THE FIELD-IONIZATION, COULOMB EXPLOSION OF DIATOMIC-MOLECULES IN INTENSE LASER FIELDS

A classical field-ionization, Coulomb explosion model indicates that t ransient molecular ions are ionized preferentially at a specific inter atomic distance, R-c, regardless of their charge state. The results of this model are combined with trajectory calculations to produce fragm ent ion energies in good agreement with experiment in the case of I-2 at 750 nm and a range of laser pulse lengths. The model predicts obser vation of the charge-asymmetric I + I2+ channel at pulse lengths below 200 fs; this prediction is confirmed by experiment, as is the enhance ment of ionization at R-c. Data on N-2 are also explained if reasonabl e assumptions are made with regard to the laser-induced dissociation o f the molecular ion. The model also explains data on Hz and the counte r-intuitive angular distribution of ions from the dissociation of HDobserved in recent two-color experiments.