Doppler-free ion imaging of hydrogen molecules produced in bimolecular reactions

We report on the use of two-color Doppler-free [(1 + 1′) + 1/1′] resonance enhanced multiphoton ionization (REMPI) for three-dimensional imaging of state-selected product molecules from bimolecular reactions. We demonstrate the viability of this method by measuring differential cross sections for the reaction H + D2 → D + HD(v′ = 1, j′ = 1,5,8) at 1.7 eV collision energy. We achieve higher resolution allowing us to observe oscillations that were not resolved by previous experiments; these oscillations agree closely with quantum mechanical calculations.