近日，日本大阪大学的Jumpei Yamada及其研究团队取得一项新进展。经过不懈努力，他们发现硬X射线自由电子激光脉冲的极端聚焦可实现7nm聚焦宽度和1022W/cm2强度。相关研究成果已于2024年3月15日在国际知名学术期刊《自然—光子学》上发表。
该研究团队提出一种直接在极小的焦斑上形成源图像的方法，成功在两个横向尺寸上实现了7nm的精细聚焦。研究人员使用的9.1keV XFELs具有惊人的1.45×10^22Wcm^-2强度，这得益于他们巧妙地将凹面和凸面X射线镜结合，有效抑制了像差并提高了角度公差。研究人员成功获取了比先前高出百倍的高强度X射线，它强烈地诱导了铬的电离，预示了固体密度重裸原子核的产生。这一研究结果不仅展示了通过形成缩微源图像实现稳定超强XFEL光束的可行性，更对原子、分子和光学物理以及高能量密度科学等多个研究领域具有直接的深远意义。
据悉，科学家通过采用明亮的强光照射物质，可以深入探究其组成与特性。特别是在波长极短的情况下，X射线自由电子激光器（XFELs）因其极高的峰值亮度，成功揭示了各类材料结构、动力学及物理特性的关键细节。尽管聚焦光学技术在增强X射线强度方面已有显著进展，但要想实现单纳米焦斑以充分利用光源性能，仍是一个极富挑战性的任务。反射光学方案产生的像差显著影响了焦斑的形成，即便在轻微角过渡和指向误差等难以避免的情况下也是如此。
附：英文原文
Title: Extreme focusing of hard X-ray free-electron laser pulses enables 7 nm focus width and 1022 W cm-2 intensity
Author: Yamada, Jumpei, Matsuyama, Satoshi, Inoue, Ichiro, Osaka, Taito, Inoue, Takato, Nakamura, Nami, Tanaka, Yuto, Inubushi, Yuichi, Yabuuchi, Toshinori, Tono, Kensuke, Tamasaku, Kenji, Yumoto, Hirokatsu, Koyama, Takahisa, Ohashi, Haruhiko, Yabashi, Makina, Yamauchi, Kazuto
Issue&Volume: 2024-03-15
Abstract: By illuminating matter with bright and intense light, researchers gain insights into material composition and properties. In the regime of extremely short wavelengths, X-ray free-electron lasers (XFELs) with exceptional peak brilliance have unveiled crucial details about the structures, dynamics and physics of various materials. Although X-ray focusing optics to enhance the intensity have progressed, achieving a single-nanometre focal spot that fully exploits the source performance remains elusive. Aberrations arising from reflective optical schemes noticeably degrade the focal spot, even in the presence of inevitably slight angular transition and pointing errors. Here we present an approach that directly forms a source image in an extremely small focal spot, achieving 7nm focusing, in both transverse dimensions, of 9.1keV XFELs with the extremely high intensity of 1.45×1022Wcm-2. This was made possible by a scheme combining concave and convex X-ray mirrors with suppressed aberrations and high angular tolerances. The attained highly intense X-rays, surpassing the previous intensity by a hundred-fold, induced the vigorous ionization of chromium, suggesting the creation of solid-density heavy bare atomic nuclei. Our results, which demonstrate the realization of stable ultraintense XFEL beams by forming demagnified source images, hold immediate significance to a wide range of research fields, including atomic, molecular and optical physics and high-energy-density sciences.
DOI: 10.1038/s41566-024-01411-4
Source: https://www.nature.com/articles/s41566-024-01411-4