@article{oai:oist.repo.nii.ac.jp:00002524,
 author = {Madéo, Julien and Man, Michael K. L. and Sahoo, Chakradhar and Campbell, Marshall and Pareek, Vivek and Wong, E. Laine and Al-Mahboob, Abdullah and Chan, Nicholas S. and Karmakar, Arka and Mariserla, Bala Murali Krishna and Li, Xiaoqin and Heinz, Tony F. and Cao, Ting and Dani, Keshav M.},
 issue = {6521},
 journal = {Science},
 month = {Dec},
 note = {Resolving momentum degrees of freedom of excitons, which are electron-hole pairs bound by the Coulomb attraction in a photoexcited semiconductor, has remained an elusive goal for decades. In atomically thin semiconductors, such a capability could probe the momentum-forbidden dark excitons, which critically affect proposed opto-electronic technologies but are not directly accessible using optical techniques. Here, we probed the momentum state of excitons in a tungsten diselenide monolayer by photoemitting their constituent electrons and resolving them in time, momentum, and energy. We obtained a direct visual of the momentum-forbidden dark excitons and studied their properties, including their near degeneracy with bright excitons and their formation pathways in the energy-momentum landscape. These dark excitons dominated the excited-state distribution, a surprising finding that highlights their importance in atomically thin semiconductors.},
 pages = {1199--1204},
 title = {Directly visualizing the momentum-forbidden dark excitons and their dynamics in atomically thin semiconductors},
 volume = {370},
 year = {2020}
}