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Author: Martín, Fernando × DDC: 500 ×

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    Anisotropic photoemission time delays close to a Fano resonance
    ([London] : Nature Publishing Group UK, 2018) Cirelli, Claudio; Marante, Carlos; Heuser, Sebastian; Petersson, C.L.M.; Galán, Álvaro Jiménez; Argenti, Luca; Zhong, Shiyang; Busto, David; Isinger, Marcus; Nandi, Saikat; Maclot, Sylvain; Rading, Linnea; Johnsson, Per; Gisselbrecht, Mathieu; Lucchini, Matteo; Gallmann, Lukas; Dahlström, J. Marcus; Lindroth, Eva; L’Huillier, Anne; Martín, Fernando; Keller, Ursula
    Electron correlation and multielectron effects are fundamental interactions that govern many physical and chemical processes in atomic, molecular and solid state systems. The process of autoionization, induced by resonant excitation of electrons into discrete states present in the spectral continuum of atomic and molecular targets, is mediated by electron correlation. Here we investigate the attosecond photoemission dynamics in argon in the 20-40 eV spectral range, in the vicinity of the 3s -1 np autoionizing resonances. We present measurements of the differential photoionization cross section and extract energy and angle-dependent atomic time delays with an attosecond interferometric method. With the support of a theoretical model, we are able to attribute a large part of the measured time delay anisotropy to the presence of autoionizing resonances, which not only distort the phase of the emitted photoelectron wave packet but also introduce an angular dependence.
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    Reconstruction of the time-dependent electronic wave packet arising from molecular autoionization
    (Washington, DC [u.a.] : Assoc., 2018) Bello, Roger Y.; Canton, Sophie E.; Jelovina, Denis; Bozek, John D.; Rude, Bruce; Smirnova, Olga; Ivanov, Mikhail Y.; Palacios, Alicia; Martín, Fernando
    Autoionizing resonances are paradigmatic examples of two-path wave interferences between direct photoionization, which takes a few attoseconds, and ionization via quasi-bound states, which takes much longer. Time-resolving the evolution of these interferences has been a long-standing goal, achieved recently in the helium atom owing to progress in attosecond technologies. However, already for the hydrogen molecule, similar time imaging has remained beyond reach due to the complex interplay between fast nuclear and electronic motions. We show how vibrationally resolved photoelectron spectra of H2 allow one to reconstruct the associated subfemtosecond autoionization dynamics by using the ultrafast nuclear dynamics as an internal clock, thus forgoing ultrashort pulses. Our procedure should be general for autoionization dynamics in molecules containing light nuclei, which are ubiquitous in chemistry and biology.