O'Neal Jordan T, Champenois Elio G, Oberli Solène, Obaid Razib, Al-Haddad Andre, Barnard Jonathan, Berrah Nora, Coffee Ryan, Duris Joseph, Galinis Gediminas, Garratt Douglas, Glownia James M, Haxton Daniel, Ho Phay, Li Siqi, Li Xiang, MacArthur James, Marangos Jon P, Natan Adi, Shivaram Niranjan, Slaughter Daniel S, Walter Peter, Wandel Scott, Young Linda, Bostedt Christoph, Bucksbaum Philip H, Picón Antonio, Marinelli Agostino, Cryan James P
Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA.
Department of Physics, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2020 Aug 14;125(7):073203. doi: 10.1103/PhysRevLett.125.073203.
Free-electron lasers provide a source of x-ray pulses short enough and intense enough to drive nonlinearities in molecular systems. Impulsive interactions driven by these x-ray pulses provide a way to create and probe valence electron motions with high temporal and spatial resolution. Observing these electronic motions is crucial to understand the role of electronic coherence in chemical processes. A simple nonlinear technique for probing electronic motion, impulsive stimulated x-ray Raman scattering (ISXRS), involves a single impulsive interaction to produce a coherent superposition of electronic states. We demonstrate electronic population transfer via ISXRS using broad bandwidth (5.5 eV full width at half maximum) attosecond x-ray pulses produced by the Linac Coherent Light Source. The impulsive excitation is resonantly enhanced by the oxygen 1s→2π^{*} resonance of nitric oxide (NO), and excited state neutral molecules are probed with a time-delayed UV laser pulse.
自由电子激光提供了一种X射线脉冲源，其脉冲持续时间足够短且强度足够高，足以驱动分子系统中的非线性效应。由这些X射线脉冲驱动的脉冲相互作用提供了一种以高时间和空间分辨率创建和探测价电子运动的方法。观察这些电子运动对于理解电子相干性在化学过程中的作用至关重要。一种用于探测电子运动的简单非线性技术——脉冲受激X射线拉曼散射（ISXRS），涉及单次脉冲相互作用以产生电子态的相干叠加。我们利用直线加速器相干光源产生的宽带宽（半高全宽为5.5电子伏特）阿秒X射线脉冲，通过ISXRS演示了电子布居转移。脉冲激发通过一氧化氮（NO）的氧1s→2π*共振得到共振增强，并用延时紫外激光脉冲探测激发态中性分子。
