Investigations of the plume accompanying pulsed ultraviolet laser ablation of graphite in vacuum
Investigations of the plume accompanying pulsed ultraviolet laser ablation of graphite in vacuum
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DOI：
10.1063/1.1330548
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发表时间：
2001-01-01
影响因子：
3.2
通讯作者：
Ashfold, MNR
中科院分区：
文献类型：
--
作者：
Claeyssens, F;Lade, RJ;Ashfold, MNR
利用波长、时间和空间分辨的发射光谱和正电荷离子的互补法拉第杯测量研究了真空中193 nm脉冲激光烧蚀石墨时产生的羽流。的时间和空间范围的光发射的证据，从电子-离子复合过程中，和随后的辐射级联从高n，l里德堡态的结果，导致的发射物种。C中性发射的分布关于表面法线对称，而观察到的C+发射出现在激光传播轴与表面法线之间的立体角中。然而，法拉第杯测量的离子产额和速度分布，作为散射角和入射脉冲能量的函数，表明总离子通量分布是沿沿着达到峰值。导出的离子速度分布被用作输入一个二维模型，解释了观察到的各向异性的C+发射的优先多光子激发和电离的C物种在膨胀的等离子体球，暴露于最大的入射193 nm的光子通量的领先部分，之前的电子-离子复合和随后的辐射衰减。(C)2001年美国物理学会。
The plume accompanying 193 nm pulsed laser ablation of graphite in vacuum has been studied using wavelength, time and spatially resolved optical emission spectroscopy and by complementary Faraday cup measurements of the positively charged ions. The temporal and spatial extent of the optical emissions are taken as evidence that the emitting species result from electron-ion recombination processes, and subsequent radiative cascade from the high n,l Rydberg states that result. The distribution of C neutral emission is symmetric about the surface normal, while the observed C+ emission appears localized in the solid angle between the laser propagation axis and the surface normal. However, Faraday cup measurements of the ion yield and velocity distributions, taken as a function of scattering angle and incident pulse energy, indicate that the total ion flux distribution is peaked along the surface normal. The derived ion velocity distributions are used as input for a two-dimensional model which explains the observed anisotropy of the C+ emission in terms of preferential multiphoton excitation and ionization of C species in the leading part of the expanding plasma ball that are exposed to the greatest incident 193 nm photon flux, prior to electron-ion recombination and subsequent radiative decay. (C) 2001 American Institute of Physics.