Photodissociation of CF{sub 3}I at 304 nm: Effects of photon energy and curve crossing on the internal excitation of CF{sub 3}
- Univ. of California, Los Angeles, CA (United States)
We present correlated measurements of the CF{sub 3} internal energy, the initial electronic excitation, and the final iodine state in the photodissociation of CF{sub 3}I at 304 nm by using state-selective photofragment translational spectroscopy. The simultaneous determination of the three properties is achieved by measuring the translational energy distribution of the state-selected iodine fragment as a function of its recoil angle with respect to the electric vector of the photolysis laser. We found that the excited state I*({sup 2}P{sub 1/2}) atoms are formed predominantly from the parallel {sup 3}Q{sub 0} {l_arrow} N transition while the I{sup 2}P{sub 3/2} atoms are formed from both the perpendicular {sup 3}Q{sub 1} {l_arrow} N transition (70%) and the parallel {sup 3}Q{sub 0} {l_arrow} N transition (30%) followed by curve crossing to the {sup 1}Q{sub 1} state. By comparing the average internal energies of CF{sub 3} produced in the two dissociation channels of the {sup 3}Q{sub 1} {l_arrow} N excitation at 304 nm with the recent results of Felder at 248 nm, we examine the effect of the photon energy and that of the curve crossing on the dynamics of the vibrational excitation. For the I* channel, we observe a strong photon energy dependence of the CF{sub 3} internal excitation, suggesting a strong final state interaction the dynamics of the {sup 3}Q{sub 0} potential as suggested by a number of model calculations. The best agreement obtained with the model calculation of van Veen et al. supports the assumption of the dominant involvement of the {nu}{sub 2} umbrella vibration. For the {sup 3}Q{sub 0} component of the I channel we observe a similar strong photon energy dependence in terms of its slopes, but with an enhanced CF{sub 3} internal excitation. This suggests the importance of the curve crossing dynamics as well as the dynamics of the {sup 1}Q{sub 1} potential. 34 refs., 7 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 458785
- Journal Information:
- Journal of Physical Chemistry, Vol. 96, Issue 22; Other Information: PBD: 29 Oct 1992
- Country of Publication:
- United States
- Language:
- English
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