Fig. 1: Dependence of friction and electron energy dissipation rate.
From: Ultrafast dynamics of electronic friction energy dissipation in defective semiconductor monolayer
a Schematic of the experimental setup. The AFM tip slides on the surface of monolayer WS2, and the dynamics of electrons is detected by a femtosecond ultrafast transient absorption spectroscopy. b Schematic of ultrafast electron dynamics in defective WS2 monolayer. There are two friction energy dissipation channels: the first is the radiative recombination present in the pristine monolayer WS2, while the second involves atomic-level friction defects capture electrons. These friction defects generate at the sliding interface and introduce defect energy levels, which capture electrons. CB: conduction band; VB: valence band. c AFM topography of the monolayer WS2 on SiO2/Si substrate. The underside of WS2 is encapsulated by hexagonal boron nitride. d AFM topography of the monolayer WS2 after tip sliding. The sliding loads from regions 1 to 7 are 100, 500, 1000, 1500, 2000, 2500, and 3000 nN, respectively. The topography experiments were independently repeated three times with similar results. e The relationship between friction coefficient and overall electron energy dissipation rate \({\tau }^{-1}\). The friction coefficient μ is used to represent the relative variation of friction. The electron energy dissipation rate \({\tau }^{-1}\) represents the speed at which excited electrons dissipate energy through various channels. The error bar is obtained by linearly fitting the friction coefficient using the least squares method. Source data of (e) is provided as a Source Data file.
