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Radiative lifetimes of two short-lived levels (i.e. 4f^8 (TF6)6p^1/2 (6, 1/2)11/2,13/2) in Tb Ⅲ are measured by time-resolved laser-induced fluorescence (LIE) technique with a two-step excitation process. Free Tb Ⅲ ions are produced in a laser-induced plasma. Lifetime values are evaluated with a deconvolution procedure of the timeresolved fluorescence signal with the temporal shape of second-step excitation pulse (about 1 ns). The lifetimes of the 4f^8 (^7F6)6p^1/2 (6, 1/2)11/2 and 4f^8(^7F6)6p^1/2 (6, 1/2)13/2 levels are determined to be 1.9 (2) and 2.0 (2)ns, respectively. 相似文献
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本文使用波长为2.8 μm的分布式反馈激光器来测量水汽辉光放电产生的物种. 使用浓度调制光谱仅观察到OH自由基和瞬态H2O分子的吸收光谱. 吸收峰的强度和方向随解调相位而变化,但是H2O的一个吸收峰的方向始终与其它峰相反. OH和H2O的不同光谱取向反映了能级中粒子数量的增加或减少. 如果在放电过程中可以检测到更多的瞬态物种,则可以更好地研究H2O的激发、电离和分解动力学. 研究表明,浓度调制光谱的解调相位关系可以用来研究分子能级的布居数变化. 相似文献
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We propose a new mechanism/scheme to explain the ultrafast population inversion of molecular ions which takes place in a time scale comparable to the femtosecond laser pulse. The nonlinear pumping process including the pump photons and the self-generated harmonic photons of the pump laser would be responsible for building up population inversion to realize remote molecule lasers in femtosecond laser filaments in gases. It is shown that the remote laser emissions in molecular ions of gases may be a universal process in the femtosecond laser filament. 相似文献
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Measurement of CO,HCN, and NO productions in atmospheric reaction induced by femtosecond laser filament 下载免费PDF全文
Xiao-Dong Huang 《中国物理 B》2022,31(9):97801-097801
It is proved that the chemical reaction induced by femtosecond laser filament in the atmosphere produces CO, HCN, and NO, and the production CO and HCN are observed for the first time. The concentrations of the products are measured by mid-infrared tunable laser absorption spectroscopy. In the reduced pressure air, the decomposition of CO2 is enhanced by vibration excitation induced by laser filament, resulting in the enhanced production of CO and HCN. At the same time, the CO and HCN generated from the atmosphere suffer rotation excitation induced by laser filament, enhancing their absorption spectra. It is found that NO, CO, and HCN accumulate to 134 ppm, 80 ppm, and 1.6 ppm in sealed air after sufficient reaction time. The atmospheric chemical reaction induced by laser filament opens the way to changing the air composition while maintaining environmental benefits. 相似文献
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Population inversion in fluorescing fragments of super-excited molecules inside an air filament 下载免费PDF全文
An original idea is reviewed.When a molecule is pumped into a super-excited state,one of its decay channels is neutral dissociation.One or more of the neutral fragments will fluoresce.Hence,if a lower state of such fluorescing fragments was populated through other channels but with a lower probability,population inversion of the fluorescing fragments would be naturally realized.This idea seems to be validated,so far,by comparing published work on three hydrocarbon molecules,CH4,C2H2,C2H4,and water vapor,H2O.After super-excitation in a femtosecond laser filament in air mixed with these molecules,the fluorescence from the CH or OH fragments exhibits population inversion,i.e.,amplified spontaneous emission was observed in the backscattering direction of the filament. 相似文献
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汽车排放的主要污染物为CO,HC,NOx(x=1,2),SO2,Pb,苯丙芘,固体颗粒等[1],其尾气的检测对维护人类自身健康具有十分重要的意义.共振增强多光子电离光谱(Resonant Enhanced Multi-Photonionization,REMPI)是一种超灵敏光谱检测技术,它的灵敏度比LIF(Laser InducedFluorescence)还要高.1979年,Brophy和Rentttner[2]提出了REMPI可以作为检测大气污染的方法.后来,不同的研究小组采用了不同的REMPI方案对大气污染类分子进行了测量研究[3-6].由于采用可调谐染料激光器为光源,可以使用同一种染料对几种具有相近特征波长的分子进行同时测定.本文报 相似文献
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超快强激光在光学介质(如空气)中传播时由于克尔自聚焦效应和等离体散焦效应动态平
衡会发生一种独特的非线性激光成丝现象。激光成丝过程会诱导一些独特的物理现象,如非线性
光频转换产生超连续光谱、等离子体诱导高压放电、锥形辐射等,在大气传感、天气控制等研究
领域具有重要的应用前景。本文针对飞秒激光大气成丝过程中与传输介质相互作用所诱导的非线
性发光过程,介绍了激光大气成丝所产生的超连续光谱(白光)激光、谐波产生和太赫兹波辐射
三种非线性光频转换现象,并着重探讨了太赫兹波辐射的物理机理、研究现状和应用前景。 相似文献
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Radiative lifetime measurements were performed by time-resolved laser-induced fluorescence (LIF) technique for eight even-parity levels of the astrophysically important ion Er over the energy range from 33753 to 55317 cm^-1. Free erbium ions were generated by a laser-induced plasma. A narrow bandwidth UV laser pulse (1 ns) was employed to populate selectively the short-lived upper levels, and the lifetime value were evaluated from the time-resolved fluorescence signals. The lifetimes reported fall in the range of 3-35ns with the experimental accuracy 5-8%. 相似文献
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