Photo-induced lattice contraction in layered materials. (16th July 2018)

• Record Type: Journal Article
• Authors: Kumazoe, Hiroyuki; Krishnamoorthy, Aravind; Bassman, Lindsay; Kalia, Rajiv K; Nakano, Aiichiro; Shimojo, Fuyuki; Vashishta, Priya
• Is Part Of: Journal of physics. Volume 30:Number 32(2018)
• Publication Date: 2018-07-16
• Subjects: MoS2 -- photo-dynamics -- van der Waals -- layered materials -- quantum molecular dynamics; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aad022
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: Structural and electronic changes induced by optical excitation is a promising technique for functionalization of 2D crystals. Characterizing the effect of excited electronic states on the in-plane covalent bonding network as well as the relatively weaker out-of-plane dispersion interactions is necessary to tune photo-response in these highly anisotropic crystal structures. In-plane atom dynamics was measured using pump-probe experiments and characterized using ab initio simulations, but the effect of electronic excitation on weak out-of-plane van der Waals bonds is less well-studied. We use non-adiabatic quantum molecular dynamics to investigate atomic motion in photoexcited MoS2 bilayers. We observe a strong athermal reduction in the lattice parameter along the out-of-plane direction within 100 fs after electronic excitation, resulting from redistribution of electrons to excited states that have lesser anti-bonding character between layers. This non-trivial behavior of weakly bonded interactions during photoexcitation could have potential applications for modulating properties in materials systems containing non-covalent interactions like layered materials and polymers.