<div class="csl-bib-body">
<div class="csl-entry">Wang, S., Yan, J., de las Heras, A., Song, S., Prodanov, A., Wu, Z., Hernandez Garcia, C., Plaja, L., Popmintchev, D., & Popmintchev, T. (2023). Surprise in Highly Correlated Two-Electron System: Extended Secondary Plateau in X-ray High Harmonic Generation from Helium Due to Double Electron Recombination. In <i>2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)</i> (pp. 1–1). IEEE. https://doi.org/10.1109/CLEO/Europe-EQEC57999.2023.10231562</div>
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dc.identifier.uri
http://hdl.handle.net/20.500.12708/190091
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dc.description.abstract
We observe experimentally, for the first time to our knowledge, a secondary plateau in UV-driven high harmonic generation in the X-ray regime, extending the conventional cutoff from 130 eV to 300 eV, due to emission of a single X-ray photon at double recombination of highly-correlated electrons in helium atoms. Intense 400 nm UV laser pulses, with a duration of 28 fs and energies of up to 2.8 mJ at 1 kHz, derived through a second harmonic upconversion of a Ti:Sapphire laser amplifier, are used to drive high harmonic generation inside a gas-filled hollow waveguide (Fig. 1A). Bright emission extending up to 120-150 eV from He, Ne, and Ar is observed within the effective phase-matching cutoffs for UV driving lasers, where low quantum diffusion of the rescattering electron and high linear refractive indices of atoms and ions contribute favorably to increase the single atom and ion yield, and the phase-matching efficiency [1]. Surprisingly, at laser intensities greater than 2.5×1015 W/cm2, the X-ray emission from He exhibits two signature plateau regions - a conventional combined plateau extending up to 130 eV from He atoms and He+ ions, determined using TDSE calculations including two active electrons [2], as well as a secondary plateau extending - well beyond the conventional 3.2Up cutoff - up to 300 eV (Fig. 1B, C, D), where Up is the ponderomotive energy. Numerical simulations predict that double-electron-recombination (DER) is the physical process of highest probability to yield a secondary plateau. In this highly-correlated electron system, fractions of the two electron wavefunctions are ionized at different laser half-cycles and travel along different trajectories, mitigating strong repulsion during local space-time correlation in the presence of the strong UV field, but recombine with the parent ion at the same instant to produce a single X-ray photon. The observed DER plateau in He is >4 orders of magnitude weaker, and has a characteristic stronger dependence on the ellipticity of the UV driver, due to the longer rescattering time (Fig. 1B). A laser intensity scan indicates that the DER cutoffs scale as 5.5Up (Fig. 1C), in agreement with earlier theoretical scaling as hnDER=Ip(1)+Ip(2)+5.5Up or Ip(1)+Ip(2)+4.7Up for ionization of the two electrons separated by a full or a half-laser cycle [3], in contrast to the single-electron recombination (SER) - hnSER=Ip(i)+3.2Up where Ip(1)=24.4 eV and Ip(2)=54.6 eV are the ionization potentials of He.
en
dc.language.iso
en
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dc.subject
high harmonic generation
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dc.subject
X-ray lasers
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dc.subject
Waveguide lasers
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dc.subject
frequency conversion
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dc.title
Surprise in Highly Correlated Two-Electron System: Extended Secondary Plateau in X-ray High Harmonic Generation from Helium Due to Double Electron Recombination
en
dc.type
Inproceedings
en
dc.type
Konferenzbeitrag
de
dc.contributor.affiliation
University of California San Diego, USA
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dc.contributor.affiliation
University of California San Diego, USA
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dc.contributor.affiliation
Universidad de Salamanca, Spain
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dc.contributor.affiliation
University of California San Diego, USA
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dc.contributor.affiliation
University of California San Diego, USA
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dc.contributor.affiliation
University of California San Diego, USA
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dc.contributor.affiliation
Universidad de Salamanca, Spain
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dc.contributor.affiliation
Universidad de Salamanca, Spain
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dc.relation.isbn
979-8-3503-4599-5
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dc.description.startpage
1
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dc.description.endpage
1
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dc.type.category
Full-Paper Contribution
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dc.relation.eissn
2833-1052
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tuw.booktitle
2023 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
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tuw.relation.publisher
IEEE
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tuw.relation.publisherplace
IEEE Explore
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tuw.researchTopic.id
M2
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tuw.researchTopic.id
Q1
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tuw.researchTopic.id
I8
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tuw.researchTopic.name
Materials Characterization
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tuw.researchTopic.name
Photonics
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tuw.researchTopic.name
Sensor Systems
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tuw.researchTopic.value
20
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tuw.researchTopic.value
60
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tuw.researchTopic.value
20
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tuw.publication.orgunit
E387-01 - Forschungsbereich Photonik
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tuw.publisher.doi
10.1109/CLEO/Europe-EQEC57999.2023.10231562
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dc.description.numberOfPages
1
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tuw.author.orcid
0000-0001-9065-9076
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tuw.author.orcid
0000-0001-8709-7295
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tuw.event.name
CLEO/EUROPE-EQEC 2023 - Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference