杯电極溶液法光谱光源中物质蒸发与弧温的研究

杯电极溶液电弧法无论应用在金属或非金属样品的光谱分析中,都受到光谱工作者们越来越多的注意。为了更进一步提高它的分析灵敏度和准确度,作者们对它的蒸发激发机构进行了研究。在燃弧过程中,曾观察到弧区是由弧焰与弧柱两个部分组成的。通过一系列实验发现:弧焰的存在直接影响到溶液样品的蒸发,而弧柱在光谱的激发过程中起着主导的作用。此外还利用OH带光谱测量弧焰及弧柱的温度分布。从得到的结果中找到提高分析灵敏度和准确度的途径。

A STUDY ON THE TRANSPORT OF VAPOR STREAM AND ARC TEMPERATURE IN THE EXCITATION SOURCE OF THE CUP SOLUTION METHOD

The cup electrode solution arc method is a new technique for spectrographic analysis. With this we analysed a variety of slags as well as some steel samples. Fractional distillation is found to be absent. In order to improve the sensitivity and precision of this method the authors studied the transport of the vapor stream and distribution of arc temperature in the light source.To begin with, we found that the arc column consists of two parts: (1) a very bright central column, (2) a moving arc flame around the central part, between the upper electrodes and the surface of the cup electrode. Experimental results show that the area of contact between the surface of the sample solution and flame determines the intensities of spectral lines. According to the OH rotational band spectra the temperature of the central part of the arc is higher than that of the flame by about 1000°K. In the spectrogram of the flame we could not find any line of the metallic elements besides that of the alkali and alkali earths (Na, K, Ca, Mg). In contrary all the metal spectral lines appeared in the spectrogram of the central column. In the discharge column the intensity of spectral lines is not uniform which is closely related to the variation of arc temperature.It is also found, that the stabilization of the position of arc flame by anexternal magnetic field results more stable volatilization of the sample solutionthus increase of precision could be attained. By focusing the image of the part with maximum intensity on the slit of the spectrograph increases sensitivity in practice.