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到目前为止,在粉末样品的光谱分析中,易挥发元素的曝光时间都比较长,例如银,有的竟长达70秒之久。长时曝光并不能提高低浓度的强度降低检出限,也不能提高准确度,工作效率低,还会带来其他许多弊病:例如,极距变化以及引起的电流变化,调弧以及引起的弧光晃动,电极头温度过高等,更重要的是,在工作曲线的下段和上段部分会造成浓度失真,相比而言,长时曝光的分析范围比较窄。在动板实验中,我们可以看到,不同浓度的银,在燃烧初期的几秒钟之内,很快就达到了峰值强度(微分强度)。以后,随着燃烧时间的增长,强度逐渐减少,低浓度的谱线先后消失。如图1所示。
So far, in the spectral analysis of powder samples, the exposure time of volatile elements is relatively long, such as silver, some as long as 70 seconds long. Long exposure does not increase the strength of low concentration to reduce the detection limit, can not improve the accuracy, low efficiency, but also bring many other ills: for example, polar changes and the resulting changes in current, adjusting arc and arc caused by Shaking, the tip temperature is too high, more importantly, in the lower part of the working curve and the upper part of the concentration will cause distortion, compared to long-term exposure analysis is relatively narrow. In the moving plate experiment, we can see that different concentrations of silver quickly reach the peak intensity (differential intensity) in the first few seconds of combustion. Later, with the increase of burning time, the intensity gradually decreased and the low-concentration spectral lines disappeared one after another. As shown in Figure 1.