Characterising S(1D) Atoms Formed by Exciting D2S Molecules via Intense Rydberg Resonances at Wavelengths ~139.1 nm and ~129.1 nm†
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Zijie Luo,
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Shunyang Zhou,
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Yucheng Wu,
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Shuaikang Yang,
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Zhenxing Li,
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Yongxin Dong,
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Wei Hua,
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Quan Shuai,
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Li Che,
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Michael N. R. Ashfold,
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Kaijun Yuan,
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Xueming Yang
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Graphical Abstract
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Abstract
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 2^1\rm 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 2^1\rm A' PES, leading to a centripetally-driven break-up.
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