaN epilayer 下载免费PDF全文
AlGaN epitaxial layer has been studied by means of temperature-dependent time-integrated photoluminescence(PL)and time-resolved photoluminescence(TRPL). An enhancing redshift phenomenon in TRPL spectra with increasing temperature was observed, and the localized excitons behaved like quasi two-dimensional excitons between 6 K and 90 K. We demonstrated that these behaviors are caused by a change in the carrier dynamics with increasing temperature due to the competition of carriers' localization and delocalization in the AlGaN alloy. 相似文献
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本文使用不同激光能流(18 J/cm2–115 J/cm2)和脉冲宽度(50 fs–4 ps)的超短脉冲激光在真空中(4×10-4 Pa)烧蚀高定向热解石墨. 通过测量烧蚀喷射物的时间分辨发射光谱研究喷射物的超快时间演化. 在喷射物发射光谱中, 观察到了C2基团的天鹅带光谱系统, 416 nm附近C15基团的由电子能级1Σu+ 和1Σg+之间的振动跃迁产生的光谱峰以及连续谱. 50 fs, 115 J/cm2的脉冲激光烧蚀产生的喷射物的连续谱的强度衰减分为快速下降和慢速下降两个阶段(以20 ns时间延迟为分界). 这表明连续谱是由两种不同的组分贡献的. 快速下降阶段, 连续谱主要由碳等离子体通过韧致辐射产生; 慢速下降阶段, 连续谱主要由烧蚀后期产生的大颗粒碳簇的热辐射贡献. 实验结果还揭示了激光能流的提高, 会明显增加喷射物中碳等离子体和激发态C2的含量, 但对质量稍大的C15的影响较小; 此外, 50 fs脉冲激光烧蚀产生的连续谱的存在时间会随着激光能流的减小而增大, 这说明低能流更有利于在烧蚀后期产生碳簇. 脉宽主要影响喷射物连续谱的时间演化. 4 ps脉冲激光烧蚀产生的连续谱的整个时间演化过程明显慢于50 fs脉冲产生的连续谱. 相似文献
6.
Time-resolved K-shell x-ray spectra of nanosecond laser-produced titanium tracer in gold plasmas 下载免费PDF全文
Zhencen He 《中国物理 B》2023,32(1):15202-015202
A study of a nanosecond laser irradiation on the titanium-layer-buried gold planar target is presented. The time-resolved x-ray emission spectra of titanium tracer are measured by a streaked crystal spectrometer. By comparing the simulated spectra obtained by using the FLYCHK code with the measured titanium spectra, the temporal plasma states, i.e., the electron temperatures and densities, are deduced. To evaluate the feasibility of using the method for the characterization of Au plasma states, the deduced plasma states from the measured titanium spectra are compared with the Multi-1D hydrodynamic simulations of laser-produced Au plasmas. By comparing the measured and simulated results, an overall agreement for the electron temperatures is found, whereas there are deviations in the electron densities. The experiment-theory discrepancy may suggest that the plasma state could not be well reproduced by the Multi-1D hydrodynamic simulation, in which the radial gradient is not taken into account. Further investigations on the spectral characterization and hydrodynamic simulations of the plasma states are needed. All the measured and FLYCHK simulated spectra are given in this paper as datasets. The datasets are openly available at http://www.doi.org/10.57760/sciencedb.j00113.00032. 相似文献
7.
A model is built to study chemical processes in atmospheric plasmas at low altitude (high pressure) and at high altitude (low pressure). The plasma lifetime and the temporal evolution of the main charged species are presented.The electron number density does not strictly obey the exponential damping law in a long period. The heavy charged species are dominant at low altitude in comparison with the light species at high altitude. Some species of small amount in natural air play an important role in the processes. 相似文献
8.
用微微秒瞬态吸收和荧光动力学测量方法,研究了四苯基卟啉-锌的三重态建立过程和单重态的衰减过德;测量了样品的系际交叉速率、单重态的寿命及其对532nm波长的吸收截面. 相似文献
9.
We present the dominant physical processes responsible for the production of
the optogalvanic signal in the spectra of neon. We have investigated the
effects on the optogalvanic signal by scanning a dye laser across the neon
transitions in the DC discharge plasma. Time-resolved spectra are obtained
at a fixed wavelength of the dye laser resonantly tuned to an optically
allowed transition. The temporal evolutions of the signals are registered on
a storage oscilloscope. Three transitions from the 3s[1/2]2 metastable
state corresponding to the ΔJ = ΔK = 0, ±1 dipole
selection rules have been selected to investigate the dominant physical
processes responsible for the optogalvanic signals. The change in the signal
amplitude as a function of the discharge current has been
registered. In addition the electron collisional ionization rate
parameter ratios have been determined for the transitions corresponding to
dipole selection rules ΔJ = ΔK = -1, ΔJ = ΔK
= 1 and ΔJ = ΔK = 0, as 1.63, 1.75 and 1.0 respectively. The
effective lifetimes of the upper levels involved in the aforementioned
transitions are also calculated as 62.5 μs, 31.25 μs and 12.85
μs respectively. 相似文献
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尝试利用漫反射光谱和荧光光谱检测鲜红斑痣皮肤在光动力治疗中的变化特点,用于分析治疗中组织光学特性的变化,指导光剂量的制定.在光动力治疗中,采用微型光纤光谱仪监测PWS皮肤的漫反射光谱和荧光光谱,结合PWS结构特点以及皮肤中主要吸光基团的吸收光谱,分析术中、术后相关组织成分变化及对应的光学特性变化.PDT治疗中PWS皮肤... 相似文献
13.
The solvent relaxation behavior of Patman (6-palmitoyl-2-[[2-(trimethylammonium) ethyl]methylamino]naphthalene chloride) was
investigated in small unilamellar vesicles composed of symmetric diacyl( 1,2-dipalmitoylphosphatidylcholine; DPPC) and diether
lipids (l,2-dihexadecylphosphatidylcholine; DHPC), calculating time-resolved emission spectra (TRES) and correlation functions.
Both the steady-state spectra as a function of temperature and excitation wavelength and the TRES of Patman in DPPC are blue-shifted
compared to those in DHPC. The solvent relaxation at three temperatures above and below the phase transition is considerably
faster in DHPC than in DPPC. As the steady-state anisotropies of Patman and TMA-DPH [l-(4-trimethylammoniumphenyl)-6-phenyl-l,3,5-hexatriene]
are similar in both lipids as a function of both temperature and emission wavelength, we conclude that the introduction of
ether linkages allows more efficient water penetration in the glycerol region, leading to a more polar environment and therefore
faster solvent relaxation of the incorporated dyes. Using a series ofn-(9-anthroyloxy) fatty acids (n = 2, 3, 6, 9, 12; 16-AP), we show that anisotropy profiles can be used to distinguish between noninterdigitated (DPPC) and
fully interdigitated (DHPC) gel-phase structures. 16-(9Antroyloxy) palmitic acid (16-AP) is an especially useful probe exhibiting
pronounced differences in the steady-state anisotropies in non- and fully interdigitated gel phases. 相似文献
14.
M. Sauer K-T Han R. Müller A. Schulz R. Tadday S. Seeger J. Wolfrum J. Arden-Jacob G. Deltau N. J. Marx K. H. Drexhage 《Journal of fluorescence》1993,3(3):131-139
New dyes with characteristic fluorescence lifetimes have been developed for bioanalytical applications. Based upon the concept of multiplex dyes, we have designed rhodamine dyes with nearly identical absorption and emission spectral characteristics but different fluorescence lifetimes. Extending this principle to applications with laser diodes, new rhodamines with functional groups for covalent coupling of analytes have been developed. The new labels exhibit absortion and fluorescence beyond 600 nm and have a high quantum efficiency, even in aqueous buffer systems. 相似文献
15.
FENG XiaoBo LI Yan QIN Yi XIAO YunFeng YANG Hong & GONG QiHuang State Key Laboratory for Mesoscopic Physics 《中国科学:物理学 力学 天文学(英文版)》2011,(8)
We demonstrate that the femtosecond time-resolved magneto-optical Kerr rotation oscillates with the direction of polarization of the probe beam when a sample of Al0.25Ga0.75As/GaAs multi-quantum wells is excited by a circularly polarized pump and detected by a linearly polarized probe at wavelengths from 800 to 830 nm. Analytical expressions are derived to explain the mechanism, which is in good agreement with the numerical computation and the experimental data. The results suggest that the Kerr signal can ... 相似文献
16.
We have measured the relative luminescence quantum yields and luminescence lifetimes of Tb(III) and Dy(III) ions in complexes
with pyrazole-5-carboxylic acids. Based on study of the time-resolved luminescence spectra of Tb(III) and Dy(III) complexes
with 3-(6-benzodioxanyl)pyrazole-5-carboxylic acid, we have demonstrated the possibility in principle of determining Dy(III)
in the presence of Tb(III) by separating the short-lived component of the luminescence of dysprosium, despite the practically
complete overlap of the analytical bands of dysprosium by the terbium bands. This method was used to determine Dy(III) in
luminescent materials: scandium borates doped with terbium and dysprosium.
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Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 3, pp. 327–331, May–June, 2007. 相似文献
17.
T. Kinoshita T. Ohkochi H. Osawa K. Arai K. Fukumoto T. Okuda M. Kotsugi T. Muro T. Nakamura T. Matsushita 《Journal of Electron Spectroscopy and Related Phenomena》2012
The present status and the recent progress of pump-probe time-resolved photoemission electron microscopy at SPring-8 are introduced. Combining the variety of bunch operation modes available at the SPring-8 storage ring with ultra-short excitation sources including pulsed magnetic fields, electric fields and lasers, the element-specific time evolution of materials in response to the excitation can be observed with spatial and temporal resolutions of (50–300) nm and (40–100) ps, respectively, with repetition frequencies of up to 42 MHz. By using the magnetic circular dichroism effect, the domain motion of sub-micron sized magnetic areas can be observed. The time evolution of electronic structures in local areas can also be studied. The experimental setups and representative activities are described. 相似文献
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A class of collision processes with memory and application to simple chemical reactions in a solvent
We apply the general formalism of a class of non-Markovian processes which we have studied elsewhere to three simple models of chemical reactions: dissociation, isomerization, and diffusion in a double-well potential. Our method leads to explicitly solvable models and numerical computations. The results are in agreement with numerical simulation and stochastic dynamics studies of other authors. 相似文献