`Short' pulse MPI of xenon: the ionization channel

Rottke, H.; Ludwig, Jan; Sandner, W.

doi:10.1088/0953-4075/29/8/012

Cited by 17 publications

(19 citation statements)

References 12 publications

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“…The ability to separate photoelectron spectra corresponding to 2 P 3/2 and 2 P 1/2 ionization channels experimentally will offer opportunity to achieve high degree of spin polarization of coherent electron source. The energy separation has been observed in multiphoton ionization by linearly polarized fields [28,29], however there is no spin polarization effect using linearly polarized fields. Thus, we turn to study the spin polarization of photoelectrons in circularly polarized ultraviolet light at 400 nm.…”

Section: (C) and 3(d)mentioning

confidence: 99%

Energy- and Momentum-Resolved Photoelectron Spin Polarization in Multiphoton Ionization of Xe by Circularly Polarized Fields

et al. 2018

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We perform a joint experimental and theoretical study on momentum- and energy-resolved photoelectron spin polarization in multiphoton ionization of Xe atoms by circularly polarized fields. We experimentally measure the photoelectron momentum distributions of Xe atoms in circularly polarized near-infrared (800 nm) and ultraviolet (400 nm) light, respectively. We analyze the momentum- and energy-resolved photoelectron spin polarization by comparing the experimental photoelectron momentum distributions with the simulations, although we cannot derive the spin polarization solely from the experiment. We show that the use of circularly polarized ultraviolet light at 400 nm can create better than 90% spin polarization with focal volume effect considered, which enables the separation of the spin states by momentum gating. This paves the way to produce high-degree spin-polarized electron sources from strong-field multiphoton ionization.

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Section: (C) and 3(d)mentioning

confidence: 99%

Energy- and Momentum-Resolved Photoelectron Spin Polarization in Multiphoton Ionization of Xe by Circularly Polarized Fields

et al. 2018

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“…Spin polarization in the channel 2 P 3/2 is less than 100 %, since the total momentum of the core J = 3/2 admits both |m j | = 3/2 and |m j | = 1/2 of the correlated photoelectron. The ability to separate photoelectron spectra corresponding to 2 P 3/2 and 2 P 1/2 ionization channels experimentally [21] offers opportunities for achieving high degree of spin polarization of coherent electron beams produced by strong field ionization. Note that similar separation of strong field photoelectron spectra correlated to different core states of a polyatomic molecule has recently been demonstrated in [22] and used to identify different channels in strong field ionization.…”

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confidence: 99%

Spin-polarized electrons produced by strong-field ionization

2013

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We show that ionization of noble gas atoms by a strong infrared circularly polarized laser field under standard experimental conditions can yield electrons with up to 100% spin polarization in energy resolved measurements. Spin polarization arises due to the interplay of the electron-core entanglement and the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state. [1,2] produced during the interaction of atoms, molecules and solids with strong infrared laser fields are promising new tools for ultrafast spectroscopy. Photoelectrons extracted by the strong laser field from the metal nano-tip can form intense, few tens of femtosecond long coherent electron pulses [2], opening new opportunities for ultrafast electron diffraction within a table top setup. Photoelectrons produced via strong field ionization of atoms and molecules can serve as an attosecond probe of optical tunneling [3-6], molecular structure [7,8] and dynamics [9]; their coherence can be used to record holographic images of atomic core [8,10]. We show that, when produced by ionization in a strong infrared circularly polarized field under standard experimental conditions [3][4][5][6], coherent ultrashort photoelectron pulses can have high and controllable degree of spin polarization, opening new opportunities for attosecond spectroscopy. Coherent ultrashort light [1] and electron beamsAnalysing one-photon ionization, U. Fano [11] has shown that usually weak effects of the spin-orbit interaction are strongly enhanced in the vicinity of the Cooper minima in the photoionization continua, leading to 100% spin polarization within a certain energy window. In the one photon ionization, spin polarization can also be achieved via ionization from a particular fine structure level of an atom or a molecule [12]. Elegant extension to resonant multi-photon ionization in the weak-field (perturbative) limit has been proposed by P. Lambropoulos [13][14][15]. Importantly, it has been demonstrated that high degree of spinpolarization is not always associated with minima in cross sections [16,17]. For example, 100% spin polarization is achieved away from the minimum in the three-photon ionization cross section of alkali atoms [16], and at the maximum of the one-photon cross section for Xe [17].All of these mechanisms rely on fine tuning the light frequency and require long, lowintensity pulses. In contrast, our mechanism does not rely on frequency tuning or intermediate resonances. It operates in the strong-field regime, for broad range of frequencies and for short pulses. Spin polarization is achieved via spin-orbit interaction in the ionic core and is due to the interplay of (i) the electron-core entanglement and (ii) the sensitivity of ionization in circularly polarized fields to the sense of electron rotation in the initial state.Consider strong field ionization of noble gas atoms by right circularly polarized field propagating in the positive direction of the z-axis. For all noble gas atoms except Helium, the o...

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“…Indeed, different ionization channels, corresponding to different I p 's should lead to photoelectron peaks with different energy. While this is indeed the case for one-photon ionization, highly non-linear nature of strong-field processes make observation of the alternative ionization channels quite challenging in the strong field regime [2].…”

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confidence: 99%

Attosecond correlation dynamics during electron tunnelling from molecules

Walters

Smirnova

2010

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

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We present analytical theory of strong field ionization of molecules, which takes into account rearrangement of multiple interacting electrons during the ionization process. We show that such rearrangement offers an alternative pathway to the ionization of orbitals more deeply bound than the Highest Occupied Molecular Orbital (HOMO). This pathway is not subject to the full exponential suppression characteristic of the direct tunnel ionization from the deeper orbitals. The departing electron produces an "attosecond correlation pulse" which controls the rearrangement during the tunneling process. The shape and duration of this pulse are determined by the electronic structure of the relevant states, molecular orientation, and the laser parameters.

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`Short' pulse MPI of xenon: the ionization channel

Cited by 17 publications

References 12 publications

Energy- and Momentum-Resolved Photoelectron Spin Polarization in Multiphoton Ionization of Xe by Circularly Polarized Fields

Energy- and Momentum-Resolved Photoelectron Spin Polarization in Multiphoton Ionization of Xe by Circularly Polarized Fields

Spin-polarized electrons produced by strong-field ionization

Attosecond correlation dynamics during electron tunnelling from molecules

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