OBSERVATION OF ENHANCED IONIZATION OF MOLECULAR-IONS IN INTENSE LASERFIELDS

Using ultrashort pulse multiphoton ionization, we launch a wave packet in the I-2(2+) state that dissociates into the fragments I2+ and I. W e measure its multiphoton ionization probability as a function of its internuclear distance with an intense delayed probe pulse. If the prob e pulse is polarized parallel to the internuclear axis, we observe a p eak in the ionization yield at a critical distance of 5-6 Angstrom. No such enhancement is seen with perpendicular polarization in agreement with the model of enhanced ionization by electron localization.