Theory of molecular tunneling ionization

Tong, Xiao-Min; Zhao, Zengxiu; Lin, C. D.

doi:10.1103/physreva.66.033402

Cited by 833 publications

(797 citation statements)

References 26 publications

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“…To see the origin of this similarity, we calculated the square of the asymptotic wavefunctions of HOMO 20) and the θ-dependent HHG signal from a single N 2 and O 2 molecule, where the angle α coincides with θ, i.e., <cos 2 θ> = 1 and <cos 4 θ> = 1 in Eqs. (5) and (6) for a molecule.…”

Section: O 2 Moleculesmentioning

confidence: 99%

Angular Dependence of High-order Harmonic Generation from Nonadiabatically Aligned Molecules

Yoshii

Miyaji

Miyazaki

2008

The Review of Laser Engineering

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We measured the dependence of high-order harmonic generation (HHG) on the angle α between polarization directions of high-intensity femtosecond laser pulses in the pump and probe experiment. The experimental results of N 2 and O 2 are compared with the calculated ones using the theory developed recently to illustrate the characteristic properties of HHG from aligned N 2 and O 2 , and then the excellent agreement is obtained. It is also shown that the observed α-dependent harmonic signal is strongly influenced by the degree of alignment of molecules and is not identical to the harmonic distribution calculated as a function of the angle between the field direction and the molecular axis.

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Section: O 2 Moleculesmentioning

confidence: 99%

Angular Dependence of High-order Harmonic Generation from Nonadiabatically Aligned Molecules

Yoshii

Miyaji

Miyazaki

2008

The Review of Laser Engineering

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“…where γ(τ, θ) is the alignment-dependent ionization rate, which can be calculated by MO-ADK theory [19] for different molecular orbitals. In Eq.…”

Section: High-harmonic Field Of Aligned Moleculesmentioning

confidence: 99%

“…(2.36) by combining the electron wave packet with the accurate d(ω, θ) obtained from quantum chemistry code [99,100] and the tunneling ionization rate N (θ) obtained from the MO-ADK theory [19].…”

Section: Molecular Targetmentioning

confidence: 99%

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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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“…For molecules, the ionization amplitude a ion is calculated with the MO-ADK theory [24], which takes into account the structure features of molecular orbitals. Ψ g is the HOMO of the molecule obtained from Gaussian 03 ab initio code [25].…”

Section: Simulating the Hhgmentioning

confidence: 99%

Influence of large permanent dipoles on molecular orbital tomography

Zhu¹,

Qin²,

Zhang³

et al. 2013

Opt. Express

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The influence of large permanent dipoles on molecular orbital tomography via high-order harmonic generation (HHG) is investigated in this work. It is found that, owing to the modification of the angle-dependent ionization rate resulting from the Stark shift, the one-side-recollision condition for the tomographic imaging can not be satisfied even with the few-cycle driving pulses. To overcome this problem, we employ a tailored driving pulse by adding a weak low-frequency pulse to the few-cycle laser pulse to control the HHG process and the recollision of the continuum electrons are effectively restricted to only one side of the core. Then we carried out the orbital reconstruction in both the length and velocity forms. The results show that, the orbital structure can only be successfully reproduced by using the dipole matrix elements projected perpendicular to the permanent dipole in both forms.

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Theory of molecular tunneling ionization

Cited by 833 publications

References 26 publications

Angular Dependence of High-order Harmonic Generation from Nonadiabatically Aligned Molecules

Angular Dependence of High-order Harmonic Generation from Nonadiabatically Aligned Molecules

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

Influence of large permanent dipoles on molecular orbital tomography

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