Competition between atomic and molecular chlorine elimination in the infrared multiphoton dissociation of CF2Cl2

• Published in: The Journal of chemical physics 1982-12, Vol.77 (12), p.5977-5989
• Main Authors: Krajnovich, D., Huisken, F., Zhang, Z., Shen, Y. R., Lee, Y. T.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.443841

Infrared multiphoton dissociation of CF2Cl2 has been reinvestigated by the crossed laser-molecular beam technique using a high repetition rate CO2 TEA laser. Both the atomic and molecular chlorine elimination channels were observed: (1) CF2Cl2→CF2Cl+Cl and (2) CF2Cl2→CF2+Cl2. No evidence was found for secondary dissociation of CF2Cl at laser energy fluences up to 8 J/cm2. Center-of-mass product translational energy distributions were obtained for both dissociation channels. In agreement with previous work, the products of reaction (1) are found to have a statistical translational energy distribution. The products of reaction (2) are formed with a mean translational energy of 8 kcal/mol, and the distribution peaks rather sharply about this value, indicating a sizeable exit barrier to molecular elimination. The product branching ratio was directly determined. Reaction (2) accounts for roughly 10% of the total dissociation yield in the fluence range 0.3–8 J/cm2. These results provide an additional test of the statistical theory of unimolecular reactions.