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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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