Driving forces for ultrafast laser-induced sp2 to sp3 structural transformation in graphite
Chenchen Song, Mengxue Guan, Yunzhe Jia, Daqiang Chen, Jiyu Xu, Cui Zhang, Sheng Meng
Abstract
Abstract Understanding the microscopic mechanism of photoinduced sp 2 -to-sp 3 structural transformation in graphite is a scientific challenge with great importance. Here, the ultrafast dynamics and characteristics of laser-induced structural transformation in graphite are revealed by non-adiabatic quantum dynamic simulations. Under laser irradiation, graphite undergoes an interlayer compression and sliding stage, followed by a key period of intralayer buckling and interlayer bonding to form an intermediate sp 2 -sp 3 hybrid structure, before completing the full transformation to hexagonal diamond. The process is driven by the cooperation of charge carrier multiplication and selective phonon excitations through electron-phonon interactions, in which photoexcited hot electrons scattered into unoccupied high-energy conduction bands play a key role in the introduction of in-plane instability in graphite. This work identifies a photoinduced non-adiabatic transition pathway from graphite to diamond and shows far-reaching implications for designing optically controlled structural phase transition in materials.