Ion-ion recombination in an ambient ion gas

Attention is drawn to collisional ion-ion recombination X + +Y - +X + (or Y - ) to XY+X + (or Y - ) which can be important when the ion density n i is very high. If, for example, X + is Kr + and Y - is F - the recombination coefficient alpha i is 3.0*10 -7 (300/ theta ) 4.5 (n i /10 15 ) cm 3 s -1 where theta is the temperature.