Einfluß der Anionen bei spektrochemischer: Spurenanalyse im lichtbogen

The influence of the addition of ammonia into the arc plasma on the spectral line intensities (with background correction) of trace elements was studied. The intensity changes caused by addition of ammonium sulphate and ammonium nitrate generally do not exceed the standard deviations. But the addition of ammonium chloride and ammonium fluoride causes a depressive effect on the spectral line intensities of volatile elements. The presence of ammonia halides in the plasma has an intensifying effect on spectral lines of Ti, present in the electrode material as impurity. In this case both ammonium sulphate and ammonium nitrate have no essential influence. Possible explanations of these effects are discussed. The depressive effect of the halides could be caused by processes in the plasma, and the intensifying of Ti-lines could be explained by the change of its volatility.Es wurde untersucht wie sich in das Bogenplasma zugegebene Ammonsalze auf die Linienintensitäten (mit Untergrundkorrektion) der untersuchten Spurenelemente auswirken. Bei Zugabe von Ammonsulfat und Ammonnitrat liegen die Intensitätsveränderungen der Spektrallinien hauptsächlich innerhalb der Fehlergrenze. Die Zugabe von Ammonchlorid und Ammonfluorid schwächt dagegen die Intensitäten der Spektrallinien der untersuchten leichtflüchtigen Elemente ausgesprochen ab. Die Ammonhalogenide erhöhen aber die Linienintensitäten des als Verunreinigung in den Elektroden anwesenden Titans. Auch in diesem Falle haben Ammonsulfat und Ammonnitrat keine ausgeprägte Wirkung gezeigt. Es wurden die möglichen Erklärungen dieses Effektes diskutiert. Der Depressionseffekt der Halogenide könnte durch Prozesse im Plasma bedingt sein, und zu einer Erhöhung der Linienintensitäten von Titan käme es infolge der Veränderung seiner Flüchtigkeit

Direct solution analysis using an arc source incorporating two plasmas rotating in a graphite tube

As a continuation of earlier work on arc sources for the spectrochemical analysis of powdered samples, a source appropriate for multi-element analysis of trace elements in solution has been developed. The nebulized solution to be analysed is introduced into a horizontal graphite tube in the gap between two plasmas rotating in a magnetic field. Both water and ethanol have been used as solvents and the effect of lithium additions on the detection limits for certain elements has been studied. This source provides advantageous conditions for the determination of trace elements present at very low concentrations. Source parameters investigated include a study of the magnetically induced rotation of the plasmas by high speed cine photography, and the temperature distribution within the tube. Both aqueous and ethanol solutions were used and the effect of lithium additions was measured

The effect of the plasma composition on characteristics of the d.c. arc - V The influence of iodine vapour on the radial temperature distribution of the arc burning in the atmosphere of nitrogen and argon

Considering the solutions of the Elenbaas-Heller energy balance equation it is possible to indicate how the chemical reactions among the components of added substances influence the radial temperature distribution in the arc. In the case of addition of iodine vapour to the atmosphere of nitrogen, and argon respectively, a core of higher temperature with a larger gradient of the radial temperature distribution in the arc centre is formed. These conclusions are confirmed by experimental determinations of the radial temperature distribution

The effect of the plasma composition on characteristics of the d.c. arc - I General discussion of the effect of the chemical reactions

The influence of chemical reactions among the components of the arc atmosphere on the radial temperature distribution is discussed. Their effect on other arc plasma characteristics and the spectrochemieal determination of elements in the arc is considered. The discussion is made in terms of the Elenbaas-Heller equation for the energy balance of the plasma. The equation is solved according to Maecker. The arc model is a freely burning arc, under conditions usually applied in spectrochemical practice. The role of dissociation energy is discussed on the basis of a theoretical model. Experimental and theoretical data for the radial temperature distribution of an arc burning in nitrogen are compared to check the appropriateness of the applied procedures

The effect of the plasma composition on characteristics of the d.c. arc-II. Arc in argon and arc in nitrogen with water vapour

The experimental and theoretical curves of the radial temperature distribution of the arc burning in argon, are compared with the corresponding curves in nitrogen. The theoretical curves are obtained by solving the Elenbaas-Heller energy balance equation according to Maecker. The model of the freely burning arc, under conditions usually applied in spectrochemical praxis, is considered. In accordance with theory and in comparison with the arc burning in pure nitrogen, the brilliant zone of arcs burning in argon has a steeper radial temperature distribution. If water vapour is added to an arc burning in nitrogen, the arc plasma is narrowed and the temperature increased. These experimental data can be interpreted theoretically from the solution of the energy balance equation

The effect of the plasma composition on characteristics of the d.c. arc—IV: Influence of lithium on an arc in nitrogen

The radial temperature distribution of the arc burning in nitrogen was measured when a large quantity of Li2CO3 evaporates in the arc. In comparison to the radial temperature distribution of the arc burning in nitrogen alone, a smaller temperature gradient was obtained. This can be interpreted by taking the variation of the electron density into account when solving the Elenbaas-Heller equation for the plasma energy balance