High-order harmonic generation with resonant core excitation by ultraintense x rays

• Published in: arXiv.org
• Main Author: Buth, Christian
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 14.10.2015
• Subjects: Continuous radiation; Electrons; Excitation; Harmonic generations; Organic chemistry; Physics - Atomic Physics; Physics - Optics; Quantum theory; Time dependence; Time varying amplitude; Vacancies; X-rays
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1303.1332

High-order harmonic generation (HHG) is combined with resonant x-ray excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process. To describe this setting, I develop a two-active-electron quantum theory for a single atom assuming no Coulomb interaction among the electrons; one electron performs a typical HHG three-step process whereas another electron is excited (or even Rabi flops) by intense x rays from the core shell into the valence hole after the first electron has left the atom. Depending on the amplitude to find a vacancy in the valence and the core, the returning continuum electron recombines with the valence and the core, respectively, emitting high-order harmonic (HH) radiation that is characteristic of the combined process. After presenting the theory of x-ray boosted HHG for continuous-wave light fields, I develop a description for x-ray pulses with a time-varying amplitude and phase. My prediction offers novel prospects for nonlinear x-ray physics, attosecond x rays, and HHG-based time-dependent chemical imaging involving core orbitals.