GAS-PHASE MODEL OF SURFACE-REACTIONS FOR N-2 AFTERGLOWS

The adequacy of the homogeneous gas phase model as a representation of the surface losses of diffusing active particles in gas phase is stud ied. As an example the recent data obtained for the surface recombinat ion coefficients are reanalyzed. The data were obtained by the applica tion of the breakdown time delay technique which consists of the measu rements of the breakdown delay times t(d) as a function of the aftergl ow period tau. It was found that for the conditions of our experiment, the diffusion should not be neglected as the final results are signif icantly different when obtained by approximate gas phase representatio n and by exact numerical solution to the diffusion equation. While app lication of the gas phase effective coefficients to represent surface losses gives an error in the value of the recombination coefficient, i t reproduces correctly other characteristics such as order of the proc ess which can be obtained from simple fits to the experimental data.