CROSSED-BEAM REACTION OF ATOMIC CARBON C(P-3(J)) WITH HYDROGEN-SULFIDE, H2S(X(1)A(1)) - OBSERVATION OF THE THIOFORMYL RADICAL, HCS(X(2)A')

One of the simplest organosulfur reactions, that between ground state carbon atoms, (P-3(j)), and hydrogen sulfide, H2S(X(1)A(1)), was studi ed at an average collision energy of 21.0 kJ mol(-1) using the crossed molecular beams technique. The product angular distribution and time- of-flight spectra of m/e = 45 ((HCS)-S-32) Were monitored. Forward-con volution fitting of our data yields an almost isotropic center-of-mass angular flux-distribution, whereas the center-of-mass translational e nergy flux distribution peaks at about 50 kT mol(-1), indicating a tig ht exit transition state from the decomposing thiohydroxycarbene HCSH complex to the reaction products. The high energy cut-off of the trans lational energy flux distribution is consistent with the formation of the thioformyl radical HCS in its X(2)A' electronic ground state. The first experimental verification of an existing thiohydroxycarbene inte rmediate and the rigorous assignment of the HCS radical product under single collision conditions explicitly suggest inclusion of the title reaction in chemical reaction networks of molecular clouds TMC-1 and O MC-1, the outflow of the carbon star IRC+10216, Shoemaker/Levy 9 impac t-induced nonequilibrium sulfur chemistry in the Jovian atmosphere, as well as combustion of sulfur containing coal. (C) 1997 American Insti tute of Physics.