Dissociative electron attachment to the highly reactive difluoromethylene molecule-importance of CF2 for negative ion formation in fluorocarbon plasmas

Dissociative electron attachment to the highly reactive difluoromethylene molecule, CF2, produced in a C3F6/He microwave plasma and stepwise via the fast atom reaction CF3I + H --> CF3 + HI and CF3 + H --> CF2 + HF, has been investigated. The upper limit for the cross section of formation of F- via dissociative electron attachment to CF2 is estimated to be 5 x 10(-4) angstrom(2). This value is four orders of magnitude smaller than the cross section previously predicted from scattering calculations. It is concluded that difluoromethylene plays a negligible role in negative ion formation in fluorocarbon plasmas.