Publication details

State-by-state emission spectra fitting for non-equilibrium plasmas: OH spectra of surface barrier discharge at argon/water interface

Authors

VORÁČ Jan SYNEK Petr PROCHÁZKA Vojtěch HODER Tomáš

Type Article in Periodical
Magazine / Source JOURNAL OF PHYSICS D-APPLIED PHYSICS
MU Faculty or unit

Faculty of Science

Citation
Web https://doi.org/10.1088/1361-6463/aa7570
Doi http://dx.doi.org/10.1088/1361-6463/aa7570
Field Plasma physics
Keywords optical emission spectroscopy; batch processing; massiveOES; spectra fitting; atmospheric pressure; surface barrier discharge; triple-line
Description Optical emission spectroscopy applied to non-equilibrium plasmas in molecular gases can give important information on basic plasma parameters, including the rotational and vibrational temperatures and densities of the investigated radiative states. In order to precisely understand the non-equilibrium of rotational-vibrational state distribution from the investigated spectra without limiting presumptions, a state-by-state temperature-independent fitting procedure is the ideal approach. In this paper, we present a novel software tool developed for this purpose, freely available for the scientific community. The introduced tool offers a convenient way to construct Boltzmann plots even from partially overlapping spectra, in a user-friendly environment. We apply the novel software to the challenging case of OH spectra in surface streamer discharges generated from the triple-line of the argon/water/dielectrics interface. After the barrier discharge is characterised by ICCD and electrical measurements, the spatially and phase resolved rotational temperatures from N2(C-B) and OH(A-X) spectra are determined and compared. The precise analysis shows that OH(A) states with quantum numbers (v'=0, 9 <= N' <= 13) are overpopulated with respect to the found two-Boltzmann distribution. We hypothesise that fast vibrational-energy transfer is responsible for this phenomenon, observed here for the first time. Finally, the vibrational temperature of the plasma and the relative populations of hot and cold OH(A) states are quantified spatially and phase resolved.
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