Cathodic sputtering within a low-pressure inert gas discharge provides a simple and convenient means for atomic spectroscopic studies of the atomic vapor produced from cathode material. However, the vapor consists of not only the atomic species but also the molecular species. These species were investigated by probing the vapors sputtered from the copper-lead cathode in the glow discharge source using a nitrogen laser pumped dye laser to excite the fluorescence. The laser-induced fluorescence spectral characteristics were used to identify the molecular species in the vapors. The identification and assignment of the spectral band systems revealed the presence of Cu2, CuO, and Pb2 species in the sputtered vapors. It is important to be aware of the reduced number density of atoms due to clustering and the possibility of spectral interferences from molecular species while using the glow discharge sputtering sources in atomic spectroscopic applications.
B. M. Patel and J. D. Winefordner, "Laser-Excited Fluorescence of Diatomic Molecules of Copper and Lead in Glow Discharge Sputtering," Appl. Spectrosc. 40, 667-672 (1986)