Electrothermal atomization from metallic surfaces: Part 2. Atom formation Processes in the tungsten-tube atomizer

A modified carbon rod atomizer (Varian M-63) is used to study the mechanism of atom formation of Al, Ba, Co, Pb, Ni and V in a tungsten-tube atomizer by a combined thermodynamic—kinetic approach. The atomizer is made from two profiled tungsten strips held in two copper supporting electrodes and forming a cylindrical cavity (5 mm long, 4 mm i.d.). Appearance temperatures and atomization energies are compared with those obtained for a graphite-tube atomizer. The major pathways leading to gaseous atoms are thermal dissociation of the metal oxide (or hydroxide) and reduction of the metal oxide followed by the atomization of free metal, depending on the protecting atmosphere (argon or argon—hydrogen mixture) and analyte.