利用自由电子激光器进行纳米级超快晶格调制
近日，美国SLAC国家加速器实验室Zhu, Diling团队报道了利用自由电子激光器进行纳米级超快晶格调制。相关论文于2026年1月27日发表在《自然—物理学》杂志上。
基于超快光学激光的技术已能以飞秒至阿秒的时间分辨率，在物质固有的时间尺度上探测原子级过程。然而，光学激光的长波长特性阻碍了其在纳米尺度空间特异性上进行探测与操控。硬X射线自由电子激光的进展推动了X射线瞬态光栅光谱学的发展，该技术旨在利用纳米尺度的X射线驻波对元激发进行相干调控。迄今为止，在纳米尺度实现该技术一直面临挑战。
研究组通过将两束硬X射线泵浦脉冲在精确控制的交叉角度下进行亚飞秒量级的同步，实现了空间周期约为10纳米的X射线瞬态光栅光谱学。这产生了一个热光栅，并优先激发了具有瞬态光栅波矢的相干纵声学声子模。随后，使用具有相同光子能量的第三束、可调延迟的X射线脉冲进行探测，通过对所诱导散射强度调制进行时间和波矢分辨的测量，为纳米尺度的弹道热输运提供了证据。这些结果凸显了X射线瞬态光栅作为一个强大平台的潜力，可用于研究凝聚态物质中的纳米尺度输运现象，以及对纳米尺度动力学进行相干调控。
附：英文原文
Title: Nanoscale ultrafast lattice modulation with a free-electron laser
Author: Li, Haoyuan, Wang, Nan, Zhang, Leon, Song, Sanghoon, Sun, Yanwen, Ng, May-Ling, Sato, Takahiro, Hanlon, Dillon, Dahal, Sajal, Balcazar, Mario D., Esposito, Vincent, She, Selene, Ornelas-Skarin, Chance Caleb, Vila-Comamala, Joan, David, Christian, Berndt, Nadia, Miedaner, Peter R., Zhang, Zhuquan, Ihme, Matthias, Trigo, Mariano, Nelson, Keith A., Hastings, Jerome B., Maznev, Alexei A., Foglia, Laura, Teitelbaum, Samuel, Reis, David A., Zhu, Diling
Issue&Volume: 2026-01-27
Abstract: Ultrafast optical laser-based techniques have enabled the probing of atomistic processes at their intrinsic temporal scales with femto- and attosecond resolution. However, the long wavelengths of optical lasers have prevented their interrogation and manipulation with nanoscale spatial specificity. Advances in hard X-ray free-electron lasers have enabled progress in developing X-ray transient-grating spectroscopy, a technique that aims to coherently control elementary excitations with nanoscale X-ray standing waves. Thus far, the realization of this technique at the nanoscale has been a challenge. Here we demonstrate X-ray transient-grating spectroscopy with spatial periods of the order of 10nm via the subfemtosecond synchronization of two hard X-ray pump pulses at a precisely controlled crossing angle. This creates a thermal grating and preferentially excites coherent longitudinal acoustic phonon modes with the transient-grating wavevector. On probing with a third, variably delayed, X-ray pulse with the same photon energy, time-and-wavevector-resolved measurements of the modulation of the induced scattering intensity provide evidence of ballistic thermal transport at nanometre scales. These results highlight the potential of X-ray transient gratings as a powerful platform for studying nanoscale transport in condensed matter and the coherent control of nanoscale dynamics.
DOI: 10.1038/s41567-025-03161-8
Source: https://www.nature.com/articles/s41567-025-03161-8
