Reactions of C2(X 1Σ+g) produced by multiphoton uv excimer laser photolysis

Direct ab initio dynamics study of the reaction of C2(A3Πu) with CH4

“…The calculated activation energy E a 4.28 kcal/mol is slightly smaller than the experimental value 5.57 6 0.11 kcal/mol [7]. It should be noted here that there is big difference between the values measured by Reisler [6] at 300 K and Pasternack previous [23] at 298 K (Exptb and Exptc in Fig. 5).…”

“…However, the rate constant of 3 C 2 with the lightest alkane methane is too small to be determined accurately below room temperature [15,19]. The differences are large between measured rate constants [6,7,15,23]. On the contrary to the reactivity of the triplet state, previous experimental kinetic studies demonstrated that the reactions of 1 C 2 with hydrocarbons are found to be significantly rapid even in very low temperature range 24-300 K, and the rate coefficients are typically one order of magnitude higher than that of 3 C 2 with saturated hydrocarbons, except for CH 4 [5,6,8,21].…”

An experimental study of the reaction kinetics of C2(X1Σg+) with hydrocarbons (CH4, C2H2, C2H4, C2H6 and C3H8) over the temperature range 24–300 K: Implications for the atmospheres of Titan and the Giant Planets

“…The energy difference between the lowest vibrational levels of these two states is only 610 cm −1 or 880 K. While many experimental studies have been carried out to measure the rate coefficients of the removal of 3 C 2 by hydrocarbons (Donnelly and Pasternack, 1979;Reisler et al, 1979Reisler et al, , 1980Pasternack et al, 1980Pasternack et al, , 1981Becker et al, 2000;Huang et al, 2004Huang et al, , 2005, data concerning the reactivity of 1 C 2 are scarcer. These were obtained in the early eighties and were only available at room temperature (Pasternack and McDonald, 1979;Reisler et al, 1980) and above (Pitts et al, 1982). Modellers used the results from this latter study for the reactivity of 1 C 2 with H 2 and CH 4 and extrapolated the given rate coefficient temperature dependences to the conditions reigning in planetary atmospheres.…”

Experimental and kinetic modeling study of the oxy-fuel oxidation of natural gas, CH4 and C2H6

“…Other C 2 radicals that may attack CO 2 are HCCO, CH 2 CHO, CH 3 O, C 2 H, C 2 O and C 2 . Experimental measurements of the upper limits at room temperature of the C 2 O + CO 2 [42,43] and C 2 + CO 2 [44,45] reactions indicated that both reactions are very slow, k(C 2 O + CO 2 ) < 6.0 Â 10 8 [43] and k(C 2 + CO 2 ) < 1.8 Â 10 10 [45] respectively, in cm 3 /mole s. Pasternack and McDonald [44] even indicated that there was no apparent reaction between C 2 and CO 2 . Both reactions are insignificant under the present conditions because their low rate constant values and the minor presence of both C 2 O and C 2 radicals.…”