近日，美国芝加哥大学Linda Young团队研究了超分辨率受激X射线拉曼光谱。这一研究成果于2025年7月16日发表在《自然》杂志上。

强X射线脉冲在致密介质中的传播导致了诸如原子X射线激光、自诱导透明和受激X射线拉曼散射（SXRS）等现象的观察。SXRS长期以来一直被预测为发射和探测价电子波包的一种手段，也是非线性X射线光谱学的基石。然而，到目前为止，SXRS的实验观测并没有提供光谱信息，理论建模主要是实现难以实现的相参阿秒脉冲。

研究组展示了具有光谱精度的SXRS，即以接近极限的联合能量时间分辨率0.1 ev - 40fs检测氖中的价态激发态。研究组在统计尖峰宽带入射x射线和散射x射线拉曼脉冲之间进行了新的协方差分析。使用18,000次单次射击，不仅超过了事件带宽（约8ev），而且还超过了大约0.2 eV的带宽。

研究组创造了超分辨率的条件，类似于超分辨率荧光显微镜。他们的实验结果得到从头算传播模拟的支持，揭示了离子中的激光和中性中的受激拉曼散射之间的竞争。研究组展示了增强的信号收集效率和宽激励窗口，超过自发拉曼效率的数量级。这种随机的SXRS方法是朝着追踪决定化学结果的基本事件迈出的第一步。

附：英文原文

Title: Super-resolution stimulated X-ray Raman spectroscopy

Author: Li, Kai, Ott, Christian, Agker, Marcus, Ho, Phay J., Doumy, Gilles, Magunia, Alexander, Rebholz, Marc, Simon, Marc, Mazza, Tommaso, De Fanis, Alberto, Baumann, Thomas M., Montano, Jacobo, Rennhack, Nils, Usenko, Sergey, Ovcharenko, Yevheniy, Chordiya, Kalyani, Cheng, Lan, Rubensson, Jan-Erik, Meyer, Michael, Pfeifer, Thomas, Gaarde, Mette B., Young, Linda

Issue&Volume: 2025-07-16

Abstract: Propagation of intense X-ray pulses through dense media has led to the observation of phenomena such as atomic X-ray lasing1,2, self-induced transparency3 and stimulated X-ray Raman scattering (SXRS)4. SXRS has been long predicted as a means to launch and probe valence-electron wavepackets and as a building block for nonlinear X-ray spectroscopies5,6. However, experimental observations of SXRS to date4,7,8 have not provided spectroscopic information, and theoretical modelling has largely implemented hard-to-realize phase-coherent attosecond pulses. Here we demonstrate SXRS with spectroscopic precision, that is, detection of valence-excited states in neon with a near Fourier-limited joint energy–time resolution of 0.1eV–40fs. We used a new covariance analysis between statistically spiky broadband incident X-ray and scattered X-ray Raman pulses. Using 18,000 single shots, we beat not only the incident (about 8eV) bandwidth but also the  approximately 0.2eV instrumental energy resolution, thus creating super-resolution conditions, in analogy to super-resolved fluorescence microscopy9. Our experimental results, supported by ab initio propagation simulations, reveal the competition between lasing in the ion and stimulated Raman scattering in the neutral. We demonstrate enhanced signal collection efficiency and a broad excitation window, surpassing spontaneous Raman efficiencies by orders of magnitude. This stochastic SXRS approach represents a first step towards tracking elementary events that determine chemical outcomes10.

DOI: 10.1038/s41586-025-09214-5

Source: https://www.nature.com/articles/s41586-025-09214-5