Speaker
Description
To induce material modification, including ion track formation, under high-energy ion irradiation in the electronic stopping regime, the electronic stopping power (S_e) is one of the important parameters. Since Se increases with ion energy at low energies and then decreases at high energies, it exhibits a maximum whose value becomes larger for heavier ions. Therefore, among monatomic ions, the highest S_e is attainable with uranium ions. However, this maximum can be exceeded by cluster ions such as C60.
For example, the maximum S_e attainable with uranium ions in diamond is approximately 50 keV/nm, which was insufficient to form ion tracks. In contrast, 9 MeV C60 ions exceed this limit and successfully form ion tracks in diamond [1]. Furthermore, the exceptionally high S_e of C60 ions enables a regime in which both the electronic and nuclear stopping powers (S_e and S_n) are simultaneously high, resulting in ion track formation in crystalline Si under low energy 60 keV C60 ion irradiation [2,3].
References
[1] H. Amekura et al., Nat. Commun. 15, 1786 (2024).
[2] H. Amekura et al., Materialia 39, 102317 (2025).
[3] H. Amekura et al., NIMB 579, 166225 (2026).