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1.
在大气环境下采用波长为800nm,脉宽为30fs的飞秒激光研究了Ni的双脉冲激光诱导击穿光谱,与单飞秒脉冲激光诱导击穿光谱相比,双飞秒脉冲在最优的双脉冲相对延时下,其信号强度增强接近10倍,实验研究了双脉冲相对延时在0-1300ps范围内不同延时对激光诱导击穿光谱信号强度增强因子的影响。整个相对延时区域可以分为三个阶段:在0-50ps区域内信号增强因子是一个持续增大的过程,在50ps左右,达到一个最大值;在50-300ps区域内,信号增强因子呈现出一个先下降后上升的过程;在300-1300ps,信号增强因子基本保持不变。  相似文献   

2.
在大气环境中,以钴为样品,通过单脉冲飞秒激光诱导击穿光谱及共轴双飞秒脉冲激光诱导击穿光谱的对比实验,研究了双脉冲激光诱导击穿光谱的谱线增强机制,测量了双脉冲激光诱导击穿光谱随脉冲时间间隔的变化趋势。结果表明,在最优化的脉冲时间间隔条件下,双脉冲激光诱导等离子体光谱获得明显增强。进一步,通过线性Boltzmann法得出了电子温度随脉冲时间间隔的演化,发现了谱线增强因子和电子温度随脉冲时间间隔呈现出相同的演化趋势,并经历两个明显的变化过程,得出了谱线信号强度的增强依赖于电子温度升高的结论。  相似文献   

3.
使用单脉冲和再加热双脉冲激光对位于空气中的钢样进行烧蚀激发等离子体,对两种方式产生的光谱进行研究。再加热双脉冲激光诱导击穿光谱采用两束激光,一束烧蚀样品激发等离子体,另外一束激光对产生的等离子进行加热。通过对比发现:采用再加热双脉冲激发样品,增强了发射光谱的信号,增大了等离子体的连续光谱,提高了信号的稳定性,十次测量信号的相对标准偏差从5.0%降低到2.0%。另外,还对影响双脉冲信号增强程度的因素进行了分析,研究了光谱的增强程度随两脉冲间隔和采集延时的变化;激发上能级对光谱增强程度的影响,上能级越高增强程度越大。  相似文献   

4.
<正>交双波长双脉冲的激光剥离-激光诱导击穿光谱技术能够在较少样品烧蚀的前提下获得高的光谱分析灵敏度,因此该技术可以从根本上解决在单脉冲激光诱导击穿光谱技术中空间分辨本领与光谱分析灵敏度之间的矛盾。为了消除在该光谱技术中的实验参数对光谱信号强度及其定量分析结果的影响,实验研究了银饰品中杂质铜的光谱信号与银元素的光谱信号的相关性。研究结果表明:324.75 nn的铜原子辐射线与328.07 nm的银原子辐射线的强度呈很高的线性相关性,因此选择以银328.07 nm的光谱线作为内标线,采用内标法就可以消除双光束激光的空间几何配置以及剥离激光脉冲能量等实验参数对铜原子辐射信号的影响,从而可以采用正交双波长双脉冲激光剥离——激光诱导击穿光谱技术开展银饰品中铜杂质含量的定量分析。选择银328.07 nm的光谱线作为内标线,基于内标法建立了铜的校正曲线。当激光烧蚀坑洞直径约为17μm时,当前实验条件下银饰品中铜元素的检出限可以达到44 ppm。  相似文献   

5.
土壤中重金属元素的双脉冲激光诱导击穿光谱研究   总被引:1,自引:0,他引:1       下载免费PDF全文
杜闯  高勋*  邵妍  宋晓伟  赵振明  郝作强  林景全 《物理学报》2013,62(4):45202-045202
基于正交预烧蚀双脉冲激光诱导击穿光谱(DP-LIBS) 技术对长春市四个地点地表土壤样品中的重金属元素进行了研究, 根据光谱线强度定性分析了重金属元素Mn, Cr, Cu, Pb含量.实验结果发现, 在532和1064 nm激光脉冲能量分别为70和100 mJ的条件下光谱增强随延时的变化出现双峰结构. 脉冲间延时20 μs时, Mn I 406.4 nm光谱增强幅度达到2.75倍, 延时为30 μs时出现第二个尖峰, 增强幅度为2.4倍.最后对正交预烧蚀DP-LIBS光谱增强机理进行了讨论. 关键词: 预烧蚀 双脉冲激光诱导击穿光谱 光谱增强 土壤污染  相似文献   

6.
为了制备高质量表面周期结构,利用法布里-珀罗腔对飞秒激光进行时域整形,输出子脉冲间隔在1~300 ps内灵活可调的飞秒激光脉冲串,在硅表面诱导亚波长周期条纹。实验结果显示,利用飞秒激光脉冲串诱导得到的亚波长周期条纹明显优于原始高斯光诱导的亚波长周期条纹。利用子脉冲间隔为100 ps的脉冲串诱导的亚波长条纹最佳,条纹周期为1008 nm,结构取向角为2.8°,边缘粗糙度为3.9 nm,可达到光刻工艺的标准。  相似文献   

7.
为了研究再加热双脉冲激光诱导击穿光谱(LIBS)对信号的增强机制,分别采用单脉冲LIBS和再加热双脉冲LIBS两种方式烧蚀合金钢样品产生等离子体,利用高分辨率的中阶梯光栅光谱仪采集等离子体发射光谱信号,同时用快速成像ICCD相机观测等离子体形态的变化,研究了两种烧蚀方式下等离子体的时空演变特性。通过比较两种烧蚀方式下等离子体产生初期光谱信号和图像的时间演变规律,发现再加热双脉冲LIBS提高了等离子体温度,且当信号采集延时等于再加热双脉冲的脉冲间隔时,等离子体温度的衰减速率发生变化;再加热双脉冲LIBS使等离子体图像强度增加,等离子体的中心区域高度和宽度分别增大了23.5%和15.1%。空间分布的研究结果表明,与单脉冲LIBS相比,当到样品表面的距离大于0.6mm时,等离子体中的FeⅡ和NⅠ谱线强度有较明显的增强,而FeⅠ谱线在空间不同位置处的增强程度都较小,局部区域有减小的现象;再加热双脉冲LIBS使等离子体温度增加了约2 000K,等离子体中产生了一个较大的高温区域。综合时空演变的实验结果说明再加热双脉冲对光谱信号增强的机制主要是由于第二束激光对第一束激光烧蚀样品产生的等离子体再次激发,使等离子体温度增加,进而引起等离子体辐射强度增加。  相似文献   

8.
激光诱导击穿光谱技术(LIBS)是一种广泛应用于科学和工程方面的元素分析技术。LIBS测量一些微量元素时存在探测极限高的不足,因此增强LIBS信号强度,降低元素探测极限,对扩展其应用范围有着重要的意义。为了实现LIBS光谱信号的增强,提出多次放电增强激光诱导击穿光谱方法,并以固体铝合金材料为例进行了光谱信号强度增强的研究。实验发现,激光作用在铝合金材料上烧蚀样品产生等离子体并溅射到样品上方高压放电电极所在区域,该区域在等离子体产生之后50 μs之内均可以诱导高压电极放电。因此采用高频脉冲电源可以实现一次LIBS产生的等离子体诱导电极多次放电。多次放电会对等离子体进行多次激发,同时多次放电对等离子的加热作用会延缓等离子体冷却速率从而延长等离子体的持续时间,两者共同作用可以增强LIBS光谱信号强度,进而降低LIBS对微量元素的探测极限。使用频率为100 kHz的高频直流脉冲电源,利用数字延迟脉冲发生器同步激光与高压电源,在激光过后3.6 μs触发高压放电,一次LIBS产生的等离子体可以诱导电极5次放电,即对等离子体进行5次激发和加热。利用光谱仪对5次放电等离子体光谱进行积分测量。实验结果表明:使用多次放电增强之后,等离子体持续时间得到大幅延长,光谱信号强度得到大幅增强,其中,Mg Ⅱ (~279 nm)的信号强度可以增强约48倍,Al Ⅱ (~358 nm)的信号强度可以增强约72倍,微量元素Mn Ⅰ (~403 nm)的信号强度增强约6.3倍,微量元素Cu Ⅰ (~403 nm) 的信号强度增强约8.3倍。Mn Ⅰ (~403 nm)和Cu Ⅰ (~403 nm) 的探测极限分别降低为LIBS单次放电的1/6和1/8。多次放电增强激光诱导击穿光谱方法很好地增强了LIBS的光谱信号强度,降低了对微量元素的探测极限,扩展了LIBS技术的应用范围。该方法有潜力应用到贵重物品、稀有材料及文物的鉴定之中。  相似文献   

9.
基于自行研制的新型液体射流的激光诱导击穿光谱(LIBS)实验装置,研究了实验条件(如积分延时、脉冲间隔、激光能量等)对K元素单脉冲LIBS和双脉冲LIBS等离子发射的影响.实验得知相对单脉冲激光激发,双脉冲激光激发可以显著提高等离子体发射谱线强度,增加谱线强度的衰减时间,提高LIBS数据的稳定性.通过最佳实验条件下K766.49nm谱线强度随溶液浓度的分析,得到该实验系统中,双脉冲激光激发时K元素的检测灵敏度和检测限约是单脉冲激光激发时的37倍.实验结果为双脉冲LIBS技术应用于水体金属的检测提供了一定依据.  相似文献   

10.
基于自行研制的新型液体射流的激光诱导击穿光谱(LIBS)实验装置,研究了实验条件(如积分延时、脉冲间隔、激光能量等)对K元素单脉冲LIBS和双脉冲LIBS等离子发射的影响.实验得知相对单脉冲激光激发,双脉冲激光激发可以显著提高等离子体发射谱线强度,增加谱线强度的衰减时间,提高LIBS数据的稳定性.通过最佳实验条件下K766.49nm谱线强度随溶液浓度的分析,得到该实验系统中,双脉冲激光激发时K元素的检测灵敏度和检测限约是单脉冲激光激发时的37倍.实验结果为双脉冲LIBS技术应用于水体金属的检测提供了一定依据.  相似文献   

11.
通过单脉冲激光诱导击穿光谱技术(LIBS),测定了Pb(NO3)2水溶液中微量重金属元素Pb的LIBS光谱。实验研究溶液中Pb元素的LIBS光谱信号的时间(300ns-1300ns)演化特性,得到了本实验的优化实验条件,光谱探测相对激光的延时为800ns,单脉冲激光能量35mJ。在最佳实验条件下测定Pb微量元素的LIBS定标曲线,计算得到LIBS用于Pb(NO3)2溶液中痕量金属元素分析的检测限为177ppm。  相似文献   

12.
Relatively large measurement uncertainty severely hindered wide application for laser-induced breakdown spectroscopy (LIBS), therefore it is of great importance to understand the mechanism of signal uncertainty generation, including initiation and propagation. It has been found that the fluctuation of plasma morphology was the main reason for signal uncertainty. However, it still remains unclear what mechanism leads to laser-induced plasma morphology fluctuation. In the present work, we employed three fast-imaging cameras to capture three successive plasma images from a same laser-induced Titanium alloy plasma, which enables us to understand more clearly of the plasma evolution process especially for the early plasma evolution stage when plasma and surrounding gases interact drastically. Seen from the images, the plasma experienced an increasing morphological fluctuation as delay time increased, transforming from a “stable plasma” before the delay time of 100 ns to a “fluctuating plasma” after the delay time of 300 ns. Notably, the frontier part of plasma showed a significant downward motion from the delay time of 150 ns to 200 ns and crashed with the lower part of the plasma, making the plasma flatter and later even splitting the plasma into two parts, which was considered as a critical process for the transformation of “stable plasma” to “unstable plasma”. By calculating the correlation coefficient of plasma image pairs at successive delay times, it was found that the higher the similarity between two plasma at early stage, the more similar at later stage; this implied that the tiny plasma fluctuation earlier than the critical delay time (150–200 ns) was amplified, causing a large plasma fluctuation at the later stage as well as LIBS measurement uncertainty. The initiation of slight fluctuation was linked with Rayleigh–Taylor Instability (RTI) due to the drastic material interpenetration at the plasma-ambient gas interface at earlier stage (before 50 ns). That is, the uncertainty generation of LIBS was proposed as: plasma morphology fluctuation was inevitably trigged by RTI at the early stage and the tiny fluctuation was amplified by the back pressed downward process of plasma frontier material, leading to severe morphology fluctuation as well as LIBS signal uncertainty.  相似文献   

13.
Yitong Liu 《中国物理 B》2022,31(10):105201-105201
Laser-induced breakdown spectroscopy (LIBS) is a good technique for detecting and analyzing material elements due to the plasma emission produced by the high-power laser pulse. Currently, a significant topic of LIBS research is improving the emission intensity of LIBS. This study investigated the effect of laser-polarization on femtosecond laser-ablated Cu plasma spectra at different sample temperatures. The measured lines under circularly polarized lasers were higher than those under linearly and elliptically polarized lasers. The enhancement effect was evident at higher Cu temperatures when comparing the plasma spectra that have circular and linear polarizations for different target temperatures. To understand the influence of laser-polarization and sample temperature on signal intensity, we calculated the plasma temperature (PT) and electron density (ED) . The change in PT and ED was consistent with the change in the atomic lines as the laser polarization was being adjusted. When raising the Cu temperature, the PT increased while the ED decreased. Raising the Cu temperature whilst adjusting the laser-polarization is effective for improving the signal of femtosecond LIBS compared to raising the initial sample temperature alone or only changing the laser polarization.  相似文献   

14.
Double-pulse Laser-Induced Breakdown Spectroscopy (LIBS) in an orthogonal configuration was used to investigate plasma temperature and electron density effects on Mg II emission spectral line broadening. The experiments were carried out with two Nd:YAG lasers, one operating at 355 nm for ablation and the other one at 1064 nm for plasma reheating in air at atmospheric pressure. Temporally resolved plasma temperature and electron density were measured at various delay times. Data in this study show prolonged emission of Mg II (280.27 nm) as well as enhancement of the signal intensity when using double-pulse excitation compared to the single-pulse case. An enhancement of ~8× was attained with a delay between the laser pulses equal to 1 μs. The enhancement was accompanied by higher plasma temperature and increased electron density. The double-pulse LIBS configuration provides energy to sustain the plasma emission at a period in time when the linewidth is minimum, thereby improving the analytical capabilities of low spectral resolution instrumentation typically used in LIBS system.  相似文献   

15.
光谱信号增强是提高激光诱导击穿光谱技术分析性能的重要手段之一,对等离子体进行空间约束由于装置简单且约束效果好而常被采用,等离子体的特性会直接影响空间约束的效果,而等离子体的特性与实验系统中激光的聚焦情况密切相关,为研究激发光源的聚焦情况对半球形空腔约束等离子体光谱增强特性的影响,通过控制透镜到样品之间的距离(LTSD)来改变激光的聚焦位置,分别在无约束和有半球形空腔约束两种实验条件下,烧蚀合金钢产生等离子体,采集15个不同LTSD位置时等离子体的时间演变光谱,得到谱线强度和增强倍数随着LTSD和采集延时的二维空间分布图。研究结果发现:无约束情况下,谱线强度分别在LTSD为94和102 mm时出现峰值,在采集延时小于8 μs时,谱线强度的最大值在LTSD为94 mm的位置,采集延时大于8 μs后,谱线强度的最大值出现在LTSD为102 mm的位置;当用半球空腔约束等离子体,谱线强度先后在采集延时范围为4~10和12~15 μs出现第一次增强和第二次增强。谱线强度出现第二次增强的主要原因是被半球腔内壁反射的冲击波与等离子体相互作用后会继续向前传播,遇到另一侧的腔壁再次被反射,进而对等离子体产生二次压缩。分析增强倍数随LTSD和采集延时的二维变化关系发现,第一次增强的最大增强倍数随LTSD的变化没有明显规律,增强倍数在2~6之间波动;谱线第二次增强时的增强倍数相对较高,最大增强倍数随着LTSD变化呈现出先增大再减小,然后再小幅增加后降低的变化规律,在LTSD为96 mm时达到最大值,两条谱线的最大增强倍数约为6倍。分析出现最大增强倍数对应的延迟时间发现,第一次增强出现的最优延迟时间在6~9 μs之间变化,当LTSD在85~93 mm范围时,最优延迟时间保持不变,当LTSD在94~105 mm时,出现先降低再增大的变化规律;第二次增强出现的延迟时间主要在14~15 μs,随着LTSD的变化没有明显的变化规律。  相似文献   

16.
Results of experimental investigations of 304 austenitic stainless steel (ASS) ultraviolet spectral range by single and double pulse laser induced breakdown spectroscopy (LIBS) at atmospheric pressure are reported. Various parameters, such as laser energy, placement of the laser beam focus with respect to the surface of illumi-nation, and collinear double laser pulse delay were used as variables. This study contributes to a better under-standing of the LIBS plasma dynamics by observing the temporal evolution of various emission lines. Temperature measurements were made by the Boltzmann diagram method using singly ionized Fe lines, and electron densities were found from Stark broadening. The temporal behaviors of these parameters were also estimated. It was found that the electron temperature for double pulses is higher than that for single pulse of the same total energy. For double pulse LIBS, the iron line emission intensities are enhanced and the analytical performance is improved. For instance, the intensity of iron line Fe I 275.01 nm was a factor of about 300 times higher if a double pulse of 2 × 20 mJ was used instead of a single pulse of 40 mJ when focusing the beam 4.7 mm behind the target surface. Published in Zhurnal Prikladnoi Spektroskopii, Vol. 79, No. 5, pp. 654–660, 2006.  相似文献   

17.
为了综合比较单双脉冲激光诱导击穿光谱技术(LIBS)在液体中重金属元素的检测效果,利用自建的液相射流单-双脉冲LIBS技术装置,对AlCl3水溶液中的Al元素LIBS特性进行测量和分析。实验中使用两台532 nm Nd∶YAG激光器作为激发光源,等离子体辐射信号通过光谱仪和ICCD进行采集。实验研究了单脉冲下Al(396.15 nm)发射谱线的谱线强度随激光能量、ICCD门延时、门宽之间的变化关系,获得了最优化实验参数激光能量为50 mJ,ICCD门延迟为1 200 ns,门宽为150 ns。在相同的实验条件下,实验考察了Al(369.15 nm)发射谱线的谱线强度随双脉冲之间的延时,激光总能量,ICCD门延时的变化关系,获得了最优化实验参数为两双脉冲之间的延时为1 000 ns,激光总能量为50 mJ,ICCD门延时为1 100 ns。单脉冲和双脉冲条件下获得重金属Al的LIBS检测限分别为26.79和10.80 ppm,双脉冲LIBS技术使元素检测限下降2倍多。实验结果表明双脉冲可以提升LIBS技术的探测灵敏度,为LIBS技术应用于水体中重金属快速检测提供了依据。  相似文献   

18.
采用波长为532nm的单脉冲激光诱导两种金属样品铜和锌,产生等离子光谱,固定激光能量40mJ、门宽100ns、光谱仪入射狭缝0.1mm、ICCD增益100等参数,研究金属样品物理化学特性对汇聚透镜焦点到样品表面距离、ICCD采集延迟等最优化实验参数的影响.实验中分别选取铜样品Cu(I)521.82nm和锌样品Zn(I)481.053nm谱线作为LIBS信号,实验测定的透镜焦点在距样品表面不同距离处的LIBS信号强度,结果表明铜和锌样品的聚焦透镜焦点分别在样品表面内距表面的距离为5mm和5.5mm时得到光谱信号强度最大;铜和锌的ICCD探测延时分别为1300ns和1100ns时等离子体光谱信号的信噪比最大并具有可观测的强度,依据铜和锌样品物理化学特性的差异对实验结果进行了合理的分析与讨论,为后续研究金属样品LIBS技术的基底效应、纳米结构增强激光诱导击穿光谱机理提供数据参考.  相似文献   

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