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  • 09월 20일 16시 이후 : 초록수정 불가능, 일정확인 및 검색만 가능

제126회 대한화학회 학술발표회 및 총회 Filming Morphological Dynamics of Black Phosphorus Revealed in Ultrafast Electron Microscopy

2020년 9월 10일 16시 41분 09초
PHYS.P-235 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 21일(수) 17:30~18:00
Physical Chemistry
저자 및
Ye-Jin Kim, Oh-Hoon Kwon*
Department of Chemistry, Ulsan National Institute of Science and Technology, Korea

With the rapid development of two-dimensional (2D) matter, orthorhombic black phosphorus (BP), composed of puckered phosphorus layers via van der Waals interactions, recently has been widely studied due to its striking anisotropic properties [1]. Despite huge interests in BP from both fundamental and technical aspects [2], investigation into its structural dynamics induced by transient strain fields, prevalent for 2D materials and tuning the material physical properties, has been overlooked. Here, we track the course of the morphological deformation and relaxation of suspended BP membranes on timescales spanning nanoseconds to microseconds observed by time-resolved diffractograms and dark-field images in ultrafast electron microscopy (UEM) using pulsed photoexcitation as the source of brief thermal stress [3,4] (Figure 1). The number of BP layers, as well as the excitation polarization, fluence, and probe axis, were all controlled to analyze the anisotropic behavior. Aided by 4D structural reconstruction, we visualize the nonequilibrium bulging of thin BP membranes and reveal the buckling transition driven by impulsive thermal stress upon photoexcitation in real time. Finite element modeling was performed to simulate the stress and strain energy accompanied by the structural transition. The transient bulging, buckling, and flattening of the suspended BP membrane showed anisotropic spatiotemporal behavior. Because the strain field in the form of ripples and buckles on the surface of 2D matter modulates many physical properties, especially the optical and electrical properties, tailoring the transient anisotropic morphology of BP may allow fast spatiotemporal responses to light and unique multi-order functionality. [1] Ling, X., et al., Proc. Natl. Acad. Sci. U.S.A 2015, 112, 4523-4530. [2] Wang, Z., et al., Nano Lett. 2016, 16, 5394-5400. [3] Kim, Y.-J., et al., Matter 2019, 1, 481-495. [4] Kim, Y.-J., et al., ACS Nano 2020, https://doi.org/10.1021/acsnano.0c03644.