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中国物理学会期刊

Uq+(q = 3—92)与H原子低能碰撞电荷转移过程

CSTR: 32037.14.aps.75.20260484

Charge transfer in low-energy Uq+ (q = 3–92) + H collisions

CSTR: 32037.14.aps.75.20260484
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  • 铀离子与氢原子碰撞的电荷转移截面及速率系数是千新星辐射输运建模、聚变等离子体诊断及重离子加速器束流设计的重要输入参数, 但迄今缺乏覆盖完整电离序列的系统理论研究. 本文在多通道Landau-Zener理论框架下, 对Uq+(q = 3—92) + H(1s)单电子俘获过程的总截面与速率系数展开系统研究, 碰撞能量覆盖0.0001—1000 eV/u, 将铀的几乎完整电离序列纳入统一的理论框架. 对于低电荷态(q\leqslant 12), 截面在各自特征转折能量E_\mathrmt以下近似遵循E^-1标度; 由于入射通道有效势垒的影响, 截面随能量升高呈现非单调变化, 且E_\mathrmt随q增大而整体升高. 对于q\geqslant13的高电荷态, 非单调转折在本文计算能区内基本消失, 截面在全能区近似保持E^-1标度行为. 截面随电荷态的演化揭示了清晰的壳层调制规律: 每当铀离子电子组态从未满壳层过渡至满壳层或满半壳层时, 交换能稳定化使电离能异常偏高, 俘获截面相应出现极小值, 该对应关系在5d, 4f, 4d, 3d等亚壳层的逐级剥离中均得到体现. 经Maxwell-Boltzmann热平均获得1—10^5 K温度下的速率系数, 其温度依赖行为与截面的能量依赖规律一致. 本文结果可为上述领域的等离子体建模与束流设计提供系统理论参考数据. 本文数据集可在https://doi.org/10.57760/sciencedb.j00213.00235中访问获取.

     

    Charge transfer cross sections and rate coefficients for ion-hydrogen collisions are fundamental input data for kilonova radiative transfer modeling, fusion edge plasma diagnostics, and heavy-ion accelerator beam lifetime evaluation. Despite this broad demand, systematic theoretical data for the Uq+ + H system at low energies were almost entirely absent before this work. In this study, total charge transfer cross sections and rate coefficients for single-electron capture in Uq+ (q = 3–92) + H(1s) collisions are investigated within the multichannel Landau-Zener (MCLZ) framework over the collision-energy range from 0.001 to 1000 eV/u, which represents the first unified treatment of nearly the entire uranium ionization sequence. The entrance-channel potential incorporates polarization attraction and short-range repulsion, while exit-channel potentials are constructed from Coulomb repulsion with asymptotic energy shifts derived from NIST spectroscopic data. Nonadiabatic coupling matrix elements are evaluated using the Butler-Dalgarno model for q \leqslant 4 and the Taulbjerg model for q \gt 4. Multichannel transition probabilities are computed via the recursive formula, and rate coefficients are obtained through Maxwell-Boltzmann thermal averaging over the temperature range 1–105 K. For low charge states (q = 3–12), the cross sections approximately follow an E^-1 scaling below their charac-teristic turnover energies E_t and exhibit non-monotonic energy dependences at higher energies. The turnover energy generally shifts upward with increasing q. For q \gtrsim 13, no resolvable turnover is observed within the present energy range, and the cross sections approximately retain the E^-1 scaling behavior over the whole calculated range. The charge state dependence of the cross sections reveals pronounced shell structure modulation. Systematic minima occur at closed-shell (\mathrmd^10 and \mathrmf^14) and half filled shell (\mathrmf^7) configurations, as exemplified by q = 15, 33, 40, and 65. This behavior is attributed to exchange energy stabilization at these configurations, which produces anomalously high ionization energies, increases the energy defect, shifts the avoided crossing to smaller internuclear distances, and suppresses the electron-capture probability. The thermally averaged rate coefficients preserve these shell-structure oscillations, and those for high charge states decrease approximately as T^-1/2. The present dataset covers temperature ranges relevant to kilonova ejecta (103–104 K), fusion edge plasmas (104–105 K), and accelerator beam pipes from room temperature to 103 K. It therefore provides systematic theoretical reference data for plasma modeling and beam-transport design. The dataset presented in this paper is openly available at https://doi.org/10.57760/sciencedb.j00213.00235.

     

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