MOLECULAR PROCESSES IN CH4-H-2 PLASMAS DILUTED WITH RARE-GASES - REACTIONS OF X(ASTERISK) ATOMS AND X(+) IONS (X=NE AND AR) WITH METHANE MOLECULES

Cross-sections and branching ratios for the reactions Ar++CH4 and NeCH4 are reported as a function of the collision energy, in the range f rom thermal to 2 eV. Cross-sections are converted to rate coefficients as a function of the translational temperature. The fragmentation of methane as obtained by these reactions is discussed, and compared with dissociative processes of CH4 with Ar metastable atoms, Ne+ ions and photons. The relevance of collisional processes involving rare gases and methane is discussed in view of their importance for explaining di lution effects in methane plasmas used for carbon and diamond film dep osition.