A spectroscopic investigation of the afterglow and recombination process in a microsecond pulsed glow discharge

The emission characteristics of afterglow in a microsecond pulsed glow discharge atomic source are studied to obtain insight into the excitation and recombination processes of analytes and fill gases. Each emission line features an initial intense peak at the beginning of the discharge pulse. The afterglow, which has been observed in the temporal behavior for some emission temporal profiles of analytes and discharge gases, exhibits an intense post-pulse signal maximized at 25–35 μs after plasma termination, with a broader profile than their initial peaks. The afterglow of Ar I and Cu I spectra last approximately 100 μs and 300 μs, respectively, after the argon discharge pulse at 2.0 torr pressure. The intensity of the afterpeak increases with the pulse width between 2 μs to 200 μs. A study of fourteen Ar I and twenty-seven Cu I lines show that transitions from high energy levels (5p [14.5–14.7 eV] for Ar and above 6 eV for Cu) are relatively stronger in the afterglow. The highly excited argon and copper atoms are thought to be generated via the recombination of ions and electrons. The results are explained primarily in terms of an electron-electron-ion three-body recombination process.