Fundamental Studies in the ICP Using a Sinusoidally Modulated Power Input

Abstract

The power input into an inductively coupled plasma has been modulated over the frequency range of 200 to 400 Hz. It was found that the plasma exhibits a nonlinear response to changes in power. In addition, the maximum excitation temperature is correlated to the peak of the modulation waveform, whereas the fluorescence intensity and therefore species number density is related to the valley of the modulation. The measured delays are a function of observation height and studied analyte but are frequency independent. Gas dynamics, energy transfer, or sample decomposition rates are suggested to be responsible for the delays.