Symmetry breakdown of electron emission in extreme ultraviolet photoionization of argon

Ilchen, Markus; Hartmann, Gregor; Грызлова, Е. В.; Achner, A.; Allaria, E.; Beckmann, A.; Braune, Markus; Buck, Jens; Callegari, Carlo; Coffee, Ryan; Cucini, Riccardo; Danailov, Miltcho; Fanis, A. De; Demidovich, Alexander; Finetti, P.; Glaser, Leif; Knie, André; Lindahl, Anton; Plekan, Oksana; Mahne, Nicola; Mazza, Tommaso; Raimondi, Lorenzo; Roussel, Eléonore; Scholz, Frank; Seltmann, Jörn; Shevchuk, Ivan; Svetina, Cristian; Walter, Peter; Zangrando, Marco; Viefhaus, Jens; Grum–Grzhimailo, A. N.; Meyer, Michael

doi:10.1038/s41467-018-07152-7

Cited by 45 publications

(29 citation statements)

References 67 publications

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“…This setup is described in more detail in Ref. [44]. In order to achieve a better spectral energy resolution, a nominal retardation voltage of 510 V was applied to the flight tubes to decelerate fast Auger electrons.…”

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confidence: 99%

Recovery of High-Energy Photoelectron Circular Dichroism through Fano Interference

et al. 2019

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It is commonly accepted that the magnitude of a photoelectron circular dichroism (PECD) is governed by the ability of an outgoing photoelectron wave packet to probe the chiral asymmetry of a molecule. To be able to accumulate this characteristic asymmetry while escaping the chiral ion, photoelectrons need to have relatively small kinetic energies of up to a few tens of electron volts. Here, we demonstrate a substantial PECD for very fast photoelectrons above 500 eV kinetic energy released from methyloxirane by a participator resonant Auger decay of its lowermost O 1s-excitation. This effect emerges as a result of the Fano interference between the direct and resonant photoionization pathways, notwithstanding that their individual effects are negligibly small. The resulting dichroic parameter has an anomalous dispersion, i.e. it changes its sign across the resonance, which can be considered as an analogue of the Cotton effect in the X-ray regime. 32.80.Hd, 33.55.+b, 81.05.Xj Photoelectron circular dichroism (PECD) is a fundamental chiroptical effect causing a forward-backward asymmetry in the laboratory-frame angular distribution of photoelectrons emitted from chiral molecules in the gas phase. PECD was first predicted theoretically for one-photon ionization [1-3] and then verified in pioneering experiments with circularly polarized synchrotron radiation [4,5]. The effect persists also in the multiphoton ionization regime using intense laser pulses [6,7]. Because PECD is a pure electric-dipole effect, it is much stronger than the traditional CD in the photoabsorption spectra of chiral molecules [8]. This fact, together with its enantioselectivity, has established PECD as a powerful tool for chiral recognition in the gas phase [8][9][10][11].Ritchie [1-3] has proven analytically that PECD arises due to an incomplete compensation of the contributions from emitted partial electron waves with different projections ±m of the carried angular momentum ℓ. Such an inequivalence occurs only for chiral molecules and has a twofold origin: It is induced by the chiral asymmetries of both, the initial bound and the final continuum electronic states entering the dipole-transition amplitudes. For slow photoelectrons with kinetic energies of a few electron volts, initial and final state contributions to PECD can be comparable [12]. As the electron kinetic energy grows, the photoelectron wave packet escapes the molecular ion quickly and does not have enough time to adopt its chiral asymmetry. In other words, both, the chiral initial state and the chiral potential of the ion can be considered almost symmetric for very fast photoelectrons. As a consequence, at high kinetic energies, typically at a few tens of electron volts [12,13] and in extreme cases at about 70 eV [14], PECD vanishes.In the present work, we demonstrate a very general mechanism of PECD recovery for electrons with kinetic energies of as high as a few hundreds of electron volts. This scenario involves an intermediate electronic resonance, which enables an excited m...

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Recovery of High-Energy Photoelectron Circular Dichroism through Fano Interference

et al. 2019

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“…Furthermore, a forward-backward asymmetry of the photoelectron angular distribution along the light propagation direction, which was previously known for the single ionization [12,13], has also been predicted in the SPDI [14][15][16] and the two-photon double ionization (TPDI) [17,18]. Recently, the forward-backward asymmetry was experimentally observed in the sequential TPDI [19] of atoms.…”

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confidence: 64%

Photon Momentum Transfer in Single-Photon Double Ionization of Helium

et al. 2020

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“…This minimum does not only influence the shape of the total cross section, but more significantly, can strongly affect the photoelectron angular distributions 32 . It has been shown theoretically before 33,34 , that strong anisotropic effects can be observed near Cooper minima due to relativistic and correlation effects, which are necessary to explain experimental measurements 32,35,36 . Moreover, large nondipole contribution has been predicted in the XUV + IR two-photon above-threshold ionisation of neon 1s electron, when XUV photon energy matches the Cooper minimum 37 .…”

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Breakdown of the electric dipole approximation at Cooper minima in direct two-photon ionisation

Hofbrucker¹,

Volotka²,

Fritzsche³

2020

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We predict breakdown of the electric dipole approximation at nonlinear Cooper minimum in direct two-photon K−shell atomic ionisation by circularly polarised light. According to predictions based on the electric dipole approximation, we expect that tuning the incident photon energy to the Cooper minimum in two-photon ionisation results in pure depletion of one spin projection of the initially bound 1s electrons, and hence, leaves the ionised atom in a fully oriented state. We show that by inclusion of electric quadrupole interaction, dramatic drop of orientation purity is obtained. The low degree of the remaining ion orientation provides a direct access to contributions of the electron-photon interaction beyond the electric dipole approximation in the two-photon ionisation of atoms and molecules. The orientation of the photoions can be experimentally detected either directly by a Stern-Gerlach analyzer, or by means of subsequent Kα fluorescence emission, which has the information about the ion orientation imprinted in the polarisation of the emitted photons. 2/113/11

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Symmetry breakdown of electron emission in extreme ultraviolet photoionization of argon

Cited by 45 publications

References 67 publications

Recovery of High-Energy Photoelectron Circular Dichroism through Fano Interference

Recovery of High-Energy Photoelectron Circular Dichroism through Fano Interference

Photon Momentum Transfer in Single-Photon Double Ionization of Helium

Breakdown of the electric dipole approximation at Cooper minima in direct two-photon ionisation

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