Ultrafast electron dynamics in two dimensional layered systems: two-photon photoemission studies of SnS2

Abstract

We performed femtosecond two-photon photoemission studies of SnS2, and measured the lifetime of electrons in the conduction band at different excitation energies. The lifetime is short (⩽ 60 fs) even at the conduction band minimum. In addition, the inverse lifetime shows a linear energy dependence. The experimental results are interpreted as due to the electron-plasmon interaction in layered two dimensional materials, which causes electron-hole recombination through the emission of a plasmon. These results are discussed in the context of the electron dephasing processes involved in the barrier crossing dynamics for electron transfer from physisorbed molecular donors at semiconductor surfaces (dye sensitization) under barrierless conditions.