Collisional charge inversion

Then the [M-H] ions may undergo a collisional charge inversion. 

Other types of reactions have been studied in collisional conditions, especially charge-inversion reactions. 

Excited states can be formed by a variety of processes, of which the important ones are photolysis (light absorption), impact of electrons or heavy particles (radiolysis), and, especially in the condensed phase, ion neutralization. To these may be added processes such as energy transfer, dissociation from super-excited and ionized states, thermal processes, and chemical reaction. Following Brocklehurst [14], it is instructive to consider some of the direct processes giving excited states and their respective inverses. Thus luminescence is the inverse of light absorption, super-elastic collision is the inverse of charged particle impact excitation, and collisional deactivation is the inverse of the thermal process, etc. 

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