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Results for “Strong-field-induced spectra”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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4 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Coherence from multiorbital tunneling ionization of molecules

We present a simple and general coherence model for multiorbital tunnel ionization of molecules, which we incorporate into our previously developed density-matrix approach for sequential double ionization. Here, the influence of this coherence is investigated through simulations of single ionization and sequential double ionization of N 2 and O 2 using few-cycle near-infrared laser pulses. In the case of single ionization, our results reveal the crucial role played by this coherence in generating population inversion in N 2 + , suggesting a potential mechanism for air lasing. Regarding sequential double ionization, we observe only minor changes in the kinetic energy release spectra when the coherence is included, while noticeable differences in the angle-dependent dication yield for both N 2 and O 2 are found. Based on these findings, we recommend the inclusion of multiorbital tunnel ionization coherence in models for single ionization of general molecules, while suggesting that it can be safely neglected in the case of sequential double ionization.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Theory of strong-field sequential double ionization of polyatomic molecules

Understanding of strong-field sequential double ionization (SDI) of molecules by a highly intense infrared laser pulse could be the key to observing electron motion in molecules in the attosecond to femtosecond timescale. Based on a novel density matrix approach for SDI (DM-SDI), a recent theoretical study has shown that SDI can be used as a probe to monitor the changes in vibronic coherence in homonuclear diatomic molecules. In this article, we extend the DM-SDI model to general molecules that could possess permanent dipole moments and arbitrary symmetry. We apply the model to SDI of a water molecule and identify the formation pathway of individual dication states. We further deduce that kinetic energy release spectra from two- and three-body fragments could carry the signature of vibronic coherence between the lowest two states of the water cation. Furthermore, our results suggest that observables from the SDI probe can be interpreted intuitively with only the knowledge of electronic structures of populated ionic states, making the SDI probe to be a highly desirable probing scheme for vibronic coherence in generic molecules.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Probing vibronic coherence in charge migration in molecules using strong-field sequential double ionization

We propose a scheme for probing vibronic coherence in charge migration in molecules utilizing strong-field sequential double ionization. To demonstrate the feasibility of this approach, we perform full simulations of a pump-probe scheme employing few-cycle intense infrared pulses for N 2 and O 2 . We predict that the vibronic coherence between the pumped states will be directly imprinted in experimental observables such as kinetic energy release spectra and branching ratios of the dissociative dications. Our simulations are based on the recently developed density matrix approach for sequential double ionization model, which is capable of efficiently accounting for molecular orientations and enabling direct comparison with experimental results. Lastly, our findings strongly encourage the use of this probing scheme in future charge migration experiments.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2024

Autoionizing polaritons with the Jaynes-Cummings model

Intense laser pulses have the capability to couple resonances in the continuum, leading to the formation of a split pair of autoionizing polaritons. These polaritons can exhibit extended lifetimes due to interference between radiative and Auger decay channels. In this work we show how an extension of the Jaynes-Cummings model to autoionizing states quantitatively reproduces the observed phenomenology. Furthermore, this extended model allows us to study how the dressing laser parameters can be tuned to control the ionization rate of the polariton multiplet.

74 ATOMIC AND MOLECULAR PHYSICS↗