利用交叉分子束研究氟分子與丙烯之反應動力學

The reaction of F2 + C3H6 was investigated using crossed molecular beam technique for a wide range of collision energy. The F + C3H6F was observed to be the only primary product channel; the HF + C3H5F product channel was searched but not found. The relative reaction cross section was measured as a function of collision energy; the reaction threshold was determined to be 2.4 ± 0.3 kcal/mol. Time-of-flight spectra and angular distributions of the products were measured and analyzed. The center-of-mass frame angular distribution displayed strongly backward, indicating that the reaction time scale is much shorter than one rotational period of the collision complex. All experimental results support a rebound reaction mechanism, which agrees with the structure of the calculated transition state. The transition state geometry suggests an early barrier; such dynamics is consistent with the small kinetic energy release of the products observed in the experiment. Compared with the F2 + C2H4 reaction, both the experimental and computational results in the present reaction give the same trend that the methyl-substitution effect in propene reduced the reaction threshold by about 3 kcal/mol.

並列關鍵字

crossed molecular beam ； dynamics ； backward scattering ； early barrier ； methyl-substitution effect

參考文獻

1 M. Sawaguchi, S. Hara, and N. Yoneda, J. Fluorine Chem. 105, 313 (2000)

2 W. T. Miller Jr. and A. L. Dittman, J. Am. Chem. Soc. 78, 2793 (1956).

4 W. T. Miller Jr. and S. D. Koch, Jr., J. Am. Chem. Soc. 79, 3084 (1956).

8 H. Frei and G. C. Pimentel, J. Chem. Phys. 78, 3698 (1983).

9 H. Frei, J. Chem. Phys. 79, 748 (1983).

國際替代計量

利用交叉分子束研究氟分子與丙烯之反應動力學

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