Impact-Parameter Dependence of X-Ray Production in Collisions between Energetic Heavy Ions and Atoms

18- to 46-MeV ${}_{53}{}^{}{}_{}{}^{}\mathrm{I}$ ions were scattered by thin ${}_{52}{}^{}{}_{}{}^{}\mathrm{Te}$ targets. The $L$ x rays produced in the nearly identical particles ${}_{53}{}^{}{}_{}{}^{}\mathrm{I}$ and ${}_{52}{}^{}{}_{}{}^{}\mathrm{Te}$ were measured in coincidence with the scattered I ions. The differential cross section for $L$ x-ray emission shows a maximum at impact parameters comparable to the $L$-shell radii. For the ion energies $E$ investigated, the total cross section for $L$ x-ray emission in I and Te was found to be proportional to $E^{0.8}$. The results are discussed and compared with theoretical models for inner-shell excitation.