Theory of photoelectron angular distributions in resonant multiphoton ionization

Dixit, S. N.; Lambropoulos, P.

doi:10.1103/physreva.27.861

Cited by 121 publications

(52 citation statements)

References 16 publications

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“…Also these processes have been used in a variety of applications in laser optics and spectroscopy. It is well known that the two-photon photoelectron angular distributions (PAD) are directly related to the relative amplitudes and the relative phase between different partial waves [8,[12][13][14][15][16]. However, these earlier works dealt with the laser pulses in the optical range whose pulse width is very long in comparison with the modern standard of femosecond laser technology.…”

Section: Introductionmentioning

confidence: 99%

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Photoelectron Angular Distribution and Phase in Two-Photon Single Ionization of H and He by a Femtosecond and Attosecond Extreme-Ultraviolet Pulse

Ishikawa

Ueda

2013

Applied Sciences

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We theoretically study the photoelectron angular distribution (PAD) from the two-photon single ionization of H and He by femtosecond and attosecond extreme-ultraviolet pulses, based on the time-dependent perturbation theory and simulations with the full time-dependent Schrödinger equation. The PAD is formed by the interference of the s and d continuum wave packets, and, thus, contains the information on the relative phase δ and amplitude ratio between them. We find that, when a spectrally broadened femtosecond pulse is resonant with an excited level, the PAD substantially changes with pulse width, since the competition between resonant and nonresonant ionization paths, leading to δ distinct from the scattering phase shift difference, changes with it. In contrast, when the Rydberg manifold is excited, and for the case of above-threshold two-photon ionization, δ and the PAD do not depend much on pulse width, except for the attosecond region. Thus, the Rydberg manifold and the continuum behave similarly in this respect. For a high-harmonic pulse composed of multiple harmonic orders, while the value of δ is different from that for a single-component pulse, the PAD still rapidly varies with pulse width. The present results illustrate a new way to tailor the continuum wave packet.

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Section: Introductionmentioning

confidence: 99%

“…Two-photon ionization (2PI), or multi-photon ionization more generally, has consistently been receiving a great deal of attention for decades (see e.g., [1][2][3][4][5][6][7][8][9][10][11]). Also these processes have been used in a variety of applications in laser optics and spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Photoelectron Angular Distribution and Phase in Two-Photon Single Ionization of H and He by a Femtosecond and Attosecond Extreme-Ultraviolet Pulse

Ishikawa

Ueda

2013

Applied Sciences

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“…Also these processes have been used in a variety of applications in laser optics and spectroscopy. It is well known that the two-photon photoelectron angular distributions are directly related to the relative amplitudes and the relative phase between different partial waves [1][2][3][4][5][6]. However, these earlier works dealt with the laser pulses in the optical range whose pulse width is very long in comparison with the modern standard of femosecond laser technology.…”

mentioning

confidence: 99%

Photoelectron angular distributions for the two-photon ionization of helium by ultrashort extreme ultraviolet free-electron laser pulses

Motomura

Ishikawa

et al. 2013

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

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Phase-shift differences and amplitude ratios of the outgoing s and d continuum wave packets generated by two-photon ionization of helium atoms are determined from the photoelectron angular distributions obtained using velocity map imaging. Helium atoms are ionized with ultrashort extreme-ultraviolet free-electron laser pulses with a photon energy of 20.3, 21.3, 23.0, and 24.3 eV, produced by the SPring-8 Compact SASE Source test accelerator. The measured values of the phase-shift differences are distinct from scattering phase-shift differences when the photon energy is tuned to an excited level or Rydberg manifold. The difference stems from the competition between resonant and non-resonant paths in two-photon ionization by ultrashort pulses. Since the competition can be controlled in principle by the pulse shape, the present results illustrate a new way to tailor the continuum wave packet.

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“…Moreover, the possibility of enhancement from an intermediate single-photon resonance can be ruled out. The nearest resonance is detuned by 2.5 eV and the FEL bandwidth is too narrow, while ac Stark shifts are found to be way too small to cause a transient resonance of any type [11,[24][25][26]. There is, however, one excited state of Ar 6+ , namely 3s3p( 1 P 1 ), lying 21.2 eV above the ground state 3s 2 , which is created through the single-photon sequence of transitions Ar 4+ (3s 2 3p 2 ) → Ar 5+ (3s3p 2 ) → Ar 6+ 3s3p.…”

Section: Resultsmentioning

confidence: 99%

Two-electron processes in multiple ionization under strong soft-x-ray radiation

et al. 2016

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In a combined experimental and theoretical study we have investigated the ionization of atomic argon upon irradiation with intense soft-x-ray pulses of 105 eV photon energy from the free-electron laser FLASH. The measured ion yields show charge states up to Ar 7+ . The comparison with the theoretical study of the underlying photoionization dynamics highlights the importance of excited states in general and of processes governed by electron correlation in particular, namely, ionization with excitation and shake-off, processes usually inaccessible by measurements of ionic yields only. The Ar 7+ yield shows a clear deviation from the predictions of the commonly used model of sequential ionization via single-electron processes and the observed signal can only be explained by taking into account the full multiplet structure of the involved configurations and by inclusion of two-electron processes. The competing process of two-photon ionization from the ground state of Ar 6+ is calculated to be orders of magnitude smaller.

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Theory of photoelectron angular distributions in resonant multiphoton ionization

Cited by 121 publications

References 16 publications

Photoelectron Angular Distribution and Phase in Two-Photon Single Ionization of H and He by a Femtosecond and Attosecond Extreme-Ultraviolet Pulse

Photoelectron Angular Distribution and Phase in Two-Photon Single Ionization of H and He by a Femtosecond and Attosecond Extreme-Ultraviolet Pulse

Photoelectron angular distributions for the two-photon ionization of helium by ultrashort extreme ultraviolet free-electron laser pulses

Two-electron processes in multiple ionization under strong soft-x-ray radiation

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