Zhao Yong-Tao

A framework for selecting indicators to assess the sustainable development of the natural heritage site

Sustainable world heritage management represents an approach for managing the resources of a property by integrating environmental, economic, and social issues. It aims to provide sustainable benefits for future generations, while protect the property and minimize the possible adverse social, economic and environmental impacts. Indicators of sustainable development, which summarize information for decision-making, are invaluable to learn the efficiency and effectiveness of property management. Scientists in many fields devised several conceptual models of environmental statistics and indicators, of which, DPSIR (Driving forces — Pressure — State — Impact — Response) is thought to be the best available one in identifying and developing indicators of sustainable development. Based on the DPSIR conceptual model and indicator selection criteria, the present paper proposed a methodology framework for selecting indicators to assess the sustainable development of a natural heritage site. The proposed framework included a multi-level hierarchical structure for various indicators and indexes, a modified DPSIR frame to identify key issues in property management and a set of indicators for evaluating the sustainability in Sichuan Giant Panda Sanctuaries.

Surface Plasmon-Assisted Excitation of Atomic Visible Light Spectral Lines in the Impact of Highly Charged Ions 126Xeq + on Solid Surfaces

We measured the visible light spectral lines of sputtering atoms from solid surfaces of Al, Ti, Ni, Ta and Au which are impacted by 150 keV 126Xeq + (6≤q≤30). It is found that intensities of the light spectral lines are greatly and suddenly enhanced when the charge state of the ion is raised up to a critical value. If assuming that potential energy released from the incident ion due to capturing one electron is enough to excite a surface plasmon, we can estimate the critical charge states and obtain the results very well consistent with the measurements for the above-mentioned target materials. This means that a surface plasmon induced by one electron capture can enhance the excitation of atomic visible light spectral lines in the impact of a highly charged ion on a solid surface.

Potential and Kinetic Electron Emissions from HOPG Surface Irradiated by Highly Charged Xenon and Neon Ions

Highly charged 129Xeq+ (q = 10−30) and 40Neq+ (q = 4−8) ion-induced secondary electron emissions on the surface of highly oriented pyrolytic graphite (HOPG) are reported. The total secondary electron yield is measured as a function of the potential energy of incident ions. The experimental data are used to separate contributions of kinetic and potential electron yields. Our results show that about 4.5% and 13.2% of ions potential energies are consumed in potential electron emission due to different Xeq+ -HOPG and Neq+ -HOPG combinations. A simple formula is introduced to estimate the fraction of ions potential energy for potential electron emission.

Guiding of Highly Charged Ions through PC Nanocapillaries

Angular distribution and current dependence of the transmitted ion fraction are investigated for 40keV Xe7+ bombarding on polycarbonate (PC) nanocapillaries. By measuring the angular distribution of the transmitted ion fraction, a strong guiding effect is found in PC nanocapillaries. Furthermore, with increase of the incident current, a turning point of the transmitted ion fraction is found, which is explained qualitatively by the discharge capacity of the nanocapillaries.

Kr L X-ray and Au M X-ray emission for 1.5 MeV—3.9 MeV Kr13+ ions impacting on an Au target

Kr L X-ray and Au M X-ray emission for Kr13+ ions with energies of 1.5 MeV and 3.9 MeV impacting on an Au target are investigated at heavy ion research facility in Lanzhou (HIRFL). The L-shell X-ray yield per ion of Kr is measured as a function of incident energy. In addition, Kr L X-ray production cross section is extracted from the yield and compared with the result obtained from the classical binary-encounter approximation (BEA) model. Furthermore, the intensity ratio of the Au Mβ3 to Mα1 X-ray is investigated as a function of incident energy.

Ionization of highly charged iodine ions in collisions near the Bohr velocity

The L-shell X-rays of iodine induced by 3MeV Iq+(q=20,22,25,26) ions impacting on Fe target were measured. The results indicated that, in addition to the ionization of L-shell, the projectile M- and N-shell were multiply ionized. The ratios of the sub-shell X-ray relative intensity were also investigated.

Fe K-shell ionization induced by Xe20+ ions near the Bohr velocity

Fe K-shell ionization cross sections by 2.4-6.0 MeV Xe20+ impact were investigated. It was found that the BEA model corrected both by the Coulomb repulsion and the effective nuclear charge gives the best agreement with the experimental data.

Charge state effect on the K-shell ionization of iron by xenon ions near the Bohr velocity

Fe K-shell ionization cross sections induced by 2.4–6.0 MeV Xe20+ are measured and compared with different binary-encounter-approximation (BEA) models. The results indicate that the BEA model corrected both by the Coulomb repulsion and by the effective nuclear charge (Zeff) agrees well with the experimental data. Comparison of Fe K-shell X-ray emission induced by 5 MeV xenon ions with different initial charge states (20+, 22+, 26+, 30+) verifies the applicability of the effective nuclear charge (Zeff) correction for the BEA model. It is found that Zeff correction is reasonable to describe direct ionization induced by xenon ions with no initial M-shell vacancies. However, when the M shell is opened, the Zeff corrected BEA model is unable to explain the inner-shell ionization, and the electron transfer by molecular-orbital promotion should be considered.

X ray spectra induced by 129 Xe 30+ impacting the Au surface

X ray emission from Xe 30+ ions (kinetic energy 350-600 keV) impacting on an Au target surface was investigated. The 1.65 keV M-X ray and the Au atomic Mα characteristic X rays were measured. The results show that because the 3d electron of the Xe ion is excited to occur a vacancy, the 1.65 keV M-X ray are emit from the electron transition between 4f to 3d energy level. The 3s electron of the Au target atom is ionized to form a hole in the M-shell, the Mα characteristic X rays are radiated by 4f electron filling in the hole. It was also found that the yield of such characteristic X rays is decreasing with increasing the projectile kinetic energy. The yield of the characteristic Au X rays increases with increasing the projectile kinetic energy. These phenomena are analyzed with the classical coulomb over the barrier mode.当不同动能(350-600 keV)高电荷态离子 129 Xe 30+ 入射Au 表面过程中, 发出了1.65 keV 的X 射线和靶原子的Mα特征X 射线. 分析表明: 高电荷态离子与Au 表面相互作用过程中, Xe 离子3d 壳层的电子被激发, 形成空穴, 4f 电子偶极跃迁辐射1.65 keV M-X 射线. 同时, 靶原子Au 的3s 电子被激发, 退激辐射Mα X 射线. 利用经典过垒模型解释了Xe 的M-X 射的产额随入射离子的动能增加而减小, 靶原子的特征X 射线产额随入射离子的动能增加而增加的原因.

Study on charge equilibration time of highly charged ions in carbon foils

Charge state distribution of 0.8MeV/u uranium ions after transmission through a thin carbon foil has been studied. It is observed that the charge state distribution is equilibrated after the uranium ions have passed through a 15 μg/cm2 carbon foil. The equilibrated average charge state is 33.72 and the charge equilibration time of uranium ions in carbon foil is less than 5.4fs.