Regular Article

Charge state effect on K-shell ionization of silicon induced by iodine^q+ ions

¹ Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, P.R. China
² University of Chinese Academy of Science, Beijing 100049, P.R. China
³ School of Science, Xi’an Jiaotong University, Xi’an 710049, P.R. China

^a e-mail: leiyu@impcas.ac.cn
^b e-mail: chengrui@impcas.ac.cn
^c e-mail: zhaoyongtao@xjtu.edu.cn

Received: 21 December 2017
Received in final form: 26 March 2018
Published online: 2 August 2018

Abstract

In near Bohr velocity ion-atom collisions, a dependence of target K-shell ionization cross sections upon the ionic charge states has been observed. Experiments were performed in silicon solid target with 2–5 MeV iodine^q+ ions incident in charge states +20 to +25. K-shell ionization cross section of silicon for q = 20 and 22 iodine ions impact with the same incident energy are almost equal, and are well described by the theory of binding-energy-modified BEA. However, for q = 25 iodine ions collisions, 3d vacancies of projectile transfer to the 1s orbit of target atom via rotational coupling of 3dπ, δ-3dσ molecular orbits in the framework of quasi-molecular model, which results in an increase of the K-shell ionization cross section of silicon.