Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang 321004, China.
J Phys Chem B. 2013 Mar 21;117(11):3258-63. doi: 10.1021/jp311422y. Epub 2013 Mar 12.
This paper employs a molecular dynamics approach to uncover the time profile of exciton formation, which can be divided into two stages: localization of electron-hole pairs and relaxation process (nuclear and electronic). Under photoexcitation, an electron-hole pair is formed by an electronic transition, and the pair in turn becomes localized through the electron-lattice interaction, which triggers the total energy to shift violently and oscillate. The oscillation during the first 40 fs induces the excitation to step into the second stage, i.e., relaxation. After the relaxation process of about 850 fs, the total energy, lattice energy, and electron energy reach certain values whereas the lattice configuration and electron remain localized, indicating the formation of a singlet exciton.
本文采用分子动力学方法揭示激子形成的时间特性，可分为两个阶段：电子-空穴对的局域化和弛豫过程（核和电子）。在光激发下，电子-空穴对通过电子跃迁形成，电子-晶格相互作用又使电子对局域化，导致总能量剧烈波动和振荡。在最初的 40fs 内的振荡，引发激发进入第二阶段，即弛豫。约 850fs 弛豫后，总能量、晶格能和电子能量达到一定值，而晶格结构和电子保持局域化，表明形成了单重激子。
