Superradiant Thomson scattering from graphite in the extreme ultraviolet

• 成果类型: Article
• 署名作者: Fasolato, Claudia; Stellino, Elena; Principi, Emiliano; Mincigrucci, Riccardo; Pelli-Cresi, Jacopo Stefano; Foglia, Laura; Postorino, Paolo; Sacchetti, Francesco; Petrillo, Caterina
• 署名单位: University of Perugia; Consiglio Nazionale delle Ricerche (CNR); Istituto dei Sistemi Complessi (ISC-CNR); Sapienza University Rome; Consiglio Nazionale delle Ricerche (CNR); Istituto Officina dei Materiali (IOM-CNR)
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-13524
• DOI: 10.1073/pnas.2221293121
• 发表日期: 2024-01-23
• 关键词: free-electron laser; x-ray-scattering; coherent; STATES

摘要

We study the Thomson scattering from highly oriented pyrolitic graphite excited by the extreme ultraviolet, coherent pulses of FERMI free electron laser (FEL). An apparent nonlinear behavior is observed and fully described in terms of the coherent nature of both exciting FEL beam and scattered radiation, producing an intensity-dependent enhancement of the Thomson scattering cross-section. The process resembles Dicke's superradiant phenomenon and is thus interpreted as the observation of superradiant Thomson scattering. The process also triggers the creation of coherent, low-q (< 0.3 & Aring;(-1)), low energy phonons. The experimental data and analysis provide quantitative information on the sample characteristics, absorption, scattering factor, and coherent phonon energies and populations and open the route for the investigation of the deep nature of complex materials.