Journal of Physical Chemistry, Vol.99, No.38, 13992-13999, 1995
Kinetics of Depletion of Ti(A(3)F), Ti(A(5)F), V(A(4)F), and V(A(6)D) Atoms by Simple Hydrocarbons
The kinetics of depletion of ground states Ti(a(3)F) and V(a(4)F) and electronic excited states Ti(a(5)F) and V(a(6)D) upon interactions with CH4, C2H2, C2H4, C2H6, C3H6, and c-C3H6 are studied in a fast-flow reactor at a He pressure of 0.70 Torr, No depletion of ground states Ti(a(3)F) and V(a(4)F) was observed upon interaction with all hydrocarbons except for propene. Two alkanes, CH4 and C2H6, were also quite inert for depletion of the excited states Ti(a(5)F) and V(a(6)D). On the other hand, hydrocarbons containing double or triple bond, C2H2, C2H4, and propene, deplete the excited states Ti(a(5)F) and V(a(6)D) very efficiently. Determined rate constants for C2H2, C2H4, and propene with Ti(a(5)F) are (476 +/- 88) x 10(-12), (266 +/- 86) x 10(-12), and (270 +/- 110) x 10(-12) cm(3) s(-1), respectively. The depletion rate constants of V(a(6)D) by these molecules are (173 +/- 44) x 10(-12), (84 +/- 3) x 10(-12), and (201 +/- 30) x 10(-12) cm(3) s(-1), respectively. These large rate constants compared with the ground state Ti and V were explained by an electron donor-acceptor interaction model that works between pi bonds in hydrocarbons and the excited state with an unfilled 4s orbital.
Keywords:TRANSLATIONAL ENERGY-DEPENDENCE;GAS-PHASE THERMOCHEMISTRY;METHANE ACTIVATION;ROOM-TEMPERATURE;IRON ATOMS;STATE;N2O;PHOTOCHEMISTRY;ASSOCIATION;REACTIVITY