MRI: Development of a Coherent and Incoherent X-Ray Facility at JILA: Ultrafast X-Ray Science and Technology at the Nanoscale

x射线科学技术的进步带来了突破性的发现，从揭开DNA和蛋白质的结构，到在纳米尺度上观察原子、分子和材料。x射线由于波长短，是纳米世界的理想探针。x射线可以成像小物体，穿透厚样品，而软x射线区域元素吸收边缘的存在允许对厚样品进行元素和化学特异性成像。最近一项令人兴奋的进展是能够从大规模和小规模装置中产生超快的相干、类似激光的x射线束。基于x射线自由电子激光器的设备现在正在美国、欧洲和日本上线，它将在一次x射线爆发中捕获生物分子或磁畴的动态图像。利用高谐波产生的极端非线性光学过程，在桌面装置中，通过将飞秒激光束上转换为更高能量的光子，可以产生光子能量小于100eV的明亮的、类似激光的极紫外光束。此外，CU最近的一项重大突破允许软x射线的明亮光束在实验中扩展到大于0.5keV，理论上扩展到10keV，从根本上实现了软x射射管的相干版本。这是通过使用中红外驱动激光器驱动高谐波过程来实现的。这项工作将实现高通量，超快，x射线束从0.1 - 7keV，驱动高谐波和激光等离子体源具有高平均功率，红外激光器。该项目将采用尖端的激光和x射线科学，利用飞秒激光在阿秒时间尺度上操纵电子的能力将用于产生明亮的、相干的和非相干的keV x射线束。这项研究将在纳米尺度上探索科学和技术的前沿。更广泛的影响是，这一努力将为不同群体的学生和教师提供突破性研究的设施。一个由科学和工程专业的大三、大四教师和学生组成的多学科团队正在共同开发一个独特的、世界级的、小型的超快x射线科学和技术设施。所有的应用，包括探测磁性材料中的极限开关速度，捕获纳米结构中的热传输，跟踪分子和电子动力学，以及高分辨率成像，都极大地受益于使用高能光子。该团队包括激光和x射线科学与技术、材料和纳米科学、机械和电气工程以及化学和生物化学科学方面的专家。

Advances in x-ray science and technology have resulted in breakthrough discoveries ranging from unraveling the structure of DNA and proteins, to visualizing atoms, molecules, and materials at the nanoscale. X-rays, by virtue of their short wavelength, are ideal probes of the nanoworld. X-rays can image small objects, penetrate thick samples, while the presence of elemental absorption edges in the soft x-ray region allow element and chemical-specific imaging of thick samples. An exciting recent advance is the ability to generate ultrafast coherent, laser-like, beams of x-rays from both large scale and small-scale setups. Facilities based on x-ray free-electron lasers are now coming on-line in the US, Europe and Japan, that will capture dynamic images of biomolecules or magnetic domains in a single burst of x-rays. Using the extreme nonlinear optical process of high harmonic generation, bright, laser-like, beams of extreme ultraviolet light at photon energies less than 100eV can be generated in a tabletop setup, by upconverting femtosecond laser beams to higher energy photons. Moreover, a major recent breakthrough at CU allows bright beams of soft x-rays to be extended to greater than 0.5keV experimentally, and in theory to 10keV, essentially enabling a coherent version of a soft x-ray tube. This was accomplished by driving the high harmonic process using mid-infrared driving lasers. The work will implement high flux, ultrafast, x-ray beams from 0.1 - 7keV, by driving high harmonic and laser plasma sources with high average power, infrared lasers. This project will employ leading-edge laser and x-ray science, where the ability to manipulate electrons on attosecond timescales using femtosecond lasers will be used to generate bright, coherent and incoherent beams of keV x-rays. The research that will be enabled will explore scientific and technological frontiers at the nanoscale. The broader impacts are that this effort will provide a facility for breakthrough research for a diverse group of students and faculty. A multidisciplinary team of junior and senior faculty and students from science and engineering are working together to develop a unique, world class, small-scale facility for ultrafast x-ray science and technology. All of the applications, including probing the limiting switching speed in magnetic materials, capturing thermal transport in nanostructures, following moleuclar and electron dynamics, and high resolution imaging, greatly benefit from using higher energy photons. The team includes experts in laser and x-ray science and technology, materials and nano science, mechanical and electrical engineering, and chemical and biochemical science.