Advance in the Excitation Source in Glow Discharge Optical Emission Spectrometry
A Grimm-style glow discharge is now an important excitation source in atomic emission spectrometry, especially for direct analysis of solid samples. Many studies have been conducted for enhancing the emission intensities from the source and thus improving the detection sensitivity in the analytical applications. This review introduces several improved Grimm-style excitation sources. The techniques employed in such sources include the modification of the source geometry, supplementary discharges caused by d.c. or microwave powers, and methods for controlling the glow discharge plasma. Improvement in the analytical performance is presented when they are compared with a conventional Grimm-style glow discharge source.