Crossed beam study of the atom-radical reaction of ground state carbon atoms (C(3P)) with the vinyl radical (C2H3(X2A))

The atom-radical reaction of ground state carbon atoms (C( 3 P )) with the vinyl radical (C 2 H 3 (X 2 A)) was conducted under single collision conditions at a collision energy of 32.3 2.9 kJ mol 1 . The reaction dynamics were found to involve a complex forming reaction mechanism, which is initiated by the barrier-less addition of atomic carbon to the carboncarbon-double bond of the vinyl radical forming a cyclic C 3 H 3 radical intermediate. The latter has a lifetime of at least 1.5 times its rotational period and decomposes via a tight exit transition state located about 45 kJ mol 1 above the separated products through atomic hydrogen loss to the cyclopropenylidene isomer (c-C 3 H 2 ) as detected toward cold molecular clouds and in star forming regions. Reactions between two open shell species are considered the holy grail in reaction dynamics. Reactions between two carbon bearing species in particular are very difficult to study experimentally, and this presents only the second study worldwide.