Characterizing S(1D) atoms formed by exciting D2S molecules via intense rydberg resonances at wavelengths ∼139.1 nm and ∼129.1 nm

We report high-resolution velocity map imaging studies of S(1D) atoms formed following excitation on two intense absorption bands of gas phase D2S molecules, centred at wavelengths ∼139.1 and ∼129.1 nm. DS–D bond fission is the dominant fragmentation pathway at these wavelengths, yielding SD fragments in both the ground (X) and excited (A) electronic states. Most S(1D) atoms arising via the rival S atom elimination channel when exciting at ∼139.1 nm are formed with D2 partners, in a wide range of rovibrational levels. The partially resolved structure in the total translational energy distributions, P(ET), derived from the S(1D) atom images, implies two dynamical routes into S(1D) + D2 products following non-adiabatic coupling from the photo-excited Rydberg state to the dissociative 21 A‘ potential energy surface (PES). Similar D2 products are evident in the P(ET) spectra derived from analysis of S(1D) images from D2S photolysis at ∼129.1 nm, but their contribution is overshadowed by a feature attributable to three-body dissociation to S(1D) + 2D fragments. These atomic products are deemed to arise via a natural extension of the dynamics responsible for the previously observed highly rotationally excited SD(A) fragments arising via the rival S–D bond fission pathway: asymmetric bond extension together with a dramatic opening of the interbond angle driven by torques generated after coupling to the highly anisotropic 21 A′ PES, leading to a centripetally-driven break-up.