[1] The quantum yield for O( 1 D) production in the photolysis of ozone in the ultraviolet region as a function of wavelength and temperature is a key input for modeling calculations in the atmospheric chemistry. To provide the modeling community with the best possible information, the available data are critically evaluated, and the best possible recommendations for the quantum yields are presented. Since the authors of this paper are the principal investigators of the groups which have provided most of the recent experimental data for the O( 1 D) quantum yields, the basic assumptions made by each group, the input parameters used in obtaining the quantum yields, and possible sources of systematic errors are well examined.

Hydrogen peroxide has been optically excited at a wavelength of 266 nm and the OH photofragment completely characterized by Doppler and polarization spectroscopy using the laser-induced fluorescence technique. The entire internal state distribution (vibration, rotation, spin, and A components), translational energy, angular distribution, rotational alignment, and vector correlations between rotational and translation motions of OH products is measured. The hydroxyl radicals are formed in the X 211 3/2 ,112 ground state with 90% of the available energy (248 kJ/mol) being released as OH recoil translation. The angular distribution is nearly a sin 2 () distribution about the electric vector of the photolysis laser. The internal motion ofOH is vibrationally cold (no vibrationally excited OH was found) while the rotational excitation in v" = 0 can be described by a Boltzmann distribution with a temperature parameter of Trot = (1530 ± 150) K. The two spin states are found to be populated nearly statistically, in contrast to the A components which show an increasing inversion with increasing OH rotation. The observed profiles of recoil Doppler broadened spectral lines are strongly dependent on the nature ofthe transition, the excitation-detection geometry, and the relative polarizations of the dissociating and analyzing laser light. However, the line intensities show only a minor dependence on geometry and polarization indicating a low alignment of OH photofragments (A ~2) ';;;0.1). For the first time the vector correlation between product rotational and translational motions was analyzed and evaluated in terms of the three bipolar moments {3 ~ (20), {3 g (22), and {3 ~ (22). The bipolar moment {3 ~ (20) corresponds to the conventionally defined anisotropy parameter {3 = 2{3 ~ (20) = -0.71. The angular distribution peaks in the direction perpendicular to the electric vector of the dissociating laser light, indicating the predominant electronic excited state in H 2 0 2 being of IA symmetry. The moment {3 g (22) increases with J OH showing a bias towards VOH and J OH being parallel to one another. The moment {3 ~ (22) is a measure of the mutual correlation of the fragment translational and rotational vectors and the transition dipole vector .... in the parent molecule. The positive value of this moment [{3 ~ (22) = 0.11] indicates that the expectation value of (J;) should be very small when .... is parallel to the z axis and VOH perpendicular to .... (x axis). (J!) originates in the torsional motion in the H 2 0 2 parent molecule, while (J;) reflects the bending vibration of nearly planar H 2 0 2 where the H atoms are in the trans position.

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