Emission of ions and charged clusters due to impulsive Coulomb explosion in ultrafast laser ablation of graphite

The dynamics of ultrafast laser ablation of graphite have been investigated by femtosecond time resolved autocorrelation measurements at 800 nm. The results indicate that multiply charged atomic ions and ionized carbon clusters are repelled by a transient electric field developed on the surface during the laser pulse, the process known as impulsive Coulomb explosion. From time resolved measurements, we estimate that the decay time constant of the surface field is 125 +/- 10 fs.