Photodissociation of CF3I at 304 nm: Effects of Photon Energy and Curve Crossing on the Internal Excitation of CF3
Abstract
We present correlated measurements of the CF3 internal energy, the initial electronic excitation, and the final iodine state in the photodissociation of CF31 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 (2P1/2) atoms are formed predominantly from the parallel 3Q(0)-N transition while the I(2P3/2) atoms are formed from both the perpendicular Q1 - N transition (70%) and the parallel 3Q(0) - N transition (30%) followed by curve crossing to the 1QI state. By comparing the average internal energies of CF3 produced in the two dissociation channels of the 3Q(O)- 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 in the dynamics of the vibrational excitation. For the I* channel, we observe a strong photon energy dependence of the CF3 internal excitation, suggesting a strong final state interaction in the dynamics of the 3Q0 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 1/2 umbrella vibration. For the 3Q(0) component of the I channel, we observe a similar strong photon energy dependence in terms of its slope, but with an enhanced CF3 internal excitation.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 27, 1992
- Accession Number
- ADA251684
Entities
People
- Hyun J. Hwang
- Mostafa El-Sayed
Organizations
- University of California, Los Angeles