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Type: article × Publisher: Bristol : IOP Publ. × Subject: attosecond physics × WGL Institute: MBI ×

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Now showing 1 - 4 of 4
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    Chiral dichroism in bi-elliptical high-order harmonic generation
    (Bristol : IOP Publ., 2018-02-28) Ayuso, David; Decleva, Piero; Patchkovskii, Serguei; Smirnova, Olga
    The application of strong bi-elliptically polarized laser fields to the generation of high-order harmonics in organic molecules offers exceptional opportunities for chiral recognition and chiral discrimination. These fields are made by combining an elliptically polarized fundamental, typically in the infrared range, with its counter-rotating second harmonic. Here we present a theoretical study of the harmonic emission from the chiral molecule propylene oxide in bi-elliptical fields. Our calculations include, for the first time in such a complex system, accurate photorecomination matrix elements, evaluated using the static-exchange density functional theory method. We show that bi-elliptical light can induce strong chiral dichroism in the harmonic spectra of chiral molecules in a broad range of harmonic numbers and ellipticities.
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    Attosecond streaking metrology with isolated nanotargets
    (Bristol : IOP Publ., 2018-01-05) Liu, Q.; Seiffert, L.; Trabattoni, A.; Castrovilli, M.C.; Galli, M.; Rupp, P.; Frassetto, F.; Poletto, L.; Nisoli, M.; Rühl, E.; Krausz, F.; Fennel, T.; Zherebtsov, S.; Calegari, F.; Kling, M.F.
    The development of attosecond metrology has enabled time-resolved studies on atoms, molecules, and (nanostructured) solids. Despite a wealth of theoretical work, attosecond experiments on isolated nanotargets, such as nanoparticles, clusters, and droplets have been lacking. Only recently, attosecond streaking metrology could be extended to isolated silica nanospheres, enabling real-time measurements of the inelastic scattering time in dielectric materials. Here, we revisit these experiments and describe the single-shot analysis of velocity-map images, which permits to evaluate the recorded number of electrons. Modeling of the recorded electron histograms allows deriving the irradiated nanoparticle statistics. Theoretically, we analyze the influence of the nanoparticle size on the field-induced delay, which is one of the terms contributing to the measured streaking delay. The obtained new insight into attosecond streaking experiments on nanoparticles is expected to guide wider implementation of the approach on other types of nanoparticles, clusters, and droplets.
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    Attosecond transient absorption spectroscopy without inversion symmetry
    (Bristol : IOP Publ., 2020) Drescher, L.; Vrakking, M.J.J.; Mikosch, J.
    Transient absorption is a very powerful observable in attosecond experiments on atoms, molecules and solids and is frequently used in experiments employing phase-locked few-cycle infrared and XUV laser pulses derived from high harmonic generation. We show numerically and analytically that in non-centrosymmetric systems, such as many polyatomic molecules, which-way interference enabled by the lack of parity conservation leads to new spectral absorption features, which directly reveal the laser electric field. The extension of attosecond transient absorption spectroscopy (ATAS) to such targets hence becomes sensitive to global and local inversion symmetry. We anticipate that ATAS will find new applications in non-centrosymmetric systems, in which the carrier-to-envelope phase of the infrared pulse becomes a relevant parameter and in which the orientation of the sample and the electronic symmetry of the molecule can be addressed. © 2020 The Author(s). Published by IOP Publishing Ltd.
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    Strong-field control and enhancement of chiral response in bi-elliptical high-order harmonic generation: an analytical model
    (Bristol : IOP Publ., 2018-05-30) Ayuso, David; Decleva, Piero; Patchkovskii, Serguei; Smirnova, Olga
    The generation of high-order harmonics in a medium of chiral molecules driven by intense bi-elliptical laser fields can lead to strong chiroptical response in a broad range of harmonic numbers and ellipticities (Ayuso et al 2018 J. Phys. B: At. Mol. Opt. Phys. 51 06LT01). Here we present a comprehensive analytical model that can describe the most relevant features arising in the high-order harmonic spectra of chiral molecules driven by strong bi-elliptical fields. Our model recovers the physical picture underlying chiral high-order harmonic generation (HHG) based on ultrafast chiral hole motion and identifies the rotationally invariant molecular pseudoscalars responsible for chiral dynamics. Using the chiral molecule propylene oxide as an example, we show that one can control and enhance the chiral response in bi-elliptical HHG by tailoring the driving field, in particular by tuning its frequency, intensity and ellipticity, exploiting a suppression mechanism of achiral background based on the linear Stark effect.