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

¹ Department of Applied Physics, Ghent University, Jozef Plateaustraat 22, 9000 Ghent, Belgium
² Laboratory of Nonlinear Plasma Processes and Technologies, Institute of Solution Chemistry, Academicheskaya 1, Ivanovo 153045, Russia
³ College of Electrical and Electronic Engineering, Huazhong University of Science and Technology, WuHan, Hubei 430074, P.R. China

^a e-mail: anton.nikiforov@Ugent.be

Received: 15 April 2011
Revised: 19 July 2011
Accepted: 3 August 2011
Published online: 28 October 2011

Abstract

The laser-induced fluorescence spectroscopy on a micro-flow discharge with water electrode is carried out in order to investigate OH radicals. The branches P₂(6), P₁(4) and P₂(3) of X²Π, ν′′ = 0−A²Σ, ν′ = 1 transition are used. Laser-induced fluorescence is used in order to estimate the 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.