Angular-momentum transfer in collisional ionization

The double-differential cross sections for ionization in ${\mathit{e}}^{\mathrm{-}}$+H(nl) collisions are reported as a function of the impact energy E of the projectile, final energy ${\mathit{E}}_{\mathit{f}}$, and angular momentum ${\mathit{L}}_{\mathit{f}}$ of the ejected electron. This process is assumed to occur via an energy-changing and angular-momentum-changing binary collision between the Rydberg electron in a prepared state (nl) and the projectile electron ${\mathit{e}}^{\mathrm{-}}$ or H(1s). The atomic projectile can also be excited during this process. Systematic trends in the variation of the classical ionization cross sections with final angular momentum ${\mathit{L}}_{\mathit{f}}$ of the ejected electron are discussed and are in accord with a previous quantal treatment, whereby the nondipole (Δl>1) transitions are much more important in the low- and intermediate-energy range of relative motion, and that the value of the final angular momentum of the ejected electron depends mainly on the initial value of the principal quantum number n of the Rydberg atom.