LIF spectroscopy of OH radicals in a micro-flow DC discharge in Ar and He with a liquid electrode

Abstract

Abstract. The laser induced fluorescence spectroscopy on a micro-flow discharge with water electrode is carried out in order to investigate OH radicals. The transitions P2(6), P1(4) and P2(3) branches of X 2 Π , ν =0 -A 2 Σ, ν =1 transition are used. Laser-induced fluorescence is used in order to estimate density of OH radicals and density of water vapor in a core of the plasma. Sputtering yield of H2O from the liquid electrode is calculated based on experimental data. It is revealed that plasma core consists of 8-10% of water in both Ar and He discharges. The density of OH radicals in the micro-flow He plasma is higher than in the glow discharge with liquid electrode and in Ar micro-flow discharge due to constriction of the positive column and different mechanism of the OH radical production.

Direct Current Atmospheric Pressure Microdischarge Generated between a Miniature Flow Helium Microjet and a Flowing Liquid Cathode

“…[1,3] There are only few studies concerning the understanding of phenomena occurring in direct current (dc) APGD generated between Ar or He microjets and liquid cathodes. [5,6,[14][15][16][17][18][19] Unfortunately, cited works are rather incomprehensive because do not focus on the dischargeliquid interaction and either do not try to find relationships between concentrations of reactive species in liquid and gas phases of mentioned microdischarges and their spectroscopic parameters under different experimental conditions. Accordingly, APGD generated in the atmosphere of the ambient air between a miniature flow Ar jet and a bulky static liquid cathode (a NaCl solution) has been reported by Shirai et al [14,15] These authors studied the emission characteristic of the microdischarge as a function of the discharge current and the temperature of a NaCl solution used as the liquid cathode, which both were found to be critical for discharge-liquid interactions.…”

“…Studies devoted to microdischarges generated between microjets and liquids were mostly undertaken to characterize resulting electrochemical products of discharge reactions, e.g., nanoparticles, nanomaterials, as well as electrical parameters of these discharges under different conditions . There are only few studies concerning the understanding of phenomena occurring in direct current (dc) APGD generated between Ar or He microjets and liquid cathodes . Unfortunately, cited works are rather incomprehensive because do not focus on the discharge–liquid interaction and either do not try to find relationships between concentrations of reactive species in liquid and gas phases of mentioned microdischarges and their spectroscopic parameters under different experimental conditions.…”

Review on reactive species in water treatment using electrical discharge plasma: formation, measurement, mechanisms and mass transfer

“…•OH formation and dynamics on the water surface were also evaluated in the discharge plasma process [111,[122][123][124]. Kanazawa et al [111] studied •OH formation on the liquid surface in the pulsed discharge plasma process by LIF and found that some gaseous •OH could migrate and dissolve into the water.…”

Physical Parameters and Chemical Composition of a Nitrogen DC Discharge with Water Cathode

“…The emission spectra show usually the radiation bands of excited states of N 2 , OH and NO and lines of atomic H and O at discharge in nitrogen containing gases [4][5][6]. As far as the discharges in contact with water are concerned, there are some studies where the OH radical concentrations in the ground state were measured in a gas phase for the atmospheric pressure DC discharge in an ambient air, He, Ar and N 2 by a LIF method [6,7] and applying the absorption in UV region for Ar/H 2 O [8]. For nitrogen, it was discovered that OH concentration was about (2-2.3) 9 10 15 cm -3 in the current range of 15-30 mA.…”