AI 中文总结
该研究利用调谐至Te N4,5边的自由电子激光脉冲，在三角碲中实现了相干晶格动力学，其驱动效率为可见光泵浦的两倍，揭示了X射线脉冲可调控材料位移响应的新机制。
AI 中文摘要
调节电子-声子耦合为控制结构位移和调控材料功能提供了途径，然而价带到导带的跃迁对驱动力的调控作用有限。本文中，我们利用调谐至碲（Te）N4,5边的自由电子激光脉冲，在三角碲中实现了相干晶格动力学。在宽通量范围内，振荡幅度遵循相干声子的位移激发（displacive excitation of coherent phonons）框架，该框架扩展至芯能级共振，驱动效率是可见光泵浦的两倍。从头算计算将力分解为竞争的多带贡献，这是光激发无法实现的，其平衡随载流子弛豫而变化。因此，可调谐极紫外和X射线脉冲开启了一个新机制，其中位移响应由依赖于能带的晶格耦合决定，而非仅由光生载流子的数量和温度决定。
英文摘要
Modulating electron-phonon coupling offers a route to control structural displacements and tune material functionality. Valence-to-conduction band transitions, however, provide limited leverage over the driving force. Here, we demonstrate coherent lattice dynamics in trigonal tellurium using free-electron laser pulses tuned to the Te N4,5-edge. Over a broad fluence range, the oscillation amplitude obeys the displacive excitation of coherent phonons framework, extended to core resonance with twice the driving efficiency of a visible pump. Ab initio calculations decompose the force into competing multiband contributions, inaccessible to optical excitation, whose balance shifts as carriers relax. Tunable extreme-ultraviolet and X-ray pulses thus open a regime in which the displacive response is set by band-dependent coupling to the lattice, not by the number and temperature of the photocarriers alone.
