The dynamical behaviour of and in a strong, femtosecond, titanium:sapphire laser field

Detailed measurements of and dissociation fragment kinetic energy dependences on laser intensity, using 150 fs, 800 nm pulses, are presented. The yields for both molecular and atomic ions are also given. The observed three-peak kinetic energy spectrum carries within it the signature of the different stages of the interaction. The two lower energy peaks are a product of bond softening (and above threshold) dissociation of the molecular ion from Franck - Condon populated vibrational levels. The third higher-energy peak results from enhanced ionization of the dissociating molecular ions. No light-induced vibrational trapping need be invoked to interpret the higher-energy fragments.