Atomic Oxygen Spectra in the Argon Inductively Coupled Plasma (ICP)

Abstract

Nonresonant, low-energy atomic oxygen transitions from high-energy (11 to 16 eV) singlet, triplet, and quintet states are observed in the 2 kW argon inductively coupled plasma (ICP). A table of ICP oxygen lines and relative emission intensities from 2500 to 10 000 Å is presented. The degree of molecular dissociation in the ICP is evaluated for several small, highly stable molecules as a function of rf power level over the range of 0.2 to 2.25 kW. Quantitative dissociation is achieved at power levels ≥1.95 kW. The use of these nonresonance O(I) lines for the analytical detection of oxygen is reported. The present detection limit for nonoptimized conditions is 0.5 μg. Considerable improvement is expected in the future. The response is linear, and the precision using a gas sampling loop is 0.5% RSD.