Studies on the mechanism of atom formation and loss from the ATOM-SOURCE cathodic sputtering atomizer for atomic absorption spectrometry

Abstract For the analysis of solution residues by cathodic sputtering in a glow discharge by atomic absorption spectrometry using the ATOMSOURCE atomizer, the entry of atoms into and loss of atoms from the analysis volume (defined by the geometry of the beam of radiation from the hollow-cathode lamp) can be described by the consecutive, first-order reactions where A is the analyte atom entering the analysis volume, B is the analyte atom that absorbs, and C is the analyte atom that is lost from the analysis volume, k 1 and k 2 are first-order rate constants. This model yields the following equation for the concentration of the absorbing atoms at time t , [B] t , where [A] o is the initial concentration of analyte atoms at time t = 0. Absorbance profiles of Ag, Al, Au, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb and V were obtained using the ATOMSOURCE in conjunction with a Perkin-Elmer Atomic Absorption Spectrophotometer, model Zeeman 5000 and the Perkin-Elmer Professional Computer, model 7500. The rate constants k 1 and K 2 were evaluated from kinetic profiles. The rate constants were then used to calculate theoretical absorbance profiles, which were compared with the experimentally obtained absorbance profiles. The results obtained fit the model well, implying that atoms are sputtered direct (i.e. without significant formation of intermediates) into the vapour phase from the solution residue on the cathode surface.