Effect of axial injection of argon on conventional spectrochemical excitation sources at atmospheric pressure—I: Behaviour of line intensities and their profiles under various experimental conditions

Abstract

The axial injection of argon into the conventional excitation sources through a hole drilled in the upper electrode is discussed. In spite of a simple electrode arrangement the argon produces unexpected and significant changes in emission phenomena. Self-reversal is practically eliminated. Intensity enhancements were studied as a function of line character, excitation potential, electrode type, concentration of analytes and concomitants, the presence of organic materials (solvents and solutes) and the purity of the argon. It was observed, that the intensity enhancement deteriorated if the concentration of excitable particles (atoms, molecules, free-radicals, etc.) in the plasma increased. Using krypton instead of argon similar results were obtained.