Formation of CaF and AlF in the arc plasma and spectrochemical determination of Ca and Al

Abstract

The influence of chemical reactions in d.c. arc plasma on the atomic emission determination of traces has been investigated. The effect of added NH4F on the intensity of spectral lines of Ca and Al was examined. A decrease of the spectral line intensities of Ca and Al in the presence of NH4F occurred, if the sample had not been mixed in the electrode with NH4F. The AlF band spectrum, transition A1Π → X1∑, was observed in absorption of the arc radiation. Further, the axial intensity distribution of Ca, Al, Ga and Ag spectral lines and of the head of the green system of CaF band, has been measured. The depressive effect of fluorine on spectral line intensities of Ca, Al, Ga and Ag has to be connected with the processes in plasma. It is suggested that the formation of fluoride radicals could take part in this effect. © 1975 Springer-Verlag.