Supplementary material

Further CAD illustrations of the instrument, Illustration of the gas-inlet manifold, Behlke switch pulsing circuits, ToF spectrum showing \emph{m/z} up to 750, Further velocity-map images, Illustration of future developments including tandem ion mobility and ion trapping, Computational chemistry methods, Assignment of rovobronic structure of the DBS and wavenumbers for the rovibronic transitions.