REACTIONS OF C2(X1-SIGMA-G(+)) PRODUCED BY MULTI-PHOTON UV-EXCIMER LASER PHOTOLYSIS

C2(X 1Σ+g) disappearance rate constants at 298 K have been determined for reactions with H2: (1.38±0.06) × 10-12 cm3 s-1 molecule -1; CH4 (1.87±0.05) × 10-11 cm3 s-1 molecule -1; C2 H6: (1.59±0.05) × 10-10 cm3 s-1 molecule -1: C2H4: (3.26±0.05) × 10-10 cm3 s-1 molecule -1: C2F4: (5.99±0.14) × 10-11 cm3 s-1 molecule -1: O2: (2.82±0.09) × 10-12 cm3 s-1 molecule -1: and CO2: no apparent reaction. The C2(X 1Σ-g) was produced by multiphoton UV excimer laser photodissociation of hexafluorobutyne-2. These results are compared to the reaction rates of C2(a3Πu). The rates for O2 reactions are the same for both C2 states and no reaction is observed for CO2 with either C2 state. However, C2(X 1Σ-g) reacts considerable faster than C2(a3Πg) with hydrogen and hydrocarbons. The presence of an allowed hydrogen atom exchange reaction for ground state C2 to form ground state C2H which is forbidden for metastable triplet C2 is postulated to account for the disparities in reaction rates. Electronic orbital correlation effects are proposed as an explanation. © 1979.