Assessing different forms of the strong-field approximation for harmonic generation in molecules

Chirilă, C. C.; Lein, Manfred

doi:10.1080/09500340601043447

Cited by 32 publications

(32 citation statements)

References 18 publications

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“…Within the plane wave approximation for the continuum, however, these three forms are not equivalent any more. The acceleration form should be preferred [6] but Chirilȃ et al [7] showed that the velocity form yields very reliable results, while being easier and faster to evaluate than the acceleration form. We thus re-write Eq.…”

Section: Uvx 2008mentioning

confidence: 99%

Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation

Haessler

Boutu

Merdji

et al. 2009

UVX 2008 - 9e Colloque Sur Les Sources Cohérentes Et Incohérentes UV, VUV Et X : Applications Et Développements Récents

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Abstract. We generate high order harmonics in aligned CO 2 molecules and measure the spectral amplitudes and phases as a function of the alignment angle. We control the quantum interference occurring in the recombination of an ultrafast laser-driven electron wavepacket with the highest occupied molecular orbital of CO 2 . By comparing to the emission of the reference system krypton, we obtain an experimental measure of the complex recombination dipole matrix element between the CO 2 HOMO and a continuum state. The measured phase jump contains signatures of Coulombic wavepacket distortion.

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Section: Uvx 2008mentioning

confidence: 99%

Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation

Haessler

Boutu

Merdji

et al. 2009

UVX 2008 - 9e Colloque Sur Les Sources Cohérentes Et Incohérentes UV, VUV Et X : Applications Et Développements Récents

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“…The recombination prefactor (6) can be written in different forms, which will lead to different results. The form of the dipole operator should not be confused with the gauge [29,31,37], which determines how the Hamiltonian is written. Explicitly, the length, velocity and acceleration forms of the dipole operator readd…”

Section: A Transition Amplitudementioning

confidence: 99%

“…The SFA, however, has serious limitations. Apart from the gauge dependence and its influence on the structural interference [28,29,35], different forms of recombination dipole matrix element affect this condition [31,36,37]. The most appropriate form to be used has raised considerable debate in the context of the tomographical reconstruction of molecular orbitals [38][39][40] If the field however is orthogonally polarized, the electron's angle of return is effectively incorporated in the two-center interference condition.…”

Section: Introductionmentioning

confidence: 99%

Shifting nodal-plane suppressions in high-order-harmonic spectra from diatomic molecules in orthogonally polarized driving fields

Das¹,

Faria²

2016

Phys. Rev. A

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We analyze the imprint of nodal planes in high-order harmonic spectra from aligned diatomic molecules in intense laser fields whose components exhibit orthogonal polarizations. We show that the typical suppression in the spectra associated to nodal planes is distorted, and that this distortion can be employed to map the electron's angle of return to its parent ion. This investigation is performed semi-analytically at the single-molecule response and single-active orbital level, using the strong-field approximation and the steepest descent method. We show that the velocity form of the dipole operator is superior to the length form in providing information about this distortion. However, both forms introduce artifacts that are absent in the actual momentum-space wavefunction. Furthermore, elliptically polarized fields lead to larger distortions in comparison to two-color orthogonally polarized fields. These features are investigated in detail for O2, whose highest occupied molecular orbital provides two orthogonal nodal planes.

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“…In this work, we will consider the length and the velocity forms of the dipole operator. In the single-active-electron framework, the former and the latter lead to the worst and best description of the two-center interference patterns [10].…”

Section: B Many-body Correctionsmentioning

confidence: 99%

“…The most well known of these is the lack of translational invariance when using the length form of the dipole operator. In the single-active electron approximation, it has been shown that the velocity form gives the most reliable results [10] and is easier to use than the acceleration form. In calculating the SFA prefactors the simplest approach is to use the highest occupied molecular orbital (HOMO) [5].…”

Section: Introductionmentioning

confidence: 99%

Multielectron corrections in molecular high-order harmonic generation for different formulations of the strong-field approximation

Augstein

Faria

2011

Journal of Modern Optics

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We make a detailed assessment of which form of the dipole operator to use in calculating high order harmonic generation within the framework of the strong field approximation, and look specifically at the role the form plays in the inclusion of multielectron effects perturbatively with regard to the contributions of the highest occupied molecular orbital. We focus on how these corrections affect the high-order harmonic spectra from aligned homonuclear and heteronuclear molecules, exemplified by N2 and CO, respectively, which are isoelectronic. We find that the velocity form incorrectly finds zero static dipole moment in heteronuclear molecules. In contrast, the length form of the dipole operator leads to the physically expected non-vanishing expectation value for the dipole operator in this case. Furthermore, the so called "overlap" integrals, in which the dipole matrix element is computed using wavefunctions at different centers in the molecule, are prominent in the first-order multielectron corrections for the velocity form, and should not be ignored. Finally, inclusion of the multielectron corrections has very little effect on the spectrum. This suggests that relaxation, excitation and the dynamic motion of the core are important in order to describe multielectron effects in molecular high-order high harmonic generation.

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Assessing different forms of the strong-field approximation for harmonic generation in molecules

Cited by 32 publications

References 18 publications

Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation

Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation

Shifting nodal-plane suppressions in high-order-harmonic spectra from diatomic molecules in orthogonally polarized driving fields

Multielectron corrections in molecular high-order harmonic generation for different formulations of the strong-field approximation

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Assessing different forms of the strong-field approximation for harmonic generation in molecules

Cited by 32 publications

References 18 publications

Measuring the complex recombination dipole of aligned CO2molecules in high-order harmonic generation

Measuring the complex recombination dipole of aligned CO2molecules in high-order harmonic generation

Shifting nodal-plane suppressions in high-order-harmonic spectra from diatomic molecules in orthogonally polarized driving fields

Multielectron corrections in molecular high-order harmonic generation for different formulations of the strong-field approximation

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Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation

Measuring the complex recombination dipole of aligned CO₂molecules in high-order harmonic generation