10.1021/acs.nanolett.5b02805.s001 Ehren M. Mannebach Ehren M. Mannebach Renkai Li Renkai Li Karel-Alexander Duerloo Karel-Alexander Duerloo Clara Nyby Clara Nyby Peter Zalden Peter Zalden Theodore Vecchione Theodore Vecchione Friederike Ernst Friederike Ernst Alexander Hume Reid Alexander Hume Reid Tyler Chase Tyler Chase Xiaozhe Shen Xiaozhe Shen Stephen Weathersby Stephen Weathersby Carsten Hast Carsten Hast Robert Hettel Robert Hettel Ryan Coffee Ryan Coffee Nick Hartmann Nick Hartmann Alan R. Fry Alan R. Fry Yifei Yu Yifei Yu Linyou Cao Linyou Cao Tony F. Heinz Tony F. Heinz Evan J. Reed Evan J. Reed Hermann A. Dürr Hermann A. Dürr Xijie Wang Xijie Wang Aaron M. Lindenberg Aaron M. Lindenberg Dynamic Structural Response and Deformations of Monolayer MoS<sub>2</sub> Visualized by Femtosecond Electron Diffraction American Chemical Society 2015 femtosecond electron Dynamic Structural Response percent peak strains material heat flow ultrafast strain engineering Direct measurements monolayer transition metal dichalcogenide MoS 2 Monolayer MoS 2 Visualized 2015-10-14 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Dynamic_Structural_Response_and_Deformations_of_Monolayer_MoS_sub_2_sub_Visualized_by_Femtosecond_Electron_Diffraction/2122420 Two-dimensional materials are subject to intrinsic and dynamic rippling that modulates their optoelectronic and electromechanical properties. Here, we directly visualize the dynamics of these processes within monolayer transition metal dichalcogenide MoS<sub>2</sub> using femtosecond electron scattering techniques as a real-time probe with atomic-scale resolution. We show that optical excitation induces large-amplitude in-plane displacements and ultrafast wrinkling of the monolayer on nanometer length-scales, developing on picosecond time-scales. These deformations are associated with several percent peak strains that are fully reversible over tens of millions of cycles. Direct measurements of electron–phonon coupling times and the subsequent interfacial thermal heat flow between the monolayer and substrate are also obtained. These measurements, coupled with first-principles modeling, provide a new understanding of the dynamic structural processes that underlie the functionality of two-dimensional materials and open up new opportunities for ultrafast strain engineering using all-optical methods.