Study of inner shell vacancy decay and photon atom scattering processes in the x ray energy region

Nirmal Singh

Akilesh Venkatesh, Phay J. Ho

We present a time-dependent Schr\"odinger equation approach within a nonrelativistic quantum electrodynamics framework to investigate resonant x-ray scattering driven by intense x-ray pulses. This method enables us to explore how coherent x-ray electron dynamics influence scattering signals from ${\mathrm{Ne}}^{+}$. We account for both resonance fluorescence and elastic scattering channels, while also considering competing photoionization and inner-shell decay processes. By computing the angular distribution and energy spectrum of scattered photons, we uncover interference effects between elastic scattering and resonance fluorescence pathways. Notably, this interference results in a small asymmetry in the energy spectrum. We discuss the experimental potential for detecting signatures of interference. Our findings demonstrate that the x-ray Rabi dynamics can be used to control scattering responses and provide insights into interference mechanisms and scattering efficiency in high-intensity x-ray regimes.

H. J. Beyer, Karl Blum, R. Hippler +1 more

1 Electron Scattering from Heavy Atoms.- 2 Spin Polarization in Electron-Atom Scattering.- 3 Electron Scattering from Chiral Molecules.- 4 Applications of Lasers in Atomic Collision Physics.- 5 Excitation and Ionization in Atomic Collisions.- 6 Inner-shell Vacancy Creation: Perturbative Approximations and Beyond.- 7 Excitation in Ion-Atom Collisions.- 8 Coherence in Grazing Ion-Surface Collisions.- 9 The Two-Photon Decay of Atomic Hydrogen and Tests of Bell's Inequality.

Lynn D. Kissel, Richard H. Pratt

Yongqiang Li, Cheng Gao, Wenpu Dong +2 more

We develop a large scale quantum master equation approach to describe dynamical processes of practical open quantum systems driven by both coherent and stochastic interactions by including more than one thousand true states of the systems, motivated by the development of highly bright and fully coherent lasers in the X-ray wavelength regime. The method combines the processes of coherent dynamics induced by the X-ray laser and incoherent relaxations due to spontaneous emissions, Auger decays, and electronic collisions. As examples, theoretical investigation of {\it real} coherent dynamics of inner-shell electrons of a neon gas, irradiated by a high-intensity X-ray laser with a full temporal coherence, is carried out with the approach. In contrast to the rate equation treatment, we find that coherence can suppress the multiphoton absorptions of a neon gas in the ultra-intense X-ray pulse, due to coherence-induced Rabi oscillations and power broadening effects. We study the influence of coherence on ionization processes of neon, and directly prove that sequential single-photon processes for both outer- and inner-shell electrons dominate the ionizations for the recently typical experiments with a laser intensity of $\approx10^{18}$ ${\rm W/cm^2}$. We discuss possible experimental implementations such as signatures for coherent evolution of inner-shell electrons via resonance fluorescence processes. The approach can also be applied to many different practical open quantum systems in atomic, quantum optical, and cold matter systems, which are treated qualitatively by a few-level master equation model before.

Jonathan Carney