Diagnostics of laser-induced plasma on carbon-based polymer material using atomic and molecular emission spectra

Time-integrated optical emission analysis of laser-induced plasma on Teflon is presented. Plasma was induced under atmospheric pressure air using transversely excited atmospheric CO₂ laser pulses. Teflon is a C-based polymer that is, among other things, interesting as a substrate for laser-induced breakdown spectroscopy analysis of liquid samples. This study aimed to determine the optimal experimental conditions for obtaining neutral and ionized C spectral lines and C₂ and CN molecular band emission suitable for spectrochemical purposes. Evaluation of plasma parameters was done using several spectroscopic techniques. Stark profiles of appropriate C ionic lines were used to determine electron number density. The ratio of the integral intensity of ionic-to-atomic C spectral lines was used to determine the ionization temperature. A spectral emission of C₂ Swan and CN violet bands system was used to determine the temperature of the colder, peripheral parts of plasma. We critically analyzed the use of molecular emission bands as a tool for plasma diagnostics and suggested methods for possible improvements.