Spatial and temporal dynamics of a pulsed spark microplasma used for aerosol analysis

The spatial and temporal dynamics of a pulsed, electrical spark microplasma used for spectrochemical analysis of aerosols was investigated. The spark discharge was generated by applying a high voltage pulse between a coaxial anode and cathode. Aerosol particles of black carbon were collected on the cathode for 2 min, following which the pulsed microplasma was introduced, leading to ablation and atomization of the collected particles. The space and time-resolved emission spectra showed that the atomic emission signal from the carbon species originated from the region close to the cathode surface during the early evolution of the microplasma. The CI and C II atomic emission reached peak intensities at 11 and 6 ps delay time, respectively. Peak emission intensities occurred between 0.5-13 mm above the cathode surface. The average excitation temperature and the electron number density of the spark microplasma were estimated to be 23,000 K, and 1.6 x 10(17) cm(-3), respectively. The effects of pulse energy on the excitation temperature and electron density were also investigated. The results provide insights into the dynamics of the pulsed spark microplasma and are helpful in optimizing elemental analysis of aerosols using this technique. (C) 2018 Elsevier B.V. All rights reserved.