Rakowski R, Golovin G, O'Neal J, Zhang J, Zhang P, Zhao B, Wilson M D, Veale M C, Seller P, Chen S, Banerjee S, Umstadter D, Fuchs M
Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588, USA.
STFC Rutherford Appleton Laboratory, Harwell, Didcot, Oxfordshire, OX11 0QX, UK.
Sci Rep. 2017 Nov 30;7(1):16603. doi: 10.1038/s41598-017-16477-0.
High-energy X-rays (HEX-rays) with photon energies on order of 100 keV have attractive characteristics, such as comparably low absorption, high spatial resolution and the ability to access inner-shell states of heavy atoms. These properties are advantageous for many applications ranging from studies of bulk materials to the investigation of materials in extreme conditions. Ultrafast X-ray diffraction allows the direct imaging of atomic dynamics simultaneously on its natural time and length scale. However, using HEX-rays for ultrafast studies has been limited due to the lack of sources that can generate pulses of sufficiently short (femtosecond) duration in this wavelength range. Here we show single-crystal diffraction using ultrashort ~90 keV HEX-ray pulses generated by an all-optical source based on inverse Compton scattering. We also demonstrate a method for measuring the crystal lattice spacing in a single shot that contains only ~10 photons in a spectral bandwidth of ~50% full width at half maximum (FWHM). Our approach allows us to obtain structural information from the full X-ray spectrum. As target we use a cylindrically bent Ge crystal in Laue transmission geometry. This experiment constitutes a first step towards measurements of ultrafast atomic dynamics using femtosecond HEX-ray pulses.
光子能量在100 keV量级的高能X射线(HEX射线)具有吸引人的特性,比如相对较低的吸收、高空间分辨率以及能够探测重原子的内壳层态。这些特性对从块状材料研究到极端条件下材料研究等众多应用都很有利。超快X射线衍射能够在原子的自然时间和长度尺度上同时对原子动力学进行直接成像。然而,由于缺乏能在该波长范围内产生持续时间足够短(飞秒)脉冲的光源,利用HEX射线进行超快研究一直受到限制。在此,我们展示了使用基于逆康普顿散射的全光光源产生的~90 keV超短HEX射线脉冲进行单晶衍射。我们还演示了一种单次测量晶格间距的方法,该方法在半高宽(FWHM)约为50%的光谱带宽中仅包含约10个光子。我们的方法使我们能够从完整的X射线光谱中获取结构信息。我们使用处于劳厄透射几何构型的圆柱形弯曲锗晶体作为靶材。该实验是朝着利用飞秒HEX射线脉冲测量超快原子动力学迈出的第一步。