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Dynamic Structural Response and Deformations of Monolayer MoS2 Visualized by Femtosecond Electron Diffraction
journal contribution
posted on 2015-10-14, 00:00 authored by Ehren
M. Mannebach, Renkai Li, Karel-Alexander Duerloo, Clara Nyby, Peter Zalden, Theodore Vecchione, Friederike Ernst, Alexander Hume Reid, Tyler Chase, Xiaozhe Shen, Stephen Weathersby, Carsten Hast, Robert Hettel, Ryan Coffee, Nick Hartmann, Alan
R. Fry, Yifei Yu, Linyou Cao, Tony F. Heinz, Evan J. Reed, Hermann A. Dürr, Xijie Wang, Aaron M. LindenbergTwo-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 MoS2 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.