Study of the circular dichroism of He<sup>+</sup> ion

Chen, Jen-Hao; Liu, Jinn-Liang; Jheng, Shih-Da; Cheng, Szu-Cheng; Jiang, Tsin-Fu

doi:10.1364/josab.36.003597

Cited by 3 publications

(5 citation statements)

References 29 publications

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“…In our p-space calculation, 1024 grid points and 32 × 32 spherical harmonics are over enough with the same time marching step. We have used the p-space method with GPU for some works [64][65][66]. In section 4.2, we demonstrate the helicity-dependent ionization of Ar(3p ± ) in the multiphoton regime by the CP pulse.…”

Section: Discussionmentioning

confidence: 99%

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Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Jheng¹,

Jiang²

2022

Phys. Scr.

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We present a numerical method to solve the time-dependent Schr\"{o}dinger equation (TDSE) in momentum representation (p-space). We show that the method is practically useful and easier than the coordinate space (r-space) method when continuous states are involved. For a single-active electron (SAE) atom, the numerically complete eigenset can be accurately constructed in p-space by quadrature method which bypasses the singularities in the Coulombic kernel. Although there is an ingenious Lande subtraction for dealing with the singularity but is not straightforward. We formulate the time marching algorithms for an SAE atom in linearly polarized (LP) laser pulse and in circularly polarized (CP) pulse, respectively. We show calibrations to literature results to justify the formulations. Argon in a resonant and a nonresonant CP pulse are investigated and show distinct properties from the case of tunneling regime. Together with the currently available powerful graphics processing unit (GPU) for massively parallel computing, the p-space method could provide a useful alternative tool for some problems such as atoms in intense light pulses.

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Section: Discussionmentioning

confidence: 99%

“…We have calibrated our GPU code for an SAE atom interacting with a CP pulse and published some research works [64][65][66]. We describe here the calibrations with the cases of [63] in detail.…”

Section: Calibration Of An Atom In Circularly Polarized Pulsementioning

confidence: 99%

Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Jheng¹,

Jiang²

2022

Phys. Scr.

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“…However, the required computing capacity is enormous due to the magnetic quantum number not being constant in the CP pulse. For the purpose of calibrating the SFA, we have developed a TDSE code in momentum space [24][25][26]. We find that the shape of the atom-Volkov SFA spectra mostly fits TDSE results but differ in the order of magnitude.…”

Section: Introductionmentioning

confidence: 93%

“…The methods of solving the SAE eigenstates and TDSE can be found in our previous works [24][25][26]. We include a brief description in the section appendix.…”

Section: Outline Of the Atom-volkov Sfa For Atom In Circularly Polari...mentioning

confidence: 99%

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Photoelectron spectra of argon in circularly polarized pulses studied by atom-Volkov strong-field approximation

Jiang¹

2022

J. Phys. B: At. Mol. Opt. Phys.

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We studied the above-threshold ionization (ATI) spectra of argon in circularly polarized pulse by the atom-Volkov strong-field approximation (SFA). A dip appears in the spectra due to the presence of a zero in the dipole matrix element, corresponding to a transition from the ground state to the L=2 continuum at electron kinetic energy $\sim$ 30.6eV. No such dip appears when the time-dependent Schr\"{o}dinger equation (TDSE) is used instead, because the transition amplitude in SFA is the first-order term in the S-matrix series while TDSE contains all orders. In contrast, the effect of Cooper minimum shows up in high-order harmonic generations, which is an inverse process of photoionization where the recombination transition is first-order. We examine several sets of pulse parameters and found that when the SFA validity conditions are satisfied, the atom-Volkov SFA generates better ATI spectra than the simple SFA.

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Modeling photoelectron spin polarization of xenon atoms in intense circularly polarized pulses

et al. 2021

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We propose a model for studying the ionization, photoelectron spectra, and spin polarization of xenon atoms under intense circularly polarized (CP) pulses by solving the time-dependent Schrödinger equation (TDSE) with an effective potential for Xe. The ionization mechanism is mainly due to multiphoton absorption in these strong CP fields. The effective potential of a single active electron for Xe consists of asymptotic Coulomb and parametric screening parts and yields low-lying levels that are comparable to those by other models for the total angular momentum J = 3 / 2 of X e + and new for J = 1 / 2 . We show in detail the absorption pathways, above-threshold ionization (ATI) spectra, and spin polarization mechanisms of photoelectrons originated from the initial state 5 p m l of Xe with the magnetic quantum number m l being − 1 , 0, or 1. There exists a substructure with sub-peaks in each of multiple ATI peaks from 5 p − 1 due to pulse effects on the valence electron passing through the absorption pathways. ATI and spin polarization results agree qualitatively with experimental data at the focal volume average to include the spatial effect of CP pulses. We also present the spin polarization results of the widely used strong-field approximation model (SFA), which are inconsistent with those of TDSE and experiments. This shows that TDSE is more accurate with more details than SFA for studying spin polarization in strong CP fields.

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Study of the circular dichroism of He⁺ ion

Cited by 3 publications

References 29 publications

Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Photoelectron spectra of argon in circularly polarized pulses studied by atom-Volkov strong-field approximation

Modeling photoelectron spin polarization of xenon atoms in intense circularly polarized pulses

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Study of the circular dichroism of He+ ion

Cited by 3 publications

References 29 publications

Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Solving time-dependent Schrödinger equation in momentum space with application to strong-field problems

Photoelectron spectra of argon in circularly polarized pulses studied by atom-Volkov strong-field approximation

Modeling photoelectron spin polarization of xenon atoms in intense circularly polarized pulses

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Study of the circular dichroism of He⁺ ion