AI 中文总结
本文研发了带平面刻线反射光栅的宽带XUV光谱仪，通过电动光阑调控XUV光束发散度，实现了光子通量与分辨率的主动控制，可快速获取薄膜固态样品尤其是强关联材料的XUV吸收光谱。
AI 中文摘要
高次谐波产生是一种多功能的桌面光源，可用于以原子级保真度和几飞秒的时间分辨率研究超快动力学。然而，飞秒极紫外（XUV）光源中交替出现的峰谷结构会导致高次谐波光谱出现强度调制，进而造成测得的XUV吸收光谱发生显著畸变。本文报道了一种宽带极紫外（XUV）光谱仪，其配备平面刻线反射光栅，可通过入口狭缝处的电动光阑孔径对光谱进行实时调整，以控制XUV光束在色散探测前的发散度。有效发散度可在0.03至1.9毫弧度之间调节，对应测得的XUV光子计数在40 eV附近从1.0×10^6光子/秒/电子伏特变化至1.5×10^7光子/秒/电子伏特。在上述条件下，对沉积在Si₃N₄膜（100 nm）上的Fe（10 nm）和Ti（10 nm）金属样品进行了测量，光谱覆盖范围超过30 eV，分辨率最高达500 meV。信噪比（SNR）与光谱分辨率之间的火山图确定了测量薄膜样品元素近边吸收光谱的权衡点。与光线追迹模拟结果一致，本文表明该设计参数可按需提供高分辨率或高SNR配置，用于快速获取薄膜固态样品，尤其是强关联材料的XUV吸收光谱。
英文摘要
High harmonic generation is a versatile tabletop source for the investigation of ultrafast dynamics with atomic fidelity and few-femtosecond time resolution. However, intensity modulations in the high harmonic spectra due to an alternating peak-and-valley structure in femtosecond extreme ultraviolet (XUV) sources can lead to significant distortions in measured XUV absorption spectra. We report a broadband extreme ultraviolet (XUV) spectrometer with a plane ruled reflection grating that can be spectrally adjusted on the fly using a motorized iris aperture in the entrance slit to control the divergence of the XUV beam prior to its dispersive detection. The effective divergence is tuned between 0.03 to 1.9 milli-radian with concomitant variation in the detected XUV photon counts of 1.0 $\times$ 10$^6$ photons/s/eV to 1.5 $\times$ 10$^7$ near 40 eV. Metallic samples of Fe (10 nm) and Ti (10 nm) deposited on Si$_3$N$_4$ membranes (100 nm) are measured under these conditions, with a spectral coverage of > 30 eV and a resolution of up to 500 meV. A volcano plot between signal-to-noise ratio (SNR) and spectral resolution determines the trade-off point in measuring elemental near-edge absorption spectra of thin film samples. Consistent with ray tracing simulations, we show that this design parameter offers on-demand high resolution or high SNR configurations for the rapid acquisition of XUV absorption spectra of thin film solid-state samples, especially strongly correlated materials.
Comments20 pages, 7 figures
