Dynamic Structural Response and Deformations of Monolayer MoS2 Visualized by Femtosecond Electron Diffraction

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• 作者：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. D眉rr ; Xijie Wang ; Aaron M. Lindenberg
• 刊名：Nano Letters
• 出版年：2015
• 出版时间：October 14, 2015
• 年：2015
• 卷：15
• 期：10
• 页码：6889-6895
• 全文大小：466K
• ISSN：1530-6992

文摘

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 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鈥損honon 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.