Fast-flow study of the CH plus CH reaction products

The multichannel CH + CH reaction was studied, at room temperature, in a lo w-pressure fast-flow reactor. CH was obtained from the reaction of CHBr3 wi th potassium atoms. An intense chemiluminescence from C2H(A(2)Pi) and a muc h weaker one from C-2(d(3)Pi(g)) were observed. The C2H(A(2)Pi) emission sp ectrum appeared as a continuum extending from 380 nm to the limit of our de tection range at 800 nm. C-2(d(3)Pi(g)) was specifically produced in the v = 2 level, and the relative ratio C-2(d(3)Pi(g))/C2H(A(2)Pi) was proportion al to the total pressure, this behavior being attributed to a production of C2 by induced collision crossing states from excited vinylidene to the sur face leading to C-2(d(3)Pi(g)) + H-2. Relative product branching ratios wer e determined over the channels yielding the following atoms: H + C2H, >90%; C + CH2, <10%.