标题： 接近桌面软X射线NEXAFS测量中激光产生等离子体源的较低时间极限 显示英文标题

标题： Approaching the Lower Temporal Limit of Laser-Produced Plasma Sources for Table-Top Soft X-ray NEXAFS Measurements

摘要： 时间分辨X射线吸收测量在理解分子和材料系统中的动态过程方面的日益流行，推动了用于脉冲X射线的桌面光源的许多进展。 我们报道了一种桌面激光产生等离子体（LPP）光源，该光源可以使用23皮秒脉冲持续时间的激光源进行软X射线（SXR）和近边缘X射线吸收精细结构（NEXAFS）测量。 光谱仪的关键规格，如亮度、分辨率和稳定性，与更常用的长脉冲持续时间的LPP光源进行了对比。 由于等离子体吸收的总能量较小，23皮秒激光产生的SXR通量比8纳秒激光弱一个数量级。 增加的重复率和实施的自参考方案仍然允许对Si3N4和TiO2薄膜进行高分辨率、类似同步辐射的NEXAFS测量，采集时间为2.5分钟。 观察到气体喷嘴的退化导致了光源的长期不稳定，这可以通过使用替代喷嘴设计来解决。 这项工作展示了未来利用桌面激光产生等离子体光源实现更高时间分辨率的时间分辨X射线吸收测量的可行性。 显示英文摘要

摘要： The increasing popularity of time-resolved X-ray absorption measurements for understanding dynamics in molecular and material systems has led to many advances in table-top sources for pulsed X-rays. We report on a table top laser-produced plasma (LPP) source that can perform soft X-ray (SXR), near edge X-ray absorption fine structure (NEXAFS) measurements using a laser source with 23 ps pulse duration. The spectrometer's key specifications, such as brilliance, resolution, and stability, are characterized against the more commonly used longer-pulse-duration LPP sources. The 23 ps laser produced approximately an order of magnitude weaker SXR flux than the 8 ns laser for a higher power density due to the smaller total energy absorbed by the plasma. The increased repetition rate and an implemented self-referencing scheme still allowed for high-resolution, synchrotron-like NEXAFS measurements of Si3N4 and TiO2 thin films with 2.5 minute acquisition times. It was observed that degradation of the gas jet nozzle led to long-term instability of the source, which can be remediated using alternative nozzle designs. This work demonstrates the feasibility of achieving higher temporal resolution in future time-resolved X-ray absorption measurements using table-top laser-produced plasma sources