Optical diagnostics of an atmospheric pressure diamond-depositing DC plasma reactor

Emission and absorption spectroscopy measurements of an atmospheric pressur e DC plasma during diamond growth were performed to examine the chemical, t hermodynamic and ionizational state of the plasma in the freestream and ins ide the thin boundary layer. In the freestream, the concentrations of C-2, CH and e(-) were found to be much higher than their equilibrium values. In the boundary layer, the concentration of C-2 falls sharply, whereas CH peak falls gradually. The temperature profile of the thermal boundary layer was also measured and was found to be in good agreement with the predictions o f a detailed computational model. (C) 2001 Elsevier Science B.V. All rights reserved.