A comparative study of the surface recombination of nitrogen atoms on various materials at atmospheric pressure

Abstract

The surface recombination of nitrogen atoms on various materials was investigated at atmospheric pressure. The afterglows of pure nitrogen discharge are injected into a surface loss test unit, whose path wall is composed of the materials to be examined. Measurement of the nitrogen atom densities at several points in the flowing afterglows reveals the temporal decay characteristics. The results are compared with two-dimensional numerical simulations to obtain the surface loss probability γ. Among the seven materials we studied (stainless steel, aluminium, titanium, alumina, Pyrex glass, aluminium nitride and boron nitride), stainless steel was found to have the highest γ value: 1.8 × 10−3; the lowest was for boron nitride: 4.8 × 10−5. The dependence of γ on surface roughness and temperature was also examined.

Numerical study of the influence of surface reaction probabilities on reactive species in an rf atmospheric pressure plasma containing humidity

“…In both cases, the surface reaction rates depend on the surface coverage of reactants and the fluxes of species incident onto the surface. As a result, reaction probabilities are strongly dependent on experimental conditions, such as pressure and gas mixture [27][28][29], wall material [25,26,28,[30][31][32][33][34], temperature [35][36][37], and surface roughness [36,37]. Ion bombardment can have a significant effect on the value of γ [27,38] through the generation of free surface sites and desorption of adsorbates.…”

Ammonia Synthesis by Radio Frequency Plasma Catalysis: Revealing the Underlying Mechanisms

“…Indeed, as mentioned above, the reaction probabilities for reactions S2–S4 on silica are 1 order of magnitude lower than for direct adsorption of N (reaction S1). When Fe catalyst is loaded in the furnace, the effective adsorption probability calculated by eq is highly overestimated, leading to an unrealistic (too low) ammonia yield, because the surfaces sites are almost completely occupied by H(s), which greatly prohibits the adsorption of N-containing species and hence the ammonia synthesis . As a result, we used the following relationship instead, to predict the effective reaction probabilities for the reactions S2–S4. …”

Non-equilibrium kinetics in N2discharges and post-discharges: a full picture by modelling and impact on the applications

“…The dependence of γ N and γ O probabilities on the fractional N 2 -O 2 mixture composition within the whole range of N 2 : O 2 concentrations was analysed in [51]. These probabilities are typically of the order of γ N ∼ 10 −4 and γ O ∼ 10 −3 -10 −2 in pure N 2 and pure O 2 discharges, respectively, on quartz surface [33,48,72], while in the post-discharges the probabilities are significantly lower [49,73].…”