Two-Photon Dissociation Dynamics of Hydroxyl Radical

Two-photon dissociation dynamics of the OH radical is studied using the high-n Rydberg atom time-of-flight (HRTOF) technique. The H(^2S)+O(^1D) and H(^2S)+O(^1S) product channels are observed in the dissociation of the OH radical on the 2^2\Pi and B^2\Sigma^+ repulsive states, respectively, from sequential two-photon excitation via the A^2\Sigma^+ (v'=2, J'=0.5-2.5) state. Both H+O product channels have anisotropic angular distributions, with \beta=-0.97 for H(^2S)+O(^1D) and 1.97 for H(^2S)+O(^1S). The anisotropic angular distributions are consistent with a mechanism of OH direct dissociation on the repulsive potential energy curves (PECs) leading to the H+O products. The OH bond dissociation energy D_0(O-H) is determined to be 35580\pm15 cm^-1.