| Abstrakt: |
The photolysis of ozone at 300 K in the Chappuis band has been investigated through collision-free coherent anti-Stokes Raman scattering (CARS) spectroscopy of the molecular oxygen photofragment. We have obtained the nascent electronic, vibrational, rotational, and translational energy distributions for nine photolysis wavelengths over the range 560–638 nm. The O2 photofragments are always formed in the ground (3Σ-g) state, there is no evidence for production of the excited (1Δg) state. Only a narrow range of high rotational levels are populated. The rotational distribution shifts to higher rotational states as the available energy increases. The vibrational distribution, however, is independent of photolysis wavelength. Only states v=0 to v=4 are populated, and there is a population inversion between v=2 and v=3. The average partitioning of energy among the vibrational, rotational, and translational degrees of freedom is 10%, 24%, and 66%, respectively. These results are interpreted to imply vibrationally adiabatic but rotationally impulsive dissociation dynamics. The O2 photofragment vibrational distribution is explained by Franck–Condon vibrational overlaps between O2 and the ground 1A1 electronic state of O3. Detailed consideration of the angular momentum disposal in the photodissociation indicates a strong correlation between the direction of the O2 angular momentum produced by the dissociative energy release, and the direction of the angular momentum of the O3 in-plane rotation. The correlation is such that of two energy degenerate final states, the one of higher orbital angular momentum is not produced. [ABSTRACT FROM AUTHOR] |
