In the literature, the chemi-ionization of Li in the
22S1/2ground level by He in a metastable state
is typically
described as an electron transfer process in which an electron from
the 2s orbital of Li is transferred to the 1s orbital of He while
an electron from the 2s orbital of He is ejected. Therefore, one would
not assume that the orbital of the valence electron of He strongly
influences the coupling strength of the collision complex to the ionization
continuum. However, we observe that the chemi-ionization rate is decreased
when He is laser-excited from the metastable 23S1level to the 23PJlevel (withJ= 0, 1, 2). A semiclassical treatment of the reaction
dynamics reveals a strong dependence of the ionization rate on the
reaction-channel-specific ionization width functions to which the
observed decrease of the rate coefficients can be related to. The
results are relevant for the improved understanding and control of
chemi-ionization processes in merged beams and in traps.