Asymmetries in production of He<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow /><mml:mo>+</mml:mo></mml:msup><mml:mrow><mml:mo>(</mml:mo><mml:mi>n</mml:mi><mml:mo>=</mml:mo><mml:mn>2</mml:mn><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>with an intense few-cycle attosecond pulse

Djiokap, J. M. Ngoko; Hu, S. X.; Jiang, Wei-Chao; Peng, Liang-You; Starace, Anthony F.

doi:10.1103/physreva.88.011401

Cited by 11 publications

(6 citation statements)

References 42 publications

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“…For single ionization of an atom by a few-cycle XUV pulse, a PT analysis [11] provides an ab initio parametrization of the ionized electron AD in terms of the key parameters of the process: the CEP of the pulse, the pulse polarization, and the electron momentum direction. This parametrization [11] for XUV pulse photoionization of He describes accurately numerical results obtained by solving the time-dependent Schrödinger equation (TDSE) [12][13][14]. In general in the PT regime, the AD asymmetry originates from interference of first-and second-order PT transition amplitudes to continuum states with the same energy E but different parities [11].…”

Section: Introductionsupporting

confidence: 55%

“…For linear polarization of the pulse, our PT parametrization is in excellent agreement with results of solutions of the full-dimensional, two-electron TDSE, validating the PT approach. These numerical results show that the normalized asymmetry in DPI significantly exceeds that for single ionization of He for I = 1-2 PW/cm 2 [12,13] and are comparable to that for single ionization plus excitation of He to He + (2s,2p) [14]. We have also investigated the CEP dependence of the AD for the special case of orthogonal geometry for which the first-order amplitude vanishes, providing a means to directly investigate the CEP dependence of the second-order PT amplitude.…”

Section: Discussionmentioning

confidence: 65%

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Carrier-envelope-phase-induced asymmetries in double ionization of helium by an intense few-cycle XUV pulse

et al. 2013

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, N. L.; Meremianin, A. V.; and Starace, Anthony F., "Carrier-envelope-phase-induced asymmetries in double ionization of helium by an intense few-cycle XUV pulse" (2013 The carrier-envelope-phase (CEP) dependence of electron angular distributions in double ionization of He by an arbitrarily polarized, few-cycle, intense XUV pulse is formulated using perturbation theory (PT) in the pulse amplitude. Owing to the broad pulse bandwidth, interference of first-and second-order PT amplitudes produces asymmetric angular distributions sensitive to the CEP. The PT parametrization is shown to be valid by comparing with results of solutions of the full-dimensional, two-electron time-dependent Schrödinger equation for the case of linear polarization.

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Section: Introductionsupporting

confidence: 55%

Section: Discussionmentioning

confidence: 65%

Carrier-envelope-phase-induced asymmetries in double ionization of helium by an intense few-cycle XUV pulse

et al. 2013

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“…Using the length gauge in the dipole approximation, the two-electron TDSE in six spatial dimensions is solved using a finite-element discrete-variable representation (FE-DVR) [56] combined with the real-spaceproduct algorithm (a split-operator method) [57][58][59][60] together with Wigner rotation transformations at each time step from the laboratory frame to the frame of the instantaneous electric field [61,62]. At the end of the two pulses, i.e., at t = T f , we freely propagate the two-electron wave packet (r 1 ,r 2 ; t) for a time T p before extracting the SDP [63] for DPI of He by projecting the two-electron continuum part, C (r 1 ,r 2 ; T f + T p ), of the wave packet (r 1 ,r 2 ; T f + T p ) onto the double-continuum final state, which is approximated by a product of two Coulomb waves (−) p 1 ,p 2 (r 1 ,r 2 ) with charge Z = 2.…”

Section: Methodsmentioning

confidence: 99%

Kinematical vortices in double photoionization of helium by attosecond pulses

et al. 2017

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Manakov, N. L.; Hu, S. X.; Madsen, L. B.; and Starace, Anthony F., "Kinematical vortices in double photoionization of helium by attosecond pulses" (2017 Two-armed helical vortex structures are predicted in the two-electron momentum distributions produced in double photoionization (DPI) of the He atom by a pair of time-delayed elliptically polarized attosecond pulses with opposite helicities. These predictions are based upon both a first-order perturbation theory analysis and numerical solutions of the two-electron, time-dependent Schrödinger equation in six spatial dimensions. The helical vortex structures originate from Ramsey interference of a pair of ionized two-electron wave packets, each having a total angular momentum of unity, and appear in the sixfold differential DPI probability distribution for any energy partitioning between the two electrons. The vortex structures are exquisitely sensitive to the time delay between the two pulses, their relative phase, their ellipticity, and their handedness; moreover, they occur in a variety of electron detection geometries. However, the vortex structures only occur when the angular separation β = cos −1 (p 1 ·p 2 ) between the electron momenta p 1 and p 2 is held fixed. The vortex structures can also be observed in the fourfold differential DPI probability distribution obtained by averaging the sixfold differential probability over the emission angles of one electron. Such kinematical vortices are a general phenomenon that may occur in any ionization process, initiated by two time-delayed short pulses with opposite ellipticities, for particular detection geometries.

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“…, where L is the total angular momentum of the two-electron system, M is its azimuthal quantum number, and l l , 1 2 are the individual electron orbital angular momenta. The twoelectron TDSE in six spatial dimensions is solved using a finite-element discrete-variable representation [25] combined with the real-space-product algorithm (a split-operator method) [26][27][28][29] together with Wigner rotation transformations at each time step from the laboratory frame to the frame of the instantaneous electric field [30,31]. At the end of the two pulses, i.e.…”

Section: Re Ementioning

confidence: 99%

Doubly-excited state effects on two-photon double ionization of helium by time-delayed, oppositely circularly-polarized attosecond pulses

Djiokap¹,

Starace²

2017

J. Opt.

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Doubly-excited state effects on two-photon double ionization of helium by time-delayed, oppositely circularly-polarized attosecond pulses" (2017). Anthony F. Starace Publications. 227. AbstractWe study two-photon double ionization (TPDI) of helium by a pair of time-delayed (nonoverlapping), oppositely circularly-polarized attosecond pulses whose carrier frequencies are resonant with 1 P o doubly-excited states. All of our TPDI results are obtained by numerical solution of the two-electron time-dependent Schrödinger equation for the six-dimensional case of circularly-polarized attosecond pulses, and they are analyzed using perturbation theory (PT). As compared with the corresponding nonresonant TPDI process, we find that the doubly-excited states change the character of vortex patterns in the two-electron momentum distributions for the case of back-to-back detection of the two ionized electrons in the polarization plane. The doublyexcited states also completely change the structure of fixed-energy, two-electron angular distributions. Moreover, both the fixed-energy and energy-integrated angular distributions, as well as the two-electron energy distributions, exhibit a periodicity with time delay τ between the two attosecond pulses of about 69as, i.e. the beat period between the ( ) s p 2 2 P o 1 doubly-excited state and the He ground state. Using PT we derive an expression for an angle-integrated energy distribution that is sensitive to the slower beat period ∼1.2fs between different doubly-excited states as well as to the long timescale ∼17fs of autoionization lifetimes. However, with our current computer codes we are only able to study numerically the time-dependent phenomena occurring on an attosecond time scale.1 See the supplementary information of [8] for a theoretical study of twophoton double ionization of the He atom by a pair of time-delayed attosecond pulses resonant with the region of doubly-excited states. 2

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Asymmetries in production of He+(n=2)with an intense few-cycle attosecond pulse

Cited by 11 publications

References 42 publications

Carrier-envelope-phase-induced asymmetries in double ionization of helium by an intense few-cycle XUV pulse

Carrier-envelope-phase-induced asymmetries in double ionization of helium by an intense few-cycle XUV pulse

Kinematical vortices in double photoionization of helium by attosecond pulses

Doubly-excited state effects on two-photon double ionization of helium by time-delayed, oppositely circularly-polarized attosecond pulses

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