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This work evaluates the wavelength reproducibility and accuracy of a sequential scanning plasma emission system. The long-term thermal and thermomechanical errors are found to be in the range of a few picometers. The short-term instability and mechanical instability are found to contribute very little error to wavelength positioning. The wavelength calibration algorithm is described. Its use improves the accuracy by a factor of 5 to 10 by comparison with results from the use of the diffraction grating equation alone.

A previously characterized sequential scanning ICP spectrometer with nominal resolution of 0.009 nm, FWHM, for a 3600-line/mm grating and 0.018 nm for a 1800-line/mm grating is used to examine wavelength positions. Five atomic lines believed to have been reported in error in the literature are identified. Alternative values for each wavelength are suggested.