Tandem Helium Plasma Spectrometry with a Capacitively Coupled Discharge Formed above a Helium ICP

Abstract
A tandem helium plasma was formed by placing a water-cooled, grounded electrode above a helium inductively coupled plasma (He ICP). The tandem plasma could be operated at 250 to 700 W. Detection limits of F, Cl, Br, S, and C at 500 W were comparable or superior to those from a He ICP operated at 1500 W. At 500 W, the electron number density for the tandem helium plasma was greater than that for the He ICP at 1500 W, but similar excitation temperatures and roughly similar rotational temperatures were obtained.