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arXiv · 1912.12266

Attosecond time-domain measurement of core-excitonic decay in magnesium oxide

Romain Géneaux·Christopher J. Kaplan·Lun Yue·Andrew D. Ross·Jens E. Bækhøj·Peter M. Kraus·Hung-Tzu Chang·Alexander Guggenmos·Mi-Ying Huang·Michael Zürch·Kenneth J. Schafer·Daniel M. Neumark·Mette B. Gaarde·Stephen R. Leone
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Abstract

Excitation of ionic solids with extreme ultraviolet pulses creates localized core-excitons, which in some cases couple strongly to the lattice. Here, core-excitonic states of magnesium oxide are studied in the time domain at the Mg $\text{L}_{2,3}$ edge with attosecond transient reflectivity spectroscopy. Attosecond pulses trigger the excitation of these short-lived quasiparticles, whose decay is perturbed by time-delayed near infrared optical pulses. Combined with a few-state theoretical model, this reveals that the optical pulse shifts the energy of bright core-exciton states as well as induces features arising from dark core-excitons. We report coherence lifetimes for the first two core-excitons of $2.3 \pm 0.2$ and $1.6 \pm 0.5$ femtoseconds and show that these short lifetimes are primarily a consequence of strong exciton-phonon coupling, disclosing the drastic influence of structural effects in this ultrafast relaxation process.

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Romain Géneaux, Christopher J. Kaplan, Lun Yue, Andrew D. Ross, Jens E. Bækhøj, Peter M. Kraus, Hung-Tzu Chang, Alexander Guggenmos, Mi-Ying Huang, Michael Zürch, Kenneth J. Schafer, Daniel M. Neumark, Mette B. Gaarde, Stephen R. Leone. 2019-12-27. Attosecond time-domain measurement of core-excitonic decay in magnesium oxide. https://doi.org/10.1103/physrevlett.124.207401

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