Reaction Chemistry in the Afterglow of an Oxygen−Helium, Atmospheric-Pressure Plasma

Abstract

The reaction chemistry in the afterglow of a non-equilibrium, capacitive discharge, operated at 600 Torr total pressure with (0.5 to 5.0) × 10 17 cm -3 of oxygen in helium, has been examined by ultraviolet absorption spectroscopy, optical emission spectroscopy, and numerical modeling. The densities of the active species,and O 3 , have been determined as a function of the operating conditions. At RF power densities between 6.1 and 30.5 W/cm 3 and a neutral temperature of 100 ( 40°C, the plasma generated (0.2 to 1.0) × 10 16 cm -3 of O( 3 P) and O 2 ( 1 ∆ g ), (0.2 to 2.0) × 10 15 cm -3 of O 2 ( 1 Σ g + ), and (0.1 to 4.0) × 10 15 cm -3 of O 3 . After the power was turned off, the singlet-sigma and singlet-delta states decayed within 0.1 and 30.0 ms, respectively. The concentration of oxygen atoms remained constant for about 0.5 ms, then fell rapidly due to recombination with O 2 to form O 3 . It was found that the etching rate of polyimide correlated with the concentration of oxygen atoms in the afterglow, indicating that the O atoms were the active species involved in this process.

Competitive and synergistic effects between excimer VUV radiation and O radicals on the etching mechanisms of polyethylene and fluoropolymer surfaces treated by an atmospheric He–O2post-discharge

“…Our experiments were consistent with the lifetimes of the He 2 3 S and the O2 M species respectively evaluated by Tachibana et al and Jeong et al under similar conditions [41,42].…”

Spatially resolved diagnostics on a microscale atmospheric pressure plasma jet

“…The main constituents are molecular oxygen including metastable O 2 (b 1 + g ) and ozone, atomic oxygen and helium atoms and will have to be measured to complete the picture. Ozone is accessible by UV absorption spectroscopy and some results for the APPJ are presented by Jeong et al [16].…”

Modelling and application of particle distribution for atmospheric plasma excitation

“…In this paper, only states of dominant dissociation pathway are considered. According to the studies of some scholars such as Jeong et al (2000) and Plumb and Ryan (1986), O 2 particles are mainly be dissociated to O and OD particles , and OD continue to be translated to O or reacts with other particles. In discharge region, excited O 2 also may generate O 3 with low rate coefficient.…”

“…They established physics reaction model of plasma under conditions of relevant electric field. Jeong et al (2000) focused on the process of plasma and detailed calculated the reaction rate coefficients of different states of product generated from O 2 , which excited in electric field. Yang et al (2003) have studied the plasma chemical reaction process under atmospheric pressure, which involved producing F particles were discussed more detailed.…”