High-brightness table-top hard X-ray source driven by sub-100-femtosecond mid-infrared pulses
High-brightness table-top hard X-ray source driven by sub-100-femtosecond mid-infrared pulses
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DOI：
10.1038/nphoton.2014.256
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发表时间：
2014-12-01
期刊：
影响因子：
35
通讯作者：
Baltuska, Andrius
中科院分区：
文献类型：
--
作者：
Weisshaupt, Jannick;Juve, Vincent;Baltuska, Andrius
凝聚态的超快结构动力学是当前物理、化学和材料科学的一个重要课题。飞秒硬x射线脉冲是应用于时间分辨x射线吸收和衍射的重要结构探针（1-4）。紧凑的激光驱动桌面光源的光泵/ x射线探针方案（5-11）允许用x射线光子统计来测量衍射强度的微小变化，这已经设定了最终的灵敏度极限（12-14）。为了解决对更高x射线通量的强烈追求，这里我们提出了第一个硬x射线等离子体源，由3.9 μ m的强中红外次100 fs脉冲驱动。相对较长的光学周期允许从Cu靶加速电子到非常高的动能，并产生每脉冲10(9)个光子的特征K α通量，比我们的800 nm驱动器多25倍（9,10）。理论模拟解释了大范围驱动场的实验结果，并预测了x射线通量的进一步增强。
Ultrafast structural dynamics in the condensed phase represents a key topic of current physics, chemistry and materials science. Femtosecond hard X-ray pulses are important structure probes that have been applied in time-resolved X-ray absorption and diffraction(1-4). Optical pump/X-ray probe schemes with compact laser-driven table-top sources(5-11) have allowed for tiny changes of diffracted intensity to be measured with X-ray photon statistics, which has set the ultimate sensitivity limit(12-14). To address the strong quest for a higher X-ray flux, here we present the first hard X-ray plasma source driven by intense mid-infrared sub-100-fs pulses at 3.9 mu m. The comparably long optical period allows for accelerating electrons from the Cu target to very high kinetic energies and for generating a characteristic K alpha flux of 10(9) photons per pulse, 25 times more than with our 800 nm driver(9,10). Theoretical simulations account for the experimental results in a wide range of driving fields and predict a further enhancement of X-ray flux.