CH3 Radical Density in Electron Cyclotron Resonance CH3OH and CH3OH/H2 Plasmas

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Abstract
CH3 radical densities in electron cyclotron resonance (ECR) discharge methanol ( CH3OH), methanol diluted with hydrogen gas ( CH3OH/H2) and methane ( CH4) plasmas were measured for the first time using infrared diode laser absorption spectroscopy (IRLAS). CH3 radical densities in the CH3OH and CH3OH/H2 plasmas were estimated to be of the order of 1011 cm-3 under the conditions of total pressure of 1.3 Pa and microwave power of 50-800 W. On the other hand, CH3 radical density in the CH4 plasma was estimated to be less than 1010 cm-3. Moreover, the production and loss processes of CH3 radical in the CH3OH plasma were discussed on the basis of the results of emission intensity of Ar*, the absorption ratio of CH3OH molecule and the decay curve analysis of CH3 radical after termination of the discharge.