Studies were performed on the effect of torch pressure on the excitation conditions within an inductively coupled plasma (ICP). Experimentally measured magnesium ion-to-atom ratios and electron densities were used to determine the deviation of the plasma from local thermodynamic equilibrium (LTE) conditions. Results of these studies indicate that the plasma is in an infrathermal state when operated at atmospheric pressure, and excitation conditions within the central channel of an ICP shift towards LTE conditions as torch pressure is increased.
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