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技术来控制火花放电以供分析使用，其独特之处在于可以通过激光照射来固定火花放电的点火点。由于火花放电很容易在特定的表面位置（例如非金属夹杂物）引发，称为选择性放电，因此在火花放电发射光谱分析中，某些元素的浓度有时会偏离其平均浓度。因此，样品表面点火点的稳定可以提高分析精度和精密度。当使用具有圆形尖端的钨针和铁板作为计数电极和样品电极时，很难引起火花放电这些电极之间的距离在空气中为几毫米，并且在我们的实验条件下产生火花放电需要小于0.7毫米的更近的间距。通过引入激光照射，电极距离可以延长至3.5毫米，同时保持稳定的火花放电。我们还将钨针电极移动到距离激光诱导等离子体击穿位置水平2毫米以内。火花通道可以保持在触针电极和击穿位置与火花通道的长度无关。发现火花放电的起始位置可以通过激光照射来控制。通过使用本发明的组合技术，Fe I 373.5 nm的发射强度比单独通过火花放电光谱法获得的发射强度增强了1.5倍。这可能是由于除了单独通过火花放电获得的采样量之外还通过激光烧蚀额外增加了采样量。