Direct measurement of charge-exchange probability during photo-dissociation of OD⁺ target

We measure the charge-exchange probability during the photo-dissociation of OD⁺ induced by intense ultrashort laser pulses, using coincidence three-dimensional momentum imaging of a fast (keV) ion beam. An upgraded two-detector setup is used to measure in coincidence the fragments with a large mass ratio (16:2). The ground electronic state (X ³Σ^-) OD⁺ ions are excited to the B ³Σ^- state by 790-nm or 395-nm photons. The dissociation limit of the B ³Σ^- state is O⁺(⁴S) + D(¹S) and unimolecular transitions from B ³Σ^- to X ³Σ^- result in O(³P) + D⁺, which is the dissociation limit of the X ³Σ^- state. The measured branching ratio between these two dissociation channels, O⁺(⁴S) + D(¹S) and O(³P) + D⁺, as a function of energy is a direct measure of the charge-exchange probability which compares well with our calculations.