The charge exchange mechanism in metal vapour lasers

It is found that the thermal energy charge transfer process in metal vapour lasers does not occur via the two-state 'near-resonant' charge transfer process. Instead, an alternative mechanism is proposed involving curve crossings of molecular states formed during the collision followed by fine-structure transition into the various atomic J levels. As an example, it is shown that this mechanism is consistent with the experimental cross section measurements for charge transfer occurring in the He-Zn laser. Possible charge transfer processes occurring in the proposed Xe-Ca metal vapour laser are discussed.