Crossed molecular beam studies of C(3P, 1D) and C2(X1Σg+, a3Πu) reactions with acetylene

The crossed molecular beam method with mass spectrometric detection is a versatile technique to study bimolecular reactions under single collision conditions, thus permitting us to elucidate the chemical dynamics and-in the case of polyatomic reactions-the nature of the primary products and their branching ratios. A review of the recent progress that has been made in the understanding of gas-phase carbon chemistry is given by illustrating some of the key results on the reactions C(P-3, D-1) and C-2(X-1 Sigma(+)(g), a (3)Pi(u)) with acetylene, one of the most important hydrocarbons in applied processes and natural environments. The results are discussed in the light of the available theoretical information on the relevant triplet and singlet C3H2 and C4H2 potential energy surfaces, and compared with the results of previous experimental work. The improvements in our experimental apparatus that have been made to accomplish the present results are highlighted and the possibility of extending the same approach to the study of other polyatomic reactions is emphasized.