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| Optical Emission From the Al Surface Bombarded by 260～520 keV Krq+(8≤q≤17) Ion |
| XU Qiu-mei |
Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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Abstract When a metal surface is bombarded by slow, highly charged ions (SHCIs), atomic particles ejected from the sample, and then some of them in excited states undergo radiative de-excitation resulting in optical emission. SHCIs will capture one or more electrons from the surface into its excited state during the interaction. Then some exciting projectiles undergo radiative de-excitation and result in the optical emission. Previous reports showed that the nuclear stopping power is closely related to the sputtering yields. In order to arrive at a better understanding of the electronic excitation of the sputtered particles, a correlation between the ion-induced photon emission and kinetic energy and potential energy is required. We have investigated the interaction between 260～520 keV Krq+ (8≤q≤17) ions and an aluminum target in the present work. A spectrum in the wavelength range of 300~550 nm was obtained by 520 keV Kr13+bombardment. The spectral lines included the resonance transitions of sputtered Al atoms at 309.0, 395.9 nm, Al+ and Al2+ ions at 358.3 and 451.6 nm, and Kr+ ions at 430.0, 434.1, 465.8, 486.0 nm. The ratio of Y(309.0)/Y(395.9), Y(358.5)/Y(395.9), Y(452.8)/Y(395.9) are presented as a function of projectile kinetic energy and potential energy. The results showed that the ratios of Y(309.0)/Y(395.9), Y(358.5)/Y(395.9), Y(452.8)/Y(395.9) increased with the increase of the kinetic energy, while the ratio Y(309.0)/Y(395.9) decreased with the increase of the potential energy. It is concluded that, in the interaction between SHCIs and Al target, the kinetic energy (electronic stopping power) and the potential energy make Al atom excitation. Compared with the excited states Al(4s), the probability of higher excited state 3d increases with the increase of the electronic stopping power, decreases with the increase of the potential energy. In optical radiation, nuclear stopping power affects the sputtering yield, and the electronic stopping power and potential energy are closely related to the excitation probability. In the interaction of SHCIs with a metal surface, both kinetic energy and potential energy contribute to optical radiation. When the kinetic energy is the same order as the potential energy, the excitation probability originated from kinetic energy is two orders smaller than the potential energy.
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Received: 2020-12-29
Accepted: 2021-02-04
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