Spectral, spatial and temporal characterization of a millisecond pulsed glow discharge: copper analyte emission and ionization

Two-dimensional maps of the spatial distributions of excited and ionized sp uttered copper atoms are presented for a millisecond pulsed argon glow disc harge. These maps demonstrate the temporal as well as spatial dependence of different excitation and ionization processes over the pulse cycle. Transi tions from the low energy electronic states for the atom, characterized by emission such as that at 324.75 nm (3.82 --> 0.00 eV), dominate the plateau time regime at a distance of 2.5 mm from the cathode surface. These proces ses originate from the electron excitation of ground state copper atoms. Tr ansitions from high-energy electronic states, such as that characterized by emission at 368.74 nm (7.16 --> 3.82 eV), predominate during the afterpeak time regime at a distance of 5.0-6.0 mm from the cathode surface. This obs ervation is consistent with the relaxation of highly excited copper atoms p roduced by electron recombination with copper ions during the afterpeak tim e regime. Analyses of afterpeak and plateau intensities for a series of cop per emission lines indicate an electron excitation temperature equivalent t o 5.78 eV at 0.8 torr and 1.5 W. Temporal profiles exhibit copper ion emiss ion only during the plateau time regime. (C) 2001 Elsevier Science B.V. All rights reserved.