It is shown that the amplitudes of electron-ion scattering and e+eβ pair
production in the Coulomb field of two colliding ions are sxpressed in the
terms of electron scattering amplitudes in the fields of the individual ions
via the Watson expansion. We have obtained the compact expressions for these
amplitudes valid in the high energy limit and discuss the crossing symmetry
relations among the considered processes.Comment: 5 pages, no figures, LaTEX; submitted to Physics Letters