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The O-2 and O-2-N-2 ([N-2] < 15%) post-discharge microwave plasma modifications of high-density polyethylene (HDPE) and hexatriacontane (HTC) surfaces have been studied as a function of the distance from the discharge and the gas composition. They are compared in terms of the in-situ XPS O/C ratios and C1s components, and the ex-situ ToF-SIMS O-/CH- ratios and relative intensities of series of peaks. The results on the effect of the distance from the discharge showed a clear correlation between the in-situ XPS results and the O-2 post-discharge modeling, exhibiting the double role of oxygen atoms: functionalization initialization by creating radicals (which react with molecular oxygen) and degradation due to the energy released by the oxygen atom recombination process. Specific in-situ XPS and ex-situ ToF-SIMS signatures of this in-situ degradation related to the oxygen atom recombination process were exhibited. When N-2 was introduced in the plasma gas, the in-situ XPS results and the ex-situ ToF-SIMS results were very different. The in-situ functionalization decreased as a function of the N-2 addition and the ex-situ functionalization exhibited a high maximum fdr the 5% N-2-95% O-2 post-discharge plasma and then decreased. Despite the absence of a complete O-2-N-2 post-discharge modeling, it can be assumed that there is also a maximum of the oxygen atom content for the 5% N-2-95% O-2 postdischarge. Thanks to the in-situ XPS and ex-situ ToF-SIMS specific signatures, it was also shown that this maximum corresponds to a low in-situ degradation effect. Nitrogen introduction could influence the role of oxygen atoms in such a way that there is a decrease in oxygen atom recombination processes (thus in degradation) for small N-2 addition and even a decrease in oxygen functionalization initialization for further N-2 incorporation in the plasma gas. No nitrogen was observed in the in-situ XPS results, whereas some ex-situ ToF-SIMS nitrogen-containing ions were observed for

Hexatriacontane (C36H74) has been used as a model molecule for the study of the surface modifications of high-density polyethylene (HDPE) in argon and oxygen radio-frequency (RF) plasmas. The combination of static secondary ion mass spectrometry (SIMS), ion scattering spectroscopy (ISS), X-ray photoelectron spectroscopy (XPS), and contact angle measurements has constituted a powerful method for the investigation of the surface modifications induced by the plasma treatments. The surface degradation and functionalization are shown to depend on both the nature of the treated material and the nature of the plasma atmosphere. The SSIMS results obtained on plasma-modified hexatriacontane and HDPE are compared in order to identify the nature of the functionalities present at the plasma-treated surfaces. Finally, plasma treatment 180 atmosphere was performed on HDPE, C36H74, and polystyrene (PS). In that case, the isotopic specificity of both ISS and SIMS allowed the determination of the relative concentrations of O-16 and O-18 in relation to the probed depth and plasma atmosphere.