1.School of Electrical and Electronic Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore
2.Solid State Institute and Faculty of Electrical and Computer Engineering, Technion – Israel Institute of Technology, Haifa 3200003, Israel
3.School of Electrical Engineering, Fleischman Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel
4.Department of Applied Physics, Stanford University, Stanford, CA 94305, USA
5.Science, Mathematics and Technology, Singapore University of Technology and Design, 8 Somapah Road, Singapore 487372, Singapore
6.Electrical and Computer Engineering Department, UCLA, 420 Westwood, Los Angeles, CA 90095, USA
7.Physics and Astronomy Department, UCLA, 475 Portola Plaza, Los Angeles, CA 90095, USA
8.SLAC National Accelerator Laboratory, Stanford University, 2575 Sand Hill Road, Menlo Park, CA 94025, USA
Liang Jie Wong (liangjie.wong@ntu.edu.sg)
Published:31 July 2024,
Published Online:24 January 2024,
Received:01 August 2023,
Revised:26 October 2023,
Accepted:18 December 2023
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Wong, L. W. W. et al. Free-electron crystals for enhanced X-ray radiation. Light: Science & Applications, 13, 1299-1309 (2024).
Wong, L. W. W. et al. Free-electron crystals for enhanced X-ray radiation. Light: Science & Applications, 13, 1299-1309 (2024). DOI: 10.1038/s41377-023-01363-4.
Bremsstrahlung—the spontaneous emission of broadband radiation from free electrons that are deflected by atomic nuclei—contributes to the majority of X-rays emitted from X-ray tubes and used in applications ranging from medical imaging to semiconductor chip inspection. Here
we show that the bremsstrahlung intensity can be enhanced significantly—by more than three orders of magnitude—through shaping the electron wavefunction to periodically overlap with atoms in crystalline materials. Furthermore
we show how to shape the bremsstrahlung X-ray emission pattern into arbitrary angular emission profiles for purposes such as unidirectionality and multi-directionality. Importantly
we find that these enhancements and shaped emission profiles cannot be attributed solely to the spatial overlap between the electron probability distribution and the atomic centers
as predicted by the paraxial and non-recoil theory for free electron light emission. Our work highlights an unprecedented regime of free electron light emission where electron waveshaping provides multi-dimensional control over practical radiation processes like bremsstrahlung. Our results pave the way towards greater versatility in table-top X-ray sources and improved fundamental understanding of quantum electron-light interactions.
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