Role of Autoionizing State in Resonant High-Order Harmonic Generation and Attosecond Pulse Production

Strelkov, V. V.

doi:10.1103/physrevlett.104.123901

Cited by 186 publications

(183 citation statements)

References 32 publications

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“…In HHG, resonances have been explored in experiment [50] and theory [51][52][53][54] recently for atomic targets. But shape resonances are rare for common atomic targets.…”

Section: E Shape Resonance In Hhg Of Aligned Nmentioning

confidence: 99%

Intensity dependence of multiple orbital contributions and shape resonance in high-order harmonic generation of aligned N2molecules

et al. 2012

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We report measurements and theoretical simulations of high-order harmonic generation (HHG) in aligned N 2 molecules using a 1200-nm intense laser field when the generating pulse is perpendicular to the aligning one. With increasing laser intensity, the minimum in the HHG spectra first shifts its position and then disappears. Theoretical simulations including the macroscopic propagation effects in the medium reproduce these observations and the disappearance of the minimum is attributed to the additional contribution of HHG from inner orbitals. We also predict that the well-known shape resonance in the photoionization spectra of N 2 should exist in the HHG spectra. It is most clearly seen when the generating laser is parallel to the aligning one and disappears gradually as the angle between the two lasers increases. No clear evidence of this shape resonance has been reported so far when using lasers with different wavelengths. Further experimentation is needed to draw conclusions.

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“…In HHG, resonances have been explored in experiment [50] and theory [51][52][53][54] recently for atomic targets. But shape resonances are rare for common atomic targets.…”

Section: E Shape Resonance In Hhg Of Aligned Nmentioning

confidence: 99%

Intensity dependence of multiple orbital contributions and shape resonance in high-order harmonic generation of aligned N2molecules

et al. 2012

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“…However, broad Feshbach resonances and shape resonances can be observed since they have widths from fractions to a few eV's. In HHG, resonances have been explored in experiment [21] and theory [20,182,183] (also see Publication [7]) recently for atomic targets. But shape resonances are rare for common atomic targets.…”

Section: Single Homo Orbital Contribution At Low Laser Intensitymentioning

confidence: 99%

“…1.1. The recombination step is either replaced by the radiationless transition to the autoionizing state or relaxation with XUV emission to describe the enhancement of the generation efficiency for the harmonic resonant with the transition between the ground and autoionizing state of the generating ion [20], or modified such that a returning electron can promote a lower-lying electron into the valance band and then recombine to the vacancy in the lower-lying state [12].…”

Section: (C)mentioning

confidence: 99%

Theory of Nonlinear Propagation of High Harmonics Generated in a Gaseous Medium

Jin

2013

Springer Theses

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In this thesis, we establish the theoretical tools to investigate high-order harmonic generation (HHG) by intense infrared lasers in a gaseous medium. The macroscopic propagation of both the fundamental and the harmonic fields is taken into account by solving Maxwell's wave equations, while the single-atom (or single-molecule) response is obtained by quantitative rescattering theory. The initial spatial mode of the fundamental laser is assumed either a Gaussian or a truncated Bessel beam. On the examples of Ar, N 2 and CO 2 , we demonstrate that the available experimental HHG spectra with isotropic and aligned target media can be accurately reproduced theoretically even though the HHG spectra are sensitive to the experimental conditions. We show that the macroscopic HHG can be expressed as a product of a macroscopic wave packet and a photorecombination cross section, where the former depends on laser and experimental conditions while the latter is the property of the target only. The factorization makes it possible to retrieve the single-atom or single-molecule structure information from experimental HHG spectra. As for the multiple molecular orbital contribution in HHG, it causes the disappearance of the minimum in the HHG spectrum of aligned N 2 with the increase of laser intensity, and the position of minimum in HHG spectrum of aligned CO 2 depending on many factors is also attributed to it, which could explain why the minima observed in different laboratories may differ. For an important application of HHG as ultrashort light source, we show that measured continuous harmonic spectrum of Xe due to the reshaping of the fundamental laser field can be used to produce an isolated attosecond pulse by spectral and spatial filtering in the far field. For on-going application of using HHG to ionize aligned molecules, we present the photoelectron angular distribution from aligned N 2 and CO 2 in the laboratory frame, which can be compared directly with future experiments. demonstrate that the available experimental HHG spectra with isotropic and aligned target media can be accurately reproduced theoretically even though the HHG spectra are sensitive to the experimental conditions. We show that the macroscopic HHG can be expressed as a product of a macroscopic wave packet and a photorecombination cross section, where the former depends on laser and experimental conditions while the latter is the property of the target only. The factorization makes it possible to retrieve the single-atom or single-molecule structure information from experimental HHG spectra. As for the multiple molecular orbital contribution in HHG, it causes the disappearance of the minimum in the HHG spectrum of aligned N 2 with the increase of laser intensity, and the position of minimum in HHG spectrum of aligned CO 2 depending on many factors is also attributed to it, which could explain why the minima observed in different laboratories may differ. For an important application of HHG as ultrashort light source, we show that measured continu...

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“…Shape and Feshbach resonances in low-energy electron scattering processes [9][10][11] are of growing interest in biological systems [12][13][14] , atmospheric sciences, lasers, and astrophysics [15][16][17][18] .…”

Section: Density Functional Theory (Dft)mentioning

confidence: 99%

Density functional resonance theory: Complex density functions, convergence, orbital energies, and functionals

Whitenack

Wasserman

2012

The Journal of Chemical Physics

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Aspects of Density Functional Resonance Theory (DFRT) [Phys. Rev. Lett. 107, 163002 (2011)], a recently developed complex-scaled version of ground-state Density Functional Theory (DFT), are studied in detail. The asymptotic behavior of the complex density function is related to the complex resonance energy and system's threshold energy, and the function's local oscillatory behavior is connected with preferential directions of electron decay. Practical considerations for implementation of the theory are addressed including sensitivity to the complex-scaling parameter, θ.In Kohn-Sham DFRT, it is shown that almost all θ-dependence in the calculated energies and lifetimes can be extinguished via use of a proper basis set or fine grid.The highest occupied Kohn-Sham orbital energy and lifetime are related to a physical affinity and width, and the threshold energy of the Kohn-Sham system is shown to be equal to the threshold energy of the interacting system shifted by a well-defined functional. Finally, various complex-scaling conditions are derived which relate the functionals of ground-state DFT to those of DFRT via proper scaling factors and a non-Hermitian coupling constant system. a) dwhitena@purdue.edu; http://www.purdue.edu/dft b) awasser@purdue.edu 1 arXiv:1202.5214v1 [quant-ph]

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Role of Autoionizing State in Resonant High-Order Harmonic Generation and Attosecond Pulse Production

Cited by 186 publications

References 32 publications

Intensity dependence of multiple orbital contributions and shape resonance in high-order harmonic generation of aligned N2molecules

Intensity dependence of multiple orbital contributions and shape resonance in high-order harmonic generation of aligned N2molecules

Theory of Nonlinear Propagation of High Harmonics Generated in a Gaseous Medium

Density functional resonance theory: Complex density functions, convergence, orbital energies, and functionals

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