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Publication - Professor Mike Ashfold

    Hydroxyl super rotors from vacuum ultraviolet photodissociation of water


    Chang, Y, Yu, Y, Wang, H, Hu, X, Li, Q, Yang, J, Su, S, He, Z, Chen, Z, Che, L, Wang, X, Zhang, W, Wu, G, Xie, D, Ashfold, MN, Yuan, K & Yang, X, 2019, ‘Hydroxyl super rotors from vacuum ultraviolet photodissociation of water’. Nature Communications, vol 10.


    Hydroxyl radicals (OH) play a central role in the interstellar medium.
    Here, we observe highly rotationally excited OH radicals with energies
    above the bond dissociation energy, termed OH “super rotors”, from the
    vacuum ultraviolet photodissociation of water. The most highly excited
    OH(X) super rotors identified at 115.2 nm photolysis have an
    internal energy of 4.86 eV. A striking enhancement in the yield of
    vibrationally-excited OH super rotors is detected when exciting the
    bending vibration of the water molecule. Theoretical analysis shows that
    bending excitation enhances the probability of non-adiabatic coupling
    between the B~ and X~ states of water at collinear O–H–H geometries following fast internal conversion from the initially excited D~ state. The present study illustrates a route to produce extremely rotationally excited OH(X)
    radicals from vacuum ultraviolet water photolysis, which may be related
    to the production of the highly rotationally excited OH(X) radicals observed in the interstellar medium.

    Full details in the University publications repository