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Stabilization of spark discharge point on sample surface and enhancement of emission intensity by laser irradiation

样品表面火花放电点的稳定和激光照射增强发射强度

基本信息

批准号：
17560649
负责人：
MATSUTA Hideyuki
金额：
$ 2.3万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17560649/
关键词：
Laser-induced plasma Spark discharge Optical emission Stabilization Control of discharge

项目摘要

A combined technique with laser irradiation is proposed to control spark discharge for analytical use, having a unique feature that firing points of the spark discharge can be fixed by laser irradiation. Because the spark discharge easily initiates at particular surface sites, such as non-metallic inclusions, called selective discharge, the concentration of some elements sometimes deviates from their average one in spark discharge optical emission spectrometry. Therefore, stabilization of firing points on a sample surface could improve the analytical accuracy and precision.When a tungsten stylus having a round-shaped tip and an iron plate were used as the counter and the sample electrodes, it was very difficult to induce spark discharges between these electrodes having distances of a few mm in air, and a closer spacing of less than 0.7 mm was required to generate the spark discharge under our experimental conditions. By introducing laser irradiation, the electrode distance could be extended up to 3.5 mm while keeping stable spark discharges.We also moved a tungsten stylus electrode to within 2 mm horizontally from the breakdown position of the laser-induced plasma The spark channel could be maintained between the stylus electrode and the breakdown position regardless of the length of the spark channels. It is found that the initiation site of a spark discharge can be controlled by laser irradiation.By using the present combined technique, emission intensity of Fe I 373.5 nm was enhanced 1.5 times brighter than the one obtained by a spark discharge spectrometry alone. This may be due to the additional increment of a sampling amount by laser ablation in addition to the one obtained by a spark discharge alone.

提出了一种与激光照射相结合的分析用火花放电控制技术，其独特之处在于可以通过激光照射来固定火花放电的着火点。由于火花放电容易在特定的表面位置发生，如非金属夹杂物，称为选择性放电，在火花放电光谱中，某些元素的浓度有时会偏离其平均值。因此，稳定样品表面的触发点可以提高分析的准确度和精密度。在我们的实验条件下，当使用圆头和铁板作为计数器和样品电极时，在空气中几毫米的距离很难在这些电极之间产生火花放电，需要更近的间距小于0.7 mm才能产生火花放电。通过引入激光照射，电极距离可以延长到3.5 mm，同时保持稳定的火花放电。我们还将钨触针电极水平移动到距离激光诱导等离子体击穿位置2 mm的范围内，无论火花通道的长度如何，触针电极与击穿位置之间的火花通道都可以保持不变。研究发现，激光可以控制火花放电的起爆位置，利用这种组合技术，Fe I 373.5 nm的发射强度比单独使用火花放电光谱的发射强度提高了1.5倍。这可能是由于除了通过单独的火花放电获得的采样量之外，通过激光烧蚀获得的采样量的额外增加。