Abstract
We examine the long-time behaviour of A + B → 0 reaction—-diffusion systems with initially separated species A and B, and arbitrary values of the diffusion constant D A and D B and initial concentrations a 0 and b 0 of the species A and B respectively. We present general formulae for the total reaction rate, the location of the reaction zone centre, and the concentration profiles of majority species outside the reaction zone. Our approach can be applied to various A + B → 0 reaction—-diffusion systems including the controversial low-dimensional systems as well as the limit D B → 0, in which the cross-over to a separate universality class is observed.