Influence of an Electric Field on the Emission and Absorption of Atoms and Ions in a Flame

Abstract

Experiments were carried out to explore the effect of an electric field upon atomic species introduced into a flame. The study involves components from a conventional flame atomic absorption apparatus with 10 × 10-cm parallel plate electrodes as the cathode and the 5-cm slot burner head as the anode. A marked decrease in the emission and absorption of many atomic species was observed, and quantification of the effect was carried out. The effect has been interpreted as a disturbance of the equilibrium, Me ≈ Me⁺ + e⁻. Relative decreases in absorption and emission were found to be functions of applied voltage and analyte concentration at low voltages, and constant for high voltages (≍ −2000 V). Temporal behavior of the effect has been investigated by observation of the speed of restoration of the emission signal from Na (589.16 nm), Sr (460.86 nm), and Sr⁺ (407.89 nm) after rapid elimination of the electric field. The effects were also studied as a function of viewing position in the flame for optimization of the position and comparison of the temporal behavior with the speed of the flame gases.