Electron excitation and 'cascade' ionisation of diatomic molecules with ultra-short pulses of strong IR lasers

Abstract

The dynamics of molecular electron excitation and ionisation is studied in real-time for ultra-short IR laser pulses of intensity I>10^{13} W/cm^{2}. The multi-electron molecule is modeled by a system of two active electrons moving in a field of frozen core. The time dependences of electron probability, electron energy, and one-electron/two-electron ionisation probability are calculated for example of the N$_{2}$ molecule and the laser pulse with λ=800 nm, τ=5 fs. The electron dynamics of the pulse - excited molecule is considered also after the pulse end. The results show that in the strong IR pulses of I\ge 10^{16} W/cm^{2} the molecule undergoes a 'cascade' ionisation, where the one electron is emitted with the same probability as a pair of electrons.