The dynamical behaviour of H-2 and D-2 in a strong, femtosecond, titanium:sapphire laser field

Detailed measurements of H-2 and D-2 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-peck 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.