LIF imaging of OH radicals in DC positive streamer coronas

Kanazawa, Susumu; Tanaka, Hiroto; Kajiwara, Atsushi; Ohkubo, T.; Nomoto, Y.; Kočík, M.; Mizeraczyk, J.; Chang, Jen‐Shih

doi:10.1016/j.tsf.2006.02.046

Cited by 49 publications

(33 citation statements)

References 11 publications

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“…N OH (t) can be considered as a constant during the laser pulse due to fast RET with rate constant about 3.5 Â 10 À9 s À1 or higher. 18,20 The same approximation has been used by others 5,8 and gives very good agreement with experiment. The spectrally and temporally integrated fluorescence can be written as…”

Section: -6supporting

confidence: 55%

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Nikiforov

Xiong

et al. 2013

Physics of Plasmas

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Recently, plasma jet systems found numerous applications in the field of biomedicine and treatment of temperature-sensitive materials. OH radicals are one of the main active species produced by these plasmas. Present study deals with the investigation of RF atmospheric pressure plasma jet in terms of OH radicals production by admixture of H 2 O into argon used as a feed gas. Generation of OH radicals is studied by laser-induced fluorescence spectroscopy. The excitation dynamics of OH radicals induced by the laser photons is studied by time-resolved spectroscopy. It is shown that vibrational and rotational energy transfer processes, which are sensitive to the surrounding species, can lead to the complication in the OH radicals diagnostics at high pressure and have to be considered during experiments. The axial and radial 2D maps of absolute densities of hydroxyl radicals at different water contents are obtained. The highest density of 1.15 Â 10 20 m À3 is measured in the plasma core for the case of 0.3% H 2 O. In the x-y-plane, the OH density steeply decreases within a range of 62 mm from its maximum value down to 10 18 m À3 . The effect of H 2 O addition on the generation of OH radicals is investigated and discussed. V C 2013 AIP Publishing LLC. [http://dx

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Section: -6supporting

confidence: 55%

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Nikiforov

Xiong

et al. 2013

Physics of Plasmas

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“…Figure 3 shows the energy diagram of the LIF using 282 nm transition. 8 ground state to the A 2 Rðv ¼ 1Þ excited state. We measure the fluorescence of direct relaxation A 2 Rðv ¼ 1Þ !…”

Section: Methodsmentioning

confidence: 99%

Density and temperature measurement of OH radicals in atmospheric-pressure pulsed corona discharge in humid air

Nakagawa¹,

Ono²,

Oda³

2011

Journal of Applied Physics

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Plasma application for environmental improvement is desirable, and it is worthwhile to clarify the behavior of OH radicals in nonthermal plasma. Under atmospheric-pressure humid air, the time evolutions and spatial distribution of relative density and rotational temperature of OH radicals are measured in pulsed positive corona discharge using laser-induced fluorescence with a tunable optical parametric oscillator laser. The density of OH radicals generated by discharge when 28 kV is applied is estimated to be about 1×1015cm-3 at 3 μs after discharge. The OH density increases with humidity. The rotational temperature rises after discharge. The rate of temperature rise increases with humidity. This phenomenon arises from fast vibration-to-translation energy relaxation of H2O. The spatial distributions of OH rotational temperature indicate that the temperature rises in the secondary streamer channel.

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“…Inactivation mechanism of E. coli O157:H7 via OH radical may proceed through some chemical or physical process; OH radicals are considered to enhance chemical reactions and also have a damaging effect on the unsaturated fatty acid side chains of lipid bilayers in various cell membranes. 38,39 The cytoplasmic membrane represents the border between the organized internal section of the cell and the environment. Therefore, it is the first and often an indispensable target for most of the chemical and/or physical decontamination techniques.…”

Section: Resultsmentioning

confidence: 99%

Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

2015

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A submerged dielectric barrier discharge plasma reactor (underwater DBD) has been used on Escherichia coli O157:H7 (ATCC 35150). Plasma treatment was carried out using clean dry air gas to investigate the individual effects of the radicals produced by underwater DBD on an E. coli O157:H7 suspension (8.0 log CFU/ml). E. coli O157:H7 was reduced by 6.0 log CFU/ml for 2 min of underwater DBD plasma treatment. Optical Emission Spectra (OES) shows that OH and NO (α, β) radicals, generated by underwater DBD along with ozone gas. E. coli O157:H7 were reduced by 2.3 log CFU/ml for 10 min of underwater DBD plasma treatment with the terephthalic acid (TA) OH radical scavenger solution, which is significantly lower (3.7 log CFU/ml) than the result obtained without using the OH radical scavenger. A maximum of 1.5 ppm of ozone gas was produced during the discharge of underwater DBD, and the obtained reduction difference in E.coli O157:H7 in presence and in absence of ozone gas was 1.68 log CFU/ml. The remainder of the 0.62 log CFU/ml reduction might be due to the effect of the NO (α, β) radicals or due to the combined effect of all the radicals produced by underwater DBD. A small amount of hydrogen peroxide was also generated but does not play any role in E. coli O157:H7 inactivation.

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LIF imaging of OH radicals in DC positive streamer coronas

Cited by 49 publications

References 11 publications

OH radicals distribution in an Ar-H2O atmospheric plasma jet

OH radicals distribution in an Ar-H2O atmospheric plasma jet

Density and temperature measurement of OH radicals in atmospheric-pressure pulsed corona discharge in humid air

Roles of individual radicals generated by a submerged dielectric barrier discharge plasma reactor during Escherichia coli O157:H7 inactivation

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