  Optical emission spectroscopy applied to non-equilibrium plasmas in molecular
gases can give important information on basic plasma parameters, including the
rotational, vibrational temperatures and densities of the investigated
radiative states. In order to precisely understand the non-equilibrium of
rotational-vibrational state distribution from 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 scientific community. The
introduced tool offers a convenient way to construct Boltzmann plots even from
partially overlapping spectra, in 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 argon/water/dielectrics interface. After the
barrier discharge is characterised by ICCD and electrical measurements, the
spatially and phase resolved rotational temperatures from N$_2$ (C-B) and
OH(A-X) spectra are measured, analysed and compared. The precise analysis shows
that OH(A) states with quantum numbers (v' = 0, 9 $\leq$ N' $\leq$ 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.
