共查询到19条相似文献,搜索用时 125 毫秒
1.
利用飞行时间谱,研究了在飞秒强激光场(60 fs,2×1016 W/cm2)作用下,大尺寸氩原子团簇Arn(n—=3×103—3×106原子/每团簇)的电离爆炸过程,测量了 团簇爆炸所产生的氩离子的平均能量与团簇尺寸(气体背压)的关系.实验发现,随着气体 背压的升高(团簇尺寸增大),氩离子的平均能量也相应升高.通过分析两个不同几何尺寸 锥形超声喷嘴所产生团簇爆炸后的离子能量,结合Hagena团簇尺寸规律,发现在激光参数保 持不变的情况下,离子的平均能量由团簇尺寸唯一确定.分析表明,团簇尺寸在3×105原 子/每团簇以下时,团簇膨胀的主要机理是库仑爆炸.随着团簇尺寸的进一步增大,团簇膨胀 机理将由库仑爆炸向流体动力学膨胀过渡,在3×105关键词:
原子团簇
飞秒强激光
库仑爆炸
流体动力学膨胀 相似文献
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利用Bathe模型,理论模拟了氩团簇在飞秒强激光中(100 fs, 1016 W/cm2)的电离和爆炸过程.研究结果显示,在团簇尺寸较小时,离子平均能量与团簇初始半径平方成正比,爆炸机制为典型的库仑爆炸.随着团簇尺寸的增加,能量增加的速度趋缓并在一定团簇尺寸后趋于饱和.模拟结果与实验数据有较好的吻合. 相似文献
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使用800nm飞秒脉冲激光研究了Xe,Ar,He等原子团簇对激光的吸收.实验结果表明,脉冲阀门的工作压力、所使用的气体种类等因素对团簇的尺寸及团簇对激光的吸收影响很大.在阀门工作压力为20×105Pa、激光功率密度为1×1015W/cm2的条件下,Xe团簇对激光的吸收高达45%.激光预脉冲的存在会降低原子团簇对激光能量的吸收.离子能量测量结果表明,团簇对激光的高效吸收导致较高离子温度等离子体的生
关键词:
原子团簇
飞秒激光
能量吸收效率
高能离子 相似文献
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利用激光烧蚀-分子束法(LA-MB)对激光烧蚀金属铝靶产生的Al等离子体与脉冲分子束超声膨胀产生的(CH3OH)n团簇在气相条件下的反应进行了研究.烧蚀激光相对于脉冲分子束之间的延时不同,观测到团簇离子序列及团簇尺寸的变化,反映出脉冲分子束状态对反应条件及激光烧蚀等离子体状态的影响.在激光烧蚀发生于脉冲分子束的前段,主要反应产物为Al (CH3OH)n,但团簇尺寸较小;在烧蚀发生于脉冲分子束的中段,主要产物为H (CH3OH)n,团簇尺寸增大,强度减弱;在烧蚀发生于脉冲分子束的后段,观测到尺寸更大的水合质子化团簇H (H2O)m(CH3OH)n.结合团簇离子速度分布的特征,对团簇的产生机理进行了讨论. 相似文献
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我们实验上发展了基于飞秒激光旋转相干光谱的整形飞秒激光转动动力学调控方法,通过脉冲整形技术调控激发脉冲的光谱相位,从而实现对飞秒激光作用下转动态相干激发过程中复原信号及转动布居数的调控. 研究了飞秒激光旋转相干光谱对激光频谱相位的响应机制,突出了飞秒激光频谱相位在气相分子转动态相干激发中的重要作用. 为飞秒激光作用下生物大分子和团簇鉴别及结构探测研究提供了新的参考. 相似文献
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飞秒强激光与团簇的相互作用是一个十分活跃的研究领域, 本文采用一种新的理论模型, 研究了飞秒激光在团簇中的传输的过程, 计算了Ar原子团簇对超强激光能量的吸收, 并通过解析计算连续曲折射程、最大穿透深度和特征时间三个重要的物理参量来重新估算了这一模型的可行性. 相似文献
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用150fs的掺钛蓝宝石激光系统, 在功率密度约为5×1015 W/cm2时 激励氩(Ar)团簇,利用具有空间分辨能力的平场光栅谱仪观察到13—23nm波段Ar的软x射线谱,并观察到Ar的11阶离子谱线.在较宽的激光脉宽和较低的激光功率密度情况下,通过激励Ar团簇,获得 了Ar的高阶电离度的实验结果,且谱线的信噪比明显好于光场感应电离的情况,说明团簇的 形成大幅度地提高了激光能量的吸收效率.
关键词:
Ar团簇
超短强激光
软x射线辐射 相似文献
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本文主要研究了超强超短激光与Ar团簇相互作用过程中X射线能谱、K壳层光子产额、能量转换效率以及激光对比度对X射线光子产额的影响.实验中得到K壳层的光子产额约为1× 1011/发,能量转换效率约为2.8× 10-5.同时观测到较强预脉冲离化团簇会导致预电离,产生膨胀等离子体,然而主脉冲与膨胀的等离子体相互作用的强度较未膨胀时降低了,从而导致K壳层光子产额降低,而使用高对比度的激光能增加X射线光子产额. 相似文献
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A time-resolved imaging technique for visualizing ultrafast propagation dynamics of intense light pulses in a medium has been demonstrated. The method probes the instantaneous birefringence induced by a pulse in the medium. Through consecutive femtosecond snapshot images of intense femtosecond laser pulses propagating in air, ultrafast temporal changes in the two-dimensional spatial distribution of the optical pulse intensity were clearly seen. 相似文献
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Döppner T Fennel T Diederich T Tiggesbäumker J Meiwes-Broer KH 《Physical review letters》2005,94(1):013401
Silver clusters grown in helium nanodroplets are excited by intense femtosecond laser pulses resulting in the formation of a hot electron plasma far from equilibrium. The ultrafast dynamics is studied by applying optically delayed dual pulses, which allows us to pursue and control the coupling of the laser field to the clusters on a femtosecond time scale. A distinct influence of the optical delay on the ionization efficiency gives strong evidence that a significant contribution of collective dipolar electron motion is present, which is verified by corresponding Vlasov dynamics simulations on a model system. The microscopic approach demonstrates the outstanding role of giant resonances in clusters also in intense laser fields. 相似文献
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Fleischer A Wörner HJ Arissian L Liu LR Meckel M Rippert A Dörner R Villeneuve DM Corkum PB Staudte A 《Physical review letters》2011,107(11):113003
We study electron correlation in sequential double ionization of noble gas atoms and HCl in intense, femtosecond laser pulses. We measure the photoelectron angular distributions of Ne+ relative to the first electron in a pump-probe experiment with 8 fs, 800 nm, circularly polarized laser pulses at a peak intensity of a few 10(15) W/cm2. Using a linear-linear pump-probe setup, we further study He, Ar, and HCl. We find a clear angular correlation between the two ionization steps in the sequential double ionization intensity regime. 相似文献
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The interaction of intense femtosecond laser pulses with rare gas clusters was studied experimentally,the time-of-flight spectra of ions from exploding clusters at different gas densities have been measured. It is found that while the relative components of ions inlow and high energy of the ion energy spectrum decrease with the increase of the gas density,the average ion energies are the same for different gas densities,which indicates that the effect of gas density on laser-cluster interaction is not important under our experimental conditions. 相似文献
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We demonstrate intense pulse guiding in efficient femtosecond end-pumped waveguides generated in clustered gases. This novel scheme provides a route to significantly lower on-axis plasma density (< 10(18) cm(-3)) more than is feasible in conventional hydrodynamic plasma waveguides. Self-focused propagation and strong absorption of intense femtosecond laser pulses are used to produce long centimeter scale channels in an argon cluster jet, and a subsequent pulse is guided with 3 x 10(17) W cm(-2) intensity and approximately 50% coupling efficiency. Preliminary results with hydrogen clusters also show guiding. 相似文献
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A. A. Ionin S. I. Kudryashov S. V. Makarov L. V. Seleznev D. V. Sinitsyn 《JETP Letters》2011,94(1):34-38
Superstrong shock waves of multimegabar level generated during ablation of an aluminum surface by intense (<1 PW/cm2) femtosecond laser pulses have been detected by observing the propagation of a shock wave in air from the ablated surface
to a broadband piezoelectric receiver. The estimated initial pressure and velocity of the shock wave (ablation plume) agree
well with data obtained earlier by various methods for shock waves propagating inside ablated targets. 相似文献
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Laarmann T Rusek M Wabnitz H Schulz J de Castro AR Gürtler P Laasch W Möller T 《Physical review letters》2005,95(6):063402
The ionization dynamics of Ar and Xe clusters irradiated with intense vacuum ultraviolet light from a free-electron laser is investigated using photoelectron spectroscopy. Clusters comprising between 70 and 900 atoms were irradiated with femtosecond pulses at 95 nm wavelength (approximately 13 eV photon energy) and a peak intensity of approximately 4 x 10(12) W/cm2. A broad thermal distribution of emitted electrons from clusters with a maximum kinetic energy up to 30-40 eV is observed. The observation of relatively low-energy photoelectrons is in good agreement with calculations using a time-dependent Thomas-Fermi model and gives experimental evidence of an outer ionization process of the clusters, due to delayed thermoelectronic emission. 相似文献