Excitation of heavy hydrogenlike ions by light atoms in relativistic collisions with large momentum transfers

We present a theory for excitation of heavy hydrogenlike projectile ions by light target atoms in collisions where the momentum transfers to the atom are very large on the atomic scale. It is shown that in this process the electrons and the nucleus of the atom behave as (quasi-) free particles with respect to each other and that their motion is governed by the field of the nucleus of the ion. The effect of this field on the atomic particles can be crucial for the contribution to the excitation of the ion caused by the electrons of the atom but, because of large nuclear mass, may be neglected in the contribution to the excitation due to the nucleus of the atom. The theory is applied to calculate excitation of Bi${}^{82+}$(1$s$) ions in collisions with hydrogen.

Figure 1

Cross sections for excitation of Bi${}^{82+}$(1$s$) projectiles into the $L$-shell in collisions with hydrogen in the inelastic target mode. Dash and solid curves show the results obtained using approach I and approach II, respectively. For more explanation, see the text.

Figure 2

Cross sections for excitation of Bi${}^{82+}\left(1s\right)$ ions into the $L$-shell by the impact of equivelocity electrons (solid curves) and protons (dash curves).