Enhanced Efficiency of Ultrafast X-ray Scattering with Intense Attosecond Pulses*

The advent of XFELs has paved the way for single-particle imaging (SPI) [1-2], an ambitious technique designed to capture the structures and ultrafast dynamics of isolated, non-crystalline samples in their native environment with atomic resolution. Despite its promise, SPI has been hindered by radiation damage from intense x-ray pulses [3], which has so far prevented atomic resolution [4-5].  The aarival of intense attosecond and few-femtosecond XFEL pulses enables new imaging strategies with unprecedented resolution. In this study, we report a significant advancement in SPI using intense soft XFEL pulses, overcoming the limitations imposed by radiation damage during imaging. Our work combines experimental and theoretical approaches to investigate diffractive imaging of isolated xenon nanoparticles as a function of photon energy (650 to 1500 eV), pulse duration (0.5 to 200 fs), and pulse energy (0.02 to 1.5 mJ).  We found that transient resonances (TRs) [6] of Xe ions, created via photoionization, enhance x-ray scattering efficiency, leading to increased brightness and improved resolution of diffraction images. The achieved resolution rivals the best spatial resolution attained so far in SPI of higher-Z nanoparticles using hard x-rays with wavelengths shorter by an order of magnitude [5]. Our study suggests that TRs may extend into the hard x-ray regime, paving the way for Ångstrom-resolution imaging of fragile and transient states.

 

[1] Neutze, et. al., Nature 406, 752 (2000).

[2] Seibert, M. M. et al.,  Nature 470, 78–81, DOI: 10.1038/nature09748 (2011).

[3] Ho, et al., Phys. Rev. A 94, 063823, (2016); Nat. Comm. 11, 1–9 (2020).

[4] Xu, et al.,Nat. Comm. 5, 1–9 (2014).

[5] Yumoto, et al., Nat. Comm. 13, 1–8 (2022).

[6] Kanter, et. al., Phys. Rev. Lett. 107, 233001 (2011).