Journal of Physics B Atomic Molecular and Optical Physics

Spectral manifestation of core coherence in photoionization

R. Grobe, Stanley L. Haan

Published Nov 28, 1994• 16 citations

Abstract

Photoionization processes are considered for situations in which the laser frequency is close to a resonant frequency of the final positive ion core. It is predicted that resonant coupling within the ionic core can split photoelectron spectral peaks into doublets, with components separated by the effective Rabi frequency of the core. The possibility of superposing this final-state effect with previously studied effects involving laser-induced autoionizing states is considered. Specific predictions are made for the splitting of photoelectron peaks in photoionization of strontium.

DOI: 10.1088/0953-4075/27/22/002

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PEAK-SWITCHING OF THE PHOTOELECTRON SPECTRUM

Guanhua Yao, XU ZHI-ZHAN, (1)中国高等科学技术中心(世界实验室)凝聚态和辐射物理分中心; (2)中国科学院上海光学精密机械研究所

The photoelectron spectrum from autoionizing atoms in strong laser field is investigated on the basis of ref [12] . Peak-switching similar to the corresponding effect in strong field multiphoton ionization is found, implying that the second-order ionization processes and high-order photoelectron peaks play essential roles in strong laser-field induced autoionization-These results show that many of previous results need to be revised.

Acta Physica SinicaJan 1, 19891 citation

Journal of Physics B Atomic Molecular and Optical Physics

Spectral manifestation of core coherence in photoionization

R. Grobe, Stanley L. Haan

Published Nov 28, 1994• 16 citations

Publisher

Abstract

DOI: 10.1088/0953-4075/27/22/002

Related papers

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Stanley L. Haan, Martin Bolt, H. Nymeyer +1 more

Single photoionization of neutral atoms is examined theoretically for a situation in which the photoionizing laser is tuned close to the resonant frequency for transitions between the ground and first-excited states of the positive ion. The resonant coupling in the positive ion is shown to have a dramatic peak-splitting effect on the kinetic-energy spectrum of the ionized electron. An essential-states analysis of the photoionization process is presented, and a comparison is made with numerical results for one-dimensional helium. The agreement between the results establishes the validity of the essential-states approach. The possibility of superposing this core-coherence effect with laser-induced autoionization effects is considered.Single photoionization of neutral atoms is examined theoretically for a situation in which the photoionizing laser is tuned close to the resonant frequency for transitions between the ground and first-excited states of the positive ion. The resonant coupling in the positive ion is shown to have a dramatic peak-splitting effect on the kinetic-energy spectrum of the ionized electron. An essential-states analysis of the photoionization process is presented, and a comparison is made with numerical results for one-dimensional helium. The agreement between the results establishes the validity of the essential-states approach. The possibility of superposing this core-coherence effect with laser-induced autoionization effects is considered.

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Kenichi L. Ishikawa, Kevin Charles Prince, Kiyoshi Ueda

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PEAK-SWITCHING OF THE PHOTOELECTRON SPECTRUM

Guanhua Yao, XU ZHI-ZHAN, (1)中国高等科学技术中心(世界实验室)凝聚态和辐射物理分中心; (2)中国科学院上海光学精密机械研究所

Acta Physica SinicaJan 1, 19891 citation

We present first-principles numerical simulations of photoionization in neon induced by bichromatic extreme ultraviolet pulses with frequencies

ω

and

2ω

, specially chosen to make

ω

equal to the energy difference between the

2s

and

2p

subshells. This allows for the production of photoelectrons from the

2s

shell by

2ω

pulse and from the

2p

shell by

ω

pulse with the same energy. Using the multi-configurational time-dependent Hartree-Fock method, we explore how Rabi coupling between subshells generates coherence between the corresponding photoelectron wave packets. Our \textit{ab initio} calculations confirm the analytical results derived from the essential-states approach in [K. L. Ishikawa, K. C. Prince, and K. Ueda, J. Phys. Chem. A 127, 10638 (2023)], validating the theoretical predictions. Although we focus on the Ne

2p

and

2s

subshells, our approach is applicable to a broad range of systems exhibiting photoionization from multiple subshells. The laser parameters employed in our simulations are available in modern Free Electron Lasers (FELs), and we anticipate that this work could stimulate experimental investigations using FELs to study ion-photoelectron coherence and entanglement.

2s/2p\phantom{\rule{4pt}{0ex}}{\mathrm{He}}^{+}

coherence is mediated by the autoionizing states below the

N=2

threshold [Phys. Rev. Res. 3, 023233 (2021)]. In the present work we study the role of the resonances both below and above the

N=3

threshold on the coherence of the

N=3\phantom{\rule{4pt}{0ex}}{\mathrm{He}}^{+}

ion, in the attosecond pump-probe ionization of the helium atom, which we simulate using the newstock ab initio code. Due to the fine-structure splitting of the

N=3{\mathrm{He}}^{+}

level, the ionic dipole beats on a picosecond timescale. We show how, from the dipole beating, it is possible to reconstruct the polarization of the ion at its inception.