Reversible photoionization excitations

In dealing with the reversible photoionization, it is very important to differentiate between the steady-state excitation accompanied by stationary fluorescence and free-ion production and the 8-pulse excitation followed by geminate recombination/separation of ions whose yields and subsequent time evolution are studied. They should be considered separately, step by step. 

Later, a very fine investigation was carried out on this reaction by Chupka et al. [204]. Producing their reactant H2 ions in selected vibrational states, or even in selected rotational states, by the use of their high-resolution photoionization mass spectrometer, they studied the cross-section of reaction (123) as a function of vibrational and kinetic energy of the reactant ions. The found that the cross-section decreases as vibrational excitation increases when ion kinetic energies are low, but the reverse is true when ion kinetic energies are high. 

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