Fragmentation of N₂ in 410 nm Intense Femtosecond Laser Field

Fragmentations of N2 in linearly polarized femtosecond 410 and 820 nm intense laser fields were studied by using the velocity mapping technique. Different behaviors of N2 at 410 and 820 nm were observed. Both the kinetic energy distributions and angular distributions of fragment ions in 410 nm field show weak dependency on laser intensities in the non-saturation regime, in contrast to the case in 820 nm. Different excited electronic states, i.e.,non-Coulombic potentials populated via vertical excitation, are suggested to play crucial roles in fragmentations at short wavelength.