【作者】 薛思敏；

【导师】 陈冠英； 袁萍；

【作者基本信息】 西北师范大学 ， 原子与分子物理， 2006， 硕士

【摘要】 随着脉冲激光烧蚀技术在各相关研究领域日益广泛的应用，脉冲激光与固体靶材的相互作用机制越来越引起有关学者的兴趣，其中包括激光等离子体的形成，样品材料的表面烧蚀，不同成份的蒸发和激发等。这些过程与脉冲激光的性质(如能量、脉宽、波长和作用时间等)、样品的物理与化学特性、环境条件以及缓冲气体等诸多性质密切相关，非常复杂，人们往往采用改变作用条件的方法，诸如不同的激光波长、脉宽、强度、靶材料和环境气体的压强以及其他因素，对靶的烧蚀速率、产物的平均动能以及产物的光辐射规律等进行大量的研究，但目前这些了解尚不完全，烧蚀粒子的能量状态、时空行为及相关机制也有待进一步揭示和完善。本文通过激光烧蚀、同时外加电场等方法产生发射光谱，研究了金属Cu、Al等离子体的一些基本特征，主要内容有：(1)激光诱导Cu产生等离子体的发射光谱研究在背景气体Ar气下激光诱导Cu产生等离子体，观察了其空间分辨发射光谱。采用的激光能量为350mJ／pulse，波长范围为440nm～540nm。在局部热力学平衡(LTE)条件下，根据谱线的相对强度，得到了等离子体的电子温度在10~4K以上。研究了原子发射谱线强度、电子温度和半高全宽(FWHM)随空间、缓冲气体压力变化的规律。结果表明，在100kPa的Ar气中和50kPa相比，铜的原子特征谱强度降低而连续谱强度增加，同时氩离子谱线强度也相应增加，同时缓冲气压的增大还导致谱线宽度的增大。(2)外加电场下激光诱导Al产生等离子体的光谱研究由调Q-Nd：YAG脉冲激光(波长1.06μm，脉宽10ns)烧蚀Al靶产生等离子体。观测了在低气压和直流电场条件下的Al等离子体发射光谱。研究了直流电场下激光功率密度和外加电压对各谱线强度的影响，分析了谱线半高全宽与外加电压，等离子体电子温度与激光能量的变化规律。结果表明，直流电场对铝原子谱线强度有显著的增强，铝原子谱线的半高全宽与直流电场的外加电压基本上呈线性关系。更多还原

【Abstract】 In view of laser-ablation has been widely used as various research domains, the interaction mechanism of a laser-pulsed with solid targets arose the interesting of more and more relevant scholars, Including laser plasma formation, ablation of the sample surface, vaporization and excitation of different species. The processes are known to depend on the laser pulse characteristics (such as energy, pulse duration ,wavelength, interacting time and so on), the physical and chemical characteristics of samples, environmental condition as well as buffer gas. The processes are rather complex. Many scholars have had plentiful research on the ablating rate of target, average kinetic energy of the production and ray radiation law of the production by the way of changing the interacting condition, including laser wavelength, pulse duration , intensity, target material and the pressure of environment gas and other factors. The comprehension is still not very clarity at present. The energy state of ablating particle, time-space action and their relevant mechanism need to be revealed and perfected gradually. In this thesis, the basic character of Cu and Al plasma are studied by the emission spectrum which is produced in the condition of laser ablation and additional electric field. Following are the details.(1) The research of laser induced Cu plasma emission spectrum.Laser induced Cu plasma in Ar buffer gas are studied. The space-resolved spectra are measured in the wavelength of 440nm～540nm at the 350mJ/pulse of laser energy. Under the model of local thermodynamic equilibrium, the electronic temperatures of Cu plasma are deduced to be in the 10~4 scale by the relative line intensities. The dependence of emission spectra line intensity and electronic temperature and FWHM (the full width half maximum) on the space and pressure of buffer gas are studied. The results show that intensity of the Cu spectral lines decrease but the intensity of the Ar ion spectral lines and background increase comparing the pressure of 100kPa with 50kPa in Ar ambient gas. At the same time, the broadening increases with increasing the pressure of buffer gas.(2) An experimental investigation on the properties of Laser - induced Al plasma under additional electric fieldThe plasma is produced by ablating Al target with Q-switch Nd:YAG Laser ( wavelength 1.06μm, pulse width 10ns). Al emission spectrum are observed in the low air pressure and the direct electricity field. The influence of the spectral line intensity in various laser power density and direct electricity field is studied. The electron temperature of plasma in various laser power density and FWHM of the spectral line in direct electricity field are measured. The results show that the spectral line intensity of Al atom is increased prominently in direct electricity field. The FWHM of spectral line of Al atom in various additional voltage of direct electricity field is linear.更多还原