| Autor: |
Cartechini, L., Bergeat, A., Capozza, G., Casavecchia, P., Volpi, G. G., Geppert, W. D., Naulin, C., Costes, M. |
| Předmět: |
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| Zdroj: |
Journal of Chemical Physics; 4/1/2002, Vol. 116 Issue 13, p5603, 9p, 4 Diagrams, 1 Chart, 9 Graphs |
| Abstrakt: |
The reaction between atomic carbon and acetylene has been investigated using complementary crossed molecular beam techniques. Differential cross sections have been obtained for the reactions of both ground and excited carbon atoms, C(³P[sub J], ¹D[sub 2])+ C[sub 2]H[sub 2](X ¹Σ[sup +, sub g], in experiments conducted with continuous supersonic beams, mass spectrometric detection, and time-of-flight analysis at a relative translational energy of 29.3 kJmol[sup -1]. The reaction C(³P[sub J]) + C[sub 2]H[sub 2](X ¹Σ[sup +, sub g]) has been found to lead to C[sub 3]H+H and C[sub 3]+H[sub 2] products in comparable amounts. Both H and H[sub 2] elimination pathways are found to proceed through the formation of a C[sub 3]H[sub 2] long-lived intermediate complex whose lifetime may be comparable to its rotational period. The spin-forbidden H[sub 2] elimination channel is attributed to the occurrence of intersystem-crossing between the triplet and singlet manifolds of the C[sub 3]H[sub 2] potential-energy surfaces. The reaction C(¹D[sub 2])+C[sub 2]H[sub 2](X ¹Σ[sup +, sub g]) has been found to lead to formation of C[sub 3]H+H, with a C[sub 3]H center-of-mass angular distribution strongly forward peaked, indicating a short-lived intermediate complex. Integral cross sections have been obtained for the C(³P[sub J]j) + C[sub 2]H[sub 2] (X ¹Σ[sup +, sub g]) → C[sub 3] H + H(²S[sub ½]) reaction in experiments conducted with pulsed, supersonic molecular beams in the range of relative translational energies E[sub T]=0.38 -25.5 kJ mol[sup -1], the H(²S[sub ½) product being detected by laser-induced fluorescence. The reaction has been found to be without a barrier, relative integral cross sections being proportional to (Er)[sup -0.80&plumsn;0.03] below E[sub T]=10 kJmol[sup -1]. These findings provide direct evidence that the C(³P[sub J]) +C[sub 2]H[sub 2] reaction can occur under... [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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