Neon in ultrashort and intense x rays from free electron lasers

Abstract

We theoretically examine neon atoms in ultrashort and intense x rays from free electron lasers and compare our results with data from experiments conducted at the Linac Coherent Light Source (LCLS). For this purpose, we treat in detail the electronic structure in all possible nonrelativistic cationic configurations using a relativistic multiconfiguration approach. The interaction with the x rays is described in rate-equation approximation. To understand the mechanisms of the interaction, a path analysis is devised which allows us to investigate what sequences of photoionization and decay processes lead to a specific configuration and with what probability. Thereby, we uncover a connection to the mathematics of graph theory and formal languages. In detail, we study the ion yields and find that plain rate equations do not provide a satisfactory description. We need to extend the rate equations for neon to incorporate double Auger decay of a $K$-shell vacancy and photoionization shake off for neutral neon. Shake off is included for valence and core ionization; the former has hitherto been overlooked but has important consequences for the ion yields from an x-ray energy below the core ionization threshold. Furthermore, we predict the photon yields from XUV and x-ray fluorescence; these allow one insights into the configurations populated by the interaction with the x rays. Finally, we discover that inaccuracies in those Auger decay widths employed in previous studies have only a minor influence on ion and photon yields.

19 pages, 5 figures, 4 tables, RevTeX4.1, revised

References in corpus (9)

• Monte Carlo calculation of ion, electron, and photon spectra of xenon atoms in x-ray free-electron laser pulses
• Strong interference effects in the resonant Auger decay of atoms induced by intense X-Ray fields
• Broadband high-resolution x-ray frequency combs
• Resonance fluorescence in ultrafast and intense x-ray free-electron-laser pulses
• Interplay between relativistic energy corrections and resonant excitations in x-ray multiphoton ionization dynamics of Xe atoms
• Quantum coherence in the dynamical excitation, ionization, and decaying of neon gas induced by X-ray laser
• LCLS in - photon out: fluorescence measurement of neon using soft x-rays
• Relativistic calculations of the non-resonant two-photon ionization of neutral atoms
• Nonlinearity in the sequential absorption of multiple photons

Cited by in corpus (10)

• Near L-Edge Single and Multiple Photoionization of Singly Charged Iron Ions
• Near L-edge photoionization of triply charged iron ions
• Near L-Edge Single and Multiple Photoionization of Doubly Charged Iron Ions
• Observation of strong two-electron--one-photon transitions in few-electron ion
• LCLS in - photon out: fluorescence measurement of neon using soft x-rays
• State-resolved ionization dynamics of neon atom induced by x-ray free-electron-laser pulses
• Near K-Edge Photoionization and Photoabsorption of Singly, Doubly, and Triply Charged Silicon Ions
• Evolution of the ionic polarization in multiple sequential ionization: general equations and an illustrative example
• Nonlinearity in the sequential absorption of multiple photons
• Dissociating diatomic molecules in ultrafast and intense light