Interaction of N and O atoms with hardwood and softwood surfaces in the flowing afterglow of N₂‐O₂ microwave plasmas

Abstract

The interaction between hardwood (Sugar Maple) and softwood (Black Spruce) surfaces and N and O atom species produced in the flowing late afterglow of a surface‐wave microwave plasma column in N2‐O2 gas mixtures was investigated using a NO titration method combined with optical emission spectroscopy. Results showed two distinct atom loss regimes following their interaction with wood surfaces: a recombination regime at low oxygen concentrations (<1% O2) and an etching regime by O atoms at higher oxygen concentrations (>1% O2). The etching reaction was confirmed by surface profilometry measurements, with the formation of sub‐millimetre trenches between low‐density early wood and high‐density late wood regions. Recombination dynamics of O and N atoms over smooth and roughened wood regions are also compared.

Ab initio study of the processes of nitrogen functionalisation in graphene

“…Since all FEs presented in table 1 are positive values, one could think the functionalised structures are unfavourable. However, functionalisation methods such as plasma-assisted doping [29,30] involve atomic nitrogen with an energy of about 5.2 eV compared to a nitrogen molecule. This means, for instance, that an isolated nitrogen would lower its energy by around 0.8 eV upon adsorption on a graphene surface when compared to the value for the bridge N configuration in table 1.…”

“…In the context of post-growth functionalisation, plasma treatments [29,30] are advantageous because of the presence of dissociated nitrogen atoms that are much more reactive than bonded N 2 molecules. With a correctly tuned treatment, other plasma particles can also provide surface activation, which helps overcome reaction barriers, without damaging significantly the material.…”

Characterization of non-thermal dielectric barrier discharges at atmospheric pressure in presence of microfibrillated cellulosic foams

“…This indicates that substrate outgassing prior to the plasma treatment strongly influences plasma-induced modification of the MFC foams. This can most likely be ascribed to the erosion of ligno-cellulosic materials in presence of air (and thus oxygen) impurities [34,35,53].…”