Sputtering and transport processes in a new laboratory-constructed sputtering atomizer

Abstract

The performance of a new, laboratory-constructed cathodic sputtering atomizer when used in atomic emission spectrometry and atomic absorption spectrometry has been studied. The atomizer employs a six gas-jet configuration with the gas-jets directed at the cathode surface. The atomizer has been constructed to provide an independent control of the flow rate and the pressure of argon gas in the atomizer since the sensitivity is dependent on both the flow rate and the pressure of the gas. The construction of the atomizer and its associated equipment is described. Studies were made of the atomic emission of copper, the atomic absorption of copper and chromium in steel, and the atomic absorption of nickel in brass, using solid, bulk samples in all cases. The effects of variation in the argon gas flow rate upon the atomic emission and the atomic absorption signals were studied at a constant pressure with either a constant voltage or a constant power. The ground state population within the analysis volume was found to be dependent on the sputtering efficiency and the transport efficiency. The excited state population within the analysis volume was found to be dependent on the transport efficiency and the discharge voltage, the latter determining the electron energy distribution. The postulated mechanism for excitation of copper is by inelastic collision of fast electrons with ground state neutral copper atoms, the number of fast electrons being the limiting species in the excitation mechanism.