Experimental measurement of the intrinsic excitonic wave function

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Man, Michael K. L.
Madéo, Julien
Sahoo, Chakradhar
Xie, Kaichen
Campbell, Marshall
Pareek, Vivek
Karmakar, Arka
Wong, E Laine
Al-Mahboob, Abdullah
Chan, Nicholas S.

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American Association for the Advancement of Science


An exciton, a two-body composite quasiparticle formed of an electron and hole, is a fundamental optical excitation in condensed matter systems. Since its discovery nearly a century ago, a measurement of the excitonic wave function has remained beyond experimental reach. Here, we directly image the excitonic wave function in reciprocal space by measuring the momentum distribution of electrons photoemitted from excitons in monolayer tungsten diselenide. By transforming to real space, we obtain a visual of the distribution of the electron around the hole in an exciton. Further, by also resolving the energy coordinate, we confirm the elusive theoretical prediction that the photoemitted electron exhibits an inverted energy-momentum dispersion relationship reflecting the valence band where the partner hole remains, rather than that of conduction band states of the electron.



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Michael K. L. Man et al. ,Experimental measurement of the intrinsic excitonic wave function.Sci. Adv.7,eabg0192(2021). DOI:10.1126/sciadv.abg0192