Title: Temporal coherent control of resonant two-photon double ionization of the hydrogen molecule via doubly excited states

Abstract

Here, we use time-delayed, counter-rotating, circularly polarized few-cycle attosecond nonoverlapping pulses to study the temporal coherent control of the resonant process of two-photon double ionization (TPDI) of hydrogen molecule via doubly excited states for pulse propagation direction along $$\hat k$$ either parallel or perpendicular to the molecular axis $$\hat R$$. For $$\hat k$$∥ $$\hat R$$ and a pulse carrier frequency of 36 eV resonantly populating the Q₂¹Π$$^+_u$$ (1) doubly excited state as well as other ¹Π$$^+_u$$ doubly excited states, we find that the indirect ionization pathway through these doubly excited states changes the character of the kinematical vortex-shaped momentum distribution produced by the two direct ionization pathways from fourfold to twofold rotational symmetry. This result is similar to what found in TPDI of the He atom involving ¹P$$^ o_ {±1}$$ doubly excited states; however, angular distributions exhibiting a quantum beat effect between the ground state and a doubly excited state seen for the He atom are observed here for its molecular counterpart with an anomaly in shape and magnitude, not in frequency. The sixfold differential probability integrated over the azimuthal angle of the photoelectron pair shows that this anomaly is due to autoionization decays and quantum beats between doubly excited states. For $$\hat k$$⟂$$\hat R$$ and a broadband pulse carrier frequency of 30 eV populating the Q₁¹Π$$^+_u$$(1), Q₁¹Σ$$^+_u$$(1), Q₂¹Π$$^+_u$$(1) , and Q₁¹Σ$$^+_u$$ (2) doubly excited states, the momentum distribution is shown to exhibit dynamical electron vortices with four spiral arms, which originates from the interplay between the ¹Δ$$^+_ g$$ ,¹Π$$^+_ g$$, and ¹Σ$$^+_ g$$ dynamical ionization amplitudes. Our treatment within either the adiabatic-nuclei approximation or fixed-nuclei approximation shows that the latter provides a very good account for this correlated process.

Authors:

Ngoko Djiokap, J. M.  ^[1];

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Starace, Anthony F. ^[1]

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1. Univ. of Nebraska, Lincoln, NE (United States)

Publication Date:

Tue May 11 00:00:00 EDT 2021

Research Org.:

Univ. of Nebraska, Lincoln, NE (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); Nebraska Research Initiative

OSTI Identifier:

1850232

Grant/Contract Number:  

FG03-96ER14646; SC0021054; TG-PHY-120003

Resource Type:

Accepted Manuscript

Journal Name:

Physical Review A

Additional Journal Information:

Journal Volume: 103; Journal Issue: 5; Journal ID: ISSN 2469-9926

Publisher:

American Physical Society (APS)

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; atomic and molecular processes in external fields; autoionization; auger processes; coherent control; electron correlation calculation for atoms and ions; multiphoton or tunneling ionization and excitation; single-and few-photon ionization and excitation; ultrafast phenomena