Photochemistry from low-lying states of HOSO.

Using configuration interaction ab initio methods, the evolution of the lowest electronic states of singlet and triplet spin multiplicities of HOSO along the stretching and bending coordinates of is investigated. Equilibrium geometries, rotational constants, and harmonic vibrational frequencies of the lowest electronic states are calculated, i.e., XA', 1A″, 1A', and 1A″. The global minimum of the 1A″ state is located below the first dissociation limit and its calculated lifetime is predicted to be 0.40 µs, making it suitable for detection by laser-induced fluorescence. According to the potential energy surfaces, HOSO should produce SO and H after ultraviolet photon absorption to the 2A' state. This work opens the door to investigate the branching ratio and the production rates of SO , SO, and OH from HOSO. These insights can help understand the SO cycle in the earth's atmosphere and its effect on cooling our planet.