辐射电子-离子复合引发的核激发
Nuclear excitation by radiative electron-ion recombination
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中文总结 AI 辅助
本文提出辐射电子-离子复合引发的核激发（NERER）机制，构建其理论框架，针对$^{229}$Th的8.4 eV同质异能素激发研究，发现NERER截面可比非弹性电子散射引发的核激发高一个数量级以上，为核激发与同质异能素制备提供新途径。
中文摘要 AI 辅助
本文从理论上提出了一种核激发机制——辐射电子-离子复合引发的核激发（NERER）。NERER是一个通过虚电子态进行的三阶过程：一个电子复合进入离子的原子空位，同时发射一个实光子并激发原子核。光子发射补偿了自由-束缚电子跃迁与核跃迁能量之间的能量失配，因此入射电子无需满足共振条件。本文构建了NERER的理论框架，并针对$^{229}$Th的8.4 eV同质异能素激发情况进行研究，以制备核钟同质异能素$^{229m}$Th。结果表明，对于高电荷离子，当与内原子壳层耦合时，NERER的截面可比已知的核激发低阶过程——非弹性电子散射引发的核激发——高出一个数量级以上。本研究成果为核激发和高效同质异能素制备提供了新途径，并支持进一步研究原子系统与核系统相互作用中的高阶效应。
英文摘要
A nuclear excitation mechanism, nuclear excitation by radiative electron-ion recombination (NERER), is put forward theoretically here. NERER is a third-order process that proceeds via a virtual electronic state: an electron recombines into an atomic vacancy of an ion with the simultaneous emission of a real photon and excitation of the nucleus. The photon emission compensates the energy mismatch between the free-bound electronic transition and the nuclear transition energies, thus there is no resonant condition imposed to the incident electron. We develop here the theoretical framework for NERER, and investigate the case of the $8.4$ eV isomeric excitation of $^{229}$Th for the production of the nuclear clock isomer $^{229m}$Th. Our results show that, with the coupling to the inner atomic shells for highly-charged ions, the NERER cross section can exceed the one of the known lower-order process of nuclear excitation by inelastic electron scattering by more than one order of magnitude. Our findings offer a new pathway for nuclear excitation and efficient isomer production, and support further investigations for high-order effects in the interplay between the atomic and nuclear systems.
