Fragmentation and cis– trans isomerization of diimide in fs laser-pulses

Abstract

The dynamics of diimide (N 2H 2) under excitation of femto-second laser pulses is investigated using nonadiabatic quantum molecular dynamics (NA-QMD). Distinct fragmentation channels are observed in particular by varying the laser frequency. It is found that the dynamics on the first excited state surface S 1 is dominated by cis– trans isomerization with a characteristic time scale of about τ ≈ 25 fs almost independent of the nuclear initial conditions. The long time behaviour of the electronic dynamics is classified into three categories: (1) persistence on the ground state surface, (2) persistence on the first excited state surface and (3) nonadiabatic switching between both surfaces.