Infrared multiphoton photophysics: Decomposition of CnF2n+1I (n = 1, 2, 3)

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Abstract
The title compounds have been subjected to unfocused radiation from a high‐power CO2‐TEA laser under collisionless conditions in a mass spectrometric flow system (VLPO/ method). We report absolute photodissociation yields as a function of fluence for CF3I and C3F7I. In the case of CF3I, we find high yields (100%) at fluences ?4 J/cm2, whereas for C3F7I yields level off at 20%–30%, depending on the wavelength. Secondary photolysis of Ċ2F5 and Ċ3F7 at fluences ?2.5 J/cm2 yields CF2 and ĊF3, but no C2F4. Interpretation of data in terms of a log–normal cumulative distribution function of reaction times or fluence suggests that CF3I interacts homogeneously with the laser field at 1070 and 1083 cm−1, but possibly inhomogeneously at 1076 cm−1, whereas C3F7I represents an inhomogeneous interaction case at all wavelengths. Based upon our photodissociation yields and the validity of a master equation representation, we calculate the infrared absorption spectrum of C3F7I as a function of internal energy.