Strong-field ionization of diatomic molecules and companion atoms: Strong-field approximation and tunneling theory including nuclear motion

Kjeldsen, Thomas Kim; Madsen, Lars Bojer

doi:10.1103/physreva.71.023411

Cited by 98 publications

(44 citation statements)

References 43 publications

(130 reference statements)

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“…In the context of suppressed ionization the predictions of MO-ADK, MO-SFA-LG, and MO-SFA-VG were compared to experimental data for a number of diatomic molecules [109]. In that work it was found that MO-SFA-LG gives the overall best agreement with experiment.…”

Section: Sae-tdse Resultsmentioning

confidence: 91%

“…Fluorine molecule is one of the exceptions where these theories have failed [103,108,152]. There are, however, evident differences in the quantitative description of the predicted suppression ratios as well as their dependence on laser-pulse parameters [109]. Furthermore, the MO-SFA results are rather strongly gauge dependent, i. e. the predictions obtained in length (LG) or velocity gauge (VG) differ substantially.…”

Section: Models and Approximations In Strong Fields Physicsmentioning

confidence: 79%

“…First, the asymptotic form to which the molecular orbital is fitted is only approximate. Second, the obtained coefficients depend quite strongly on the model and the numerical quality of the electronic-structure calculation with which the molecular orbitals are obtained, as is discussed in [109]. In [109] it was also found that this difference is even more pronounced for larger molecules than H 2 .…”

Section: Comparison To Mo-adkmentioning

confidence: 81%

“…Second, the obtained coefficients depend quite strongly on the model and the numerical quality of the electronic-structure calculation with which the molecular orbitals are obtained, as is discussed in [109]. In [109] it was also found that this difference is even more pronounced for larger molecules than H 2 . Nevertheless, as is evident from Table 3.1, even for H 2 rather substantial differences between the C l coefficients can be found.…”

Section: Comparison To Mo-adkmentioning

confidence: 81%

“…Molecular effects have recently also been incorporated [108] into the model. However, there is some dispute about the use of length or velocity gauge and the applicability of a Coulomb-correction factor [109].…”

Section: Enhanced Ionization Molecules Show Very High Ionization Ratementioning

confidence: 99%

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Molecules in Strong Laser Fields

Corkum¹,

Dietrich²,

Strickland³

2008

Theoretical Femtosecond Physics

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A method for solving the time-dependent Schrödinger equation (TDSE) describing the electronic motion of the molecules exposed to very short intense laser pulses has been developed. The time-dependent electronic wavefunction is expanded in terms of a superposition of field-free eigenstates. The field-free eigenstates are calculated in two ways. In the first approach, which is applicable to two electron systems like H 2 , fully correlated field-free eigenstates are obtained in complete dimensionality using configuration-interaction calculation where the one-electron basis functions are built from B splines. In the second approach, which is even applicable to larger molecules, the field-free eigenstates are calculated within the single-active-electron (SAE) approximation using density functional theory. In general, the method can be divided into two parts, in the first part the field-free eigenstates are calculated and then in the second part a time propagation for the laser pulse parameters is performed. The H 2 molecule is the testing ground for the implementation of both the methods. The reliability of the configuration interaction (CI) based method for the solution of TDSE (CI-TDSE) is tested by comparing results in the low-intensity regime to the prediction of lowest-order perturbation theory. Another test for the CI-TDSE method is in the united atom limit for the H 2 molecule. By selecting a very small value of the internuclear distance close to zero for the H 2 molecule, Helium atom is obtained. The results in this united-atom limit are compared to the existing results for Helium atom. Once the functionality and the reliability of the method is established, it is used for obtaining accurate results for molecular hydrogen exposed to intense laser fields. The results for the standard 800 nm Titanium-Sapphire laser and its harmonics at 400 nm and 266 nm are shown. The results for a scan over a wide range of incident photon energies as well as dependence on the internuclear distance are presented. The photoelectron spectra including above-threshold-ionization peaks is also demonstrated. The CI-TDSE results for H 2 are used for testing the validity of SAE approximation. In strong field physics, there are models based on the SAE approximation. Most popular are the Ammosov-Delone-Krainov (ADK) model, a molecular version of the ADK model called MO-ADK (MO stands for molecular orbital) and the strong field approximation (SFA). The validity of the second method for the solution of TDSE in SAE approximation is investigated by applying it to H 2 molecule where the exact two-electron results were already calculated using CI-TDSE. The SAE method uses density-functional-theory (DFT) for the description of field-free eigenstates and is thus abbreviated as DFT-SAE-TDSE. Since DFT is used for the calculation of field-free states, different functionals were also tested. The validity of MO-ADK model is also investigated. After establishing the DFT-SAE-TDSE method, the first excited state B 1 Σ + u of H 2 is studied over a large...

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Section: Sae-tdse Resultsmentioning

confidence: 91%

Section: Models and Approximations In Strong Fields Physicsmentioning

confidence: 79%

Section: Comparison To Mo-adkmentioning

confidence: 81%

Section: Comparison To Mo-adkmentioning

confidence: 81%

Section: Enhanced Ionization Molecules Show Very High Ionization Ratementioning

confidence: 99%

See 3 more Smart Citations

Molecules in Strong Laser Fields

Corkum¹,

Dietrich²,

Strickland³

2008

Theoretical Femtosecond Physics

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Attosecond Nuclear Dynamics in the Ammonia Cation: Relation between High‐Harmonic and Photoelectron Spectroscopies

Kraus

Wörner

2013

ChemPhysChem

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We report measurements of the umbrella motion in the ammonia cation on the attosecond time scale. The motion is prepared by strong‐field ionization and probed by photorecombination through the process of high‐harmonic generation. Performing such measurements at multiple wavelengths (0.8, 1.44, 1.8 μm) enables us to follow the nuclear dynamics over a broad temporal range (0.8–3.8 fs). The intensity of the driving field is found to have a significant impact on the observed dynamics through the vibrational‐state dependence of the strong‐field ionization rates. We derive a general model that includes these effects and establishes a new link between high‐harmonic spectroscopy and classical photoelectron spectroscopy. Our model reproduces the observed dynamics and their dependence on the intensity of the driving field. Moreover, the model predicts much richer nuclear dynamics on the few‐fs timescale than most previous theories. The newly predicted features are shown to reflect the quantized vibronic level structure of the molecular cation.

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Theoretical Study of the Inversion Motion of the Ammonia Cation with Subfemtosecond Resolution for High‐Harmonic Spectroscopy

Förster

Sáenz

2013

ChemPhysChem

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In a recent PACER (Probing Attosecond dynamics with Chirp-Encoded Recollisions) experiment on ammonia that comprises a comparison of the high-harmonic spectra of the isotopes NH3 and ND3, the nuclear dynamics of the created ammonia cation is traced with a time resolution of about 100 attoseconds. For modelling the experiment the autocorrelation functions between the neutral initial state and the ionic wave packet are extracted from experimental photoelectron spectra incorporating a correction for the geometry-dependent strong-field ionisation probability. Good agreement is found between model and experiment, but in addition an unexpected maximum in the autocorrelation ratio is predicted by the model, however occurring at 5 fs and thus outside the experimentally covered time interval. In this work the autocorrelation functions are calculated explicitly using a one-dimensional model for describing the inversion motion of ammonia and its cation, adopting a position-dependent mass for considering the coupling with the stretching mode of the hydrogen atoms in neutral ammonia. This results in a clear physical picture explaining the occurrence of the previously predicted maximum in the ratio of the autocorrelation functions. Furthermore, different initial states and two different ways of incorporating strong-field corrections to the Franck-Condon approximation are briefly discussed.

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Strong-field ionization of diatomic molecules and companion atoms: Strong-field approximation and tunneling theory including nuclear motion

Cited by 98 publications

References 43 publications

Molecules in Strong Laser Fields

Molecules in Strong Laser Fields

Attosecond Nuclear Dynamics in the Ammonia Cation: Relation between High‐Harmonic and Photoelectron Spectroscopies

Theoretical Study of the Inversion Motion of the Ammonia Cation with Subfemtosecond Resolution for High‐Harmonic Spectroscopy

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