The State-selective Charge Exchange Of Low Energy N⁶⁺ Ions Colliding With He And Ne Atoms

The study of ion-atom collision is a very important topic in the field of atomic physics.It can not only be used to explain the problem of multi-body dynamics,but also provide an important basis for the research of plasma physics,material modification,astrophysics,and other related fields.The reaction microscopy of the Institute of Modern Physics,Chinese Academy of Sciences has been used to systematically measure the impact reactions of N⁶⁺ions with He in the energy range of 2.1 ke V/u to 8.6 ke V/u.The state selective cross-sections and angular differential cross-sections of single-electron capture and double electron transfer processes have been obtained.Also,the state selective single-electron capture processes of N⁶⁺ions colliding with Ne with energies of 6 ke V/u and 8.6 ke V/u have been studied.The state selective cross-section and angular differential cross-section have been measured experimentally for the single electron capture process of N⁶⁺and He collisions.The results show that the capture of the principal quantum number n=3 is the main capture channel,followed by n=4.Comparing the results of the molecular Coulomb over barrier model,it is found that the theoretical prediction of the state selection cross-section for n=3 is in good agreement with the experimental results,but there has a bigger difference for n=4.Due to the limitations of the classical model,the molecular Coulomb over barrier model only predicts the small-angle scattering.By comparing the angular differential cross sections calculated by the continuum distorted wave method,it is found that the large-angle peak comes from the interaction between the projectile nucleus and the target nucleus,while the small-angle peak comes from the interaction between the nucleus and the electron.For the double electron transfer process of N⁶⁺and He collision,the relativistic multi-configuration Dirac-Fock method is used to calculate the double excited state energy levels of N ⁴⁺(1 sn ln'l')ions.The double excited states of the double electron transfer population are identified successfully,and the population mechanisms of the true double capture process and the transfer ionization process are analyzed.The state selective cross-section and angular differential cross-section are measured experimentally for the single electron capture process of N⁶⁺and Ne collision.The experimental results show that the state populations of the two systems are different.The single electron capture of Ne target is dominated by the state of n=4,followed by the contribution of n=3 and the smallest contribution of n=5.As for the experimental results of angular differential cross-sections,it is found that the captured states of n=4 and 5 have larger scattering angles,while the captured states of n=3 have smaller scattering angles,which is quite different from the images of the classical model.