Evolution of N-2(A(3)Sigma(+)(u)) in streamer discharges: influence of oxygen admixtures on formation of low vibrational levels. Simek, M., Ambrico, P. F., & Prukner, V. JOURNAL OF PHYSICS D-APPLIED PHYSICS, DEC 20, 2017. doi abstract bibtex The formation of N-2(A(3)Sigma(+)(u)) metastable species, produced by cathode-directed streamer discharge, was investigated using the technique of laser-induced fluorescence. A triggered single streamer filament was periodically produced in pure nitrogen (and in nitrogen with admixtures of oxygen) at total pressure of 50 Torr and metastable species were monitored during the streamer channel decay in the centre of the discharge gap. We revealed the dynamics of individual vibrational (v = 0-8) levels of N-2(A(3)Sigma(+)(u)) for various oxygen admixtures (0-20%). In pure nitrogen, the observed evolution of the N-2(A(3)Sigma(+)(u)) during the decaying streamer channel is evidence of initial vibrational relaxation of high vibrational levels towards the v = 2 and 3 levels, followed by a delayed increase of terminal (v = 0, 1) levels. A calibration procedure based on the rate of energy-pooling processes was used to place all detected vibronic levels in pure nitrogen on the absolute scale. Population maxima exceeding 1 x 10(14) cm(-3) were fixed for the v = 2 and 3 vibrational levels, while the lowest v = 0 level reaches only 3 x 10(13) cm(-3). Populations of v = 2-5 vibrational levels were also estimated for N-2 + O-2 mixtures after scaling of laser-induced fluorescence signals obtained at various oxygen admixtures. The total N-2(A(3)Sigma(+)(u)) population in an air-like mixture is formed mainly by v = 3-4 vibronic levels with the population maximum of similar to 3 x 10(13) cm(-3) fixed at the shortest analyzed delay. This observation, together with the fact that we were unable to detect v = 0 and 1 levels (fluorescence signals below detection threshold), gives a strong evidence of the inhibition of Delta v = 2 vibrational relaxation towards terminal v = 0 and 1 levels, causing much lower populations of the lowest v = 0-1 levels. By analyzing data obtained in pure nitrogen and in nitrogen with three different oxygen admixtures, we have estimated the quenching rate constants of N-2(A(3)Sigma(+)(u), v) + O-2 and N-2(A(3)Sigma(+)(u), v) + N-2 processes for v = 2-6 vibrational levels which are consistent with data from the literature. Quenching rate constants for nitrogen reflect the N-2(A(3)Sigma(+)(u), v) -> N-2(A(3)Sigma(+)(u), v-2) relaxation process, however the v = 2 rate constant shows a much larger value compared with the published data.
@article{ ISI:000416005900001,
Author = {Simek, M. and Ambrico, P. F. and Prukner, V.},
Title = {{Evolution of N-2(A(3)Sigma(+)(u)) in streamer discharges: influence of
oxygen admixtures on formation of low vibrational levels}},
Journal = {{JOURNAL OF PHYSICS D-APPLIED PHYSICS}},
Year = {{2017}},
Volume = {{50}},
Number = {{50}},
Month = {{DEC 20}},
Abstract = {{The formation of N-2(A(3)Sigma(+)(u)) metastable species, produced by
cathode-directed streamer discharge, was investigated using the
technique of laser-induced fluorescence. A triggered single streamer
filament was periodically produced in pure nitrogen (and in nitrogen
with admixtures of oxygen) at total pressure of 50 Torr and metastable
species were monitored during the streamer channel decay in the centre
of the discharge gap.
We revealed the dynamics of individual vibrational (v = 0-8) levels of
N-2(A(3)Sigma(+)(u)) for various oxygen admixtures (0-20\%). In pure
nitrogen, the observed evolution of the N-2(A(3)Sigma(+)(u)) during the
decaying streamer channel is evidence of initial vibrational relaxation
of high vibrational levels towards the v = 2 and 3 levels, followed by a
delayed increase of terminal (v = 0, 1) levels. A calibration procedure
based on the rate of energy-pooling processes was used to place all
detected vibronic levels in pure nitrogen on the absolute scale.
Population maxima exceeding 1 x 10(14) cm(-3) were fixed for the v = 2
and 3 vibrational levels, while the lowest v = 0 level reaches only 3 x
10(13) cm(-3).
Populations of v = 2-5 vibrational levels were also estimated for N-2 +
O-2 mixtures after scaling of laser-induced fluorescence signals
obtained at various oxygen admixtures. The total N-2(A(3)Sigma(+)(u))
population in an air-like mixture is formed mainly by v = 3-4 vibronic
levels with the population maximum of similar to 3 x 10(13) cm(-3) fixed
at the shortest analyzed delay. This observation, together with the fact
that we were unable to detect v = 0 and 1 levels (fluorescence signals
below detection threshold), gives a strong evidence of the inhibition of
Delta v = 2 vibrational relaxation towards terminal v = 0 and 1 levels,
causing much lower populations of the lowest v = 0-1 levels.
By analyzing data obtained in pure nitrogen and in nitrogen with three
different oxygen admixtures, we have estimated the quenching rate
constants of N-2(A(3)Sigma(+)(u), v) + O-2 and N-2(A(3)Sigma(+)(u), v) +
N-2 processes for v = 2-6 vibrational levels which are consistent with
data from the literature. Quenching rate constants for nitrogen reflect
the N-2(A(3)Sigma(+)(u), v) -> N-2(A(3)Sigma(+)(u), v-2) relaxation
process, however the v = 2 rate constant shows a much larger value
compared with the published data.}},
DOI = {{10.1088/1361-6463/aa96f3}},
Article-Number = {{504002}},
ISSN = {{0022-3727}},
EISSN = {{1361-6463}},
ResearcherID-Numbers = {{Simek, Milan/E-6941-2014}},
ORCID-Numbers = {{Simek, Milan/0000-0003-1730-8493}},
Unique-ID = {{ISI:000416005900001}},
}
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A triggered single streamer filament was periodically produced in pure nitrogen (and in nitrogen with admixtures of oxygen) at total pressure of 50 Torr and metastable species were monitored during the streamer channel decay in the centre of the discharge gap. We revealed the dynamics of individual vibrational (v = 0-8) levels of N-2(A(3)Sigma(+)(u)) for various oxygen admixtures (0-20%). In pure nitrogen, the observed evolution of the N-2(A(3)Sigma(+)(u)) during the decaying streamer channel is evidence of initial vibrational relaxation of high vibrational levels towards the v = 2 and 3 levels, followed by a delayed increase of terminal (v = 0, 1) levels. A calibration procedure based on the rate of energy-pooling processes was used to place all detected vibronic levels in pure nitrogen on the absolute scale. Population maxima exceeding 1 x 10(14) cm(-3) were fixed for the v = 2 and 3 vibrational levels, while the lowest v = 0 level reaches only 3 x 10(13) cm(-3). Populations of v = 2-5 vibrational levels were also estimated for N-2 + O-2 mixtures after scaling of laser-induced fluorescence signals obtained at various oxygen admixtures. The total N-2(A(3)Sigma(+)(u)) population in an air-like mixture is formed mainly by v = 3-4 vibronic levels with the population maximum of similar to 3 x 10(13) cm(-3) fixed at the shortest analyzed delay. This observation, together with the fact that we were unable to detect v = 0 and 1 levels (fluorescence signals below detection threshold), gives a strong evidence of the inhibition of Delta v = 2 vibrational relaxation towards terminal v = 0 and 1 levels, causing much lower populations of the lowest v = 0-1 levels. By analyzing data obtained in pure nitrogen and in nitrogen with three different oxygen admixtures, we have estimated the quenching rate constants of N-2(A(3)Sigma(+)(u), v) + O-2 and N-2(A(3)Sigma(+)(u), v) + N-2 processes for v = 2-6 vibrational levels which are consistent with data from the literature. Quenching rate constants for nitrogen reflect the N-2(A(3)Sigma(+)(u), v) -> N-2(A(3)Sigma(+)(u), v-2) relaxation process, however the v = 2 rate constant shows a much larger value compared with the published data.","doi":"10.1088/1361-6463/aa96f3","article-number":"504002","issn":"0022-3727","eissn":"1361-6463","researcherid-numbers":"Simek, Milan/E-6941-2014","orcid-numbers":"Simek, Milan/0000-0003-1730-8493","unique-id":"ISI:000416005900001","bibtex":"@article{ ISI:000416005900001,\nAuthor = {Simek, M. and Ambrico, P. F. and Prukner, V.},\nTitle = {{Evolution of N-2(A(3)Sigma(+)(u)) in streamer discharges: influence of\n oxygen admixtures on formation of low vibrational levels}},\nJournal = {{JOURNAL OF PHYSICS D-APPLIED PHYSICS}},\nYear = {{2017}},\nVolume = {{50}},\nNumber = {{50}},\nMonth = {{DEC 20}},\nAbstract = {{The formation of N-2(A(3)Sigma(+)(u)) metastable species, produced by\n cathode-directed streamer discharge, was investigated using the\n technique of laser-induced fluorescence. A triggered single streamer\n filament was periodically produced in pure nitrogen (and in nitrogen\n with admixtures of oxygen) at total pressure of 50 Torr and metastable\n species were monitored during the streamer channel decay in the centre\n of the discharge gap.\n We revealed the dynamics of individual vibrational (v = 0-8) levels of\n N-2(A(3)Sigma(+)(u)) for various oxygen admixtures (0-20\\%). In pure\n nitrogen, the observed evolution of the N-2(A(3)Sigma(+)(u)) during the\n decaying streamer channel is evidence of initial vibrational relaxation\n of high vibrational levels towards the v = 2 and 3 levels, followed by a\n delayed increase of terminal (v = 0, 1) levels. A calibration procedure\n based on the rate of energy-pooling processes was used to place all\n detected vibronic levels in pure nitrogen on the absolute scale.\n Population maxima exceeding 1 x 10(14) cm(-3) were fixed for the v = 2\n and 3 vibrational levels, while the lowest v = 0 level reaches only 3 x\n 10(13) cm(-3).\n Populations of v = 2-5 vibrational levels were also estimated for N-2 +\n O-2 mixtures after scaling of laser-induced fluorescence signals\n obtained at various oxygen admixtures. The total N-2(A(3)Sigma(+)(u))\n population in an air-like mixture is formed mainly by v = 3-4 vibronic\n levels with the population maximum of similar to 3 x 10(13) cm(-3) fixed\n at the shortest analyzed delay. This observation, together with the fact\n that we were unable to detect v = 0 and 1 levels (fluorescence signals\n below detection threshold), gives a strong evidence of the inhibition of\n Delta v = 2 vibrational relaxation towards terminal v = 0 and 1 levels,\n causing much lower populations of the lowest v = 0-1 levels.\n By analyzing data obtained in pure nitrogen and in nitrogen with three\n different oxygen admixtures, we have estimated the quenching rate\n constants of N-2(A(3)Sigma(+)(u), v) + O-2 and N-2(A(3)Sigma(+)(u), v) +\n N-2 processes for v = 2-6 vibrational levels which are consistent with\n data from the literature. Quenching rate constants for nitrogen reflect\n the N-2(A(3)Sigma(+)(u), v) -> N-2(A(3)Sigma(+)(u), v-2) relaxation\n process, however the v = 2 rate constant shows a much larger value\n compared with the published data.}},\nDOI = {{10.1088/1361-6463/aa96f3}},\nArticle-Number = {{504002}},\nISSN = {{0022-3727}},\nEISSN = {{1361-6463}},\nResearcherID-Numbers = {{Simek, Milan/E-6941-2014}},\nORCID-Numbers = {{Simek, Milan/0000-0003-1730-8493}},\nUnique-ID = {{ISI:000416005900001}},\n}\n\n","author_short":["Simek, M.","Ambrico, P. 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