论文标题
非线性谐振X射线拉曼散射
Nonlinear resonant X-ray Raman scattering
论文作者
论文摘要
我们报告了在硬X射线范围内的新型非线性效应的观察。在照亮的Fe和Cu金属箔带有强烈的X射线脉冲附近调节的k边缘时，发射传入光子能的光子几乎是两倍。该信号随传入强度的次数上升，与两光子激发一致。发射的高能光子的光谱包括多个与入射光子能量分散的拉曼线。达到双K壳电离阈值后，信号强度会出现明显的上升。在此阈值之上，线路停止分散，变成具有比单电子过渡可获得的能量要大得多的发色线，并且出现了其他拉曼线。我们将这些过程归因于涉及双核孔激发和各种两电源脱启发过程的电子相关介导的多电体转换，涉及一个或多个L和M核孔的最终状态。
We report the observation of a novel nonlinear effect in the hard x-ray range. Upon illuminating Fe and Cu metal foils with intense x-ray pulses tuned near their respective K edges, photons at nearly twice the incoming photon energy are emitted. The signal rises quadratically with the incoming intensity, consistent with two-photon excitation. The spectrum of emitted high-energy photons comprises multiple Raman lines that disperse with the incident photon energy. Upon reaching the double K-shell ionization threshold, the signal strength undergoes a marked rise. Above this threshold, the lines cease dispersing, turning into orescence lines with energies much greater than obtainable by single electron transitions, and additional Raman lines appear. We attribute these processes to electron-correlation mediated multielectron transitions involving double-core hole excitation and various two-electron de-excitation processes to a final state involving one or more L and M core-holes.
