Shao Yabin, Chen Chen, He Qing, Wu Wenzhi, Li Chensha, Gao Yachen
Electronic Engineering College, Heilongjiang University, Harbin 150080, China.
Department of Computer & Electrical Engineering, East University of Heilongjiang, Harbin 150086, China.
Nanomaterials (Basel). 2020 Dec 17;10(12):2544. doi: 10.3390/nano10122544.
The TiC nanosheet, as a new two-dimensional (2D) group, has been found to have attractive characteristics as material for electromagnetic shielding and energy storage. In this study, the nonlinear broadband absorption and ultrafast dynamics of the TiC nanosheet were investigated using nanosecond open-aperture Z-scan and transient absorption techniques. The mechanism of two-photon absorption (TPA) was revealed in the visible region (475-700 nm). At lower incident energies, nonlinear absorption could not happen. When the laser energy increased to 0.64 GW/cm, electrons in the valence band could absorb two photons and jump to the conduction band, with TPA occurring, which meant that the sample exhibited reverse saturable absorption (RSA). In addition, when transient absorption was used to investigate the ultrafast carrier dynamics of the sample, it demonstrated that the relaxation contains a fast decay component and a slow one, which are obtained from electron-phonon and phonon-phonon interactions, respectively. Moreover, with the increasing pump fluence, the fast decay lifetime τ increased from 3.9 to 4.5 ps, and the slow one τ increased from 11.1 to 13.2 ps. These results show that the TiC nanosheet has potential applications in broadband optical limiters.
作为一种新型二维（2D）材料，TiC纳米片已被发现具有作为电磁屏蔽和能量存储材料的诱人特性。在本研究中，利用纳秒开孔Z扫描和瞬态吸收技术研究了TiC纳米片的非线性宽带吸收和超快动力学。在可见光区域（475 - 700 nm）揭示了双光子吸收（TPA）机制。在较低的入射能量下，不会发生非线性吸收。当激光能量增加到0.64 GW/cm时，价带中的电子可以吸收两个光子并跃迁到导带，发生TPA，这意味着样品表现出反饱和吸收（RSA）。此外，当用瞬态吸收研究样品的超快载流子动力学时，结果表明弛豫包含一个快速衰减分量和一个缓慢衰减分量，它们分别由电子 - 声子相互作用和声子 - 声子相互作用产生。而且，随着泵浦通量的增加，快速衰减寿命τ从3.9 ps增加到4.5 ps，缓慢衰减寿命τ从11.1 ps增加到13.2 ps。这些结果表明TiC纳米片在宽带光限幅器中具有潜在应用。
