Influence of target surfaces on the atomic oxygen distribution in the effluent of a micro-scaled atmospheric pressure plasma jet

Abstract

Micro-scaled plasma jets with reactive process gases, e.g. oxygen, are applied for localized surface treatment. Here, investigations of the development and the spatial distribution of atomic oxygen are reported in the post-discharge effluent of a micro-scaled atmospheric pressure plasma jet. These measurements are supplemented by installation of planar targets of various materials in the effluent. The reactive species are detected by means of two-photon laser-induced fluorescence spectroscopy from the discharge, through the free effluent, up to distances of about 200 µm in front of a planar surface. Ozone density profiles are measured by UV absorption spectroscopy. The effect of the effluent on gold and plastic substrates and vice versa is investigated. In the free effluent, the atomic oxygen density falls off exponentially to about 2 × 10 15 cm −3 at a distance of 6 mm from the jet's nozzle. The implementation of a plastic target does not disturb the O distribution, resulting in a strictly localized etching of the target. In contrast, mounting of a gold target increases the oxygen density and spreads its distribution close to the target. For correlation, surface modifications by plasma treatment of plastic and gold substrates are analysed by UV laser microscopy and x-ray photoelectron spectroscopy.

Surface modification of polymeric materials by cold atmospheric plasma jet

“…Now not only the ozone but also some short-living active species, such as, atomic oxygen and OH radical may interact with the central part of the substrate leading to an enhanced hydrophilicity. As shown in [14,36] the atomic oxygen can actually spread up to 2.0-2.5 mm way from the plasma column. The computer modeling of active species generated by Ar plasma jet in [31] predicted that along the gas flow oxygen atoms could cover even larger distances (∼ cm).…”

“…Since the UV photons propagate preferentially along the plasma column they would rather interact only with the target surface that is located just under the plasma jet [33]. As shown in [36] besides the VUV/UV radiation the long-lived active species, like O 3 can also reach the surface and spread radially over a large area of the sample. As can be noted in Fig.…”

“…In the case of plasma jets, the exited and ionized argon atoms from the discharge create reactive species (mostly atomic oxygen, ozone and OH radical [32,36]) by reaction with the ambient air. These highly reactive species can etch polymers and roughen their surface [14,36]. The AFM images of the untreated PP and the polymer samples treated by APPJ at different processing time are presented in Fig.…”

Absolute OH and O radical densities in effluent of a He/H2O micro-scaled atmospheric pressure plasma jet

“…It has been shown that this microplasma jet, under selected conditions, is operated in a homogeneous α-mode glow [17] with typical plasma densities around − 10 cm 11 3 [2,18,19]. This jet has already been used with He/O 2 and He/N 2 gas mixtures, where production of O, N, or O 3 has already been investigated by TALIF and MBMS [20][21][22][23]. The coordinate system used in this work has its origin (0,0,0) at the exit of the jet.…”

Investigation of Surface Etching of Poly(Ether Ether Ketone) by Atmospheric-Pressure Plasmas

“…Thus, measurements in direct vicinity to the surface are essential. Comparable measurements of the atomic-oxygen density in front of a target surface, in the effluent of the helium-driven μ-APPJ, offer a clue to this problem [42]. Here, dependent on the target material, a broadening of the radial oxygen distribution close to the surface was measured.…”